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Wood MJ, Alkhaibari AM, Butt TM. Stress-Mediated Responses of Aedes aegypti (Diptera: Culicidae) Larvae When Exposed to Metarhizium brunneum (Hypocreales: Clavicipitaceae) and Toxorhynchites brevipalpis (Diptera: Culicidae). JOURNAL OF MEDICAL ENTOMOLOGY 2022; 59:1732-1740. [PMID: 35938709 PMCID: PMC9473657 DOI: 10.1093/jme/tjac110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Indexed: 06/15/2023]
Abstract
Aedes aegypti mosquitoes are capable of vectoring a wide range of diseases including dengue, yellow fever, and Zika viruses, with approximately half of the worlds' population at risk from such diseases. Development of combined predator-parasite treatments for the control of larvae consistently demonstrates increased efficacy over single-agent treatments, however, the mechanism behind the interaction remains unknown. Treatments using the natural predator Toxorhynchites brevipalpis and the entomopathogenic fungus Metarhizium brunneum were applied in the laboratory against Ae. aegypti larvae as both individual and combined treatments to determine the levels of interaction between control strategies. Parallel experiments involved the removal of larvae from test arenas at set intervals during the course of the trial to record whole body caspase and phenoloxidase activities. This was measured via luminometric assay to measure larval stress factors underlying the interactions. Combined Metarhizium and Toxorhynchites treatments were seen to drastically reduce lethal times as compared to individual treatments. This was accompanied by increased phenoloxidase and caspase activities in combination treatments after 18 h (p < 0.001). The sharp increases in caspase and phenoloxidase activities suggest that combined treatments act to increase stress factor responses in the larvae that result in rapid mortality above that of either control agent individually. This work concludes that the underlying mechanism for increased lethality in combined parasite-predator treatments may be related to additive stress factors induced within the target host larvae.
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Affiliation(s)
| | | | - Tariq M Butt
- Department of Biosciences, Faculty of Science and Engineering, Swansea University, Swansea, UK
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2
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Di Battista CM, Fischer S, Campos RE. Susceptibility of the floodwater mosquito Aedes albifasciatus from eggs of different dormancy times to the nematode parasite Strelkovimermis spiculatus. MEDICAL AND VETERINARY ENTOMOLOGY 2020; 34:432-439. [PMID: 32671880 DOI: 10.1111/mve.12460] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 06/03/2020] [Accepted: 06/09/2020] [Indexed: 06/11/2023]
Abstract
This study aimed to evaluate the effects of egg dormancy times on susceptibility of larvae of the floodwater mosquito Aedes albifasciatus (Diptera: Culicidae) to parasitism by their natural enemy Strelkovimermis spiculatus (Nematoda: Mermithidae) and on their life history traits. Aedes albifasciatus eggs stored for 2, 4, 6, 8 and 10 months were hatched, and the larvae either exposed to S. spiculatus (treatment group) or not exposed (control group). Egg dormancy time had a negative effect on the retention of parasites, but no effect on the prevalence and intensity of parasitism or the melanization of nematodes. The survival to adulthood of control individuals decreased as dormancy time increased, whereas that of exposed individuals that remained uninfected was constant and low. A trend towards increasing development times with longer dormancy times was detected in the control group, but not in the exposed noninfected group. The results suggest nonconsumptive effects of parasites in exposed but not infected larvae from eggs with short dormancy times. In contrast, the relatively low fitness of larvae from eggs with long dormancy times regardless of their contact with the nematodes may be the result of the nutritional deprivation during the egg stage.
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Affiliation(s)
- C M Di Battista
- Instituto de Limnología "Dr. Raúl A. Ringuelet", Universidad Nacional de La Plata-CONICET, CCT La Plata, La Plata, Buenos Aires, Argentina
| | - S Fischer
- Departamento de Ecología, Genética y Evolución, and Instituto IEGEBA (CONICET-UBA), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires. Ciudad Universitaria, Buenos Aires, Argentina
| | - R E Campos
- Instituto de Limnología "Dr. Raúl A. Ringuelet", Universidad Nacional de La Plata-CONICET, CCT La Plata, La Plata, Buenos Aires, Argentina
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3
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Bitencourt RDOB, Salcedo-Porras N, Umaña-Diaz C, da Costa Angelo I, Lowenberger C. Antifungal immune responses in mosquitoes (Diptera: Culicidae): A review. J Invertebr Pathol 2020; 178:107505. [PMID: 33238166 DOI: 10.1016/j.jip.2020.107505] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 10/27/2020] [Accepted: 11/17/2020] [Indexed: 02/08/2023]
Abstract
Mosquitoes transmit many parasites and pathogens to humans that cause significant morbidity and mortality. As such, we are constantly looking for new methods to reduce mosquito populations, including the use of effective biological controls. Entomopathogenic fungi are excellent candidate biocontrol agents to control mosquitoes. Understanding the complex ecological, environmental, and molecular interactions between hosts and pathogens are essential to create novel, effective and safe biocontrol agents. Understanding how mosquitoes recognize and eliminate pathogens such as entomopathogenic fungi may allow us to create insect-order specific biocontrol agents to reduce pest populations. Here we summarize the current knowledge of fungal infection, colonization, development, and replication within mosquitoes and the innate immune responses of the mosquitoes towards the fungal pathogens, emphasizing those features required for an effective mosquito biocontrol agent.
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Affiliation(s)
- Ricardo de Oliveira Barbosa Bitencourt
- Program in Veterinary Science, Institute of Veterinary Science, Rural Federal University of Rio de Janeiro, Seropédica, RJ, Brazil; Centre for Cell Biology, Development and Disease, Department of Biological Sciences, Simon Fraser University, Burnaby BC V5A 1S6, British Columbia, Canada.
| | - Nicolas Salcedo-Porras
- Centre for Cell Biology, Development and Disease, Department of Biological Sciences, Simon Fraser University, Burnaby BC V5A 1S6, British Columbia, Canada
| | - Claudia Umaña-Diaz
- Centre for Cell Biology, Development and Disease, Department of Biological Sciences, Simon Fraser University, Burnaby BC V5A 1S6, British Columbia, Canada
| | - Isabele da Costa Angelo
- Department of Epidemiology and Public Health, Veterinary Institute, Rural Federal University of Rio de Janeiro, Seropédica, RJ, Brazil
| | - Carl Lowenberger
- Centre for Cell Biology, Development and Disease, Department of Biological Sciences, Simon Fraser University, Burnaby BC V5A 1S6, British Columbia, Canada.
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Onyango MG, Attardo GM, Kelly ET, Bialosuknia SM, Stout J, Banker E, Kuo L, Ciota AT, Kramer LD. Zika Virus Infection Results in Biochemical Changes Associated With RNA Editing, Inflammatory and Antiviral Responses in Aedes albopictus. Front Microbiol 2020; 11:559035. [PMID: 33133033 PMCID: PMC7561680 DOI: 10.3389/fmicb.2020.559035] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 09/14/2020] [Indexed: 12/11/2022] Open
Abstract
Rapid and significant range expansion of both the Zika virus (ZIKV) and its Aedes vector species has resulted in the declaration of ZIKV as a global health threat. Successful transmission of ZIKV by its vector requires a complex series of interactions between these entities including the establishment, replication and dissemination of the virus within the mosquito. The metabolic conditions within the mosquito tissues play a critical role in mediating the crucial processes of viral infection and replication and represent targets for prevention of virus transmission. In this study, we carried out a comprehensive metabolomic phenotyping of ZIKV infected and uninfected Ae. albopictus by untargeted analysis of primary metabolites, lipids and biogenic amines. We performed a comparative metabolomic study of infection state with the aim of understanding the biochemical changes resulting from the interaction between the ZIKV and its vector. We have demonstrated that ZIKV infection results in changes to the cellular metabolic environment including a significant enrichment of inosine and pseudo-uridine (Ψ) levels which may be associated with RNA editing activity. In addition, infected mosquitoes demonstrate a hypoglycemic phenotype and show significant increases in the abundance of metabolites such as prostaglandin H2, leukotriene D4 and protoporphyrinogen IX which are associated with antiviral activity. These provide a basis for understanding the biochemical response to ZIKV infection and pathology in the vector. Future mechanistic studies targeting these ZIKV infection responsive metabolites and their associated biosynthetic pathways can provide inroads to identification of mosquito antiviral responses with infection blocking potential.
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Affiliation(s)
- Maria G. Onyango
- Wadsworth Center, New York State Department of Health, Slingerlands, NY, United States
| | - Geoffrey M. Attardo
- Department of Entomology and Nematology, University of California, Davis, Davis, CA, United States
| | - Erin Taylor Kelly
- Department of Entomology and Nematology, University of California, Davis, Davis, CA, United States
| | - Sean M. Bialosuknia
- Wadsworth Center, New York State Department of Health, Slingerlands, NY, United States
- School of Public Health, State University of New York, Albany, NY, United States
| | - Jessica Stout
- Wadsworth Center, New York State Department of Health, Slingerlands, NY, United States
| | - Elyse Banker
- Wadsworth Center, New York State Department of Health, Slingerlands, NY, United States
| | - Lili Kuo
- Wadsworth Center, New York State Department of Health, Slingerlands, NY, United States
| | - Alexander T. Ciota
- Wadsworth Center, New York State Department of Health, Slingerlands, NY, United States
- School of Public Health, State University of New York, Albany, NY, United States
| | - Laura D. Kramer
- Wadsworth Center, New York State Department of Health, Slingerlands, NY, United States
- School of Public Health, State University of New York, Albany, NY, United States
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Lu JB, Zhang MQ, Li LC, Zhang CX. DDC plays vital roles in the wing spot formation, egg production, and chorion tanning in the brown planthopper. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2019; 101:e21552. [PMID: 31033045 DOI: 10.1002/arch.21552] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 03/25/2019] [Accepted: 03/28/2019] [Indexed: 06/09/2023]
Abstract
The gene dopa decarboxylase (Nlddc) of the brown planthopper (BPH, Nilaparvata lugens) was identified in the genome and transcriptome of the insect. The open reading frame of Nlddc is 1,434 bp in length and, it has the potential to encode a protein of 477 amino acid with a conserved pyridoxal-dependent decarboxylase domain and a typical motif, NFNPHKW. Real-time quantification polymerase chain reaction analyses revealed that this gene was highly expressed in the integument and brain, and transcript level peaked in the late stages of egg period and each nymph instar with periodicity. RNA interference results revealed that Nlddc played essential roles in pigment synthesis, formation of wing spot, egg production, and tanning of the chorion. A rapid accumulation of Nlddc transcripts was detected, and it coincided with the injection of the hormone 20-hydroxyecdysone (20E), suggesting that Nlddc transcription was regulated by 20E.
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Affiliation(s)
- Jia-Bao Lu
- State Key Laboratory of Rice Biology and Ministry of Agriculture Key Lab of Molecular Biology of Crop Pathogens and Insects, Institute of Insect Science, Zhejiang University, Hangzhou, China
| | - Meng-Qiu Zhang
- State Key Laboratory of Rice Biology and Ministry of Agriculture Key Lab of Molecular Biology of Crop Pathogens and Insects, Institute of Insect Science, Zhejiang University, Hangzhou, China
| | - Ling-Chen Li
- State Key Laboratory of Rice Biology and Ministry of Agriculture Key Lab of Molecular Biology of Crop Pathogens and Insects, Institute of Insect Science, Zhejiang University, Hangzhou, China
| | - Chuan-Xi Zhang
- State Key Laboratory of Rice Biology and Ministry of Agriculture Key Lab of Molecular Biology of Crop Pathogens and Insects, Institute of Insect Science, Zhejiang University, Hangzhou, China
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Cooling MD, Hoffmann BD, Gruber MAM, Lester PJ. Indirect evidence of pathogen-associated altered oocyte production in queens of the invasive yellow crazy ant, Anoplolepis gracilipes, in Arnhem Land, Australia. BULLETIN OF ENTOMOLOGICAL RESEARCH 2018; 108:451-460. [PMID: 28920560 DOI: 10.1017/s0007485317000967] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Anoplolepis gracilipes is one of the six most widespread and pestiferous invasive ant species. Populations of this invader in Arnhem Land, Australia have been observed to decline, but the reasons behind these declines are not known. We investigated if there is evidence of a pathogen that could be responsible for killing ant queens or affecting their reproductive output. We measured queen number per nest, fecundity and fat content of queens from A. gracilipes populations in various stages of decline or expansion. We found no significant difference in any of these variables among populations. However, 23% of queens were found to have melanized nodules, a cellular immune response, in their ovaries and fat bodies. The melanized nodules found in dissected queens are highly likely to indicate the presence of pathogens or parasites capable of infecting A. gracilipes. Queens with nodules had significantly fewer oocytes in their ovaries, but nodule presence was not associated with low ant population abundances. Although the microorganism responsible for the nodules is as yet unidentified, this is the first evidence of the presence of a pathogenic microorganism in the invasive ant A. gracilipes that may be affecting reproduction.
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Affiliation(s)
- M D Cooling
- School of Biological Sciences,Victoria University of Wellington,PO Box 600,Wellington 6140,New Zealand
| | - B D Hoffmann
- CSIRO,Tropical Ecosystems Research Centre,PMB 44,Winnellie,NT 0822,Australia
| | - M A M Gruber
- School of Biological Sciences,Victoria University of Wellington,PO Box 600,Wellington 6140,New Zealand
| | - P J Lester
- School of Biological Sciences,Victoria University of Wellington,PO Box 600,Wellington 6140,New Zealand
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7
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League GP, Estévez-Lao TY, Yan Y, Garcia-Lopez VA, Hillyer JF. Anopheles gambiae larvae mount stronger immune responses against bacterial infection than adults: evidence of adaptive decoupling in mosquitoes. Parasit Vectors 2017; 10:367. [PMID: 28764812 PMCID: PMC5539753 DOI: 10.1186/s13071-017-2302-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2017] [Accepted: 07/20/2017] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND The immune system of adult mosquitoes has received significant attention because of the ability of females to vector disease-causing pathogens while ingesting blood meals. However, few studies have focused on the immune system of larvae, which, we hypothesize, is highly robust due to the high density and diversity of microorganisms that larvae encounter in their aquatic environments and the strong selection pressures at work in the larval stage to ensure survival to reproductive maturity. Here, we surveyed a broad range of cellular and humoral immune parameters in larvae of the malaria mosquito, Anopheles gambiae, and compared their potency to that of newly-emerged adults and older adults. RESULTS We found that larvae kill bacteria in their hemocoel with equal or greater efficiency compared to newly-emerged adults, and that antibacterial ability declines further with adult age, indicative of senescence. This phenotype correlates with more circulating hemocytes and a differing spatial arrangement of sessile hemocytes in larvae relative to adults, as well as with the individual hemocytes of adults carrying a greater phagocytic burden. The hemolymph of larvae also possesses markedly stronger antibacterial lytic and melanization activity than the hemolymph of adults. Finally, infection induces a stronger transcriptional upregulation of immunity genes in larvae than in adults, including differences in the immunity genes that are regulated. CONCLUSIONS These results demonstrate that immunity is strongest in larvae and declines after metamorphosis and with adult age, and suggest that adaptive decoupling, or the independent evolution of larval and adult traits made possible by metamorphosis, has occurred in the mosquito lineage.
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Affiliation(s)
- Garrett P. League
- Department of Biological Sciences, Vanderbilt University, Nashville, TN USA
| | | | - Yan Yan
- Department of Biological Sciences, Vanderbilt University, Nashville, TN USA
| | | | - Julián F. Hillyer
- Department of Biological Sciences, Vanderbilt University, Nashville, TN USA
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8
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Stevens L, Yan G, Pray LA. CONSEQUENCES OF INBREEDING ON INVERTEBRATE HOST SUSCEPTIBILITY TO PARASITIC INFECTION. Evolution 2017; 51:2032-2039. [DOI: 10.1111/j.1558-5646.1997.tb05126.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/1997] [Accepted: 08/11/1997] [Indexed: 12/01/2022]
Affiliation(s)
- Lori Stevens
- Department of Biology University of Vermont Marsh Life Science Building Burlington Vermont 05405‐0086
| | - Guiyun Yan
- Department of Biology University of Vermont Marsh Life Science Building Burlington Vermont 05405‐0086
| | - Leslie A. Pray
- Department of Biology University of Vermont Marsh Life Science Building Burlington Vermont 05405‐0086
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9
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Yan G, Severson DW, Christensen BM. COSTS AND BENEFITS OF MOSQUITO REFRACTORINESS TO MALARIA PARASITES: IMPLICATIONS FOR GENETIC VARIABILITY OF MOSQUITOES AND GENETIC CONTROL OF MALARIA. Evolution 2017; 51:441-450. [DOI: 10.1111/j.1558-5646.1997.tb02431.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/1995] [Accepted: 10/01/1996] [Indexed: 11/29/2022]
Affiliation(s)
- Guiyun Yan
- Department of Animal Health and Biomedical Sciences; University of Wisconsin; 1655 Linden Drive Madison Wisconsin 53706
| | - David W. Severson
- Department of Animal Health and Biomedical Sciences; University of Wisconsin; 1655 Linden Drive Madison Wisconsin 53706
| | - Bruce M. Christensen
- Department of Animal Health and Biomedical Sciences; University of Wisconsin; 1655 Linden Drive Madison Wisconsin 53706
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10
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Gleave K, Cook D, Taylor MJ, Reimer LJ. Filarial infection influences mosquito behaviour and fecundity. Sci Rep 2016; 6:36319. [PMID: 27796352 PMCID: PMC5087081 DOI: 10.1038/srep36319] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 10/14/2016] [Indexed: 12/19/2022] Open
Abstract
Understanding vector-parasite interactions is increasingly important as we move towards the endpoint goals set by the Global Programme for the Elimination of Lymphatic Filariasis (GPELF), as interaction dynamics may change with reduced transmission pressure. Elimination models used to predict programmatic endpoints include parameters for vector-specific transmission dynamics, despite the fact that our knowledge of the host-seeking behaviour of filariasis infected mosquitoes is lacking. We observed a dynamic, stage-specific and density dependent change in Aedes aegypti behaviour towards host cues when exposed to Brugia malayi filarial parasites. Infected mosquitoes exhibited reduced activation and flight towards a host during the period of larval development (L1/L2), transitioning to a 5 fold increase in activation and flight towards a host when infective stage larvae (L3) were present (p < 0.001). In uninfected control mosquitoes, we observed a reduction in convergence towards a host during the same period. Furthermore, this behaviour was density dependent with non-activated mosquitoes harbouring a greater burden of L1 and L2 larvae while activated mosquitoes harboured a greater number of L3 (p < 0.001). Reductions in fecundity were also density-dependent, and extended to mosquitoes that were exposed to microfilariae but did not support larval development.
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Affiliation(s)
- Katherine Gleave
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Darren Cook
- Department of Parasitology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Mark J Taylor
- Department of Parasitology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Lisa J Reimer
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK.,Department of Parasitology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
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11
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Abstract
Immune defense and reproduction are physiologically and energetically demanding processes and have been observed to trade off in a diversity of female insects. Increased reproductive effort results in reduced immunity, and reciprocally, infection and activation of the immune system reduce reproductive output. This trade-off can manifest at the physiological level (within an individual) and at the evolutionary level (genetic distinction among individuals in a population). The resource allocation model posits that the trade-off arises because of competition for one or more limiting resources, and we hypothesize that pleiotropic signaling mechanisms regulate allocation of that resource between reproductive and immune processes. We examine the role of juvenile hormone, 20-hydroxyecdysone, and insulin/insulin-like growth factor-like signaling in regulating both oogenesis and immune system activity, and propose a signaling network that may mechanistically regulate the trade-off. Finally, we discuss implications of the trade-off in an ecological and evolutionary context.
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Affiliation(s)
- Robin A Schwenke
- Field of Genetics, Genomics, and Development
- Department of Entomology
| | - Brian P Lazzaro
- Field of Genetics, Genomics, and Development
- Department of Entomology
| | - Mariana F Wolfner
- Field of Genetics, Genomics, and Development
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853; , ,
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12
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Juneja P, Ariani CV, Ho YS, Akorli J, Palmer WJ, Pain A, Jiggins FM. Exome and transcriptome sequencing of Aedes aegypti identifies a locus that confers resistance to Brugia malayi and alters the immune response. PLoS Pathog 2015; 11:e1004765. [PMID: 25815506 PMCID: PMC4376896 DOI: 10.1371/journal.ppat.1004765] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 02/25/2015] [Indexed: 11/18/2022] Open
Abstract
Many mosquito species are naturally polymorphic for their abilities to transmit parasites, a feature which is of great interest for controlling vector-borne disease. Aedes aegypti, the primary vector of dengue and yellow fever and a laboratory model for studying lymphatic filariasis, is genetically variable for its capacity to harbor the filarial nematode Brugia malayi. The genome of Ae. aegypti is large and repetitive, making genome resequencing difficult and expensive. We designed exome captures to target protein-coding regions of the genome, and used association mapping in a wild Kenyan population to identify a single, dominant, sex-linked locus underlying resistance. This falls in a region of the genome where a resistance locus was previously mapped in a line established in 1936, suggesting that this polymorphism has been maintained in the wild for the at least 80 years. We then crossed resistant and susceptible mosquitoes to place both alleles of the gene into a common genetic background, and used RNA-seq to measure the effect of this locus on gene expression. We found evidence for Toll, IMD, and JAK-STAT pathway activity in response to early stages of B. malayi infection when the parasites are beginning to die in the resistant genotype. We also found that resistant mosquitoes express anti-microbial peptides at the time of parasite-killing, and that this expression is suppressed in susceptible mosquitoes. Together, we have found that a single resistance locus leads to a higher immune response in resistant mosquitoes, and we identify genes in this region that may be responsible for this trait.
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Affiliation(s)
- Punita Juneja
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Cristina V. Ariani
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Yung Shwen Ho
- Biological and Environmental Sciences and Engineering (BESE) Division, King Abdullah University of Science & Technology, Thuwal, Kingdom of Saudi Arabia
| | - Jewelna Akorli
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
- Department of Parasitology, Noguchi Memorial Institute for Medical Research, Accra, Ghana
| | - William J. Palmer
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Arnab Pain
- Biological and Environmental Sciences and Engineering (BESE) Division, King Abdullah University of Science & Technology, Thuwal, Kingdom of Saudi Arabia
| | - Francis M. Jiggins
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
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13
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Breaux JA, Schumacher MK, Juliano SA. What does not kill them makes them stronger: larval environment and infectious dose alter mosquito potential to transmit filarial worms. Proc Biol Sci 2015; 281:rspb.2014.0459. [PMID: 24827444 DOI: 10.1098/rspb.2014.0459] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
For organisms with complex life cycles, larval environments can modify adult phenotypes. For mosquitoes and other vectors, when physiological impacts of stressors acting on larvae carry over into the adult stage they may interact with infectious dose of a vector-borne pathogen, producing a range of phenotypes for vector potential. Investigation of impacts of a common source of stress, larval crowding and intraspecific competition, on adult vector interactions with pathogens may increase our understanding of the dynamics of pathogen transmission by mosquito vectors. Using Aedes aegypti and the nematode parasite Brugia pahangi, we demonstrate dose dependency of fitness effects of B. pahangi infection on the mosquito, as well as interactions between competitive stress among larvae and infectious dose for resulting adults that affect the physiological and functional ability of mosquitoes to act as vectors. Contrary to results from studies on mosquito-arbovirus interactions, our results suggest that adults from crowded larvae may limit infection better than do adults from uncrowded controls, and that mosquitoes from high-quality larval environments are more physiologically and functionally capable vectors of B. pahangi. Our results provide another example of how the larval environment can have profound effects on vector potential of resulting adults.
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Affiliation(s)
- Jennifer A Breaux
- School of Biological Sciences, Illinois State University, Normal, IL 61790-4120, USA
| | - Molly K Schumacher
- School of Biological Sciences, Illinois State University, Normal, IL 61790-4120, USA
| | - Steven A Juliano
- School of Biological Sciences, Illinois State University, Normal, IL 61790-4120, USA
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14
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How effective is integrated vector management against malaria and lymphatic filariasis where the diseases are transmitted by the same vector? PLoS Negl Trop Dis 2014; 8:e3393. [PMID: 25501002 PMCID: PMC4263402 DOI: 10.1371/journal.pntd.0003393] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 11/05/2014] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND The opportunity to integrate vector management across multiple vector-borne diseases is particularly plausible for malaria and lymphatic filariasis (LF) control where both diseases are transmitted by the same vector. To date most examples of integrated control targeting these diseases have been unanticipated consequences of malaria vector control, rather than planned strategies that aim to maximize the efficacy and take the complex ecological and biological interactions between the two diseases into account. METHODOLOGY/PRINCIPAL FINDINGS We developed a general model of malaria and LF transmission and derived expressions for the basic reproductive number (R0) for each disease. Transmission of both diseases was most sensitive to vector mortality and biting rate. Simulating different levels of coverage of long lasting-insecticidal nets (LLINs) and larval control confirms the effectiveness of these interventions for the control of both diseases. When LF was maintained near the critical density of mosquitoes, minor levels of vector control (8% coverage of LLINs or treatment of 20% of larval sites) were sufficient to eliminate the disease. Malaria had a far greater R0 and required a 90% population coverage of LLINs in order to eliminate it. When the mosquito density was doubled, 36% and 58% coverage of LLINs and larval control, respectively, were required for LF elimination; and malaria elimination was possible with a combined coverage of 78% of LLINs and larval control. CONCLUSIONS/SIGNIFICANCE Despite the low level of vector control required to eliminate LF, simulations suggest that prevalence of LF will decrease at a slower rate than malaria, even at high levels of coverage. If representative of field situations, integrated management should take into account not only how malaria control can facilitate filariasis elimination, but strike a balance between the high levels of coverage of (multiple) interventions required for malaria with the long duration predicted to be required for filariasis elimination.
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15
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Ferguson LV, Smith TG. Fecundity reduction in the second gonotrophic cycle of Culex pipiens infected with the apicomplexan blood parasite, Hepatozoon sipedon. J Parasitol 2014; 100:442-6. [PMID: 24650105 DOI: 10.1645/13-378.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Fecundity reduction is a well-recognized phenomenon of parasite infection in insects. Reduced production of eggs might increase longevity of a host and release nutrients to both host and parasite that would otherwise be used for oogenesis. The objective of this study was to assess effects on fecundity caused by Hepatozoon sipedon, an apicomplexan blood parasite of snakes, in its invertebrate host, the mosquito Culex pipiens. In the first gonotrophic cycle, the mean number of eggs laid by mosquitoes infected with H. sipedon did not differ significantly from those laid by uninfected mosquitoes. However, in the second gonotrophic cycle infected mosquitoes laid significantly fewer eggs than did uninfected mosquitoes, and fecundity was reduced by 100% in mosquitoes with parasite burdens of more than 60 oocysts. There was a significant negative correlation between parasite burden, or the number of oocysts, and the number of eggs produced in the second gonotrophic cycle. Significantly fewer viable larvae hatched from eggs laid by infected compared to uninfected mosquitoes in the second gonotrophic cycle. These data indicate that fecundity reduction occurs in this system, although the physiological mechanisms driving this phenotype are not yet known.
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Affiliation(s)
- Laura V Ferguson
- Department of Biology, Acadia University, Wolfville, Nova Scotia, Canada B4P 2R6. Correspondence should be sent to:
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Fuchs S, Behrends V, Bundy JG, Crisanti A, Nolan T. Phenylalanine metabolism regulates reproduction and parasite melanization in the malaria mosquito. PLoS One 2014; 9:e84865. [PMID: 24409310 PMCID: PMC3883676 DOI: 10.1371/journal.pone.0084865] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Accepted: 11/20/2013] [Indexed: 11/25/2022] Open
Abstract
The blood meal of the female malaria mosquito is a pre-requisite to egg production and also represents the transmission route for the malaria parasite. The proper and rapid assimilation of proteins and nutrients in the blood meal creates a significant metabolic challenge for the mosquito. To better understand this process we generated a global profile of metabolite changes in response to blood meal of Anopheles gambiae, using Gas Chromatography-Mass Spectrometry (GC-MS). To disrupt a key pathway of amino acid metabolism we silenced the gene phenylalanine hydroxylase (PAH) involved in the conversion of the amino acid phenylalanine into tyrosine. We observed increased levels of phenylalanine and the potentially toxic metabolites phenylpyruvate and phenyllactate as well as a reduction in the amount of tyrosine available for melanin synthesis. This in turn resulted in a significant impairment of the melanotic encapsulation response against the rodent malaria parasite Plasmodium berghei. Furthermore silencing of PAH resulted in a significant impairment of mosquito fertility associated with reduction of laid eggs, retarded vitellogenesis and impaired melanisation of the chorion. Carbidopa, an inhibitor of the downstream enzyme DOPA decarboxylase that coverts DOPA into dopamine, produced similar effects on egg melanization and hatching rate suggesting that egg chorion maturation is mainly regulated via dopamine. This study sheds new light on the role of amino acid metabolism in regulating reproduction and immunity.
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Affiliation(s)
- Silke Fuchs
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Volker Behrends
- Department of Surgery and Cancer, Imperial College London, London, United Kingdom
| | - Jacob G. Bundy
- Department of Surgery and Cancer, Imperial College London, London, United Kingdom
| | - Andrea Crisanti
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Tony Nolan
- Department of Life Sciences, Imperial College London, London, United Kingdom
- * E-mail:
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Moreno-García M, Córdoba-Aguilar A, Condé R, Lanz-Mendoza H. Current immunity markers in insect ecological immunology: assumed trade-offs and methodological issues. BULLETIN OF ENTOMOLOGICAL RESEARCH 2013; 103:127-139. [PMID: 22929006 DOI: 10.1017/s000748531200048x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The field of ecological immunology currently relies on using a number of immune effectors or markers. These markers are usually used to infer ecological trade-offs (via conflicts in resource allocation), though physiological nature of these markers remains elusive. Here, we review markers frequently used in insect evolutionary ecology research: cuticle darkening, haemocyte density, nodule/capsule formation, phagocytosis and encapsulation/melanization via use of nylon filaments and beads, phenoloxidase activity, nitric oxide production, lysozyme and antimicrobial peptide production. We also provide physiologically based information that may shed light on the probable trade-offs inferred when these markers are used. In addition, we provide a number of methodological suggestions to improve immune marker assessment.
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Affiliation(s)
- M Moreno-García
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, México
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Quigley BJZ, García López D, Buckling A, McKane AJ, Brown SP. The mode of host-parasite interaction shapes coevolutionary dynamics and the fate of host cooperation. Proc Biol Sci 2012; 279:3742-8. [PMID: 22740644 PMCID: PMC3415897 DOI: 10.1098/rspb.2012.0769] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Antagonistic coevolution between hosts and parasites can have a major impact on host population structures, and hence on the evolution of social traits. Using stochastic modelling techniques in the context of bacteria–virus interactions, we investigate the impact of coevolution across a continuum of host–parasite genetic specificity (specifically, where genotypes have the same infectivity/resistance ranges (matching alleles, MA) to highly variable ranges (gene-for-gene, GFG)) on population genetic structure, and on the social behaviour of the host. We find that host cooperation is more likely to be maintained towards the MA end of the continuum, as the more frequent bottlenecks associated with an MA-like interaction can prevent defector invasion, and can even allow migrant cooperators to invade populations of defectors.
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Murdock CC, Paaijmans KP, Bell AS, King JG, Hillyer JF, Read AF, Thomas MB. Complex effects of temperature on mosquito immune function. Proc Biol Sci 2012; 279:3357-66. [PMID: 22593107 PMCID: PMC3385736 DOI: 10.1098/rspb.2012.0638] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Over the last 20 years, ecological immunology has provided much insight into how environmental factors shape host immunity and host–parasite interactions. Currently, the application of this thinking to the study of mosquito immunology has been limited. Mechanistic investigations are nearly always conducted under one set of conditions, yet vectors and parasites associate in a variable world. We highlight how environmental temperature shapes cellular and humoral immune responses (melanization, phagocytosis and transcription of immune genes) in the malaria vector, Anopheles stephensi. Nitric oxide synthase expression peaked at 30°C, cecropin expression showed no main effect of temperature and humoral melanization, and phagocytosis and defensin expression peaked around 18°C. Further, immune responses did not simply scale with temperature, but showed complex interactions between temperature, time and nature of immune challenge. Thus, immune patterns observed under one set of conditions provide little basis for predicting patterns under even marginally different conditions. These quantitative and qualitative effects of temperature have largely been overlooked in vector biology but have significant implications for extrapolating natural/transgenic resistance mechanisms from laboratory to field and for the efficacy of various vector control tools.
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Affiliation(s)
- C C Murdock
- Department of Entomology, Center for Infectious Disease Dynamics, Merkle Lab, University Park, PA 16802, USA.
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Abstract
Throughout their lifetime, mosquitoes are exposed to pathogens during feeding, through breaks in their cuticle and following pathogen-driven cuticular degradation. To resist infection, mosquitoes mount innate cellular and humoral immune responses that are elicited within minutes of exposure and can lead to pathogen death via three broadly defined mechanisms: lysis, melanization and hemocyte-mediated phagocytosis. This chapter reviews our current understanding of the mosquito immune system, with an emphasis on the physical barriers that prevent pathogens from entering the body, the organs and tissues that regulate immune responses and the mechanistic and molecular bases of immunity.
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Affiliation(s)
- Julián F Hillyer
- Department of Biological Sciences, Institute for Global Health, Vanderbilt University, Nashville, Tennessee, USA.
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Koskella B, Taylor TB, Bates J, Buckling A. Using experimental evolution to explore natural patterns between bacterial motility and resistance to bacteriophages. ISME JOURNAL 2011; 5:1809-17. [PMID: 21509046 DOI: 10.1038/ismej.2011.47] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Resistance of bacteria to phages may be gained by alteration of surface proteins to which phages bind, a mechanism that is likely to be costly as these molecules typically have critical functions such as movement or nutrient uptake. To address this potential trade-off, we combine a systematic study of natural bacteria and phage populations with an experimental evolution approach. We compare motility, growth rate and susceptibility to local phages for 80 bacteria isolated from horse chestnut leaves and, contrary to expectation, find no negative association between resistance to phages and bacterial motility or growth rate. However, because correlational patterns (and their absence) are open to numerous interpretations, we test for any causal association between resistance to phages and bacterial motility using experimental evolution of a subset of bacteria in both the presence and absence of naturally associated phages. Again, we find no clear link between the acquisition of resistance and bacterial motility, suggesting that for these natural bacterial populations, phage-mediated selection is unlikely to shape bacterial motility, a key fitness trait for many bacteria in the phyllosphere. The agreement between the observed natural pattern and the experimental evolution results presented here demonstrates the power of this combined approach for testing evolutionary trade-offs.
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Affiliation(s)
- Britt Koskella
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA, USA
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Moreno-García M, Lanz-Mendoza H, Córdoba-Aguilar A. Genetic variance and genotype-by-environment interaction of immune response in Aedes aegypti (Diptera: Culicidae). JOURNAL OF MEDICAL ENTOMOLOGY 2010; 47:111-120. [PMID: 20380290 DOI: 10.1603/me08267] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Immune response can be negatively affected by resource limitation, so it is expected that organisms evolve strategies to minimize the impact of this environmental outcome. Phenotypic plasticity in immune response could represent a genetic response to face such situations. We investigated the effects of high and low quality and quantity of food at the larval stage on two important immune components, phenoloxidase activity (PO) and nitric oxide production (NO) measured in adults of the Dengue vector, Aedes aegypti. We reared families to determine the magnitude and pattern of expression of genetic variance, environmental variance and genotype-by-environment interaction (GEI). In addition, we quantified whether there were differences in plastic immune responses in both sexes. Our results indicated additive variance for PO and NO, but rearing environment did not produce differences among individuals. For NO and PO in males, there were large differences among families in plasticity, as indicated by the different slopes produced by each reaction norm. Therefore, there is additive genetic variation in plasticity for NO production and PO activity. One possible interpretation of these results is that different genotypes may be favored to fight pathogens under the different food quality situations. Males and females showed similar overall GEI strategies but there were differences in PO and NO. Males showed a phenotypic correlation between PO and NO, but we did not find genetic correlations between immune parameters in both sexes.
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Affiliation(s)
- Miguel Moreno-García
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Circuito Exterior s/n, Apdo. Postal 70-275, México, D. F. 04510, México.
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Shostak AW. Tapeworm (Hymenolepis diminuta) infection in flour beetles (Tribolium confusum): does it cause a trade-off between host fecundity and egg size? CAN J ZOOL 2009. [DOI: 10.1139/z09-102] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Inter- and intra-specific comparisons commonly reveal an inverse relationship between fecundity and offspring size. Many animals also vary egg size in response to environmental conditions. Infection of flour beetles Tribolium confusum Jaquelin Du Val, 1868 with the rat tapeworm Hymenolepis diminuta (Rudolphi, 1819) causes a major reduction in host fecundity. This study tested if this fecundity reduction was associated with changes in host egg size. Age-matched beetles were either fasted and then exposed to parasites, fasted only, or neither, and egg production and egg length determined for 5 weeks postexposure. Control beetles that were neither fasted nor exposed to parasites had steady egg production, but produced smaller eggs as they aged. Beetles that were fasted only, produced fewer but larger eggs for 1–2 weeks after the fast ended. Then, fecundity and egg size returned to control levels. Infected beetles also produced fewer, larger eggs for 1–2 weeks, but at levels indistinguishable from beetles that had been fasted only. After 2 weeks, while fecundity of infected beetles remained low, egg size became similar to noninfected hosts. Beetles appeared to trade-off fecundity and egg size in response to reduced feeding, but not to the presumed nutritional stress of parasitic infection.
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Affiliation(s)
- Allen W. Shostak
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada (e-mail: )
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Hurd H. Evolutionary drivers of parasite-induced changes in insect life-history traits from theory to underlying mechanisms. ADVANCES IN PARASITOLOGY 2009; 68:85-110. [PMID: 19289191 DOI: 10.1016/s0065-308x(08)00604-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Many hosts are able to tolerate infection by altering life-history traits that are traded-off one against another. Here the reproductive fitness of insect hosts and vectors is reviewed in the context of theories concerning evolutionary mechanisms driving such alterations. These include the concepts that changes in host reproductive fitness are by-products of infection, parasite manipulations, host adaptations, mafia-like strategies or host compensatory responses. Two models are examined in depth, a tapeworm/beetle association, Hymenolepis diminuta/Tenebrio molitor and malaria infections in anopheline mosquitoes. Parasite-induced impairment of vitellogenesis ultimately leads to a decrease in female reproductive success in both cases, though by different means. Evidence is put forwards for both a manipulator molecule of parasite origin and for host-initiated regulation. These models are backed by other examples in which mechanisms underlying fecundity reduction or fecundity compensation are explored. It is concluded that evolutionary theories must be supported by empirical evidence gained from studying molecular, biochemical and physiological mechanisms underlying changes in host life-history traits, ideally using organisms that have evolved together and that are in their natural environment.
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Affiliation(s)
- Hilary Hurd
- Institute for Science and Technology in Medicine, Centre for Applied Entomology and Parasitilogy, School of life Sciences, Keele University, United Kingdom
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Schulenburg H, Kurtz J, Moret Y, Siva-Jothy MT. Introduction. Ecological immunology. Philos Trans R Soc Lond B Biol Sci 2009; 364:3-14. [PMID: 18926970 DOI: 10.1098/rstb.2008.0249] [Citation(s) in RCA: 187] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
An organism's fitness is critically reliant on its immune system to provide protection against parasites and pathogens. The structure of even simple immune systems is surprisingly complex and clearly will have been moulded by the organism's ecology. The aim of this review and the theme issue is to examine the role of different ecological factors on the evolution of immunity. Here, we will provide a general framework of the field by contextualizing the main ecological factors, including interactions with parasites, other types of biotic as well as abiotic interactions, intraspecific selective constraints (life-history trade-offs, sexual selection) and population genetic processes. We then elaborate the resulting immunological consequences such as the diversity of defence mechanisms (e.g. avoidance behaviour, resistance, tolerance), redundancy and protection against immunopathology, life-history integration of the immune response and shared immunity within a community (e.g. social immunity and microbiota-mediated protection). Our review summarizes the concepts of current importance and directs the reader to promising future research avenues that will deepen our understanding of the defence against parasites and pathogens.
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Affiliation(s)
- Hinrich Schulenburg
- Zoological Institute, University of Kiel, Am Botanischen Garten, 24098 Kiel, Germany.
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26
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Santa-Ana M, Capela RA, Christensen BM. Reproductive costs of the immune response of the autogenous mosquito Culex pipiens molestus against inoculated Dirofilaria immitis. Vector Borne Zoonotic Dis 2008; 7:541-6. [PMID: 17979531 DOI: 10.1089/vbz.2007.0102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Culex pipiens molestus is an autogenous mosquito, a vector of Dirofilaria immitis in Madeira Island, and it mounts a melanotic encapsulation response when inoculated intrathoracically with D. immitis microfilariae (mf). Because Cx. p. molestus is autogenous, this mosquito is a good model from which to gain a better understand the relationship between oviposition and melanization, independent of the signaling pathways related to blood feeding. The present work assessed the impact follicle growth might have on melanization of intrathoracically inoculated mf. The ovaries from mosquitoes undergoing melanotic encapsulation developed more eggs than those that could not melanize the mf. Possible explanations are discussed in this article.
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Affiliation(s)
- Marta Santa-Ana
- Centro de Estudos da Macaronésia, Universidade da Madeira, Funchal, Portugal.
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27
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Hu C, Rio RVM, Medlock J, Haines LR, Nayduch D, Savage AF, Guz N, Attardo GM, Pearson TW, Galvani AP, Aksoy S. Infections with immunogenic trypanosomes reduce tsetse reproductive fitness: potential impact of different parasite strains on vector population structure. PLoS Negl Trop Dis 2008; 2:e192. [PMID: 18335067 PMCID: PMC2265429 DOI: 10.1371/journal.pntd.0000192] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2007] [Accepted: 01/17/2008] [Indexed: 11/18/2022] Open
Abstract
The parasite Trypanosoma brucei rhodesiense and its insect vector Glossina morsitans morsitans were used to evaluate the effect of parasite clearance (resistance) as well as the cost of midgut infections on tsetse host fitness. Tsetse flies are viviparous and have a low reproductive capacity, giving birth to only 6-8 progeny during their lifetime. Thus, small perturbations to their reproductive fitness can have a major impact on population densities. We measured the fecundity (number of larval progeny deposited) and mortality in parasite-resistant tsetse females and untreated controls and found no differences. There was, however, a typanosome-specific impact on midgut infections. Infections with an immunogenic parasite line that resulted in prolonged activation of the tsetse immune system delayed intrauterine larval development resulting in the production of fewer progeny over the fly's lifetime. In contrast, parasitism with a second line that failed to activate the immune system did not impose a fecundity cost. Coinfections favored the establishment of the immunogenic parasites in the midgut. We show that a decrease in the synthesis of Glossina Milk gland protein (GmmMgp), a major female accessory gland protein associated with larvagenesis, likely contributed to the reproductive lag observed in infected flies. Mathematical analysis of our empirical results indicated that infection with the immunogenic trypanosomes reduced tsetse fecundity by 30% relative to infections with the non-immunogenic strain. We estimate that a moderate infection prevalence of about 26% with immunogenic parasites has the potential to reduce tsetse populations. Potential repercussions for vector population growth, parasite-host coevolution, and disease prevalence are discussed.
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Affiliation(s)
- Changyun Hu
- Department of Epidemiology and Public Health, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Rita V. M. Rio
- Department of Epidemiology and Public Health, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Jan Medlock
- Department of Epidemiology and Public Health, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Lee R. Haines
- Department of Biochemistry and Microbiology, Petch Building, University of Victoria, Victoria, British Columbia, Canada
| | - Dana Nayduch
- Department of Epidemiology and Public Health, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Amy F. Savage
- Department of Epidemiology and Public Health, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Nurper Guz
- Department of Epidemiology and Public Health, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Geoffrey M. Attardo
- Department of Epidemiology and Public Health, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Terry W. Pearson
- Department of Biochemistry and Microbiology, Petch Building, University of Victoria, Victoria, British Columbia, Canada
| | - Alison P. Galvani
- Department of Epidemiology and Public Health, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Serap Aksoy
- Department of Epidemiology and Public Health, Yale University School of Medicine, New Haven, Connecticut, United States of America
- * E-mail:
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Mayhew GF, Bartholomay LC, Kou HY, Rocheleau TA, Fuchs JF, Aliota MT, Tsao IY, Huang CY, Liu TT, Hsiao KJ, Tsai SF, Yang UC, Perna NT, Cho WL, Christensen BM, Chen CC. Construction and characterization of an expressed sequenced tag library for the mosquito vector Armigeres subalbatus. BMC Genomics 2007; 8:462. [PMID: 18088419 PMCID: PMC2262096 DOI: 10.1186/1471-2164-8-462] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2007] [Accepted: 12/18/2007] [Indexed: 11/28/2022] Open
Abstract
Background The mosquito, Armigeres subalbatus, mounts a distinctively robust innate immune response when infected with the nematode Brugia malayi, a causative agent of lymphatic filariasis. In order to mine the transcriptome for new insight into the cascade of events that takes place in response to infection in this mosquito, 6 cDNA libraries were generated from tissues of adult female mosquitoes subjected to immune-response activation treatments that lead to well-characterized responses, and from aging, naïve mosquitoes. Expressed sequence tags (ESTs) from each library were produced, annotated, and subjected to comparative analyses. Results Six libraries were constructed and used to generate 44,940 expressed sequence tags, of which 38,079 passed quality filters to be included in the annotation project and subsequent analyses. All of these sequences were collapsed into clusters resulting in 8,020 unique sequence clusters or singletons. EST clusters were annotated and curated manually within ASAP (A Systematic Annotation Package for Community Analysis of Genomes) web portal according to BLAST results from comparisons to Genbank, and the Anopheles gambiae and Drosophila melanogaster genome projects. Conclusion The resulting dataset is the first of its kind for this mosquito vector and provides a basis for future studies of mosquito vectors regarding the cascade of events that occurs in response to infection, and thereby providing insight into vector competence and innate immunity.
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Affiliation(s)
- George F Mayhew
- Department of Pathobiological Sciences, University of Wisconsin-Madison, 1656 Linden Dr,, Madison Wisconsin, 53706, USA.
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Luong LT, Polak M. Environment-dependent trade-offs between ectoparasite resistance and larval competitive ability in the Drosophila–Macrocheles system. Heredity (Edinb) 2007; 99:632-40. [PMID: 17700633 DOI: 10.1038/sj.hdy.6801040] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Costs of resistance are expected to contribute to the maintenance of genetic variation for resistance in natural host populations. In the present study, we experimentally test for genetic trade-offs between parasite resistance and larval competitive ability expressed under varying levels of crowding and temperature. Artificial selection for increased behavioral resistance was applied against an ectoparasitic mite (Macrocheles subbadius) in replicate lines of the fruit fly Drosophila nigrospiracula. We then measured correlated responses to selection in larval competitive ability by contrasting replicate selected and control (unselected) lines in the absence of parasitism. Experiments were conducted under variable environmental conditions: two temperatures and three levels of larval density. Our results reveal a negative genetic correlation between resistance and larval-adult survival under conditions of moderate and severe intra-specific competition. At both low and high temperature, percent emergence was significantly higher among control lines than selected lines. This divergence in larval competitive ability was magnified under high levels of competition, but only at low temperature. Hence, the interaction between selection treatment and larval density was modified by temperature. As predicted, larvae experiencing medium and high levels of competition exhibited an overall reduction in female body size compared to larvae at low levels of competition. Female flies emerging from selected lines were significantly smaller than those females from control lines, but this effect was only significant under conditions of moderate to severe competition. These results provide evidence of environment-dependent trade-offs between ectoparasite resistance and larval competitive ability, a potential mechanism maintaining genetic polymorphism for resistance.
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Affiliation(s)
- L T Luong
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, USA.
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30
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Ahmed AM, Hurd H. Immune stimulation and malaria infection impose reproductive costs in Anopheles gambiae via follicular apoptosis. Microbes Infect 2006; 8:308-15. [PMID: 16213176 DOI: 10.1016/j.micinf.2005.06.026] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2005] [Revised: 06/21/2005] [Accepted: 06/23/2005] [Indexed: 10/25/2022]
Abstract
The employment of defense mechanisms is recognized as a costly life-history trait. In the malaria vector Anopheles gambiae, reproductive costs have been associated with both humoral and cellular innate immune responses and also with malaria infection. The resorption of developing oocytes associated with malaria infection is preceded by the programmed cell death, or apoptosis, of follicular cells. Here we demonstrate that apoptosis in ovarian follicular epithelial cells also occurs when mosquitoes are subjected to artificial immune-elicitors that induce a melanization response or humoral antimicrobial activity. Caspases are key cysteine proteases involved in apoptosis. Caspase-like activity was detected in epithelial cells in approximately 4.0% of the developing ovarian follicles of untreated, blood-fed, mosquitoes. Lipopolysaccharide injection resulted in a significant increase in anti-Micrococcus luteus humoral activity and a significant increase of 257.7% of follicles exhibiting apoptosis compared to results after saline injections. Melanization also triggered follicular apoptosis, which increased by 106.25% or 134.37% in Sephadex C-25 or G-25 bead-inoculated mosquitoes, respectively, compared to that in sham-injected ones. Ovaries from Plasmodium yoelii nigeriensis-infected mosquitoes exhibited a significant increase in follicular apoptosis of 440.9% compared to non-infected ones. Thus, at the time point investigated, infection had a much greater effect than artificial immune-elicitors. Death of follicular epithelial cells has been shown to lead to follicle resorption and hence a decrease in egg production. We propose the trade-off between reproductive fitness and immune defense in A. gambiae operates via the induction of apoptosis in ovarian follicles and that different immune responses impose costs via the same pathway.
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Affiliation(s)
- Ashraf M Ahmed
- Department of Zoology, Faculty of Sciences, University of El-Minia, El-Minia, Egypt
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31
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Huang CY, Christensen BM, Chen CC. Role of dopachrome conversion enzyme in the melanization of filarial worms in mosquitoes. INSECT MOLECULAR BIOLOGY 2005; 14:675-82. [PMID: 16313567 DOI: 10.1111/j.1365-2583.2005.00597.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Melanization is an effective defence reaction of mosquito hosts against invading parasites. In mosquitoes, the biosynthesis of melanin is initiated by the hydroxylation of tyrosine to DOPA by phenoloxidase (PO). DOPA is a branch point of the melanization reaction; it may be oxidized to dopaquinone by PO or be decarboxylated to dopamine by dopa decarboxylase. Further oxidation of dopaquinone by PO produces dopachrome. Dopachrome is then converted to 5, 6-dihydroxyindole by dopachrome conversion enzyme (DCE) to produce melanin. The conversion of dopachrome is a rate-limiting step of the melanization reaction, and the presence of PO and DCE significantly accelerates melanization reactions. In this study, a cDNA encoding DCE was cloned from the mosquito Armigeres subalbatus. Real-time PCR analysis revealed increased transcripts from haemocytes in microfilariae (mf)-inoculated mosquitoes. Gene silencing using double-stranded RNA was used to elucidate the role of DCE in the melanization reaction of parasites in Ar. subalbatus. The levels of both DCE transcripts and protein in gene knockdown mosquitoes were dramatically reduced. Compared with controls, the degree of melanization of mf in DCE-knockdown mosquitoes was significantly decreased. These results suggest that DCE is a critical enzyme that is required for effective melanization immune responses.
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Affiliation(s)
- C-Y Huang
- Department of Tropical Medicine, National Yang-Ming University, Taipei, Taiwan
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32
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Hurd H, Taylor PJ, Adams D, Underhill A, Eggleston P. EVALUATING THE COSTS OF MOSQUITO RESISTANCE TO MALARIA PARASITES. Evolution 2005. [DOI: 10.1111/j.0014-3820.2005.tb00969.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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33
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Huang CY, Chou SY, Bartholomay LC, Christensen BM, Chen CC. The use of gene silencing to study the role of dopa decarboxylase in mosquito melanization reactions. INSECT MOLECULAR BIOLOGY 2005; 14:237-44. [PMID: 15926892 DOI: 10.1111/j.1365-2583.2004.00552.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Mosquito melanization involves hydroxylation of tyrosine to dopa, which then is oxidized to dopaquinone by phenoloxidase, or decarboxylated to dopamine by dopa decarboxlase (DDC). An Armigeres subalbatus cDNA encoding DDC was cloned and real-time PCR analysis revealed increased transcripts in blood-fed and microfilariae (mf)-inoculated mosquitoes. A double subgenomic Sindbis virus was used to silence DDC and assess its role in melanization of mf. DDC transcription and activity were significantly decreased in silenced mosquitoes, as was the degree of mf melanization 48 h postinoculation; however, melanization increased after 72 and 96 h, demonstrating that DDC influences the rate of melanization. DDC-silenced mosquitoes also exhibit high mortality, over-feeding and abnormal movement, consistent with an involvement of DDC in neurotransmission.
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Affiliation(s)
- C-Y Huang
- Department of Tropical Medicine, National Yang-Ming University, Taipei, Taiwan
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Abstract
The production and deposition of melanin pigments on invading pathogens and parasites represents a unique, innate immune response in the phylum Arthropoda. This immune response has started to receive considerable attention because of the potential to exploit this mechanism to control mosquito-borne diseases. In this article, we summarize knowledge about this complex biochemistry, the use of melanin biosynthesis in diverse physiological processes and the gaps in knowledge that must be addressed if this immune process is to be manipulated in genetic-based control strategies.
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Affiliation(s)
- Bruce M Christensen
- Department of Animal Health and Biomedical Sciences, 1656 Linden Drive, University of Wisconsin, Madison, WI 53706, USA.
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35
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Zhong D, Pai A, Yan G. Costly resistance to parasitism: evidence from simultaneous quantitative trait loci mapping for resistance and fitness in Tribolium castaneum. Genetics 2005; 169:2127-35. [PMID: 15687267 PMCID: PMC1449612 DOI: 10.1534/genetics.104.038794] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2004] [Accepted: 01/10/2005] [Indexed: 11/18/2022] Open
Abstract
Information on the molecular basis of resistance and the evolution of resistance is crucial to an understanding of the appearance, spread, and distribution of resistance genes and of the mechanisms of host adaptation in natural populations. One potential important genetic constraint for the evolution of resistance is fitness cost associated with resistance. To determine whether host resistance to parasite infection is associated with fitness costs, we conducted simultaneous quantitative trait loci (QTL) mapping of resistance to parasite infection and fitness traits using the red flour beetle (Tribolium castaneum) and the tapeworm parasite (Hymenolepis diminuta) system in two independent segregating populations. A genome-wide QTL scan using amplified fragment length polymorphism (AFLP) markers revealed three QTL for beetle resistance to tapeworm infection. These three QTL account for 44-58% variance in beetle infection intensity. We identified five QTL for fecundity and five QTL for egg-to-adult viability, which accounted for 36-57% and 36-49%, respectively, of the phenotypic variance in fecundity and egg-to-adult viability. The three QTL conferring resistance were colocalized with the QTL affecting beetle fitness. The genome regions that contain the QTL for parasite resistance explained the majority of the variance in fecundity and egg-to-adult viability in the mapping populations. Colocalization of QTL conferring resistance to parasite infection and beetle fitness may result from the pleiotropic effects of the resistance genes on host fitness or from tight linkages between resistance genes and adverse deleterious mutations. Therefore, our results provide evidence that the genome regions conferring resistance to tapeworm infection are partially responsible for fitness costs in the resistant beetle populations.
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Affiliation(s)
- Daibin Zhong
- Department of Biological Sciences, State University of New York at Buffalo, 14260, USA
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36
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Anderson JR, Schneider JR, Grimstad PR, Severson DW. Quantitative genetics of vector competence for La Crosse virus and body size in Ochlerotatus hendersoni and Ochlerotatus triseriatus interspecific hybrids. Genetics 2005; 169:1529-39. [PMID: 15654112 PMCID: PMC1449537 DOI: 10.1534/genetics.104.033639] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2004] [Accepted: 12/07/2004] [Indexed: 11/18/2022] Open
Abstract
La Crosse virus is a leading cause of pediatric encephalitis in the United States. The mosquito Ochlerotatus triseriatus is an efficient vector for La Crosse virus, whereas the closely related O. hendersoni transmits only at very low rates. Quantitative trait loci (QTL) affecting the ability to orally transmit this virus and adult body size were identified in 164 F(2) female individuals from interspecific crosses of O. hendersoni females and O. triseriatus males using a combination of composite interval mapping (CIM), interval mapping (IM) for binary traits, and single-marker mapping. For oral transmission (OT), no genome locations exceeded the 95% experimentwise threshold for declaring a QTL using IM, but single-marker analysis identified four independent regions significantly associated with OT that we considered as tentative QTL. With two QTL, an increase in OT was associated with alleles from the refractory vector, O. hendersoni, and likely reflect epistatic interactions between genes that were uncovered by our interspecific crosses. For body size, two QTL were identified using CIM and a third tentative QTL was identified using single-marker analysis. The genome regions associated with body size also contain three QTL controlling OT, suggesting that these regions contain either single genes with pleiotropic effects or multiple linked genes independently determining each trait.
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Affiliation(s)
- Justin R Anderson
- Center for Tropical Disease Research and Training, Department of Biological Sciences, University of Notre Dame, Indiana 46556, USA
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37
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Abstract
Evolutionary ecology seeks to understand the selective reasons for the design features of the immune defense, especially with respect to parasitism. The molecular processes thereby set limitations, such as the failure to recognize an antigen, response specificity, the cost of defense, and the risk of autoimmunity. Sex, resource availability, and interference by parasites also affect a response. In turn, the defense repertoire consists of different kinds of immune responses--constitutive or induced, general or specific--and involves memory and lasting protection. Because the situation often defies intuition, mathematical analysis is typically required to identify the costs and benefits of variation in design, but such studies are few. In all, insect immune defense is much more similar to that of vertebrates than previously thought. In addition, the field is now rapidly becoming revolutionized by molecular data and methods that allow unprecedented access to study evolution in action.
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Affiliation(s)
- Paul Schmid-Hempel
- Ecology and Evolution, ETH Zürich, ETH-Zentrum NW, CH-8092 Zürich, Switzerland.
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38
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Carton Y, Nappi AJ, Poirie M. Genetics of anti-parasite resistance in invertebrates. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2005; 29:9-32. [PMID: 15325520 DOI: 10.1016/j.dci.2004.05.004] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2004] [Revised: 04/21/2004] [Accepted: 05/12/2004] [Indexed: 05/24/2023]
Abstract
This review summarizes and compares available data on genetic and molecular aspects of resistance in four well-described invertebrate host-parasite systems: snail-schistosome, mosquito-malaria, mosquito-filarial worm, and Drosophila-wasp associations. It underlies that the major components of the immune reaction, such as hemocyte proliferation and/or activation, and production of cytotoxic radicals are common to invertebrate hosts. Identifying genes responsible for naturally occurring resistance will then be helpful to understand the mechanisms of invertebrate immune defenses and to determine how virulence factors are used by parasites to overcome host resistance. Based on these four well-studied models, invertebrate resistance appears as generally determined by one major locus or a few loci, displaying at least partial dominance. Interestingly, specificity of resistance is highly variable and would involve processes other than simple recognition mechanisms. Finally, resistance was shown to be generally costly but is nevertheless observed at high frequencies in many natural populations, suggesting a high potential for host parasite coevolution.
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Affiliation(s)
- Y Carton
- Laboratoire Populations, Génétique et Evolution, CNRS, 91198 Gif, Yvette, France.
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Hurd H, Taylor PJ, Adams D, Underhill A, Eggleston P. EVALUATING THE COSTS OF MOSQUITO RESISTANCE TO MALARIA PARASITES. Evolution 2005. [DOI: 10.1554/05-211.1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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40
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Infanger LC, Rocheleau TA, Bartholomay LC, Johnson JK, Fuchs J, Higgs S, Chen CC, Christensen BM. The role of phenylalanine hydroxylase in melanotic encapsulation of filarial worms in two species of mosquitoes. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2004; 34:1329-1338. [PMID: 15544946 DOI: 10.1016/j.ibmb.2004.09.004] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2004] [Revised: 09/15/2004] [Accepted: 09/24/2004] [Indexed: 05/24/2023]
Abstract
Melanin formation has a significant influence on mosquito vector competence by limiting the development of metazoan parasites. Tyrosine, the rate-limiting substrate of melanin production, can be obtained exogenously or derived from phenylalanine by phenylalanine hydroxylase (PAH). The characteristics of this defense mechanism, such as temporal expression of constituent enzymes involved in the biosynthetic pathway, can vary considerably between mosquito species. We investigated the functional role of PAH in the melanotic encapsulation response in Aedes aegypti and Armigeres subalbatus, two mosquito species with markedly different melanization responses. We used double-stranded RNA (dsRNA) to knock down PAH and observed the phenotypic effects on melanin formation. PAH transcripts were dramatically reduced in both mosquito species after gene knock down. The abundance of PAH proteins was decreased in gene knockdown mosquitoes that were inoculated with Dirofilaria immitis microfilariae (mf) as compared to inoculation controls. A significant reduction of mf melanization also was observed in these knockdown mosquitoes as compared to inoculation controls. Our data suggest that PAH is required for a fully functional melanotic encapsulation response in both mosquito vectors.
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Affiliation(s)
- Li-Chun Infanger
- Department of Animal Health & Biomedical Sciences, University of Wisconsin-Madison, 1656 Linden Dr., Madison, WI 53706, USA
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41
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Vontas JG, McCarroll L, Karunaratne SHPP, Louis C, Hurd H, Hemingway J. Does environmental stress affect insect-vectored parasite transmission? PHYSIOLOGICAL ENTOMOLOGY 2004; 29:210-213. [PMID: 19330047 PMCID: PMC2661066 DOI: 10.1111/j.0307-6962.2004.00410.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
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42
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Rivero A, Ferguson HM. The energetic budget of Anopheles stephensi infected with Plasmodium chabaudi: is energy depletion a mechanism for virulence? Proc Biol Sci 2003; 270:1365-71. [PMID: 12965027 PMCID: PMC1691381 DOI: 10.1098/rspb.2003.2389] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Evidence continues to accumulate showing that the malaria parasites (Plasmodium spp.) reduce the survival and fecundity of their mosquito vectors (Anopheles spp.). Our ability to identify the possible epidemiological and evolutionary consequences of these parasite-induced fitness reductions has been hampered by a poor understanding of the physiological basis of these shifts. Here, we explore whether the reductions in fecundity and longevity are the result of a parasite-mediated depletion or reallocation of the energetic resources of the mosquito. Mosquitoes infected with Plasmodium chabaudi were expected to have less energetic resources than uninfected mosquitoes, and energy levels were predicted to be lowest in mosquitoes infected with the most virulent parasite genotypes. Not only was there no evidence of a parasite-mediated reduction in the overall energetic budget of mosquitoes, but Plasmodium was actually associated with increased levels of glucose, a key insect nutritional and energetic resource. The data strongly suggest the existence of an increase in sugar feeding in mosquitoes infected with Plasmodium. We suggest different adaptive explanations for an enhanced sugar uptake in infected mosquitoes and call for more studies to investigate the physiological role of glucose in the Plasmodium-mosquito interaction.
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Affiliation(s)
- A Rivero
- Institute of Cell, Animal and Population Biology, University of Edinburgh, West Mains Road, Edinburgh EH9 3JT, UK.
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43
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Kraaijeveld AR, Ferrari J, Godfray HCJ. Costs of resistance in insect-parasite and insect-parasitoid interactions. Parasitology 2003; 125 Suppl:S71-82. [PMID: 12622330 DOI: 10.1017/s0031182002001750] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Most, if not all, organisms face attack by natural enemies and will be selected to evolve some form of defence. Resistance may have costs as well as its obvious benefits. These costs may be associated with actual defence or with the maintenance of the defensive machinery irrespective of whether a challenge occurs. In this paper, the evidence for costs of resistance in insect-parasite and insect-parasitoid systems is reviewed, with emphasis on two host-parasitoid systems, based on Drosophila melanogaster and pea aphids as hosts. Data from true insect-parasite systems mainly concern the costs of actual defence; evidence for the costs of standing defences is mostly circumstantial. In pea aphids, the costs of standing defences have so far proved elusive. Resistance amongst clones is not correlated with life-time fecundity, whether measured on good or poor quality plants. Successful defence by a D. melanogaster larva results in a reduction in adult size and fecundity and an increased susceptibility to pupal parasitoids. Costs of standing defences are a reduction in larval competitive ability though these costs only become important when food is limited. It is concluded that costs of resistance can play a pivotal role in the evolutionary and population dynamic interactions between hosts and their parasites.
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Affiliation(s)
- A R Kraaijeveld
- NERC Centre for Population Biology and Department of Biological Sciences, Imperial College at Silwood Park, Ascot, Berks, SL5 7PY, UK.
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44
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Lima CA, Almeida WR, Hurd H, Albuquerque CMR. Reproductive aspects of the mosquito Culex quinquefasciatus (Diptera:Culicidae) infected with Wuchereria bancrofti (Spirurida: Onchocercidae). Mem Inst Oswaldo Cruz 2003; 98:217-22. [PMID: 12764437 PMCID: PMC2474805 DOI: 10.1590/s0074-02762003000200009] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study reports on the relationship between Wuchereria bancrofti infection and female body size, intake of blood and fecundity in the mosquito Culex quinquefasciatus, vector of this filarial parasite in Recife (Brazil). Adults from field collected larvae were infected via a membrane feeding procedure, using blood with parasitaemia ranging from 724-6,000 mf/ml. A positive correlation was observed between mosquito size (measured by wing length) and egg production in uninfected females. However, this relationship did not exist in W. bancrofti infected mosquitoes. This change is unlikely to be the result of changes in blood ingestion as no significant difference was found when infected and uninfected females were compared. Variation in egg production observed between trials could not be associated with parasite density in the blood. These results suggest infection with W. bancrofti may disrupt the relationship between mosquito size and egg production during the first gonotrophic cycle of C. quinquefasciatus such that fecundity is sometimes reduced. However, this overall affect is variable and many groups of mosquitoes do not respond in this way.
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Affiliation(s)
- Catarina A Lima
- Departamento de Zoologia, Universidade Federal de Pernambuco, Av. Moraes Rego s/n, 50670-420 Recife PE, Brasil
| | - Walkiria R Almeida
- Departamento de Zoologia, Universidade Federal de Pernambuco, Av. Moraes Rego s/n, 50670-420 Recife PE, Brasil
| | | | - Cleide MR Albuquerque
- Departamento de Zoologia, Universidade Federal de Pernambuco, Av. Moraes Rego s/n, 50670-420 Recife PE, Brasil
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45
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Abstract
The evolutionary-ecology approach to studying immune defences has generated a number of hypotheses that help to explain the observed variance in responses. Here, selected topics are reviewed in an attempt to identify the common problems, connections and generalities of the approach. In particular, the cost of immune defence, response specificity, sexual selection, neighbourhood effects and questions of optimal defence portfolios are discussed. While these questions still warrant further investigation, future challenges are the development of synthetic concepts for vertebrate and invertebrate systems and also of the theory that predicts immune responses based on a priori principles of evolutionary ecology.
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46
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Hillyer JF, Schmidt SL, Christensen BM. Rapid phagocytosis and melanization of bacteria and Plasmodium sporozoites by hemocytes of the mosquito Aedes aegypti. J Parasitol 2003; 89:62-9. [PMID: 12659304 DOI: 10.1645/0022-3395(2003)089[0062:rpamob]2.0.co;2] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Mosquitoes are vectors of many deadly and debilitating pathogens. In the current study, we used light and electron microscopies to study the immune response of Aedes aegypti hemocytes to bacterial inoculations, Plasmodium gallinaceum natural infections, and latex bead injections. After challenge, mosquitoes mounted strong phagocytic and melanization responses. Granulocytes phagocytosed bacteria singly or pooled them inside large membrane-delimited vesicles. Phagocytosis of bacteria, Plasmodium sporozoites, and latex beads was extensive; we estimated that individual granulocytes have the capacity to phagocytose hundreds of bacteria and thousands of latex particles. Oenocytoids were also seen to internalize bacteria and latex particles, although infrequently and with low capacity. Besides phagocytosis, mosquitoes cleared bacteria and sporozoites by melanization. Interestingly, the immune response toward 2 species of bacteria was different; most Escherichia coli were phagocytosed, but most Micrococcus luteus were melanized. Similar to E. coli, most Plasmodium sporozoites were phagocytosed. The immune response was rapid; phagocytosis and melanization of bacteria began as early as 5 min after inoculation. The magnitude and speed of the cellular response suggest that hemocytes, acting in concert with the humoral immune response, are the main force driving the battle against foreign invaders.
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Affiliation(s)
- Jullán F Hillyer
- Department of Animal Health and Biomedical Sciences, University of Wisconsin-Madison, 1656 Linden Drive, Madison, Wisconsin 53706, USA
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47
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McCarroll L, Hemingway J. Can insecticide resistance status affect parasite transmission in mosquitoes? INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2002; 32:1345-1351. [PMID: 12225925 DOI: 10.1016/s0965-1748(02)00097-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Affiliation(s)
- L McCarroll
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK
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48
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Ahmed AM, Baggott SL, Maingon R, Hurd H. The costs of mounting an immune response are reflected in the reproductive fitness of the mosquitoAnopheles gambiae. OIKOS 2002. [DOI: 10.1034/j.1600-0706.2002.970307.x] [Citation(s) in RCA: 129] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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49
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Abstract
Many of the most harmful parasitic diseases are transmitted by blood-feeding insect vectors. During this stage of their life cycles, selection pressures favor parasites that can manipulate their vectors to enhance transmission. Strategies may include increasing the amount of contact between vector and host, reducing vector reproductive output and consequently altering vector resource management to increase available nutrient reserves, and increasing vector longevity. Manipulation of these life-history traits may be more beneficial at some phase of the parasite's developmental process than at others. This review examines empirical, experimental, and field-based evidence to evaluate examples of changes in vector behavior and physiology that might be construed to be manipulative. Examples are mainly drawn from malaria-infected mosquitoes, Leishmania-infected sandflies, and Trypanosoma-infected tsetse flies.
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Affiliation(s)
- Hilary Hurd
- Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Keele, Staffordshire ST5 5BG, United Kingdom.
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50
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Rolff J. Effects of age and gender on immune function of dragonflies (Odonata, Lestidae) from a wild population. CAN J ZOOL 2001. [DOI: 10.1139/z01-190] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Immunity is a crucial determinant of fitness. Despite this, very few studies have addressed the expression of immune function in insect populations in the wild. I present data on two immune parameters, hemocyte load and expression of phenoloxidase, in adult damselflies (Lestes viridis) from a wild population. In a comparison of newly emerged with sexually mature adults, it was found that the latter had higher hemocyte loads but lower phenoloxidase expression. Mature females showed significantly higher phenoloxidase expression than mature males. The sexual differences might be explained by gender differences in life history.
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