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Espinoza J, Medina C, Aniñir W, Escobar-Bahamondes P, Ungerfeld E, Urzúa A, Quiroz A. Insecticidal, Repellent and Antifeedant Activity of Essential Oils from Blepharocalyx cruckshanksii (Hook. & Arn.) Nied. Leaves and Pilgerodendron uviferum (D. Don) Florin Heartwood against Horn Flies, Haematobia irritans (Diptera: Muscidae). Molecules 2021; 26:6936. [PMID: 34834029 PMCID: PMC8621377 DOI: 10.3390/molecules26226936] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 11/11/2021] [Accepted: 11/12/2021] [Indexed: 11/28/2022] Open
Abstract
Haematobia irritans is a cosmopolitan obligate blood-feeding ectoparasite of cattle and is the major global pest of livestock production. Currently, H. irritans management is largely dependent on broad-spectrum pesticides, which has led to the development of insecticide resistance. Thus, alternative control methods are needed. Essential oils have been studied as an alternative due to their wide spectrum of biological activities against insects. Thus, the main aim of this study was to evaluate the insecticidal, repellent and antifeedant activity of the essential oils from Blepharocalyx cruckshanksii leaves and Pilgerodendron uviferum heartwood against horn flies in laboratory conditions. The composition of the essential oils was analyzed using gas chromatography coupled to mass spectrometry. Accordingly, α-pinene (36.50%) and limonene (20.50%) were the principal components of the B. cruckchanksii essential oil, and δ-cadinol (24.16%), cubenol (22.64%), 15-copaenol (15.46%) and δ-cadinene (10.81%) were the most abundant compounds in the P. uviferum essential oil. Mortality of flies and feeding behavior were evaluated by non-choice tests, and olfactory response was evaluated using a Y-tube olfactometer. Both essential oils were toxic to horn flies, with LC50 values for B. cruckchanksii essential oil of 3.58 µL L-1 air at 4 h, and for P. uviferum essential oil of 9.41 µL L-1 air and 1.02 µL L-1 air at 1 and 4 h, respectively. Moreover, the essential oils exhibited spatial repellency in the olfactometer using only 10 µg of each oil, and these significantly reduced the horn fly feeding at all doses evaluated. Although further laboratory and field studies related to the insectistatic and insecticide properties of these essential oils against H. irritans are necessary, B. cruckshanksii leaves and P. uviferum heartwood essential oils are promising candidates for horn fly management.
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Affiliation(s)
- Javier Espinoza
- Laboratorio de Ecología Química, Departamento de Ciencias Químicas y Recursos Naturales, Universidad de La Frontera, Casilla 54-D, Avenida Francisco Salazar 01145, Temuco 4811230, Chile; (C.M.); (W.A.)
- Centro de Excelencia en Investigación Biotecnológica Aplicada al Medio Ambiente (CIBAMA), Universidad de La Frontera, Avenida Francisco Salazar 01145, Temuco 4811230, Chile
| | - Cristian Medina
- Laboratorio de Ecología Química, Departamento de Ciencias Químicas y Recursos Naturales, Universidad de La Frontera, Casilla 54-D, Avenida Francisco Salazar 01145, Temuco 4811230, Chile; (C.M.); (W.A.)
- Centro de Excelencia en Investigación Biotecnológica Aplicada al Medio Ambiente (CIBAMA), Universidad de La Frontera, Avenida Francisco Salazar 01145, Temuco 4811230, Chile
- Doctorado en Ciencias de Recursos Naturales, Universidad de La Frontera, Av. Francisco Salazar 01145, Temuco 4811230, Chile;
| | - Washington Aniñir
- Laboratorio de Ecología Química, Departamento de Ciencias Químicas y Recursos Naturales, Universidad de La Frontera, Casilla 54-D, Avenida Francisco Salazar 01145, Temuco 4811230, Chile; (C.M.); (W.A.)
- Centro de Excelencia en Investigación Biotecnológica Aplicada al Medio Ambiente (CIBAMA), Universidad de La Frontera, Avenida Francisco Salazar 01145, Temuco 4811230, Chile
- Doctorado en Ciencias de Recursos Naturales, Universidad de La Frontera, Av. Francisco Salazar 01145, Temuco 4811230, Chile;
| | - Paul Escobar-Bahamondes
- Centro Regional de Investigación Carillanca, Vilcún, Instituto de Investigaciones Agropecuarias (INIA), Región de La Araucanía, Temuco 7500502, Chile; (P.E.-B.); (E.U.)
| | - Emilio Ungerfeld
- Centro Regional de Investigación Carillanca, Vilcún, Instituto de Investigaciones Agropecuarias (INIA), Región de La Araucanía, Temuco 7500502, Chile; (P.E.-B.); (E.U.)
| | - Alejandro Urzúa
- Doctorado en Ciencias de Recursos Naturales, Universidad de La Frontera, Av. Francisco Salazar 01145, Temuco 4811230, Chile;
| | - Andrés Quiroz
- Laboratorio de Ecología Química, Departamento de Ciencias Químicas y Recursos Naturales, Universidad de La Frontera, Casilla 54-D, Avenida Francisco Salazar 01145, Temuco 4811230, Chile; (C.M.); (W.A.)
- Centro de Excelencia en Investigación Biotecnológica Aplicada al Medio Ambiente (CIBAMA), Universidad de La Frontera, Avenida Francisco Salazar 01145, Temuco 4811230, Chile
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Antifeedant Effects and Repellent Activity of Loline Alkaloids from Endophyte-Infected Tall Fescue against Horn Flies, Haematobia irritans (Diptera: Muscidae). Molecules 2021; 26:molecules26040817. [PMID: 33557353 PMCID: PMC7915221 DOI: 10.3390/molecules26040817] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 01/31/2021] [Accepted: 02/01/2021] [Indexed: 11/17/2022] Open
Abstract
Haematobia irritans is an obligate bloodsucking ectoparasite of cattle and is the global major pest of livestock production. Currently, H. irritans management is largely dependent upon broad-spectrum pesticides, which lately has led to the development of insecticide resistance. Thus, alternative control methods are necessary. Endophyte-infected grasses have been studied as an alternative due to their capability to biosynthesize alkaloids associated with anti-insect activities. Thus, the main aim of this study was to evaluate the antifeedant and repellent activity of lolines obtained from endophyte-infected tall fescue against H. irritans adults in laboratory conditions. The alkaloid extract (ALKE) was obtained by acid–base extraction. N-formyl loline (NFL) and N-acetyl loline (NAL) were isolated by preparative thin layer chromatography (pTLC) and column chromatography (CC), and the loline was prepared by acid hydrolysis of a NFL/NAL mixture. Loline identification was performed by gas chromatography coupled to mass spectrometry (GC/MS). Feeding behavior was evaluated by a non-choice test, and olfactory response was evaluated using a Y-tube olfactometer. Accordingly, all samples showed antifeedant activities. NFL was the most antifeedant compound at 0.5 µg/µL and 1.0 µg/µL, and it was statistically equal to NAL but different to loline; however, NAL was not statistically different to loline. NFL and NAL at 0.25 µg/µL were more active than loline. All samples except loline exhibited spatial repellency in the olfactometer. Thus, the little or non-adverse effects for cattle and beneficial activities of those lolines make them suitable candidates for horn fly management.
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Smythe BG, Zepeda R, Hogsette J. Establishing a Method to Evaluate the Efficacy of Compounds Aimed at Repelling Horn Fly (Diptera: Muscidae) Infestations on Cattle in a Laboratory Setting. JOURNAL OF ECONOMIC ENTOMOLOGY 2020; 113:3011-3016. [PMID: 32964237 DOI: 10.1093/jee/toaa208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Indexed: 06/11/2023]
Abstract
Use of nonpesticidal chemicals to minimize or eliminate horn fly (Haematobia irritans) populations on cattle could be helpful in combating insecticide resistance. One recent approach is the use of natural products with repellent properties against the target pest. A rapid on-animal evaluation system that accounts for both host and pest interactions and bypasses the need for costly multiyear field assessments is needed. The objective of this study was to develop a system to quantify product repellency of horn flies on cattle in a laboratory setting. Animal pair treatment groups were utilized to assess product efficacy and carrier effects across three experimental trials. A treatment solution consisting of 3% geraniol in mineral oil was the natural product repellent. Horn fly populations on animal pairs receiving the geraniol treatment were significantly reduced when compared with untreated animal pairs. However, animal pairs receiving a mineral oil-only treatment showed reduced horn fly populations similar to animals treated with mineral oil plus geraniol. Thus, there was a strong carrier effect that could be difficult to distinguish in the field but was easily observed using laboratory methods.
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Affiliation(s)
- Brandon G Smythe
- Center for Animal Health & Food Safety, New Mexico State University, Las Cruces, NM
| | - Ramon Zepeda
- Center for Animal Health & Food Safety, New Mexico State University, Las Cruces, NM
| | - Jerome Hogsette
- USDA-ARS, Center for Medical, Agricultural and Veterinary Entomology, Gainesville, FL
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Toxicity of fluralaner, a companion animal insecticide, relative to industry-leading agricultural insecticides against resistant and susceptible strains of filth flies. Sci Rep 2020; 10:11166. [PMID: 32636470 PMCID: PMC7341816 DOI: 10.1038/s41598-020-68121-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Accepted: 06/10/2020] [Indexed: 01/11/2023] Open
Abstract
Filth flies cause billions of dollars of losses annually to the animal production industry. Fluralaner is a relatively new pesticide currently sold for control of fleas, ticks, and mites on companion animals and poultry. We examined the efficacy of fluralaner against three species of filth flies. Insecticide-susceptible horn flies and stable flies were tested topically. Fluralaner outperformed permethrin by > 2-fold for the horn flies but underperformed permethrin by > 45-fold for stable flies at 24 h. House flies were tested topically with fluralaner in comparison to permethrin at 48 h and orally with fluralaner in comparison to imidacloprid at 24 h. Topical fluralaner was 6- to 28-fold as toxic as permethrin in four pyrethroid-resistant strains and not significantly less toxic than permethrin in a susceptible strain and a mildly pyrethroid-resistant strain. There was slight cross-resistance between topically applied fluralaner and permethrin in all five insecticide-resistant strains tested. Oral fluralaner was more toxic than imidacloprid in all four house fly strains tested, 9- to 118-fold as toxic. Oral cross-resistance between imidacloprid and fluralaner was not detected, but imidacloprid resistance was not high in any of the tested strains. Fluralaner shows promise for control of horn flies and house flies.
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Li Z, Guerrero F, Pérez de León AA, Foil LD, Swale DR. Small-Molecule Inhibitors of Inward Rectifier Potassium (Kir) Channels Reduce Bloodmeal Feeding and Have Insecticidal Activity Against the Horn Fly (Diptera: Muscidae). JOURNAL OF MEDICAL ENTOMOLOGY 2020; 57:1131-1140. [PMID: 32006426 DOI: 10.1093/jme/tjaa015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Indexed: 06/10/2023]
Abstract
Bloodmeal feeding by the horn fly, Haematobia irritans (L.), is associated with reduced milk production and blood loss that ultimately prevents weight gain of calves and yearlings. Thus, blood feeding by H. irritans causes significant economic losses in several continents. As with other arthropods, resistance to the majority of commercialized insecticides reduces the efficacy of current control programs. Thus, innovative technologies and novel biochemical targets for horn fly control are needed. Salivary gland and Malpighian tubule function are critical for H. irritans survivorship as they drive bloodmeal acquisition and maintain ion- and fluid homeostasis during bloodmeal processing, respectively. Experiments were conducted to test the hypothesis that pharmacological modulation of H. irritans inward rectifier potassium (Kir) channels would preclude blood feeding and induce mortality by reducing the secretory activity of the salivary gland while simultaneously inducing Malpighian tubule failure. Experimental results clearly indicate structurally diverse Kir channel modulators reduce the secretory activity of the salivary gland by up to fivefold when compared to control and the reduced saliva secretion was highly correlated to a reduction in bloodmeal acquisition in adult flies. Furthermore, adult feeding on blood treated with Kir channel modulators resulted in significant mortality. In addition to validating the Kir channels of H. irritans as putative insecticide targets, the knowledge gained from this study could be applied to develop novel therapeutic technologies targeting salivary gland or Malpighian tubule function to reduce the economic burden of horn fly ectoparasitism on cattle health and production.
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Affiliation(s)
- Zhilin Li
- Department of Entomology, Louisiana State University AgCenter, Baton Rouge, LA
| | | | - Adalberto A Pérez de León
- Knipling-Bushland Livestock Insects Research Laboratory and Veterinary Pest Genomics Center, United States Department of Agriculture-Agricultural Research Service, Kerrville, TX
| | - Lane D Foil
- Department of Entomology, Louisiana State University AgCenter, Baton Rouge, LA
| | - Daniel R Swale
- Department of Entomology, Louisiana State University AgCenter, Baton Rouge, LA
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Ribeiro JM, Debat HJ, Boiani M, Ures X, Rocha S, Breijo M. An insight into the sialome, mialome and virome of the horn fly, Haematobia irritans. BMC Genomics 2019; 20:616. [PMID: 31357943 PMCID: PMC6664567 DOI: 10.1186/s12864-019-5984-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 07/19/2019] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The horn fly (Haematobia irritans) is an obligate blood feeder that causes considerable economic losses in livestock industries worldwide. The control of this cattle pest is mainly based on insecticides; unfortunately, in many regions, horn flies have developed resistance. Vaccines or biological control have been proposed as alternative control methods, but the available information about the biology or physiology of this parasite is rather scarce. RESULTS We present a comprehensive description of the salivary and midgut transcriptomes of the horn fly (Haematobia irritans), using deep sequencing achieved by the Illumina protocol, as well as exploring the virome of this fly. Comparison of the two transcriptomes allow for identification of uniquely salivary or uniquely midgut transcripts, as identified by statistically differential transcript expression at a level of 16 x or more. In addition, we provide genomic highlights and phylogenetic insights of Haematobia irritans Nora virus and present evidence of a novel densovirus, both associated to midgut libraries of H. irritans. CONCLUSIONS We provide a catalog of protein sequences associated with the salivary glands and midgut of the horn fly that will be useful for vaccine design. Additionally, we discover two midgut-associated viruses that infect these flies in nature. Future studies should address the prevalence, biological effects and life cycles of these viruses, which could eventually lead to translational work oriented to the control of this economically important cattle pest.
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Affiliation(s)
- J. M. Ribeiro
- Section of Vector Biology, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, 12735 Twinbrook Parkway Room 3E28, Rockville, MD 20852 USA
| | - Humberto Julio Debat
- Instituto de Patología Vegetal, Centro de Investigaciones Agropecuarias, Instituto Nacional de Tecnología Agropecuaria (IPAVE-CIAP-INTA), Córdoba, Argentina
| | - M. Boiani
- Unidad de Reactivos y Biomodelos de Experimentación, Facultad de Medicina, Universidad de la República, Gral. Flores, 2125 Montevideo, Uruguay
| | - X. Ures
- Unidad de Reactivos y Biomodelos de Experimentación, Facultad de Medicina, Universidad de la República, Gral. Flores, 2125 Montevideo, Uruguay
| | - S. Rocha
- Unidad de Reactivos y Biomodelos de Experimentación, Facultad de Medicina, Universidad de la República, Gral. Flores, 2125 Montevideo, Uruguay
| | - M. Breijo
- Unidad de Reactivos y Biomodelos de Experimentación, Facultad de Medicina, Universidad de la República, Gral. Flores, 2125 Montevideo, Uruguay
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Domingues LN, Guerrero FD, Foil LD. Impacts of long-term insecticide treatment regimes on skdr and kdr pyrethroid resistance alleles in horn fly field populations. Parasitol Res 2019; 118:2485-2497. [PMID: 31280327 DOI: 10.1007/s00436-019-06386-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Accepted: 06/24/2019] [Indexed: 11/26/2022]
Abstract
We evaluated the effects of four different 6-year duration control strategies on the resistance levels and frequency of the pyrethroid target site resistance alleles, superkdr (skdr) and kdr, at four field populations of Haematobia irritans irritans (Linnaeus, 1758) (Diptera: Muscidae) in Louisiana, USA. Consecutive use of pyrethroid ear tags for 6 years caused a significant increase in the resistance ratio to pyrethroids as well as the frequencies of both skdr and kdr resistance alleles. After 3 years of consecutive use of pyrethroid ear tags, followed by 1 year with no treatment, and followed by 2 years with organophosphate ear tags, the resistance ratio for pyrethroid was not significantly affected, the %R-skdr significantly dropped while the %R-kdr allele remained relatively high and stable. Similar results were observed when pyrethroid ear tags were used for three consecutive years, followed by 1 year with no treatment, and followed by 2 years with endosulfan ear tags; however, this treatment resulted in a slight increase in the resistance ratio for pyrethroids. In a mosaic, the resistance ratio for pyrethroids showed a 2.5-fold increase but the skdr-kdr genetic profiles did not change, as the %R alleles (skdr and kdr) remained low and stable through the 6 years. Lack of exposure to pyrethroid insecticides for 3 years significantly affected the skdr mutation but not the kdr mutation, preventing re-establishment of susceptibility to pyrethroids. SS-SR (skdr-kdr) individuals were responsible for the maintenance of the kdr mutation in two of the populations studied, and fitness cost seems to strongly affect the SR-RR genotype. None of the four treatment regimens evaluated in the study had satisfactory results for the management of kdr resistance alleles.
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Affiliation(s)
- Luísa N Domingues
- USDA-ARS Knipling-Bushland U. S. Livestock Insects Research Lab, 2700 Fredericksburg Road, Kerrville, TX, 78028, USA.
| | - Felix D Guerrero
- USDA-ARS Knipling-Bushland U. S. Livestock Insects Research Lab, 2700 Fredericksburg Road, Kerrville, TX, 78028, USA
| | - Lane D Foil
- Department of Entomology, Louisiana State University, 404 Life Sciences Building, Baton Rouge, LA, 70803, USA
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Holderman CJ, Swale DR, Bloomquist JR, Kaufman PE. Resistance to Permethrin, β-cyfluthrin, and Diazinon in Florida Horn Fly Populations. INSECTS 2018; 9:insects9020063. [PMID: 29895770 PMCID: PMC6023543 DOI: 10.3390/insects9020063] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 05/25/2018] [Accepted: 06/07/2018] [Indexed: 11/16/2022]
Abstract
Horn flies, Haematobia irritans, a major cattle pest in the USA, cause substantial economic losses and current control methods rely heavily on insecticides. Three horn fly populations were evaluated for insecticide susceptibility to permethrin, β-cyfluthrin, and diazinon. Susceptibility was variable by population, with the greatest resistance exhibited by a 66-fold resistance ratio (RR) to permethrin and >14-fold RR to diazinon. Mechanisms of resistance were determined using molecular techniques and enzymatic assays. The knockdown resistance (kdr) genotype (L150F) associated with pyrethroid resistance, and a G262A mutation in acetylcholinesterase, previously associated with organophosphate resistance, were found in all field populations evaluated. Insensitivity of diazoxon at the acetylcholinesterase (AChE) target site was significantly different in horn flies from one of the field sites. For metabolic detoxifying enzymes, cytochrome P450 nor general esterases showed a significant difference between field strains and a laboratory susceptible strain. Pyrethroid resistance was likely due to the presence of the L150F mutation in the population. In vitro studies targeting the AChE enzyme did not support the notion that the G262A mutation was the sole cause of resistance to organophosphates, and, therefore, the exact resistance mechanism to diazinon was not able to be confirmed.
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Affiliation(s)
- Chris J Holderman
- Entomology and Nematology Department, University of Florida, Gainesville, FL 32611, USA.
| | - Daniel R Swale
- Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, USA.
| | - Jeffery R Bloomquist
- Entomology and Nematology Department, University of Florida, Gainesville, FL 32611, USA.
- Emerging Pathogens Institute, University of Florida, Gainesville, FL 32611, USA.
| | - Phillip E Kaufman
- Entomology and Nematology Department, University of Florida, Gainesville, FL 32611, USA.
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Swale DR, Li Z, Kraft JZ, Healy K, Liu M, David CM, Liu Z, Foil LD. Development of an autodissemination strategy for the deployment of novel control agents targeting the common malaria mosquito, Anopheles quadrimaculatus say (Diptera: Culicidae). PLoS Negl Trop Dis 2018; 12:e0006259. [PMID: 29641515 PMCID: PMC5894962 DOI: 10.1371/journal.pntd.0006259] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 01/22/2018] [Indexed: 12/14/2022] Open
Abstract
Background The reduced efficacy of current Anopheline mosquito control methods underscores the need to develop new methods of control that exploit unique target sites and/or utilizes novel deployment methods. Autodissemination methodologies using insect growth regulators (IGRs) is growing in interest and has been shown to be effective at controlling Aedes mosquitoes in semi-field and field environments, yet little information exists for Anopheline mosquitoes. Therefore, we tested the hypothesis that female-driven autodissemination of an IGR combined with a new mechanism of action insecticide (Kir channel inhibitor) could be employed to reduce Anopheline populations. Methodology We studied the ability of three IGRs to be transferred to the larval habitat during oviposition in laboratory and semi-field environments. Adult mosquitoes were exposed to the chemicals for 4 hours immediately after blood feeding and efficacy was tested using classical methodologies, including adult emergence inhibition and High Performance Liquid Chromatography (HPLC). A complete autodissemination design was tested in a semi-field environment. Principal findings Larval survivability and adult emergence were significantly reduced in habitats that were visited by novaluron treated adults, but no statistical differences were observed with pyriproxyfen or triflumuron. These data suggested novaluron, but not pyriproxyfen or triflumuron, was horizontally transferred from the adult mosquito to the larval habitat during oviposition. HPLC studies supported the toxicity data and showed that novaluron was present in the majority of larval habitats, suggesting that novaluron can be horizontally transferred by Anopheles quadrimaculatus. Importantly, the combination of novaluron and the Kir channel inhibitor, VU041, was capable of reducing adult and larval populations in semi-field environments. Conclusions Novaluron can be transferred to the adult at a greater efficacy and/or is not degraded as quickly during the gonotropic cycle when compared to pyriproxyfen or triflumuron. Pending field confirmation, autodissemination approaches with novaluron may be a suitable tool to manage Anopheles populations. Efforts to control the mosquito vector of malaria, Anopheles gambiae, have been dominated by the use of insecticide-treated bednets or residual spraying efforts for the previous 2–3 decades. The persistent use of these methods has led to a decline in control efficacy and has highlighted the need to 1) identify novel molecular targets and 2) novel translational deployment methods to control mosquito vectors. To address this, we employed biological and chemical methods to test the hypothesis that insect growth regulators (IGR) are capable of being transferred to an oviposition site at lethal concentrations when Anopheles adults are exposed immediately after blood feeding. Subsequently, we tested the hypothesis that K+ channel modulators and an IGR used in combination will reduce the mosquito population in a semi-field environment through adult toxicity and IGR transfer. The data presented in this study provides a proof-of-concept that autodissemination methods using specific IGRs and K+ channel modulators are potentially capable of reducing the burden of malaria through a method that is novel, cost efficient, long lasting, and requires minimal human intervention.
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Affiliation(s)
- Daniel R. Swale
- Louisiana State University AgCenter, Department of Entomology, Baton Rouge, LA, United States of America
- * E-mail:
| | - Zhilin Li
- Louisiana State University AgCenter, Department of Entomology, Baton Rouge, LA, United States of America
| | - Jake Z. Kraft
- Louisiana State University AgCenter, Department of Entomology, Baton Rouge, LA, United States of America
| | - Kristen Healy
- Louisiana State University AgCenter, Department of Entomology, Baton Rouge, LA, United States of America
| | - Mei Liu
- Louisiana State University AgCenter, School of Renewable Natural Resources, Baton Rouge, LA, United States of America
| | - Connie M. David
- Louisiana State University, Department of Chemistry, Baton Rouge, LA, United States of America
| | - Zhijun Liu
- Louisiana State University AgCenter, School of Renewable Natural Resources, Baton Rouge, LA, United States of America
| | - Lane D. Foil
- Louisiana State University AgCenter, Department of Entomology, Baton Rouge, LA, United States of America
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Breijo M, Rocha S, Ures X, Pastro L, Alonzo P, Fernández C, Meikle A. Evaluation of Hematobin as a Vaccine Candidate to Control Haematobia irritans (Diptera: Muscidae) Loads in Cattle. JOURNAL OF ECONOMIC ENTOMOLOGY 2017; 110:1390-1393. [PMID: 28387808 DOI: 10.1093/jee/tox104] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Indexed: 06/07/2023]
Abstract
The horn fly, Haematobia irritans (L.), is a blood-sucking livestock ectoparasite responsible for substantial livestock losses. In the present work, the potential use of recombinant hematobin (HTB), a horn fly salivary protein, as an antigen for cattle vaccination was investigated. In this trial, horn fly loads and H. irritans's blood intake were assessed in vaccinated (n = 4) and control (n = 4) crossbred dark-coated steers, which were naturally infected. The vaccinated group received a 1 ml subcutaneous injection of 100 µg of HTB protein emulsified in 500 µl of Incomplete Freund Adjuvant (AIF) on days 0 and 30. The control group received on the same days 1 ml of distilled water emulsified in 500 µl of AIF. The vaccinated group had significantly more HTB-specific IgG antibodies after the HTB booster and had a lower fly load than the control group (206 ± 23 vs. 285 ± 23 flies per animal, respectively). Blood intake by H. irritans did not differ between groups. In summary, these results suggest that vaccinating cattle with HTB could reduce cattle H. irritans load.
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Affiliation(s)
- M Breijo
- Unidad de Reactivos y Biomodelos de Experimentación, Facultad de Medicina, Universidad de la República, Gral. Flores 2125, Montevideo, Uruguay ( ; ; ; )
- Corresponding author, e-mail:
| | - S Rocha
- Unidad de Reactivos y Biomodelos de Experimentación, Facultad de Medicina, Universidad de la República, Gral. Flores 2125, Montevideo, Uruguay (; ; ; )
| | - X Ures
- Unidad de Reactivos y Biomodelos de Experimentación, Facultad de Medicina, Universidad de la República, Gral. Flores 2125, Montevideo, Uruguay (; ; ; )
| | - L Pastro
- Laboratorio de Interacciones Moleculares, Facultad de Ciencias, Iguá 4225, 11400 Montevideo, Uruguay
| | - P Alonzo
- Unidad de Reactivos y Biomodelos de Experimentación, Facultad de Medicina, Universidad de la República, Gral. Flores 2125, Montevideo, Uruguay (; ; ; )
| | - C Fernández
- Instituto de Higiene, Cátedra de Inmunología, Av. Alfredo Navarro 3051, 11600 Montevideo, Uruguay
| | - A Meikle
- Laboratorio de Técnicas Nucleares, Facultad de Veterinaria, Universidad de la República, Lasplaces 1550, Montevideo, Uruguay
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Swiger SL, Payne RD. Selected Insecticide Delivery Devices for Management of Horn Flies (Haematobia irritans) (Diptera: Muscidae) on Beef Cattle. JOURNAL OF MEDICAL ENTOMOLOGY 2017; 54:173-177. [PMID: 28082645 DOI: 10.1093/jme/tjw144] [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] [Received: 04/27/2016] [Accepted: 08/07/2016] [Indexed: 06/06/2023]
Abstract
The horn fly, Haematobia irritans (L.) (Diptera: Muscidae), is one of the most important pests of the beef cattle industry. Horn fly adults are blood feeders that remain in constant contact with cattle, providing management opportunities via insecticide-impregnated ear tags. Controlling horn flies in the United States is time consuming and costly, but failure to implement management can lead to weight loss and decreased weight gain of calves and yearlings. In the past decade, new chemical combinations have been impregnated into ear tags for pest management. The objectives of this project were to 1) evaluate the efficacy of ear tags against horn fly populations and 2) determine if reduced fly density results in economic return. During 2013, data were compiled by insecticide class; treated cows averaged fly reductions of 198 (s = 38.91; n = 3) for macrocyclic lactone treatments, 175 (s = 62.74; n = 4) for pyrethroid treatments, and 174 (s = 35.28; n = 8) for organophosphate treatments compared with untreated animals (214; s = 50.38; n = 9). During 2014, mean fly reductions were 187 (s = 14.15; n = 4) for macrocyclic lactone, 147 (s = 61.41; n = 13) for pyrethroid, and 143 (s = 77.16; n = 8) for organophosphate treatments relative to the untreated (200; s = 99.83; n = 14). A novel technology, the VetGun application system, tested in 2014, resulted in fly reductions (121 ±, n = 4), but means were not statistically significant from the control (200; s = 99.83; n = 14). Treatment of cattle with ear tags significantly reduced horn fly numbers compared with untreated cattle.
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Affiliation(s)
- Sonja Lise Swiger
- Department of Entomology, Texas A&M AgriLife Research and Extension Center, 1229 North US 281, Stephenville, TX 76401
| | - Richard D Payne
- Department of Statistics, Texas A&M University, College Station, TX 77843
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Parra L, Mutis A, Chacón M, Lizama M, Rojas C, Catrileo A, Rubilar O, Tortella G, Birkett MA, Quiroz A. Horn fly larval survival in cattle dung is reduced by endophyte infection of tall fescue pasture. PEST MANAGEMENT SCIENCE 2016; 72:1328-1334. [PMID: 26373352 DOI: 10.1002/ps.4153] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 09/09/2015] [Accepted: 09/12/2015] [Indexed: 06/05/2023]
Abstract
BACKGROUND The potential for using endophytic microorganisms in pest control has increased during the last 40 years. In this study, we investigated the impact of endophyte (Neotyphodium coenophialum) infection of cattle pasture upon the survival of the horn fly, Haematobia irritans, a major agricultural pest affecting livestock in many parts of the world. RESULTS In laboratory assays, where cattle dung collected from endophyte-infected (E+) tall fescue cultivar K-31 was used as the oviposition substrate, larval development was significantly reduced compared with development on cattle dung from steers that grazed uninfected (E-) tall fescue. Furthermore, studies with cattle dung supplemented with the alkaloid fraction extracted from the endophytic fungi revealed significant larval mortality, and HPLC analysis identified two alkaloids, peramine and lolitrem B. The development of larvae was shown to be significantly reduced in field-collected cattle dung. These results suggest that part of the toxicity of alkaloids contained in endophytes is transferred to faecal matter, causing an increase in mortality of H. irritans. CONCLUSION These data suggest that endophyte infection of cattle pasture, i.e. modified pasture management, can significantly affect horn fly development. © 2015 Society of Chemical Industry.
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Affiliation(s)
- Leonardo Parra
- Laboratorio de Química Ecológica, Departamento de Ciencias Químicas y Recursos Naturales, Universidad de La Frontera, Av. Francisco Salazar 01145, Casilla 54-D, Temuco, Chile
| | - Ana Mutis
- Laboratorio de Química Ecológica, Departamento de Ciencias Químicas y Recursos Naturales, Universidad de La Frontera, Av. Francisco Salazar 01145, Casilla 54-D, Temuco, Chile
| | - Manuel Chacón
- Laboratorio de Química Ecológica, Departamento de Ciencias Químicas y Recursos Naturales, Universidad de La Frontera, Av. Francisco Salazar 01145, Casilla 54-D, Temuco, Chile
- Programa de Doctorado en Ciencias de Recursos Naturales, Universidad de La Frontera, Temuco, Chile
| | - Marcelo Lizama
- Laboratorio de Química Ecológica, Departamento de Ciencias Químicas y Recursos Naturales, Universidad de La Frontera, Av. Francisco Salazar 01145, Casilla 54-D, Temuco, Chile
| | - Claudio Rojas
- Instituto de Investigaciones Agropecuarias, Centro Regional de Investigación Carillanca, Temuco, Chile
| | - Adrián Catrileo
- Instituto de Investigaciones Agropecuarias, Centro Regional de Investigación Carillanca, Temuco, Chile
| | - Olga Rubilar
- Departamento de Ingeniería Química, Universidad de La Frontera, Temuco, Chile
| | - Gonzalo Tortella
- Departamento de Ingeniería Química, Universidad de La Frontera, Temuco, Chile
| | - Michael A Birkett
- Biological Chemistry and Crop Protection Department, Rothamsted Research, Harpenden, Herts, UK
| | - Andrés Quiroz
- Laboratorio de Química Ecológica, Departamento de Ciencias Químicas y Recursos Naturales, Universidad de La Frontera, Av. Francisco Salazar 01145, Casilla 54-D, Temuco, Chile
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13
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Smythe BG, Pitzer JB, Wise ME, Cibils AF, Vanleeuwen D, Byford RL. Behavioral Responses of Cattle to Naturally Occurring Seasonal Populations of Horn Flies (Diptera: Muscidae) Under Rangeland Conditions. JOURNAL OF ECONOMIC ENTOMOLOGY 2015; 108:2831-2836. [PMID: 26470391 DOI: 10.1093/jee/tov247] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2015] [Accepted: 07/24/2015] [Indexed: 06/05/2023]
Abstract
The behavioral responses of cattle under the influence of naturally occurring seasonal horn fly, Haematobia irritans (L.), populations were evaluated under rangeland conditions. This study was replicated four times using 10 cows as the subsampling unit equipped with GPS collars scheduled to receive locational fixes every 5 min for 6 d prior to, and 6 d following horn fly insecticidal control application. Data derived from GPS collars were used to evaluate potential horn fly-induced behavioral modifications expressed during predawn, daytime, and nighttime periods. These data were used to analyze variables, which included distance travelled, daily area explored, vertical and horizontal head movements, and inferred activities such as resting, grazing, and walking. Horn fly populations were estimated using daily visual counts and were reduced significantly on animals following insecticidal application. There was no significant difference between treatment periods in any of the aforementioned analyzed variables. During the night-time hours estimated differences (pretreatment minus posttreatment) for distance travelled, area explored, and vertical head movements were 0.81 ± 0.46 km/d, 0.35 ± 0.21 km(2)/d, and 7.25 ± 5.30 counts/d, respectively. The implications of these observations are discussed.
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Affiliation(s)
- Brandon G Smythe
- Center for Animal Health & Food Safety, New Mexico State University, Las Cruces, NM 88003.
| | - Jimmy B Pitzer
- Department of Biological Sciences, University of California, Sacramento, CA 95819
| | - Mark E Wise
- Center for Animal Health & Food Safety, New Mexico State University, Las Cruces, NM 88003
| | - Andres F Cibils
- Department of Animal and Range Sciences, New Mexico State University, Las Cruces, NM 88003
| | - Dawn Vanleeuwen
- Economics, Applied Statistics & International Business Department, New Mexico State University, Las Cruces, NM 88003
| | - Ronnie L Byford
- Center for Animal Health & Food Safety, New Mexico State University, Las Cruces, NM 88003
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Venail R, Lhoir J, Fall M, del Río R, Talavera S, Labuschagne K, Miranda M, Pagès N, Venter G, Rakotoarivony I, Allène X, Scheid B, Gardès L, Gimonneau G, Lancelot R, Garros C, Cêtre-Sossah C, Balenghien T, Carpenter S, Baldet T. How do species, population and active ingredient influence insecticide susceptibility in Culicoides biting midges (Diptera: Ceratopogonidae) of veterinary importance? Parasit Vectors 2015; 8:439. [PMID: 26310789 PMCID: PMC4551713 DOI: 10.1186/s13071-015-1042-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 08/12/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Culicoides biting midges are biological vectors of internationally important arboviruses of livestock and equines. Insecticides are often employed against Culicoides as a part of vector control measures, but systematic assessments of their efficacy have rarely been attempted. The objective of the present study is to determine baseline susceptibility of multiple Culicoides vector species and populations in Europe and Africa to the most commonly used insecticide active ingredients. Six active ingredients are tested: three that are based on synthetic pyrethroids (alpha-cypermethrin, deltamethrin and permethrin) and three on organophosphates (phoxim, diazinon and chlorpyrifos-methyl). METHODS Susceptibility tests were conducted on 29,064 field-collected individuals of Culicoides obsoletus Meigen, Culicoides imicola Kieffer and a laboratory-reared Culicoides nubeculosus Meigen strain using a modified World Health Organization assay. Populations of Culicoides were tested from seven locations in four different countries (France, Spain, Senegal and South Africa) and at least four concentrations of laboratory grade active ingredients were assessed for each population. RESULTS The study revealed that insecticide susceptibility varied at both a species and population level, but that broad conclusions could be drawn regarding the efficacy of active ingredients. Synthetic pyrethroid insecticides were found to inflict greater mortality than organophosphate active ingredients and the colony strain of C. nubeculosus was significantly more susceptible than field populations. Among the synthetic pyrethroids, deltamethrin was found to be the most toxic active ingredient for all species and populations. CONCLUSIONS The data presented represent the first parallel and systematic assessment of Culicoides insecticide susceptibility across several countries. As such, they are an important baseline reference to monitor the susceptibility status of Culicoides to current insecticides and also to assess the toxicity of new active ingredients with practical implications for vector control strategies.
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Affiliation(s)
| | - Jonathan Lhoir
- Cirad, UMR15 CMAEE; INRA, UMR1309 CMAEE, 34398, Montpellier, France.
| | - Moussa Fall
- Institut sénégalais de recherches agricoles (ISRA), BP 1386, Dakar, Senegal.
| | - Ricardo del Río
- Laboratory of Zoology, University of the Balearic Islands (UIB), Km 7.5, Palma de Mallorca, Spain.
| | - Sandra Talavera
- Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Campus de la Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain.
| | - Karien Labuschagne
- Agricultural Research Council - ARC- Onderstepoort Veterinary Institute, Private Bag X5, Onderstepoort, 0110, Republic of South Africa.
| | - Miguel Miranda
- Laboratory of Zoology, University of the Balearic Islands (UIB), Km 7.5, Palma de Mallorca, Spain.
| | - Nonito Pagès
- Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Campus de la Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain.
| | - Gert Venter
- Agricultural Research Council - ARC- Onderstepoort Veterinary Institute, Private Bag X5, Onderstepoort, 0110, Republic of South Africa.
| | | | - Xavier Allène
- Cirad, UMR15 CMAEE; INRA, UMR1309 CMAEE, 34398, Montpellier, France.
| | | | - Laëtitia Gardès
- Cirad, UMR15 CMAEE; INRA, UMR1309 CMAEE, 34398, Montpellier, France.
| | - Geoffrey Gimonneau
- Cirad, UMR15 CMAEE; INRA, UMR1309 CMAEE, 34398, Montpellier, France.
- Institut sénégalais de recherches agricoles (ISRA), BP 1386, Dakar, Senegal.
| | - Renaud Lancelot
- Cirad, UMR15 CMAEE; INRA, UMR1309 CMAEE, 34398, Montpellier, France.
| | - Claire Garros
- Cirad, UMR15 CMAEE; INRA, UMR1309 CMAEE, 34398, Montpellier, France.
| | | | - Thomas Balenghien
- Cirad, UMR15 CMAEE; INRA, UMR1309 CMAEE, 34398, Montpellier, France.
| | - Simon Carpenter
- The Pirbright Institute, Vector-borne Viral Disease Programme, Woking, GU24 0NF, UK.
| | - Thierry Baldet
- Cirad, UMR15 CMAEE; INRA, UMR1309 CMAEE, 34398, Montpellier, France.
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Bergamo LW, Fresia P, Azeredo-Espin AML. Incongruent nuclear and mitochondrial genetic structure of new world screwworm fly populations due to positive selection of mutations associated with dimethyl- and diethyl-organophosphates resistance. PLoS One 2015; 10:e0128441. [PMID: 26030866 PMCID: PMC4451984 DOI: 10.1371/journal.pone.0128441] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 04/27/2015] [Indexed: 11/30/2022] Open
Abstract
Livestock production is an important economic activity in Brazil, which has been suffering significant losses due to the impact of parasites. The New World screwworm (NWS) fly, Cochliomyia hominivorax, is an ectoparasite and one of the most important myiasis-causing flies endemic to the Americas. The geographic distribution of NWS has been reduced after the implementation of the Sterile Insect Technique (SIT), being eradicated in North America and part of Central America. In South America, C. hominivorax is controlled by chemical insecticides, although indiscriminate use can cause selection of resistant individuals. Previous studies have associated the Gly137Asp and Trp251Leu mutations in the active site of carboxylesterase E3 to resistance of diethyl and dimethyl-organophosphates insecticides, respectively. Here, we have sequenced a fragment of the carboxylesterase E3 gene (ChαE7), comprising part of intron iII, exon eIII, intron iIII and part of exon eIV, and three mitochondrial gene sequences (CR, COI and COII), of NWS flies from 21 locations in South America. These markers were used for population structure analyses and the ChαE7 gene was also investigated to gain insight into the selective pressures that have shaped its evolution. Analysis of molecular variance (AMOVA) and pairwise FST analysis indicated an increased genetic structure between locations in the ChαE7 compared to the concatenated mitochondrial genes. Discriminant analysis of principal components (DAPC) and spatial analysis of molecular variance (SAMOVA) indicated different degrees of genetic structure for all markers, in agreement with the AMOVA results, but with low correlation to geographic data. The NWS fly is considered a panmitic species based on mitochondrial data, while it is structured into three groups considering the ChαE7 gene. A negative association between the two mutations related to organophosphate resistance and Fay & Wu’s H significant negative values for the exons, suggest that these mutations evolved under positive selection.
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Affiliation(s)
- Luana Walravens Bergamo
- Center for Molecular Biology and Genetic Engineering (CBMEG), Campinas State University (UNICAMP), Campinas, SP, Brazil
- Department of Genetics, Evolution and Bioagents (DGEB), Institute of Biology (IB), Campinas State University (UNICAMP), Campinas, SP, Brazil
- * E-mail:
| | - Pablo Fresia
- Center for Molecular Biology and Genetic Engineering (CBMEG), Campinas State University (UNICAMP), Campinas, SP, Brazil
| | - Ana Maria L. Azeredo-Espin
- Center for Molecular Biology and Genetic Engineering (CBMEG), Campinas State University (UNICAMP), Campinas, SP, Brazil
- Department of Genetics, Evolution and Bioagents (DGEB), Institute of Biology (IB), Campinas State University (UNICAMP), Campinas, SP, Brazil
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Barros ATM, Schumaker TTS, Koller WW, Klafke GM, Albuquerque TAD, Gonzalez R. Mechanisms of pyrethroid resistance in Haematobia irritans (Muscidae) from Mato Grosso do Sul state, Brazil. ACTA ACUST UNITED AC 2013; 22:136-42. [PMID: 23538495 DOI: 10.1590/s1984-29612013005000016] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Accepted: 02/05/2013] [Indexed: 11/22/2022]
Abstract
Horn fly resistance to pyrethroid insecticides occurs throughout Brazil, but knowledge about the involved mechanisms is still in an incipient stage. This survey was aimed to identify the mechanisms of horn fly resistance to cypermethrin in Mato Grosso do Sul state, Brazil. Impregnated filter paper bioassays using cypermethrin, synergized or not with piperonyl butoxide (PBO) and triphenyl phosphate (TPP), were conducted from March 2004 to June 2005 in horn fly populations (n = 33) from all over the state. All populations were highly resistant to cypermethrin, with resistance factors (RF) ranging from 89.4 to 1,020.6. Polymerase chain reaction (PCR) assays to detect the knockdown resistance (kdr) mutation also were performed in 16 samples. The kdr mutation was found in 75% of the tested populations, mostly with relatively low frequencies (<20%), and was absent in some highly resistant populations. Addition of TPP did not significantly reduce the LC50 in any population. However, PBO reduced LC50s above 40-fold in all tested populations, resulting in RFs ≤ 10 in most cases. Horn fly resistance to cypermethrin is widespread in the state, being primarily caused by an enhanced activity of P450 mono-oxygenases and secondarily by reduced target site sensitivity.
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Barros ATM, Saueressig TM, Gomes A, Koller WW, Furlong J, Girão ES, Pinheiro ADC, Alves-Branco FDPJ, Sapper MDFM, Braga RM, Oliveira AAD. Susceptibility of the horn fly, Haematobia irritans irritans (Diptera: Muscidae), to insecticides in Brazil. REVISTA BRASILEIRA DE PARASITOLOGIA VETERINARIA 2012; 21:125-32. [DOI: 10.1590/s1984-29612012000200010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Accepted: 03/20/2012] [Indexed: 11/22/2022]
Abstract
Since horn fly populations became established throughout Brazil, complaints regarding control failure have increased around the country. A broad survey to evaluate the susceptibility of horn flies to both organophosphate (OP) and pyrethroid insecticides was conducted from October 2000 to April 2003. Bioassays using filter papers impregnated with cypermethrin, permethrin or diazinon were conducted on 154 horn fly populations in 14 states and 78 municipalities. Resistance to cypermethrin, the active ingredient present in most insecticide products for horn fly control in Brazil, was detected in 98.46% of the populations, with resistance ratios (RR) ranging from 2.5 to 719.9. Resistance to permethrin (RRs < 6.3) was found in 96.67% of the populations, despite its lack of use. In general, pyrethroid resistance was detected in 97.18% of the horn fly populations, with frequencies greater than 87% in all regions of the country. The status of susceptibility of horn fly populations in Brazil to insecticides can be characterized by high susceptibility to OPs and widespread resistance to pyrethroids, potentially compromising the efficacy of pyrethroid products in most cases. Although some partial results have previously been presented, a general picture of horn fly susceptibility in Brazil is presented here for the first time.
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Affiliation(s)
| | | | | | | | - John Furlong
- Empresa Brasileira de Pesquisa Agropecuária, Brasil
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