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Erdei AL, David AB, Savvidou EC, Džemedžionaitė V, Chakravarthy A, Molnár BP, Dekker T. The push-pull intercrop Desmodium does not repel, but intercepts and kills pests. eLife 2024; 13:e88695. [PMID: 38477562 PMCID: PMC11021049 DOI: 10.7554/elife.88695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 03/07/2024] [Indexed: 03/14/2024] Open
Abstract
Over two decades ago, an intercropping strategy was developed that received critical acclaim for synergizing food security with ecosystem resilience in smallholder farming. The push-pull strategy reportedly suppresses lepidopteran pests in maize through a combination of a repellent intercrop (push), commonly Desmodium spp., and an attractive, border crop (pull). Key in the system is the intercrop's constitutive release of volatile terpenoids that repel herbivores. However, the earlier described volatile terpenoids were not detectable in the headspace of Desmodium, and only minimally upon herbivory. This was independent of soil type, microbiome composition, and whether collections were made in the laboratory or in the field. Furthermore, in oviposition choice tests in a wind tunnel, maize with or without an odor background of Desmodium was equally attractive for the invasive pest Spodoptera frugiperda. In search of an alternative mechanism, we found that neonate larvae strongly preferred Desmodium over maize. However, their development stagnated and no larva survived. In addition, older larvae were frequently seen impaled and immobilized by the dense network of silica-fortified, non-glandular trichomes. Thus, our data suggest that Desmodium may act through intercepting and decimating dispersing larval offspring rather than adult deterrence. As a hallmark of sustainable pest control, maize-Desmodium push-pull intercropping has inspired countless efforts to emulate stimulo-deterrent diversion in other cropping systems. However, detailed knowledge of the actual mechanisms is required to rationally improve the strategy, and translate the concept to other cropping systems.
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Affiliation(s)
- Anna L Erdei
- Department of Plant Protection Biology, Swedish University of Agricultural SciencesAlnarpSweden
- Department of Chemical Ecology, HUN-REN Centre for Agricultural Research Plant Protection InstituteBudapestHungary
| | - Aneth B David
- Department of Plant Protection Biology, Swedish University of Agricultural SciencesAlnarpSweden
- Department of Molecular Biology and Biotechnology, University of Dar-es-Salaam (UDSM)SalaamUnited Republic of Tanzania
| | - Eleni C Savvidou
- Department of Plant Protection Biology, Swedish University of Agricultural SciencesAlnarpSweden
- Department of Agriculture Crop Production and Rural Environment, University of ThessalyVolosGreece
| | - Vaida Džemedžionaitė
- Department of Plant Protection Biology, Swedish University of Agricultural SciencesAlnarpSweden
| | - Advaith Chakravarthy
- Department of Plant Protection Biology, Swedish University of Agricultural SciencesAlnarpSweden
| | - Béla P Molnár
- Department of Chemical Ecology, HUN-REN Centre for Agricultural Research Plant Protection InstituteBudapestHungary
| | - Teun Dekker
- Department of Plant Protection Biology, Swedish University of Agricultural SciencesAlnarpSweden
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Ioannou CS, Savvidou EC, Apocha L, Terblanche JS, Papadopoulos NT. Insecticide resistant mosquitoes remain thermal stress resistant, without loss of thermal plasticity. Sci Total Environ 2024; 912:169443. [PMID: 38114031 DOI: 10.1016/j.scitotenv.2023.169443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 11/07/2023] [Accepted: 12/15/2023] [Indexed: 12/21/2023]
Abstract
A major component of mosquito's climate change response is their heat tolerance, and any ability to rapidly adjust to extreme environmental conditions through phenotypic plasticity. The excessive use of insecticides for the control of major mosquito species leads to resistant populations, however it is largely unclear if this concurrently impacts thermal stress resistance and their potential to adjust tolerance via phenotypic plasticity. Culex pipiens pipiens, Culex pipiens molestus and Aedes albopictus populations obtained from the same region were subjected for 12 generations to selection trials to larvicides Diflubenzuron (DFB) and Bacillus thuringiensis subsp. israelensis (Bti) to develop insecticide resistance. Adults emerging from the selected populations were acclimated at different temperatures and the upper and lower critical thermal limits (CTmax and CTmin) were estimated using dynamic thermal assays. In addition, the supercooling points (SCPs) of non-acclimated adults of resistant and control populations were determined. Our results revealed marked differences in thermal response among the three species, the different acclimation regimes and sexes. Aedes albopictus was more resistant in high than low temperatures compared to both Culex pipiens biotypes. Culex forms responded similarly to heat but differently to cold stress. In both forms, females responded better than males to all thermal stressors. Acclimation at higher and lower temperatures improves CTmax and CTmin values, respectively in both insecticide resistant and control populations of all three species. Overall, selection to insecticides did not affect the thermal performance of adults. Hence, insecticide-resistant mosquito populations perform similarly to untreated ones and are capable of readily adapting to new environmental changes rising concerns regarding their geographic range expansion and disease transmission globally.
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Affiliation(s)
- Charalampos S Ioannou
- Laboratory of Entomology and Agricultural Zoology, Department of Agriculture, Crop Production and Rural Environment, University of Thessaly, Greece
| | - Eleni C Savvidou
- Laboratory of Entomology and Agricultural Zoology, Department of Agriculture, Crop Production and Rural Environment, University of Thessaly, Greece
| | - Lemonia Apocha
- Laboratory of Entomology and Agricultural Zoology, Department of Agriculture, Crop Production and Rural Environment, University of Thessaly, Greece
| | - John S Terblanche
- Centre for Invasion Biology, Department of Conservation Ecology & Entomology, Stellenbosch University, South Africa
| | - Nikos T Papadopoulos
- Laboratory of Entomology and Agricultural Zoology, Department of Agriculture, Crop Production and Rural Environment, University of Thessaly, Greece.
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Blanco-Sierra L, Savvidou EC, Mpakovasili ED, Ioannou CS, Bartumeus F, Papadopoulos NT. Effect of water salinity on immature performance and lifespan of adult Asian tiger mosquito. Parasit Vectors 2024; 17:24. [PMID: 38238765 PMCID: PMC10797731 DOI: 10.1186/s13071-023-06069-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Accepted: 11/26/2023] [Indexed: 01/22/2024] Open
Abstract
BACKGROUND Aedes albopictus (Skuse, 1894) is a vector for pathogens like dengue, chikungunya, and Zika viruses. Its adaptive capacity enables reproduction in temperate climates and development mainly in artificial containers with fresh water in urbanized areas. Nevertheless, breeding in coastal areas may also occur along with its aggressive invasiveness. Global warming and the consequent rise in sea levels will increase saline (> 30 ppt) or brackish (0.5-30 ppt salt) water in coastal regions. To address whether Ae. albopictus can breed in brackish water, we initiated the current study that analyses the survival of immature stages at different salinity concentrations and explores whether carryover effects occur in the resulting adults. This possible adaptation is important when considering the potential for development in new habitats and expansion of one of the world's most invasive species. METHODS We investigated the influence of salinity on the survival of Ae. albopictus larvae and adults under laboratory-controlled conditions. First instar larvae were exposed to different salinity concentrations (0 to 30 ppt) and their development time, pupation, adult emergence, and overall survival were monitored daily. We used Kaplan-Meier and Cox regression models to analyze the survival rates at different salinity levels. Furthermore, life tables were constructed under each salinity concentration. RESULTS Increasing salt concentrations significantly increased the mortality risk during immature development, while no significant effect was observed on adult mortality risk. A comparison between distilled and bottled water revealed a notable increase in overall mortality risk for individuals developing in distilled water. However, no significant effects were found when analyzing survival from the first larval stage to adult emergence and adult lifespan. The life expectancy of immature stages decreased with increasing salt concentrations, although salinity concentration did not significantly impact adult life expectancy. CONCLUSIONS Our findings suggest that Ae. albopictus, previously considered freshwater species, can successfully develop and survive in brackish waters, even in the absence of characteristic structures found in euryhaline species. These adaptations may enable Ae. albopictus to establish new breeding sites and colonize unexplored territories. Knowledge of these physiological adaptations of Ae. albopictus to salinity should be pursued to increase the range of control of the species, and to make more accurate predictions of its dispersal and vectoring ability.
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Affiliation(s)
- Laura Blanco-Sierra
- Centre d'Estudis Avançats de Blanes (CEAB-CSIC), Carrer d'Accés Cala Sant Francesc, 17300, Blanes, Girona, Spain.
| | - Eleni C Savvidou
- Laboratory of Entomology and Agricultural Zoology, Department of Agriculture, Crop Production and Rural Environment, University of Thessaly, Phytokou Str, 38446, Nea Ionia, Magnesia, Greece
| | - Evangelia D Mpakovasili
- Laboratory of Entomology and Agricultural Zoology, Department of Agriculture, Crop Production and Rural Environment, University of Thessaly, Phytokou Str, 38446, Nea Ionia, Magnesia, Greece
| | - Charalampos S Ioannou
- Laboratory of Entomology and Agricultural Zoology, Department of Agriculture, Crop Production and Rural Environment, University of Thessaly, Phytokou Str, 38446, Nea Ionia, Magnesia, Greece
| | - Frederic Bartumeus
- Centre d'Estudis Avançats de Blanes (CEAB-CSIC), Carrer d'Accés Cala Sant Francesc, 17300, Blanes, Girona, Spain
- ICREA, Institució Catalana de Recerca i Estudis Avançats, Passeig de Lluís Companys, 23, 08010, Barcelona, Barcelona, Spain
- CREAF, Ecological and Forestry Applications Research Centre, Campus de Bellaterra (UAB), 08193, Barcelona, Barcelona, Spain
| | - Nikos T Papadopoulos
- Laboratory of Entomology and Agricultural Zoology, Department of Agriculture, Crop Production and Rural Environment, University of Thessaly, Phytokou Str, 38446, Nea Ionia, Magnesia, Greece
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