Biology subjects

Epelboin, Y.

Publications and source records attributed to Epelboin, Y..

4 recordsLinked to original sources

bioRxiv2025

Bridging laboratory and field research: method adjustments to manipulate field-derived Aedes aegypti

Reference strains of Aedes aegypti, reared over numerous generations under laboratory conditions, are selected to fit laboratory conditions and commonly used in research due to their consistency and ease of handling. However, working exclusively with such strains may not fully reflect the traits of natural populations. While working on such strains is relevant in terms of reproducibility between labs, it is also important to perform some work on field-collected mosquitoes and their progeny to capture more representative biological and behavioural variation. In this study, we used the New Orleans reference strain as a control to adjust and evaluate methods to manipulate the F1 progeny of field-collected mosquitoes from Cayenne (French Guiana). To improve blood feeding rate, we tested the impact of several blood feeding systems for mosquitoes kept in a cage or in individual vials and adjusted starvation time. To monitor fertilization, we assessed if dissection buffer affects burst of spermatheca during dissection, whether mosquitoes were collected alive of shortly after death. The results described here may be helpful for studies on mosquito fitness, particularly on field-derived mosquitoes or on experiments requiring individual level monitoring. Author summaryAedes aegypti is the major vector of dengue virus, causing hundreds of millions of cases per year. To fight against disease transmission, mosquitoes are studied in the laboratory, notably using colonies of mosquitoes kept over decades in the laboratory. These reference strains have been selected to fit laboratory conditions and may thus not fully reflect the traits of natural populations. While working on such strains is relevant in a sake of consistency between labs and ease of handling, it is also important to work on field-collected mosquitoes and their progeny to capture more representative biological and behavioural variation. In this study, we adjusted and evaluated methods to manipulate the F1 progeny of field-collected mosquitoes from Cayenne (French Guiana), using the New Orleans reference strain as a control. To improve blood feeding rate, we tested the impact of several blood feeding systems for mosquitoes kept in a cage or in individual vials and adjusted starvation time. To monitor fertilization, we assessed if dissection buffer affects burst of spermatheca during dissection, whether mosquitoes were collected alive of shortly after death. The results described here may be helpful for studies on mosquito fitness, particularly on field-derived mosquitoes or on experiments requiring individual level monitoring.

zoology↗

bioRxiv2024

Extracellular microbes are required for mosquito development even in the presence of Wolbachia

Wolbachia is an endosymbiotic bacterium infecting a wide array of invertebrates that gained attention for its potential to curb the transmission of vector-borne diseases. Its capacity to colonize arthropod populations is generally driven by vertical transmission and reproductive manipulation. In some insect species, Wolbachia additionally became an essential nutritional symbiont, providing vitamins to its host. As mosquito larvae require microbe-derived vitamins for development, we studied whether such a support of Wolbachia would exist in mosquitoes but be masked by the presence of other microbes. We chose Culex quinquefasciatus species to address this question, as it is highly colonized with Wolbachia. We developed a method to produce Culex quinquefasciatus devoid of extracellular microbiota and demonstrated that Wolbachia alone is insufficient to support larval development. Using transient colonization with Escherichia coli, we managed to produce adult Culex quinquefasciatus harboring Wolbachia only. When curbing Wolbachia infection of these E. coli-colonized larvae via tetracycline treatment, we obtained a higher larval development. Together, our data indicate that Wolbachia does not support development but rather acts here as a metabolic burden, and that E. coli is sufficient for development success even in a species that grows in "dirty" water. This opens the way towards gnotobiology studies in Culex quinquefasciatus and highlights the complex relationships between Wolbachia and its mosquito host. Author summaryWolbachia is a bacterium infecting many invertebrates that gained attention for its potential to curb the transmission of vector-borne diseases, such as dengue. In some insect species, Wolbachia provides vitamins to its host. As mosquito larvae require microbe-derived vitamins for development, we studied whether such a support of Wolbachia would exist in mosquitoes but be masked by the presence of other microbes. We chose Culex quinquefasciatus species to address this question, as it is highly colonized with Wolbachia. We developed a method to produce Culex quinquefasciatus devoid of extracellular microbiota and demonstrated that Wolbachia alone is insufficient to support larval development. We transiently colonized these larvae with Escherichia coli to rescue larval development and to produce adults harboring Wolbachia only. When curbing Wolbachia infection of these E. coli-colonized larvae via tetracycline treatment, we obtained a higher larval development. Together, our data indicate that Wolbachia does not support development but rather acts here as a metabolic burden, and that E. coli is sufficient for development success even in a mosquito species that grows in "dirty" water.

microbiology↗

bioRxiv2022

Relevance study of vector competence and insecticide resistance in Aedes aegypti laboratory lines

The urban mosquito species Aedes aegypti is the main vector of arboviruses worldwide. Mosquito control with insecticides is the most prevalent method for preventing transmission in the absence of effective vaccines and available treatments; however, the extensive use of insecticides has led to the development of resistance in mosquito populations throughout the world, and the number of epidemics caused by arboviruses has increased. Three mosquito lines with different resistance profiles to deltamethrin were isolated in French Guiana, including one with the I1016 knock-down resistant allele. Significant differences were observed in the cumulative proportion of mosquitoes with a disseminated chikungunya virus infection over time. In addition, certain genes (CYP6BB2, CYP6N12, GST2, trypsin) were variably overexpressed in the midgut at 7 days after an infectious blood meal in these three lines. Therefore, detoxification enzymes and kdr mutations may contribute to an enhanced midgut barrier and reduced dissemination rate. Our work shows that vector competence for chikungunya virus varied between Ae. aegypti laboratory lines with different deltamethrin-resistance profiles. More accurate verification of the functional association between insecticide resistance and vector competence remains to be demonstrated. ImportanceThree Ae. aegypti lines, isolated from the same collection site, underwent different insecticide selection pressures against deltamethrin under laboratory conditions. As a result, they developed different resistant profiles. In this study, when these lines were fed an artificial infectious blood meal containing chikungunya virus, all three lines including the reference strain showed a high infection rate. There was no statistical difference in infection rate found; however, the dissemination rate of the virus from midgut to head were significantly different. A higher resistance level detected by the WHO test was correlated with a lower viral dissemination rate for each strain. This study presented evidence that the insecticide selection pressure or the existence of insecticide resistance could lead to differences in viral dissemination or even transmission in mosquito populations. We hope that our study can give more insights into understanding the roles of mosquito insecticide resistance on viral transmission.

molecular biology↗

bioRxiv2020

Variation in pyrethroid resistance phenotypes in Anopheles darlingi from residual malaria transmission area: warning on suspected resistance built-up in French Guiana.

Anopheles darlingi is the major vector of malaria in South America. In French Guiana, malaria transmission occurs inland and along the rivers with a particular reemergence in the lower Oyapock area. Control against malaria vector is performed using deltamethrin indoor residual spraying and long lasting impregnated bednets. For four years, the level of resistance to pyrethroids was monitored using CDC bottle tests in An. darlingi populations. Resistance built-up was suspected in a mosquito population in malaria endemic area but did not sustained, supposably due to the reintroduction of susceptible alleles. No mutation on the insecticide target genes was found, metabolic resistance is then suspected.

zoology↗