Abstract:The detection of water sources is crucial for insects such as mosquitoes to avoid desiccation and survive. In addition, mosquitoes use humidity cues to successfully navigate the environment to find a suitable oviposition site. Previous studies have implicated some members of the ionotropic receptor family in humidity sensing by Drosophila. Here, we investigate if IR8a co-receptor mediates water detection in Aedes aegypti mosquitoes. Using a simple behavioral assay, we examined the attraction of Ir8a mutant mos… Show more
“…5c ), which suggests that when mosquitoes were more drawn to water the mortality was even lower during the assay. We speculate that mutants with reduced olfactory receptor function may be more attracted to water sources, as has been previously seen in Ir8a mutants 21 .…”
Section: Resultssupporting
confidence: 63%
“…5a and Supplementary Fig. 5b ), and may suggest that Gr3 cfp/cfp mutants may also exhibit increased water attraction similar to Ir8a mutants 21 . Fig.…”
Where a female mosquito lays her eggs creates the conditions for reproductive success. Here we identify a communal behavior among ovipositing female mosquitoes. When choosing equal breeding sites, gravid Aedes aegypti aggregate more often than expected. This aggregation occurs when water contact is restricted and does not require the presence of eggs. Instead, the aggregation is regulated by the number of females present at the breeding site. Using assays with both occupied and empty oviposition sites, we show that the Orco olfactory co-receptor and a carbon dioxide receptor, Gr3, detect the presence of mosquitoes. orco mutants aggregate more often in empty sites, suggesting attractive olfactory cues influence females to associate with one another. Gr3 mutant females do not prefer either site, suggesting that the CO2 receptor is necessary to evaluate mosquito population density at breeding sites. Further, raising CO2 levels is sufficient to cause wild-type mosquitoes to avoid empty oviposition sites. Our results demonstrate that female mosquitoes can regulate their own population density at breeding sites using attractive and repellent communal cues.
“…5c ), which suggests that when mosquitoes were more drawn to water the mortality was even lower during the assay. We speculate that mutants with reduced olfactory receptor function may be more attracted to water sources, as has been previously seen in Ir8a mutants 21 .…”
Section: Resultssupporting
confidence: 63%
“…5a and Supplementary Fig. 5b ), and may suggest that Gr3 cfp/cfp mutants may also exhibit increased water attraction similar to Ir8a mutants 21 . Fig.…”
Where a female mosquito lays her eggs creates the conditions for reproductive success. Here we identify a communal behavior among ovipositing female mosquitoes. When choosing equal breeding sites, gravid Aedes aegypti aggregate more often than expected. This aggregation occurs when water contact is restricted and does not require the presence of eggs. Instead, the aggregation is regulated by the number of females present at the breeding site. Using assays with both occupied and empty oviposition sites, we show that the Orco olfactory co-receptor and a carbon dioxide receptor, Gr3, detect the presence of mosquitoes. orco mutants aggregate more often in empty sites, suggesting attractive olfactory cues influence females to associate with one another. Gr3 mutant females do not prefer either site, suggesting that the CO2 receptor is necessary to evaluate mosquito population density at breeding sites. Further, raising CO2 levels is sufficient to cause wild-type mosquitoes to avoid empty oviposition sites. Our results demonstrate that female mosquitoes can regulate their own population density at breeding sites using attractive and repellent communal cues.
“…In H. armigera , knockout of IR8a reduced the EAG responses and trend behavior to acetic acid ( Zhang et al, 2021 ). Additionally, IR8a was found to be essential to detect human odors and water detection in Aedes aegypti ( Raji et al, 2019a , b ). Meanwhile, IR40a , IR93a and IR25a mediate the humidity preference in D. melanogaster ( Enjin et al, 2016 ).…”
The insect chemosensory system plays an important role in many aspects of insects’ behaviors necessary for their survival. Despite the complexity of this system, an increasing number of studies have begun to understand its structure and function in different insect species. Nonetheless, the chemosensory system in the orange spiny whitefly Aleurocanthus spiniferus, as one of the most destructive insect pests of citrus in tropical Asia, has not been investigated yet. In this study, the sensillum types, morphologies and distributions of the male and female antennae of A. spiniferus were characterized using scanning electron microscopy. In both sexes, six different sensilla types were observed: trichodea sensilla, chaetica sensilla, microtrichia sensilla, coeloconic sensilla, basiconic sensilla, and finger-like sensilla. Moreover, we identified a total of 48 chemosensory genes, including 5 odorant-binding proteins (OBPs), 12 chemosensory proteins (CSPs), 3 sensory neuron membrane proteins (SNMPs), 6 odorant receptors (ORs), 8 gustatory receptors (GRs), and 14 ionotropic receptors (IRs) using transcriptome data analysis. Tissue-specific transcriptome analysis of these genes showed predominantly expression in the head (including antennae), whereas CSPs were broadly expressed in both head (including the antennae) and body tissue of adult A. spiniferus. In addition, the expression profiling of selected chemosensory genes at different developmental stages was examined by quantitative real time-PCR which was mapped to the transcriptome. We found that the majority of these genes were highly expressed in adults, while AspiORco, AspiGR1, AspiGR2, and AspiIR4 genes were only detected in the pupal stage. Together, this study provides a basis for future chemosensory and genomic studies in A. spiniferus and closely related species. Furthermore, this study not only provides insights for further research on the molecular mechanisms of A. spiniferus-plant interactions but also provides extensive potential targets for pest control.
“…A feeding opportunity was presented every 24 hours after the initial feeding for a total of three days. These assays were repeated with the use of mutant lines to assess refeeding potential, which included the following mutants: ionotropic receptor 8a (38), gustatory receptor 3 - Gr3 (40), Ir93a (39), and odorant receptor co-receptor - Orco5 and Orco16 (41) to assess host cue detection. The time until each mosquito bite was recorded to determine the time until initial feeding (bites on day 1) and time until refeeding (days 2-4).…”
Section: Methodsmentioning
confidence: 99%
“…This suggests an early increase in activity and decrease in sleep after a bloodmeal when females do not rest in an environment with sufficient relative humidity to maintain water balance. Increases in activity and host feeding suggest there may be a reconstitution of host-sensing, which we examined through the utilization of mutant mosquitoes with impaired or altered host or humidity detection (38)(39)(40)(41)(42). In general, most of the mutant strains showed a similar response to the control lines, both in the time it took the mosquitoes to feed on the host (Fig.…”
Section: Dry Conditions Increase Activity and Prompt An Early Return ...mentioning
Survival through periods of drought is critical for mosquitoes to reside in semi-arid regions with humans, but water sources may be limited. Previous studies have shown that dehydrated mosquitoes will increase blood feeding propensity, but how this would occur over extended dry periods is unknown. Following a bloodmeal, prolonged exposure to dry conditions increased secondary blood feeding in mosquitoes by nearly two-fold, and chronic blood feeding allowed mosquitoes to survive twenty days without access to water sources. This refeeding did not alter the number of eggs generated, suggesting this refeeding is for hydration and nutrient replenishment. Exposure to desiccating conditions following a bloodmeal resulted in increased activity, decreased sleep levels, and prompted a return of CO2sensing before egg deposition. The increased blood feeding during the vitellogenic stage and higher survival during dry periods are predicted to increase pathogen transmission and explain the elevated levels of specific arbovirus cases during dry conditions. These results solidify our understanding of the role of dry periods on mosquito blood feeding and how mosquito dehydration contributes to vectorial capacity and disease transmission dynamics.
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