Effect of infection and gonotrophic cycle on Aedes aegypti behavior and preferences

Targeting gravid females through chemical lures is a promising strategy in vector control; however, it requires the understanding of the factors susceptible to alter female oviposition behaviour. Here, we evaluated the effect of infection with chikungunya virus (CHIKV) and the number of gonotrophic cycles (GCs) on oviposition activity in Ae. aegypti. Dual choice oviposition assays were performed, where dodecanoic acid, pentadecanoic acid, n-heneicosane and a Sargasssum fluitans (Børgesen) Børgesen extract were tested in uninfected females and females infected with CHIKV, at the 1st and 2nd GC. Infected females displayed a lower percentage of oviposition and a higher number of eggs laid at the 1st GC. Then, combined effects of GC and CHIKV induced the preference towards the tested candidates to either increase or decrease with a chemical-dependent effect. These results allow a deeper understanding of the mechanisms involved in oviposition site selection and highlight the need for taking into account physiological stage changes to increase the control programs efficacy.

利用化学诱饵靶向雌蚊是媒介生物防控领域极具前景的策略，但该方案的落地需明晰可干扰雌蚊产卵行为的各类影响因素。本研究以埃及伊蚊（Aedes aegypti，简称Ae. aegypti）为研究对象，评估了基孔肯雅病毒（chikungunya virus, CHIKV）感染以及生殖营养周期（gonotrophic cycles, GCs）数量对其产卵活性的影响。实验设置了双选择产卵行为测试：针对第1、第2个生殖营养周期的未感染雌蚊与基孔肯雅病毒感染雌蚊，分别测试十二烷酸、十五烷酸、正二十一烷以及马尾藻（Sargasssum fluitans (Børgesen) Børgesen）提取物的诱集效果。结果显示，感染病毒的雌蚊在第1个生殖营养周期时产卵率更低，但单雌产卵总量更高；进一步分析发现，生殖营养周期与基孔肯雅病毒感染的联合作用，会使受试候选化学物质的产卵偏好性出现升或降的变化，且该效应呈现化学物质依赖性。本研究结果深化了学界对产卵位点选择相关机制的认知，同时强调在开展媒介生物防控项目时，需纳入雌蚊生理阶段变化因素，以提升防控方案的实施效能。