Disease Vector Group, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Box 190, 234 22, Lomma, Sweden.
Parasit Vectors. 2023 Aug 4;16(1):264. doi: 10.1186/s13071-023-05867-1.
Olfaction plays an important role in the selection and assessment of oviposition sites by mosquitoes. Volatile organic compounds (VOCs) associated with potential breeding sites affect the behaviour of gravid mosquitoes, with VOCs from aquatic stages of conspecific mosquitoes influencing and regulating oviposition. The purpose of this study was to conduct a systematic analysis of the behavioural response of gravid Aedes aegypti to conspecific aquatic stage-conditioned water, to identify the associated bioactive VOCs and to determine how blends of these VOCs regulate oviposition site selection and stimulate egg-laying.
Using a multi-choice olfactory oviposition assay, controlling for other sensory modalities, the responses of individual females to water conditioned with different densities of conspecific aquatic stages were assessed. The conditioned water samples from the most preferred density of each aquatic stage were subsequently compared to each other using the same oviposition assay and analysed using an analysis of variance (ANOVA) followed by a Tukey post-hoc test. Using combined gas chromatography and electroantennographic detection or mass spectrometry, bioactive VOCs from the preferred density of each aquatic stage were identified. Synthetic blends were prepared based on the identified ratios of bioactive VOCs in the aquatic stages, and then tested to determine the oviposition choice of Ae. aegypti in a dose-dependent manner, against a solvent control, using a dual-choice assay. This dataset was analysed using nominal logistic regression followed by an odds ratio comparison.
Gravid Ae. aegypti responded stage- and density-dependently to water conditioned with eggs, second- and fourth-instar larvae, and pupal exuviae, but not to water conditioned with pupae alone. Multi-choice assays demonstrated that gravid mosquitoes preferred to oviposit in water conditioned with fourth-instar larvae, over the other aquatic stage-conditioned water. Gravid Ae. aegypti were attracted, and generally stimulated, to oviposit in a dose-dependent manner to the individual identified synthetic odour blends for the different aquatic stages.
Intraspecific VOCs regulate oviposition site selection in Ae. aegypti in a stage- and density-dependent manner. We discuss the need for further studies to evaluate the identified synthetic blends to modulate the odour-mediated oviposition of Ae. aegypti under field conditions.
嗅觉在蚊子选择和评估产卵场所方面起着重要作用。与潜在繁殖地相关的挥发性有机化合物 (VOC) 会影响怀孕蚊子的行为，而同种蚊子水生阶段的 VOC 会影响和调节产卵。本研究的目的是对怀孕埃及伊蚊对同种水生阶段条件水的行为反应进行系统分析，以确定相关的生物活性 VOC，并确定这些 VOC 混合物如何调节产卵地点选择和刺激产卵。
使用多项选择嗅觉产卵测定法，控制其他感觉模式，评估个体雌性对不同密度同种水生阶段条件水的反应。随后，使用相同的产卵测定法比较来自每个水生阶段最受欢迎密度的条件水样本，并使用方差分析 (ANOVA) 进行分析，然后使用 Tukey 事后检验进行比较。使用气相色谱和电触角检测或质谱联用，从每个水生阶段的首选密度中鉴定出生物活性 VOC。根据水生阶段中生物活性 VOC 的鉴定比例制备合成混合物，然后使用双选择测定法，以剂量依赖性方式测试它们对埃及伊蚊产卵选择的影响，与溶剂对照进行比较。该数据集使用名义逻辑回归进行分析，然后进行优势比比较。
怀孕埃及伊蚊对用卵、二龄和四龄幼虫以及蛹蜕-conditioned 的水表现出阶段和密度依赖性的反应，但对单独用蛹-conditioned 的水没有反应。多项选择测定法表明，与其他水生阶段条件水相比，怀孕蚊子更喜欢在第四龄幼虫条件水中产卵。埃及伊蚊在剂量依赖性的情况下被吸引并普遍刺激在单独鉴定的不同水生阶段的合成气味混合物中产卵。
种内 VOC 以阶段和密度依赖的方式调节埃及伊蚊的产卵地点选择。我们讨论了进一步研究的必要性，以评估所鉴定的合成混合物在野外条件下调节埃及伊蚊气味介导的产卵的能力。
