斜纹夜蛾嗅觉反应昼夜节律及其调控机制

Study on circadian rhythms of olfactory response and its regulatory mechanisms in Spodoptera litura

目的:研究斜纹夜蛾嗅觉反应的昼夜节律和调控机制,为更有效的防治提供新的思路和方法。方法:通过测定多种寄主植物气味化合物和性信息素在昼夜8个不同时间点下的斜纹夜蛾触角电位(EAG)反应,发现斜纹夜蛾的EAG反应昼夜节律并筛选出斜纹夜蛾EAG反应最为强烈的化合物,进一步通过风洞技术测定黑暗期5个不同时间点斜纹夜蛾对这些化合物的行为反应,验证其行为昼夜节律;同时通过RT-qPCR技术检测多个调控昼夜节律的时钟基因和嗅觉受体基因在昼夜各个不同时间点的表达水平差异。结果:斜纹夜蛾雄虫对所有测试植物气味化合物和性信息素的EAG反应都表现出双峰模式,即都在黑暗之后3h和9h的反应最为强烈,并筛选出斜纹夜蛾最为敏感的5种化合物:Z9E12-14:OAc、Z9E11-14:OAc、石竹烯、芳樟醇和苯乙醛。斜纹夜蛾在黑暗期5个时间点对这5种化合物行为反应也表现出与EAG反应相类似的夜间节律。从基因表达水平来看,大部分嗅觉受体基因和时钟基因都在黑暗之后3h和(或)9h表达水平达到最高峰值。结论:斜纹夜蛾的嗅觉反应昼夜节律与嗅觉基因和时钟基因表达的昼夜节律大体上是一致的,表明斜纹夜蛾的嗅觉反应节律可能都是由这些时钟基因和嗅觉基因在其体内进行表达调控的。

Objective： To study circadian rhythms of olfactory response and its regulatory mechanisms in Spodoptera litura, providing new insight in controlling this pest. Methods： Electroantennogram （EAG） was used to determine the electrophysiological responses of S. litura to chemicals originated from sex pheromones and host plants at eight different time points during day, finding the circadian rhythms of EAG responses in S. litura and selecting out the compounds to which the moths strongly responded. Then the wind tunnel was used to measure the behavioral responses of S. litura to these compounds at the same five time points during the scotophase. In addition, the expression levels of genes regulating circadian rhythms and olfaction at the same time points were detected by the real-time fluorescence quantitative PCR （RT-qPCR） technique to reveal the molecular regulatory mechanism of olfactory circadian rhythms in S. litura. Results： The results showed that the strongest EAG re- sponses of male S. litura to all tested plant odor compounds and sex pheromone components occurred after 3 hours and 9 hours in the dark, showing a bimodal pattern. A total of five compounds： Z9E 12-14：OAc, Z9E 11-14：OAc, caryophyllene, linalool and phenylacetaldehyde were selected and tested in behavioral responses （wind tunnel）. The behavioral responses of S. litura to the five chemicals at five time points during scotophase showed similar patterns to that obtained from the EAG tests. The expression levels of the most olfactory receptor and clock genes reached the peak after 3 and 9 hours in the dark, which is largely consistent with the circadian rhythms of olfac- tory responses in S. litura. Conclusion： The circadian rhythms of olfactory responses were consistent with those of expression levels of olfactory and clock genes in S. litura, suggesting that the circadian rhythms are probably essentially regulated by clock and olfactory genes.