中红侧沟茧蜂对烟草挥发物的触角电生理及行为反应

Electrophysiological and behavioural responses of Microplitis mediator to tobacco plant volatiles

中红侧沟茧峰 Microplitis mediator是棉铃虫 H elicoverpa armigera的主要内寄生蜂 ,是优良的蜂种 ,在生物防治上具有广阔的应用前景。但迄今 ,有关中红侧沟茧蜂的化学生态的研究甚少。利用触角电位技术 ,测定了中红侧沟茧蜂对烟草叶片粗提物和烟草中 10种挥发物的触角电生理反应 ,并测定了中红侧沟茧蜂的触角电位反应随日龄的变化。以嗅觉仪测定了中红侧沟茧蜂对烟草粗提物、烟草中 4种挥发物的行为反应。结果表明中红侧沟茧蜂利用烟草释放的气味向烟草定向 ,进而找到其寄主——棉铃虫 ,也佐证了烟草同样是棉铃虫的重要寄主植物的论点。雌蜂对脂肪族化合物反应最强 ,对芳香族化合物和糠醛 (杂环化合物 )的反应居中 ,对萜类化合物反应较弱或者不反应。表明烟草挥发性物质在中红侧沟茧蜂寻找寄主的过程中起着重要的作用 ,但挥发物各组分的作用存在着差异。雌性中红侧沟茧蜂对顺 - 3-己烯醇的触角电位反应随日龄的增加而变化。 1日龄的雌蜂的反应较弱 ,2日龄、3日龄的雌蜂反应较强 ,4日龄、5日龄的雌蜂的反应又减弱。这与该蜂产卵习性相符 :羽化当天的雌蜂产卵较少 ,羽化 2～

Microplitis mediator (Hymenoptera: Braconidae) is an indigenous parasitoid species attacking larvae of the cotton bollworm, Helicoverpa armigera, in China, and its application in biological control is promising. Knowledge of its chemical ecology is limited. Electroantennograms were recorded from female parasitoids Microplitis mediator to extracts of tobacco plants and 10 tobacco volatile compounds. The EAG responses of (1～5) days old female parasitoids to cis-3-hexen-1-ol were also tested. Their behavioral responses to tobacco extract and 4 tobacco volatile compounds were tested in a four-armed olfactometer. The results indicated that M. mediator oriented to tobacco via volatiles released by tobacco, then found its host, cotton bollworm. Aliphatic compounds elicited strong responses, and aromatic compounds and furfural (heterocyclic compound) elicited moderate responses, while trapezoids elicited the lowest or no responses. It suggested that tobacco volatiles played a vital role in their host-finding behaviour, however, each component played on different role. The EAG responses of (1～5) days old female parasitoids showed the 1-day-old wasps were least responsive, while 2 and 3 day old ones were the most responsive, and the responses of 4 and 5 day parasitoids decreased, which was in accord with oviposition behavior, namely few eggs are laid on the first day after eclosion and most eggs are laid on the second and third days after eclosion.