黑头酸臭蚁-扶桑绵粉蚧互作影响班氏跳小蜂寄主定位的行为机制

The ecological consequences of mutualistic interactions between ants and honeydew-producing hemipterans are abundant and widespread. Study of effects of the interactions on parasitoids of hemipterans is important to understand the relationships of ants-hemipterans-natural enemies. Currently, many studies have qualitatively and quantitatively described the phenomenon that parasitization is suppressed by the interactions between ants and hemipterans. However, little research has been done to explain how exactly the interactions influence the behavior of parasitoids. Previous studies indicated that interactions between the ghost ants Tapinoma melanocephalum and the invasive mealybugs Phenacoccus solenopsis significantly interfere with the host-location of the parasitoids Aenasius bambawalei. This project will explore the follow aspects: (1) determine the effects of volatile released by host plants induced by ant-mealybug interactions on host-location of parasitoids; (2) test the effects of volatile released mealybugs and honeydew induced by the interactions on host-location of parasitoids; (3) examine the effects of pygidial gland secretions produced by ghost ants on host-location of parasitoids; (4) estimate the effects of visual signal of ghost ants on host-location of parasitoids. These results will not only reveal the behavioural mechanisms by which ant-mealybug interactions interfere with host-location of parasitoids, but also contribute to provide theoretical foundation for the study of interactions of ants-hemipterans-natural enemies, and enemies conservation and utilization.

蚂蚁-半翅目排蜜昆虫互作影响了排蜜昆虫天敌的行为，但这种互作关系影响天敌行为的作用机制还不明确，如果能够明确这种互作关系影响排蜜昆虫天敌行为的机制，将对认识和理解蚂蚁-排蜜昆虫-天敌三者的互作机理具有重要意义。前期的研究发现黑头酸臭蚁与排蜜昆虫-扶桑绵粉蚧互作影响了班氏跳小蜂的寄主定位，而这种互作关系通过何种途径影响其寄主定位还不清楚。本项目拟研究黑头酸臭蚁-扶桑绵粉蚧互作介导的棉花挥发物、扶桑绵粉蚧虫体及蜜露挥发物、黑头酸臭蚁臀腺分泌物以及互作的视觉信号在班氏跳小蜂寄主定位中的作用，以期明确黑头酸臭蚁-扶桑绵粉蚧互作影响班氏跳小蜂寄主定位的行为机制。研究结果将为蚂蚁-排蜜昆虫-天敌三者互作机理的研究奠定理论基础，为全面的认识影响寄生蜂行为的因素提供理论依据，还可为天敌昆虫的保护与利用提供理论参考。

蚂蚁与半翅目排蜜昆虫间的互利互惠是常见的生态学现象，蚂蚁的照看行为抑制了天敌对半翅目昆虫的干扰。然而，已有的研究大多是定性或定量的描述了这一生态学现象，对蚂蚁-半翅目排蜜昆虫互作如何调控天敌的行为仍然缺乏系统的研究。同时，这种互作关系影响天敌寄主定位的作用机制也不清楚。本研究以黑头酸臭蚁-扶桑绵粉蚧互作对班氏跳小蜂寄生率的影响为切入点，利用GC-MS及HPLC测定了互作介导的棉花挥发物、蜜露及黑头酸臭蚁臀腺分泌物和视觉信号在班氏跳小蜂寄主定位中的作用，明确了黑头酸臭蚁-扶桑绵粉蚧互作影响班氏跳小蜂寄主定位的行为机制。研究结果表明，不同为害程度下，棉花挥发物种类和含量均发生了明显的变化。其中1-辛烯-3-酮及2,4,4-三甲基-2-戊烯含量随扶桑绵粉蚧为害程度增加而升高。利用EAG及Y型嗅觉仪测试了差异物质的电生理及行为活性，结果表明班氏跳小蜂对1-辛烯-3-酮及2,4,4-三甲基-2-戊烯具有明显的趋性。研究发现，黑头酸臭蚁的照看行为改变了扶桑绵粉蚧蜜露成分。黑头酸臭蚁照看之后，扶桑绵粉蚧蜜露中蔗糖含量显著上升，葡萄糖含量显著下降；当照看行为被撤除之后，蜜露中蔗糖含量又显著降低，而葡萄糖含量显著增加。这些结果表明扶桑绵粉蚧可以调整蜜露的组成，以响应黑头酸臭蚁对能量物质的需求，从而使二者间的互惠关系得以稳定与持续。进一步的研究发现，扶桑绵粉蚧蜜露组成的改变导致班氏跳小蜂对寄主的搜寻时间显著减少，寿命显著缩短，寄生率显著下降。此外，扶桑绵粉蚧蜜露挥发物对班氏跳小蜂有明显的引诱作用，班氏跳小蜂的搜寻时间、寿命及寄生率随蜜露量的增加而增加，而黑头酸臭蚁对蜜露的搬运抑制了班氏跳小蜂的寄生效能。黑头酸臭蚁臀腺分泌物对班氏跳小蜂有明显的趋避作用，而视觉信号对班氏跳小蜂寄生无明显影响。研究结果为蚂蚁-排蜜昆虫-天敌三者互作机理的研究奠定了理论基础，为全面的认识影响寄生蜂行为的因素提供了理论依据，为寄生性天敌的保护与利用提供了理论参考。