斑痣悬茧蜂寄生对甜菜夜蛾幼虫行为的影响

Behaviors of Spodoptera exigua larvae as affected by parasitization of Meteorus pulchricornis (Braconidae,Hymenoptera)

采用"固定时间间隔扫描抽样"观察法,在大透明罩内观察了被斑痣悬茧蜂寄生和未寄生甜菜夜蛾幼虫的活动、取食和栖境选择行为。结果表明:到寄主幼虫生长后期,被寄生幼虫的取食行为比例(3.74%)极显著低于未被寄生幼虫(15.71%),空间位移比例(8.19%)极显著低于未被寄生幼虫(32.04%),在植物叶正面的比例(47.00%)极显著高于未被寄生幼虫(24.27%),但在叶背面与未被寄生的寄主幼虫无显著差异。在植株的上部、中部和外部,两类寄主幼虫出现的比例直到幼虫生长后期才表现出显著差异。在植株上部和外部,被寄生的寄主幼虫出现的比例(分别为26.09%、5.89%)显著低于未被寄生幼虫(38.88%、17.50%),在植株中部则相反,被寄生幼虫出现的比例(63.57%)显著高于未被寄生幼虫(35.74%);然而在植株的下部,两类寄主幼虫只在幼虫生长前期表现出差异,被寄生的寄主幼虫出现的比例(5.50%)极显著低于未被寄生幼虫(21.96%)。

To understand the adaptation of behaviors of host larvae manipulated by parasitism of parasitoids,we observed behaviors on potted soybean plants of Spodoptera exigua larvae parasitized by Meteorus pulchricornis by using the fixed-interval time scan sampling method. The results showed that up to the later developmental stage,parasitized host larvae were significantly different from healthy host larvae in proportion feeding behavior （ 3. 74% versus 15. 71% ） and proportion spatial displacement （ 8. 19% versus 32. 04% ） . On the upper side of leaves,parasitized host larvae were more often present than the healthy up to the later developmental stage （ 47. 00% versus 24. 27% ） ,but were not different on the under side of leaves. At the top,middle parts and outside of the plant,the two host larvae significantly differed in proportion until the later developmental stage,where the parasitized host larvae appeared less often than the healthy larvae at the top （ 26. 09% versus 38. 88% ） and outside （ 5. 89% versus 17. 50% ） of the plant,while at the middle the parasitized host larvae appeared more often than the healthy larvae （ 63. 57% versus 35. 74% ） . At the lower part of the plant,however,the two host larvae were significantly different at the early developmental stage,where the parasitized host larvae appeared much less often than the healthy larvae （ 5. 50% versus 21. 96% ） . Finally,the adaptive function of behavioral changes in parasitized host larvae was discussed.