卷叶螟绒茧蜂寄生棉大卷叶螟的行为及其与寄主密度的关系

Parasitic behavior of Apanteles derogatae Watanabe and its relation to the density of Sylepta derogata Fabricius

卷叶螟绒茧蜂Apanteles derogatae Watanabe是棉大卷叶螟Sylepta derogata Fabricius幼虫期的一种重要内寄生蜂,对棉大卷叶螟种群有较好的控制作用。在实验室条件下,运用人工接虫观察法研究卷叶螟绒茧蜂对棉大卷叶螟幼虫的寄生行为。结果表明,该蜂搜寻寄主的时间平均为2．38 min,处理寄主的时间仅需0．86 min;寄生寄主的最适龄期为寄主2龄幼虫;对1龄幼虫的致死率达32%,但其寄生率仅为16%,其余16%的个体为穿刺致死。饲喂蜂蜜水能显著增加该蜂的产卵量,延长其产卵历期和增强其穿刺能力。寄生蜂的寄生能力与寄主密度的关系呈抛物线型:在寄生蜂均为16头/m^3雌蜂条件下,当寄主密度从80头/m^3增加到320头/m^3时,寄主的被寄生个体数随之增加,但当寄主密度超过320头/m^3后,寄主的被寄生个体数反而随寄主密度的上升呈下降趋势。

Apanteles derogatae Watanabe is major larva endoparasitoid and plays an important role in controlling Sylepta derogata Fabricius. This paper studied the parasitic behavior of A. derogatae with the method of artificial inoculation under laboratory conditions. The results indicated the searching time of the parasitoid was 2.38 min on average and the attacking time was 0. 86 rain. A. derogatae preferred the 2nd instar larvae to other instar larvae. The death rate of the 1st instar larvae of host was 32%, while the parasific rate was only 16%, the other 16% died because of puncturing. It can prolong the parasitism and puncturing time when the parasitoids were fed with honey water solution. The correlation showed a parabolic curve between the parasitic ability of parasitoid and the host density. When parasitoid density was 16/m^3 female, the number of parasitized larvae increased as the increase of host density from 80/m^3 to 320/m^3, but the number of parasitized larvae gradually decreased when the host density increased over 320/m^3.