卵跳小蜂Ooencyrtus nezarae Ishii对豆缘蝽和豆璧蝽卵的选择性和密度反应

摘要

本文研究了卵跳小蜂对豆缘蝽(R.clavatus Thunberg)和豆璧蝽(P.hybneri Gmelin)卵的选择性和密度反应.在自由选择试验中,两种豆蝽卵中羽化的卵跳小蜂在不同的卵密度和比例中均选择豆缘蝽;而在非选择性试验中,从豆璧蝽中羽化的卵跳小蜂同时选择豆缘蝽和豆璧蝽卵,寄生率较高;然而,从豆缘蝽卵羽化的卵跳小蜂对豆璧蝽卵的寄生率非常低.嗅觉试验表明,从豆缘蝽卵上释放的气味对卵跳小蜂的搜寻和寄生行为影响很大.卵跳小蜂寄生的卵数量随着豆缘蝽和豆璧蝽卵密度的增加而提高;然而,卵跳小蜂对豆璧蝽的寄生率随着卵的密度增加而降低,尤其是从豆缘蝽卵中羽化的寄生蜂.研究还表明,卵跳小蜂在大田中对豆缘蝽卵的寄生存在着空间或时间上的障碍.%The preference and density response tests of egg parasitoid, Ooencyrtus nezarae Ishii, to the eggs of soybean stick bugs, Riptortus clavatus Thunberg and Piezodorus hybneri Gmelin, were carried out in this study. In the free choice test, O. nezarae emerged from both eggs of stick bug prefer R. clavatus eggs only in the various ra tios of host egg densities. In non-choice test, O. nezarae emerged from P. hybneri eggs parasitize both R. clavatus and P. hybneri eggs, showing a high parasitism on host eggs. However, O. nezarae reared on R. clavatus eggs had a significantly lower parasitism on the eggs of P. hybneri. Olfactometer test showed that the odor emitted from R. clavatus eggs had a great influence on the host searching and parasitizing behavior of O. nezarae. The number of R. clavatus and P. hybneri eggs parasitized by O. nezarae gradually increased with the increase of host egg densi ties. However, the parasitism of O. nezarae to R. clavatus eggs decreased with the increase of host density. The parasitism of O. nezarae are significantly lower ( P ＜ 0.05) on host egg P. hybneri under the laboratory condition,especially for O. nezarae emerged from R. clavatus eggs. This research results implied that in the soybean field,there were some optimal or spatial barriers for O. nezarae to fmd R. clavatus eggs efficiently.