Department of Plant Protection, Urmia University, Urmia, Iran.
Department of Entomology, Kansas State University, Agricultural Research Center-Hays, Hays, KS.
J Insect Sci. 2020 Nov 1;20(6). doi: 10.1093/jisesa/ieaa129.
Bacillus thuringiensis Berliner subsp. kurstaki (Btk) and Habrobracon hebetor Say are both biological control agents of Helicoverpa armigera Hubner. The present study evaluated their compatibility for combined application against this pest by examining the acceptability of Btk-inoculated hosts for H. hebetor females and testing for negative life-history impacts on developing progeny. Second-instar H. armigera larvae fed for 72 h on potted chickpea plants treated with three concentrations of Btk (LC15, LC35, and LC70) and were then used in bioassays of parasitoid development and parasitism behavior. Survival of parasitoids was significantly reduced, and immature development prolonged, on hosts fed chickpea plants treated with LC35 and LC70 Btk, but not on plants treated with LC15 Btk. Parasitoids failed to discriminate against hosts treated with LC15 or LC35 Btk in choice tests, but attacked fewer hosts treated with LC70 Btk, paralyzing and parasitizing more healthy hosts, and laying more eggs on them. In contrast, a no-choice test revealed that more hosts treated with LC35 and LC70 Btk were paralyzed compared with control or LC15-treated hosts, but the numbers of hosts parasitized and eggs laid did not vary among Btk treatments. Thus, females required an experience with healthy hosts, as they had in the choice test, to discriminate against diseased ones. We conclude that H. hebetor and Btk are compatible for joint application against H. armigera, which could potentially improve biological control of this pest.
苏云金芽孢杆菌亚种 kurstaki（Btk）和阔柄跳小蜂 Habrobracon hebetor Say 都是棉铃虫 Helicoverpa armigera Hubner 的生物防治剂。本研究通过检查 Btk 感染的宿主对 H. hebetor 雌虫的可接受性，并测试对发育后代的负面生活史影响，评估了它们联合应用防治这种害虫的相容性。用三种浓度的 Btk（LC15、LC35 和 LC70）处理盆栽鹰嘴豆植株，处理 72 小时后，取二龄棉铃虫幼虫喂养，然后进行寄生蜂发育和寄生行为的生物测定。在 LC35 和 LC70 Btk 处理的宿主上，寄生蜂的存活率显著降低，未成熟发育延长，但在 LC15 Btk 处理的宿主上则没有。在选择试验中，寄生蜂未能区分 LC15 或 LC35 Btk 处理的宿主，但在 LC70 Btk 处理的宿主上攻击的宿主较少，对健康的宿主麻痹和寄生的更多，在其上产卵也更多。相比之下，在非选择试验中，与对照或 LC15 处理的宿主相比，更多用 LC35 和 LC70 Btk 处理的宿主被麻痹，但用 Btk 处理的宿主被寄生和产卵的数量没有差异。因此，雌蜂需要有健康宿主的经验，就像它们在选择试验中一样，才能区分患病的宿主。我们得出结论，H. hebetor 和 Btk 可以联合应用于防治 H. armigera，这可能会提高对这种害虫的生物防治效果。
