ABSTRACT

Laboratory studies that evaluated lethal and sublethal effects of a commercial biopesticide containing Chrysodeixis includens nucleopolyhedrovirus (ChinNPV: Baculoviridae: Alphabaculovirus) infecting different larval ages of soybean looper (SBL), Chrysodeixis includens (Walker) (Lepidoptera: Noctuidae) are presented. Larvae were infected with different concentrations of ChinNPV by droplet feeding (neonates) and diet surface spray bioassays (neonates and third instar). The following biological parameters were evaluated: larval survival at 7- and 14-d post-infection and at moth eclosion; duration of larval, pupal and larval-to-adult periods; larval and pupal weights; sex ratio; moth deformities; fecundity and fertility. A fertility life table was also developed. Results indicated that neonates of SBL did not develop into adults at the highest concentrations of ChinNPV in both bioassays methods. In contrast, a proportion of the exposed larvae survived to adulthood when exposed to the lowest concentrations (neonates) and in all concentrations tested (third instar). SBL neonates surviving exposure to estimated LC₅₀ and LC₇₅ concentrations (droplet feeding bioassays) had low larval weight, reduced fecundity and fertility, altered sex ratio, and produced fewer females per female. Surviving third instar SBL exposed to the highest concentrations showed low weight and sex ratio alterations. Our findings indicated that, beyond lethal effects, the commercially available baculovirus-based insecticide containing ChinNPV also had substantial sublethal effects on neonates and third instar SBL. In field conditions, these sublethal effects can potentially cause a significant impact in the local population dynamics, including reduction in numbers and infestation levels.

摘要

评估含有Chrysodeixis includens核多角体病毒（ChinNPV：杆状病毒科：Alphabaculovirus）的商业生物农药的致死和亚致死效应的实验室研究感染不同年龄的大豆钩虫(SBL)、Chrysodeixis includens(Walker) (鳞翅目：夜蛾科)。通过液滴喂养（新生儿）和饮食表面喷雾生物测定（新生儿和三龄），幼虫被不同浓度的 ChinNPV 感染。评估了以下生物学参数：感染后 7 天和 14 天以及飞蛾羽化时的幼虫存活率；幼虫、蛹和幼虫到成虫的持续时间；幼虫和蛹的重量；性别比例；蛾畸形; 繁殖力和生育能力。还制定了生育生命表。结果表明，在两种生物测定方法中，在最高浓度的 ChinNPV 下，SBL 的新生儿都没有发育成成人。相比之下，当暴露于最低浓度（新生儿）和所有测试浓度（三龄）时，一部分暴露的幼虫存活到成年。SBL 新生儿暴露于估计的 LC₅₀和 LC ₇₅浓度（液滴喂养生物测定）的幼虫体重低，繁殖力和生育力降低，性别比例改变，每只雌性产生较少的雌性。在最高浓度下存活的三龄 SBL 显示出低的体重和性别比改变。我们的研究结果表明，除了致死作用外，市售的含有 ChinNPV 的杆状病毒杀虫剂对新生儿和三龄 SBL 也具有显着的亚致死作用。在野外条件下，这些亚致死效应可能会对当地人口动态产生重大影响，包括数量和感染水平的减少。