Department of Entomology and MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, China.
Department of Entomology, Kansas State University, Agricultural Research Center-Hays, Hays, KS, USA.
Pest Manag Sci. 2022 Aug;78(8):3608-3619. doi: 10.1002/ps.7003. Epub 2022 Jun 10.
The entomopathogenic fungus Beauveria bassiana and the egg parasitoid Trichogramma dendrolimi can both contribute to biological control of the global fruit borer Grapholita molesta. To derive insights for optimizing their combined application in augmentation programs, we assayed fungal pathogenicity to both G. molesta (eggs, larvae and adults) and adult parasitoids, and assessed wasp acquisition and transmission of fungal spores following their emergence from B. bassiana-treated host eggs.
Concentrations of 10 conidia mL of B. bassiana and higher caused virtually complete mortality of G. molesta larvae, but less than 30% mortality of eggs, and female moths surviving treatments had reduced fecundity. More than 80% of adult T. dendrolimi survived B. bassiana treatments of 10 conidia mL , and more than 60% survived 10 conidia mL , with surviving females achieving reproductive success equivalent to controls. Parasitoid females preferred healthy eggs over B. bassiana-infected ones in choice tests; wasps emerging from treated eggs carried about 10 conidia each and contributed an additional 11% host mortality in trials combining both agents.
Our results indicate that combined applications of B. bassiana and T. dendrolimi can have complimentary impacts on G. molesta, the wasps compensating for low fungal pathogenicity to eggs and their progeny potentially aiding in subsequent disease transmission. Although foraging wasps tended to avoid infected eggs, negative interactions between the two agents might be further mitigated by timing B. bassiana applications from late instar larva to early moth stage, and T. dendrolimi releases several days later to coincide with peak oviposition periods. © 2022 Society of Chemical Industry.
球孢白僵菌和松毛虫赤眼蜂都能对桃蛀果蛾的生物防治做出贡献。为了深入了解如何优化两者的联合应用，我们测定了真菌对桃蛀果蛾（卵、幼虫和成虫）和成虫寄生蜂的致病性，并评估了寄生蜂在从球孢白僵菌处理过的寄主卵中羽化后对真菌孢子的获取和传播情况。
浓度为 10 个分生孢子/毫升及以上的球孢白僵菌几乎能使桃蛀果蛾幼虫全部死亡，但对卵的死亡率不到 30%，而且幸存的雌蛾产卵量减少。超过 80%的成年松毛虫赤眼蜂能在 10 个分生孢子/毫升的球孢白僵菌处理下存活，超过 60%能在 10 个分生孢子/毫升的处理下存活，幸存的雌蜂达到了与对照相当的生殖成功。在选择试验中，寄生蜂雌蜂更喜欢健康的卵而不是感染了球孢白僵菌的卵；从处理过的卵中羽化出来的蜂携带约 10 个分生孢子，在将两种药剂结合使用的试验中，可额外导致 11%的寄主死亡。
我们的结果表明，球孢白僵菌和松毛虫赤眼蜂的联合应用对桃蛀果蛾可能会产生互补的影响，寄生蜂对卵及其后代的低真菌致病性起到补偿作用，从而可能有助于随后的疾病传播。虽然觅食蜂往往会避开感染的卵，但通过将球孢白僵菌的应用时间从幼虫后期推迟到成虫早期，并在几天后释放松毛虫赤眼蜂以与产卵高峰期相吻合，可以进一步减轻两种药剂之间的负交互作用。 © 2022 化学工业协会。
