Lee Shao-Hung Dennis, Zhao Man, Lee Chow-Yang
Department of Entomology, University of California, Riverside, CA, USA.
Henan International Laboratory for Green Pest Control, College of Plant Protection, Henan Agricultural University, Zhengzhou, China.
J Econ Entomol. 2025 Jun 20. doi: 10.1093/jee/toaf124.
The German cockroach, Blattella germanica (L.), is a major urban insect pest primarily controlled by insecticides, including pyrethroid sprays, fipronil baits, and indoxacarb baits. However, widespread pyrethroid resistance increases the probability that cockroaches will survive treatments in the field. Many insecticides are applied concurrently or repetitively on a periodic basis, meaning survivors have the chance to be re-treated, but any lasting physiological effects from initial survival may impact the performance of subsequent treatments. We investigated the effects of sublethal deltamethrin exposure on the susceptibility of susceptible (UCR) and resistant (Ryan) strains of German cockroaches. Ineffective pyrethroid treatment was simulated by treating cockroaches with the LD20 of deltamethrin. Survivors were treated again with the same dose of deltamethrin, a food source containing the LC50 of fipronil, or a food source containing the LC50 of indoxacarb. Both strains of cockroaches experienced greater mortality when treated with deltamethrin 3 d (49.8% to 67.6%), after the sublethal exposure. No impact on fipronil or indoxacarb susceptibility was observed after pre-treatment with deltamethrin. Because surviving a deltamethrin treatment did not induce tolerance to deltamethrin or other insecticides, this suggests no within-generation drawback of current conventional management practices of applying multiple treatments in the same site. Furthermore, sequential exposure to deltamethrin caused greater mortality than expected, indicating that this insecticide may remain useful even if initial efficacy is low. Comprehensive examinations of additional resistant strains treated with formulated products are warranted to understand whether these effects may impact field control.
德国小蠊（Blattella germanica (L.)）是一种主要的城市害虫，主要通过杀虫剂进行控制，包括拟除虫菊酯喷雾剂、氟虫腈饵剂和茚虫威饵剂。然而，广泛的拟除虫菊酯抗性增加了蟑螂在田间处理中存活的可能性。许多杀虫剂会同时或定期重复使用，这意味着幸存者有机会再次接受处理，但最初存活所产生的任何持久生理影响可能会影响后续处理的效果。我们研究了亚致死剂量溴氰菊酯暴露对德国小蠊敏感品系（UCR）和抗性品系（Ryan）敏感性的影响。通过用溴氰菊酯的LD20处理蟑螂来模拟无效的拟除虫菊酯处理。幸存者再次用相同剂量的溴氰菊酯、含有氟虫腈LC50的食物源或含有茚虫威LC50的食物源进行处理。在亚致死暴露后3天，用溴氰菊酯处理时，两个品系的蟑螂死亡率都更高（49.8%至67.6%）。用溴氰菊酯预处理后，未观察到对氟虫腈或茚虫威敏感性的影响。由于在溴氰菊酯处理中存活并未诱导对溴氰菊酯或其他杀虫剂的耐受性，这表明在同一地点进行多次处理的当前常规管理做法在代内没有缺点。此外，连续接触溴氰菊酯导致的死亡率高于预期，这表明即使初始效果较低，这种杀虫剂可能仍然有用。有必要对用制剂处理的其他抗性品系进行全面检查，以了解这些影响是否会影响田间防治。
