The use of chemical insecticides is the main control method for Blattella germanica worldwide. The prolonged and frequent use of insecticides produced the selection of insecticide-resistant individuals. The German cockroach is one of the most widespread urban pests in Argentina. In the last decades, resistance monitoring studies in this country demonstrated that there is a high prevalence of pyrethroid-resistant populations of B. germanica in the field. In this work, we studied the resistance mechanisms of a field-collected strain of B. germanica at toxicological, enzymatic, and molecular levels. A resistance ratio of 100 was obtained for the resistant strain when it was exposed to β-cypermethrin. The pretreatment with specific synergists (piperonyl butoxide and triphenyl phosphate) led to a significant increase in the toxicity of the pyrethroid, suggesting an involvement of oxidases and esterases in the detoxification of this insecticide. Moreover, esterase and oxidase activities in the resistant strain were 1.5-fold and 2-fold higher respectively, compared to the susceptible individuals. On the other hand, the voltage-gated sodium channel gene of the resistant cockroaches did not show nucleotidic substitutions in the domain II which are associated to knockdown resistance in this species. These results suggest that the main mechanism of resistance of the studied cockroaches' strain is metabolic, mainly due to an increase in the activity of oxidase and esterase enzymes. The results of this work in addition to other reports found in literature show that the extended use of a single active principle for cockroach control promotes the development of resistance leading to control failure in the field. In contrast, integrated pest management strategies include the use of different control tools in addition to chemical insecticides, which delay the appearance of resistance increasing the efficacy of pest control.

化学杀虫剂的使用是世界范围内德国小蠊的主要防治方法。长期和频繁使用杀虫剂产生了对杀虫剂抗药性个体的选择。德国蟑螂是阿根廷最普遍的城市害虫之一。在过去的几十年中，该国的抗药性监测研究表明，该领域的德国双歧杆菌抗拟除虫菊酯种群的流行率很高。在这项工作中，我们研究了田间采集的德国芽孢杆菌菌株的抗性机制在毒理学、酶学和分子水平。抗性菌株暴露于 β-氯氰菊酯时的抗性比为 100。用特定的增效剂（胡椒基丁醚和磷酸三苯酯）预处理导致拟除虫菊酯的毒性显着增加，表明氧化酶和酯酶参与了这种杀虫剂的解毒。此外，与易感个体相比，抗性菌株中的酯酶和氧化酶活性分别高出 1.5 倍和 2 倍。另一方面，抗性蟑螂的电压门控钠通道基因在结构域 II 中没有显示出与该物种的击倒抗性相关的核苷酸取代。这些结果表明，所研究的蟑螂的主要抗性机制 菌株是代谢的，主要是由于氧化酶和酯酶的活性增加。除了文献中发现的其他报告外，这项工作的结果表明，广泛使用单一活性成分来控制蟑螂会促进抵抗力的发展，从而导致该领域的控制失败。相比之下，综合虫害管理策略包括使用除化学杀虫剂之外的不同控制工具，从而延缓抗药性的出现，从而提高害虫防治效果。