Sublethal Effects of Lambda-Cyhalothrin, Imidacloprid, and Indoxacarb on Some of the Behavioral and Physiological Patterns of German Cockroach (Dictyoptera: Blattellidae)

Abstract

German cockroach, Blattella germanica (L.), is a common household pets and a serious global public health risk. This study aimed to investigate the sublethal effects of lambda-cyhalothrin, imidacloprid, and indoxacarb on aggregation behavior, sexual communication, feeding efficiency, bodyweight, and nutritional indices of B. germanica. However, the study showed that the LD10 and LD25 doses of these insecticides impaired aggregation behavior and sexual communication of B. germanica; In addition, the data analyses of Excess Proportion Index (EPI), indicated that the aggregation response and sexual communication of adult cockroaches were decreased due to its exposure to LD10 and LD25 compared to the control treatment (LD0). Although the cockroaches’ food intake increased, their bodyweight decreased after being exposed to LD10 and LD25 compared with the control treatment. Moreover, a negative impact of LD10 and LD25 was observed on some nutritional indices e.g. approximate digestibility (AD), relative growth rate (RGR), and efficiency of conversion of digested food (ECD). On the other hand, the LD10 and LD25 have positively affected on other nutritional indices, including efficient conversion of ingested food (ECI) and relative consumption rate (RCR) when compared with control group. This study showed that the sublethal effects of lambda-cyhalothrin, imidacloprid, and indoxacarb employed to control insect pests widely, have considerable effects on the insect’s behavioral and physiological patterns.