Comparative studies of the efficacy and mode of action of Cypermethrin, Chlorpyrifos and ‘Tofeto’ against Periplaneta americana (L) (Dictyoptera: Blattodea)

Abstract

The American cockroach, Periplaneta americana, is an invasive household pest posing significant public health threats and contributing to home allergen issues. Management is necessary due to its economic and health impacts. Several studies have reported that American cockroaches demonstrate tolerance to certain commercial insecticides, potentially due to physiological factors or specific modes of insecticide application. This study assessed the toxicity of a locally sold insecticide, ‘Tofeto’, and two conventional commercial insecticides, chlorpyrifos and cypermethrin, on adult Periplaneta americana. Efficacy was evaluated by comparing knockdown time (KT100) and lethality time (LT100) following both topical and injection applications. Data were analyzed using one-way Analysis of Variance (ANOVA) and Fisher’s Least Significant Difference (LSD) test. ‘Tofeto’ was identified as the most efficient knockdown agent in both sexes of roaches, regardless of application method. The order of effectiveness observed was Tofeto > cypermethrin > chlorpyrifos. Cypermethrin resulted in quicker lethality via injection. Both injection and topical as says indicated that the cuticular barrier influenced insecticide effectiveness, as KT100 was reduced by 6-79 folds and LT100 by 3-95 folds. Across all assays, ‘Tofeto’ was more effective as knockdown and mortality insecticide than cy permethrin and chlorpyrifos. Therefore ‘Tofeto’ is recommended for the control of cochroaches at home.