Toxicity of insecticidal gel baits against several developmental stages of American cockroach Periplaneta americana (Blattodea: Blattidae)

The American cockroach (Periplaneta americana (L.); Blattodea: Blattidae) is an important peridomestic pest with high significance in public health. This study evaluated the toxicity of eleven gel-based insecticidal gel bait formulations with different modes of action and active ingredients such as abamectin B1, boric acid, clothianidin, dinotefuran, emamectin benzoate, fipronil, imidacloprid, and indoxacarb, against several developmental stages of P. americana (adults of both sexes and nymphs of varying sizes). A completely randomized block design was used to estimate final mortality and median survival times (MSTs) over a 14-day period. Gel baits, preferred for their efficacy in sensitive environments and reduced environmental contamination, demonstrated variable effectiveness. Hotshot (Dinotefuran 0.05%) and Alpine (Dinotefuran 0.5%) did not cause significant mortality (P > 0.05) compared to the control across small and medium nymphal stages. Except for the female adults, these two insecticides were comparatively less effective than others. Combat gel bait (Fipronil 0.01%) and MaxForce FC Magnum (Fipronil 0.05%) exhibited the highest efficacy, achieving the lowest MST of 24-48 hr across all tested stages. All other gel baits were moderately effective for all the developmental stages. Boric acid (33.3%), except for small and large nymphs, was efficient in controlling other stages of P. americana. These findings highlight the potential of fipronil-based gel baits as a reliable tool for managing all the stages of P. americana populations, emphasizing the importance of active ingredient selection for optimal pest control.