Toxicity and Sublethal Effects of Commonly Used Insecticides on South American Tomato Pinworm, Tuta absoluta Meyrick, 1917 (Lepidoptera: Gelechiidae)

This study investigates the toxicity and sub-lethal effects of four insecticides, flubendiamide, emamectin benzoate+lufenuron, thiocyclam, and spinosad, on third instar larvae, eggs and pupae of Tuta absoluta, a major pest in tomato cultivation. The findings of this study can help inform the development of effective and sustainable pest management strategies for Tuta absoluta in tomato cultivation. The LC50 values of these insecticides was assessed through bioassays, and the results showed varying levels of toxicity depending on the insecticide and the stage of the pest. Spinosad exhibiting the highest toxicity at 7.05 mg a.i/L against third instar larvae, followed by emamectin benzoate+lufenuron (14.24 mg a.i/L), flubendiamide (37.29 mg a.i/L), and thiocyclam (65.17 mg a.i/L). Additionally, the study evaluated the sub-lethal effects of these insecticides, including their impact on demographic parameters such as net reproductive rate (R-0), intrinsic rate of increase (r(m)), finite rate of increase (lambda), mean generation time (T), and doubling time (DT). The results indicated that all tested insecticides demonstrated high efficacy in controlling the larval stage of T. absoluta, while also exhibiting good efficacy against other growth stages, such as eggs and pupae. The larval stage was found to be the most susceptible to insecticides, while the pupal stage exhibited the lowest susceptibility to spinosad and emamectin benzoate+lufenuron. Pest eggs showed the lowest susceptibility to flubendiamide and thiocyclam. Therefore, the study suggests that spinosad and emamectin benzoate+lufenuron are highly toxic against T. absoluta and may be valuable in integrated pest management programs for controlling this pest.