Efficacy, Biological and Biochemical Impacts of selected Bacillus thuringiensis-Based and Synthetic Bioinsecticides on the Black Cutworm, Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae)

Abstract

<title>Abstract</title> The black cutworm, <italic>Agrotis ipsilon</italic> , is a destructive lepidopteran pest with a broad host range and a strong capacity to develop resistance to conventional insecticides, posing a major threat to tomato production. This study evaluated the field and laboratory efficacy, sublethal biological effects, and oxidative stress responses induced by selected bioinsecticides, including <italic>Bacillus thuringiensis</italic> (Bt) formulations (Dipel-DF® and Protecto®), spinosad (Tracer®), emamectin benzoate (Proclaim®), and spinetoram (Radiant®), against second-instar <italic>A. ipsilon</italic> larvae during two consecutive growing seasons (2022–2023). Field-laboratory trials revealed that spinetoram, emamectin benzoate, and spinosad consistently exhibited high efficacy, with mean mortality rates exceeding 97%, whereas Bt formulations showed strong initial activity followed by a pronounced decline over time. Laboratory bioassays demonstrated that Cry1C shortened larval duration but prolonged pupal development and altered sex ratio, while Dipel-DF® and Protecto® significantly delayed development, reduced pupation and adult emergence, and suppressed reproductive performance in a dose-dependent manner. Biochemical analyses indicated significant modulation of catalase and superoxide dismutase activities, particularly at early exposure intervals, reflecting oxidative stress responses. Overall, the results support integrating bioinsecticides with distinct modes of action, especially spinetoram and emamectin benzoate, into sustainable integrated pest management programs targeting <italic>A. ipsilon</italic> .