Radiation Hormesis to Improve the Quality of Adult Spodoptera litura (Fabr.)

SIMPLE SUMMARY: Spodoptera litura (Fabr.) is a serious noctuid lepidopteran pest in India that can be managed using the eco-friendly, radio-genetic inherited sterility (IS) technique. Improving the quality of laboratory-reared moths might increase the efficacy of released sterile moths using this technique. In the present study, radiation hormesis using low-dose ionizing radiation administered to different ontogenetic stages was studied. The growth potential and survival of the developing stages derived from these treated stages was assessed, followed by an assessment of the expression profile of longevity- and viability-related genes. The findings indicated that ionizing radiation doses of 0.75–1.0 Gy might be used as hormetic treatments in eggs, larvae, or the pupal stages of S. litura. This would result in more viable and competitive adult moths for use in the IS technique. ABSTRACT: Mass rearing of insects of high biological quality is a crucial attribute for the successful implementation of sterile insect release programs. Various ontogenetic stages of Spodoptera litura (Fabr.) were treated with a range of low doses of ionizing radiation (0.25–1.25 Gy) to assess whether these gamma doses could elicit a stimulating effect on the growth and viability of developing moths. Doses in the range of 0.75 Gy to 1.0 Gy administered to eggs positively influenced pupal weight, adult emergence, and growth index, with a faster developmental period. The enhanced longevity of adults derived from eggs treated with 0.75 Gy and 1.0 Gy, and for larvae and pupae treated with 1.0 Gy, indicated a hormetic effect on these life stages. Furthermore, the use of these hormetic doses upregulated the relative mRNA expression of genes associated with longevity (foxo, sirtuin 2 like/sirt1, atg8) and viability/antioxidative function (cat and sod), suggesting a positive hormetic effect at the transcriptional level. These results indicated the potential use of low dose irradiation (0.75–1 Gy) on preimaginal stages as hormetic doses to improve the quality of the reared moths. This might increase the efficiency of the inherited sterility technique for the management of these lepidopteran pests.