Radiation biology of a serious tropical pigeon pea pest, <i>Maruca vitrata</i> (Fabricius) (Lepidoptera: Crambidae) and potential of radiation mediated ‘inherited (F₁) sterility technique’ for the pest suppression

<b>Purpose:</b> The impact of gamma radiation on the reproductive biology of the spotted pod borer, <i>Maruca vitrata</i> (Fabr.) (Lepidoptera: Crambidae) was ascertained to explore the potential of the radio-genetic ‘Inherited (F₁) Sterility’ technique (modified Sterile Insect technique) to control this serious pigeonpea pest in India. <b>Materials and methods:</b> Radio-biological investigations involved dose–response studies, at a range of 100–250 Gy, with respect to radiation induced adverse effects on reproductive behavior in substerilized parent (P₁) moths, inheritance of sterility and associated metamorphic disruption in F₁ progeny. The reproductive competence of P₁ male moths and their F₁ progeny was evaluated by ascertaining the survival, mating success, sperm transfer and amphimixis of gametes from irradiated male parents and their F₁ progeny. Daily ovipositional and egg fertility profile were evaluated as crucial parameters for simulation modeling for this radio-genetic technique. <b>Results:</b> Radiation-induced check in insemination rate and sterility in P₁ and F₁ generation had a positive correlation with gamma dose. The metamorphic adverse effects in F₁ progeny of substerilized P₁ males were influenced by P₁ irradiation. A higher dose of 200 Gy that resulted in 21.1% fertility in parent cross (P₁♂x N♀) could form only 14.4% F₁ adults that were all malformed. A gamma dose of 150 Gy (administered to P₁ males) could be considered as a suitable dose for F₁ sterility, that induced 57.4% control of reproduction in parent generation, followed by 72–85% control of reproduction in F₁ progeny involved in three crosses -F₁♂xN♀, N♂xF₁♀, F₁♂xF₁♀. Daily fertility profile of the eggs laid indicated a marked reduction on 4th day onwards during the ovipositional span in P₁ and F₁ generation. High degree of mating competitiveness value (CV) was noticed for 150 Gy irradiated male P₁ moths (0.78–0.93), and their F₁ male progeny (0.70–0.89), released in different sex ratios in the field cages having untreated moths. Reduced relative damage to the pigeon pea plants by the released F₁ progeny in the field cages was observed in comparison to control. <b>Conclusion:</b> The present study indicated the potential use of a dose of 150 Gy to apply the ‘F₁ sterility’ technique for parabiological suppression of the pigeon pea pod borer. The present findings and reproductive performance of the irradiated moths in F₂ generation along with other compatible biorational pest control tactics (that are in progress), might help in formulating an effective integrated pest management module, including the F₁ sterility technique as an integral component.