DOI: 10.6084/m9.figshare.11418489.v1
title: Radiation biology of a serious tropical pigeon pea pest, <i>Maruca vitrata</i> (Fabricius) (Lepidoptera: Crambidae) and potential of radiation mediated ‘Inherited (F<sub>1</sub>) Sterility technique’ for the pest suppression

description: <b><i>Purpose:</i></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 (F<sub>1</sub>) Sterility’ technique (modified Sterile Insect technique) to control this serious pigeonpea pest in India. <b><i>Materials and methods:</i></b> Radio-biological investigations involved dose-response studies, at a range of 100-250 Gy, with respect to radiation induced adverse effects on reproductive behaviour in substerilized parent (P<sub>1</sub>) moths, inheritance of sterility and associated metamorphic disruption in F<sub>1</sub> progeny. The reproductive competence of P<sub>1</sub> male moths and their F<sub>1</sub> progeny was evaluated by ascertaining the survival, mating success, sperm transfer and amphimixis of gametes from irradiated male parents and their F<sub>1</sub> progeny. Daily ovipositional and egg fertility profile were evaluated as crucial parameters for simulation modelling for this radio-genetic technique. <b><i>Results:</i></b> Radiation induced check in insemination rate and sterility in P<sub>1</sub> and F<sub>1</sub> generation had a positive correlation with gamma dose. The metamorphic adverse effects in F<sub>1</sub> progeny of substerilized P<sub>1</sub> males were influenced by P<sub>1</sub> irradiation. A higher dose of 200 Gy that resulted in 21.1% fertility in parent cross (P<sub>1</sub>♂x N♀) could form only 14.4% F<sub>1</sub> adults that were all malformed. A gamma dose of 150 Gy (administered to P<sub>1</sub> males) could be considered as a suitable dose for F<sub>1</sub> sterility, that induced 57.4% control of reproduction in parent generation, followed by 72-85% control of reproduction in F<sub>1</sub> progeny involved in three crosses -F<sub>1</sub>♂xN♀, N♂xF<sub>1</sub>♀, F<sub>1</sub>♂xF<sub>1</sub>♀. Daily fertility profile of the eggs laid indicated a marked reduction on 4<sup>th</sup> day onwards during the ovipositional span in P<sub>1</sub> and F<sub>1</sub> generation. High degree of mating competitiveness value (CV) was noticed for 150 Gy irradiated male P<sub>1</sub> moths (0.78-0.93), and their F<sub>1</sub> 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 F<sub>1</sub> progeny in the field cages was observed in comparison to control. <b><i>Conclusion:</i></b> The present study indicated the potential use of a dose of 150 Gy to apply the ‘F<sub>1</sub> sterility’ technique for parabiological suppression of the pigeon pea pod borer. The present findings and reproductive performance of the irradiated moths in F<sub>2</sub> 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 F<sub>1</sub> sterility technique as an integral component.