Molecular Characterization Of Insecticides Resistance In Key Stored Grain Insect Pests

Abstract

Red flour beetle, T. castaneum (Herbst) (Coleoptera: Tenebrionidae), rice weevil, newlineSitophilus oryzae (L.) (Coleoptera; Curculionidae), and lesser grain borer, Rhyzopertha newlinedominica (Fabricus) (Coleoptera; Bostrichidae) are the major and destructive insect pests newlineof stored cereal grains and allied products globally, including India. They cause newlinesignificant damage to stored grains, rendering them unsuitable for human feeding, newlineprocessing, and export. In India, phosphine fumigation and prophylactic treatment with newlinedeltamethrin (synthetic pyrethroid) and malathion (organophosphate) are employed to newlinemanage these pests. Over the years, the continuous applications of these insecticides have newlineincreased more selection pressure, resulting in the evolution of resistance allele and newlinedevelopment of resistance, posing threat to these insecticides. To address this, the current newlinestudy was conducted to document the resistance against these insecticides, identify newlinepossible mutation conferring resistance to these insecticides, and assess the frequency, newlinedistribution, and gene flow of resistance alleles in T. castaneum, S. oryzae, and R. newlinedominica collected from grain supply chains, Trichy and Theni identified in Tamil Nadu newlineand bulk grain storages of southern India. newlineThe frequency of strong resistance to insecticides was identified in all newlineT. castaneum, S. oryzae, and R. dominica populations. Among the clusters of grain newlinesupply chains, the samples collected from bulk grain storage recorded a high frequency of newlinestrong resistance to phosphine in T. castaneum, S. oryzae, and R. dominica and it was newlineranged from 48.00 to 85.56 per cent, 49.33 to 59.33 per cent and 47.33 to 92.59 per cent, newlinerespectively at high concentration. Two populations of S. oryzae from the retail shop and newlinehousehold storage in grain supply chain-1 were found susceptible to phosphine. Strong newlineresistance to phosphine was estimated in all T. castaneum, S. oryzae, and R. dominica newlinepopulations collected from bulk grain storages of south India. At high concentration (0.25 newlinemg L-1), the frequen