Relative toxicity and insecticide resistance of different field population of tomato leaf miner, Tuta absoluta (Meyrick)

Abstract

South American tomato moth, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), is an oligophagous insect pest that infests solanaceous crops like tomato, brinjal and potato. The incidence of T. absoluta could cause significant yield losses of up to 100% on tomato crop and therefore farmers are following chemical management practices to tackle the pest. However, continuous and indiscriminate usage of certain insecticides may lead to development of resistance in T. absoluta. The aim of the study therefore was to know the level of resistance to different commonly used insecticides viz., indoxacarb14.5SC, flubendiamide 39.35SC, emamectin benzoate 5SG, spinosad 45SC, spinetoram 11.1SC and cyantraniliprole 10.25SC from different field population of T. absoluta viz., Bangalore and Kolar districts ofKarnataka,Madurai and Salemdistricts of Tamil Nadu and Ananthpur district in Andhra Pradesh, India. A variable level of susceptibility of different field population of T. absoluta was noticed against frequently used insecticides viz. flubendiamide 39.35SC, cyantraniliprole 10.25SC and indoxacarb14.5SC. Biochemical assays indicated a significant increase in cytochrome P450 monooxygenase and esterase level in all relatively resistant population of T. absoluta. The cytochrome P450 monooxygenase and esterase enzymes therefore play a major role in the development of resistance in field population of T. absoluta. The reduced susceptibility of T. absoluta to various field collected population thus indicates a development of resistance to various insecticides necessitating the judicious use of chemicals for its management