Designing a Biointensive Module for the Management of Tomato Leafminer, Tuta Absoluta Meyrick (Lepidoptera: Gelechiidae)

Abstract In India, tomato cultivation is highly threatened by the invasive South American tomato leaf miner, Tuta absoluta Meyrick. Application of chemical insecticides is the most commonly recommended practice for the management of T. absoluta. Hence, considering the ill effects of the pesticides on environment, natural enemies and human health, alternate ecofriendly strategies for the management of T. absoluta has to be worked out. Keeping this in view, present investigation was carried out to design a biointensive module for the management of T. absoluta on tomato. Laboratory bioassays with four isolates of B. bassiana and one isolate of M. anisopliae indicated that the B. bassiana isolate (Bb 112) had the lowest LC₅₀ values (0.45 x 105 and 0.77 x 10⁶ spores ml⁻ ¹, respectively) and was highly virulent against both the eggs and larvae of T. absoluta. Among the parasitoids, T. achaeae was found to be more effective (55.00 and 23.27%) followed by T. Chilonis (40.60 and 3.70%) and T. japonicum at (23.60 and 2.32%) at 1:1 ratio against freshly laid eggs of T. absoluta. Based on the laboratory findings, two field trials viz., one at Madampatti and another one at Thondamuthur village of Coimbatore district, Tamil Nadu were conducted during 2020–2021 to evaluate the efficacy of three biointensive modules in comparison with two modules exclusively with insecticides and an untreated control with four replications. Among the modules tested, Module 3 (Pheromone trap @ 40 / ha + T. achaea @ 5 cc / ha + spinetoram 11.7% SC @ 500 ml /ha + cyantraniliprole 10.26 OD @ 150 ml / ha) recorded the highest per cent reduction in larval population (60.02 and 63.08%) and fruit damage (60.58 and 64.96%). The effective BIPM Module 3, identified from the above experiments validated under farmer’s field in Thodamuthur during 2021–2022 showed its consistent efficacy in checking the T. absoluta population (62.48%) and fruit damage (65.87%) followed by farmer’s practice. The tomato fruits harvested from the experimental plots analyzed through QuEChERS method revealed detectable levels of cyantraniliprole residue @ 0.01 mg / kg of tomato and spinetoram @ 0.01 mg / kg of tomato in the plots treated with BIPM module. However, the residue levels did not exceed the CODEX MRL of 0.06 mg / kg of tomato for spinetoram and 0.5 mg / kg of fruiting vegetables for cyantraniliprole. While, in farmer’s practice, the residue level of cyantraniliprole was 0.15 mg /kg of tomato which was 10 fold more than that of the BIPM module.