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Capsicum is generally infested with many biotic agents mainly sucking insects, among them the major is aphid (Myzus persicae). Chemical management is one of the most common strategies for their management. However, there are no recommended insecticides for insect management in polyhouse. An experiment was designed to assess the bio-potency of four popularly used insecticides (Imidacloprid-17.8SL, Acephate-75SP, Dimethoate-30EC and Buprofezin-25SC), a botanical (Neem oil 10000 ppm) and two entomopathogenic fungi (Metarhizium anisopliae 1.15%WP and Lecanicillium lecanii 1.15%WP) for two consecutive seasons. Most effective and the highest reduction of aphid population (78.14–81.92 %) were found in imidacloprid (17.8SL) treated plots. This effective molecule imidacloprid was further studied for its dissipation pattern under polyhouse and open condition and found that the imidacloprid residues in capsicum fruit dissipated below quantification limit (BQL) within 10days after final spray and the residues in the soil sampled at harvest time were found below the detection level. The half-lives of imidacloprid were 1.88 and 2.61 days under polyhouse and 1.07 and 1.52 days in open field at recommended doses (25 g a.i. ha−1) and double doses (50 g a.i. ha−1) of application respectively. The dietary exposure of imidacloprid on capsicum fruit under both conditions exposed that hazard quotient (HQ) values obtained from the different treatment doses have not exceeded the upper limit of toxicity (HQ < 1) and imidacloprid residues in the fruits were found below the existing MRL (Maximum Residue Limit) values (0.5 mg/kg) at 3 days after its final applications. Thus, imidacloprid may be considered as the effective chemical management option against aphids in capsicum under polyhouse and open field having no harmful effect on human consumption.
Ningarajappa et al. (Thu,) studied this question.