Persistence and toxicity of biopesticides against mustard aphid, Lipaphis erysimi under laboratory and field conditions

Abstract

Studies on the persistence and intrinsic toxicity of biopesticides against mustard aphid, Lipaphis erysimi were carried out at Department of Entomology, CSK Himachal Pradesh Krishi Vishvavidyalaya, Palampur during 2013-14 and 2014-15. The persistent toxicity studies based on PT value for the years 2013-14 and 2014-15 revealed that the order of effectiveness of tested pesticides was malathion (366.7, 366.7) > azadirachtin (336.7, 333.3) > melia (326.7, 323.3) > melia-SFE (300.0, 303.3) > eupatorium-SFE (283.3, 283.3) > eupatorium (280.0, 283.3). The lethal concentrations computed against second instar nymph of L. erysimi revealed that among tested biopesticides, azadirachtin was the most toxic with LC50 and LC90 values of 0.00008 per cent and 0.00037 per cent, respectively followed by malathion (0.0055 and 0.0246%), melia (0.0063 and 0.303%), melia-SFE (0.0097 and 0.0370%), eupatorium (0.0084 and 0.0460%), eupatorium-SFE (0.0119 and 0.0428%) and spinosad (0.0041 and 0.0810 %). Result of this study indicated that among tested biopesticides, azadirachtin proved highly effective and spinosad was least effective against mustard aphid, L. erysimi under field and laboratory conditions.