Field efficacy, non-target toxicity and economics of novel systemic molecules against Lipaphis erysimi K. and its seasonal incidence in mustard

Abstract

Population of mustard aphid Lipaphis erysimi Kalt., was observed to buildup from mid December and attained peak after mid January irrespective of plant parts of rapeseed variety Subinoy during 2013–2014 and 2014–2015 at Instructional Farm, Jaguli, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, West Bengal. Minimum temperature, relative humidity and dew point were observed to be positively correlated with population buildup; while, maximum temperature and rainfall showed a negative relationship. The field efficacy of azadirachtin 5% w/w, pyriproxyfen 10 EC, flonicamid 50 WG, acephate 75 SP, dimethoate 30 EC, chlorpyrifos 20 EC, imidacloprid 17.8 SL, thiamethoxam 25 WG, thiacloprid 21.7 SC and acetamiprid 20 SP revealed that flonicamid (84.9 to 94.7% mortality) and pyriproxyfen (81.7 to 93.00%) effectively managed this pest up to 15–18 days followed by imidacloprid (77.5 to 89.00%) and thiacloprid (71.9 to 85.8%) for first 10 days. Azadirachtin and organophosphates showed significant results for first 5–6 days with 44.1 to 56.3% and 52.7 to 74.1% mean population reduction during first and second season, respectively. Flonicamid and pyriproxyfen were found to be comparatively safe to the predators viz. Coccinella septempunctata and Episyrphus balteatus in contrast to others. Highest mean seed yield (16.3 q/ha) was obtained with flonicamid along with 1: 10.06 cost: benefit ratio followed by thiacloprid (1: 8.24), imidacloprid (1: 7.72) and pyriproxyfen (1: 7.55).