Safety of new generation insecticides to bee pollinators

Abstract

The investigation on “Safety of new generation insecticides to bee pollinators” was conducted at the AICRP on Honey bee and Pollinators, Department of Agricultural Entomology, College of Agriculture, Vellayani during 2012- 2013. The objectives were to determine the safety of newer molecules of insecticides to bee pollinators mainly Apis cerana indica F., Apis mellifera L. and Trigona iridipennis Smith. under laboratory and field conditions. New generation insecticides with label claim, suggested for pest management recommended against defoliators and sucking pests in vegetable ecosystems were chosen for the study. The insecticides selected were chlorantraniliprole 18.5 SC @ 30 g a.i. ha-1, flubendiamide 480 SC @ 75 g a.i. ha-1, emamectin benzoate 5 SG @ 10 g a.i. ha-1, spinosad 45 SC @ 75 g a.i. ha-1, indoxacarb 15.8 SC @ 75 g a.i. ha-1, thiodicarb 75 WP @ 750 g a.i. ha-1, fipronil 5 SC @ 50 g a.i. ha-1 and cartap hydrochloride 50 SP @ 500 g a.i. ha-1 (against defoliators). Acetamiprid 20 SP @ 10 g a.i. ha-1, thiacloprid 21.7 SC @ 30 g a.i. ha-1, imidacloprid 17.8 SL @ 20 g a.i. ha-1, clothianidin 50 WDG @ 20 g a.i. ha-1, buprofezin 25 SC @ 250 g a.i. ha-1, acephate 25 SC @ 292 g a.i. ha-1 were chosen (against sucking pests) with dimethoate 30 EC @ 200 g a.i. ha-1 as insecticidal check and untreated check. Laboratory evaluation of the two sets of new generation insecticides showed that chlorantraniliprole 18.5 SC @ 30 g a.i. ha-1, emamectin benzoate 75 g a.i. ha-1 and spinosad 45 SC @ 75 g a.i. ha-1 recorded low mortality of bees ranging from 9.40 to 20.00 per cent and acetamiprid 20 SP @ 10 g a.i. ha-1, imidacloprid 20 g a.i. ha-1 and buprofezin 250 g a.i. ha-1 recorded the per cent mortality ranging between 17.23 and 34.60 per cent. These new generation insecticides along with cartap hydrochloride 50 SP @ 500 g a.i. ha-1 and dimethoate 30 EC @ 200 g a.i. ha-1 were selected for field evaluation in culinary melon (C. melo var. acidulus). Prior to the evaluation of new generation insecticides, the number of flower visitors/ pollinators recorded on culinary melon was found to be 15. Of these, the important groups were hymenoptera (40 per cent), coleoptera (20 per cent), lepidoptera (16 per cent), diptera (16 per cent) and hemiptera (8 per cent). Highest activity of insect pollinators were recorded under pesticide free condition. Maximum foraging activity of bee pollinators was recorded during 10 AM to 11 AM. A. c. indica was the dominant bee pollinator in culinary melon. Foliar application of the selected new generation insecticides done at 10 per cent flowering showed that chlorantraniliprole 18.5 SC @ 30 g a.i. ha-1 and buprofezin 250 g a.i. ha-1 were safe to bee pollinators compared to other insecticides. The foraging activity of bee pollinators observed in terms of their relative abundance and foraging time revealed that there was no significant difference between treatments and untreated check. To conclude, among the new generation insecticides evaluated for their safety to bee pollinators like A. c. indica, A. mellifera and T. iridipennis, chlorantraniliprole 18.5 SC @ 30 g a.i. ha-1 was safe when sprayed against defoliators and buprofezin 25 SC @ 250 g a.i. ha-1 was safe when sprayed against sucking pests of culinary melon (C. melo var. acidulus).