Bio efficacy of newer isecticides against leaf hopper, empoasca motti pruthi in bitter gourd

Abstract

Bio efficacy of newer insecticides was evaluated by two field experiments at the College of Horticulture, Vellanikkara during rabi, 2001 and summer, 2002.against major pests of bitter gourd. Imidacloprid (2 g a.i.kg") and acetamiprid (1.5 g a.i.kg") were used as a seed dressers .The newer molecules namely acetamiprid, ethofenprox and imidacloprid were sprayed at different crop stages viz., early vegetative (30 DAS), pre flowering (50 DAS) and fruiting stage (64 DAS) as separate treatments. Acephate was used as a standard check. The present investigation revealed that acetamiprid (1.5 g a. i. kg") was the most effective insecticide as seed dressers against sap feeders viz., leaf hoppers and aphids. Foliar spray application revealed that both imidacloprid (20 g a.i.ha") and acetamiprid (10 g a.i. ha") consistently effective in reducing the sucking pests viz., leaf hopper and aphids followed by ethofenprox (50 g a.i.ha") in both the season. Fruiting stage spray by acetamiprid and imidacloprid had registered the lowest fruitfly infestation .The fruit borer infestation was less in the plots, which received the preflowering and fruiting stage insecticide sprays. The highest yield of bitter gourd was recorded in the imidacloprid (pre flowering stage spray) treated plots in both rabi (1 o 1. 66'fruits/Sm2) and summer (1 02. 66fruits/Sm2) seasons. Seed treatment of newer insecticides had no harmful effect 'on soil micro flora (fungi, bacteria and actinomycetes). Population of natural enemies was unaffected by the insecticide applied along with the seed compared to the foliar applications. Studies on the residues of imidacloprid by high performance liquid chromatography indicated that imidacloprid applied at different stage of the crop viz., sowing, early vegetative, preflowering and fruiting stage to bitter gourd resulted no detectable residue in the harvested fruits.