Evaluating Of Synthetic And Neem-based Insecticides For Managing Aphids On Okra (Malvaceae) In Kenya.

Abstract

This field study was conducted to evaluate the efficacy of two synthetic insecticides (Imidacloprid 350 g L-1 (Gaucho FSR) and Lambda-cyhalothrin 17.5 g L-1 (Karate 1.75 ECR), two neem products (Azadirachtin 0.15%w/w (AchookR) and Azadirachtin 0.6% w/w (Neem extractiveR) and a spray alternation of Azadirachtin 0.6% w/w and Lambda-cyhalothrin, in the management of aphids (Aphis gossypii Glover) infesting okra (Abelmoschus esculentus L. Moench). The crop was established in two seasons, December 2003-March 2004 and February-May 2004 at Kibwezi, Eastern Kenya. Imidacloprid was applied as a seed dresser while the other insecticides were foliar applied. The population of live and parasitized aphids was monitored on the leaves and pods of the plants for 9 and 7 weeks, respectively. The number of live and parasitized aphids was significantly (p<0.05) lower in plots treated with Imidacloprid, causing more than 95% aphid reduction. Plots treated with spray alternation of Lambda-cyhalothrin and Azadirachtin 0.6% had higher pest infestation than the other treated plots. Plants in Imidacloprid-treated plots had slightly higher yields than in other treatments. The results of this present study show that neem products are as effective as the synthetic insecticides in the management of aphids infesting okra. The study provides the best alternative of managing aphids` pests in okra that can reduce both the cost of production and chemical residue levels in the produce