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Pakistan Journal of Biological Sciences

Year: 2002  |  Volume: 5  |  Issue: 8  |  Page No.: 858 - 861

Resistance and Resurgence Studies of Neem Oil 50% EC Against Rice Brown Planthopper, Nilaparvata lugens (Stål)

N.M. Mozaddedul Haque, M. Fazle Rabbi, A.N.M. Rezaul Karim, Mainul Haq and M.A. Chowdhury

Abstract

Probit analysis showed that the LC50 of Neem oil (NO) 50% EC for two sets of brown planthopper (BPH), Nilaparvata lugens (Stal) (mother population) were 0.202 and 0.224%. The LC50 values of NO 50 % EC to BPH increased by 1.65 folds in the 10th generation of the first set, and also increased 1.63 folds in the 5thand 1.54 folds in 7thgeneration of the second set. These increases may be caused either due to loss of bio-efficacy or inconsistency in killing efficacy of neem oil. After three applications of the treatments, the population of BPH increased in monocrotophos and as well as neem treated plots. However, resurgence ratios among different treatments (NO 3 ml/litre of water, NO 4.5ml/litre of water, monocrotophos and deltamethrin) showed no significant differences. It may be concluded that further studies are needed to recommend neem oil for use commercially to control BPH.

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