Evaluation of various Synthetic Insecticides against Thrips (Thrips tabaci) in Bt Cotton
Abstract
Cotton (Gossypium spp.) popularly known as ‘white gold’ is one of the most ancient important cash crop of India . Apart from its value as fibre, it has great potential to be used as edible oil, food f or animals and other by products like particle board and boxes. The development of Bt cotton containing a genetically introgresses endotoxin gene from the gram negative soil bacteria (Bacillus thuringiensis Hubner) represents a significant technological land mark in the global cotton research. Thrips is a major sucking pest on cotton crop, causing quantitative and qualitative losses to cotton. An experiment was conducted at Agriculture Research Station , Sri Ganganagar in Randomized Block Design with 10 treatments including control and replicated three times, to evaluate various insecticides against thrips in Bt cotton. The study revealed that maximum reduction (56.00%) in thrips population was recorded with the treatment of Acephate 75% SP, followed by Imida cloprid 17.8% SL (49.66%). Both the treatments were at par and significantly superior over the other treatments. The phytotoxic effect on crop could not be observed during the experimental period.
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Introduction
Cotton is one of the prominent industrial and economic crops of india. The pest spectrum of cotton crop is quite complex and these pests not only reduce the yield but also adversely affect the quality of lint and seed. The development of Bt cotton containing a genetically introgresses endotoxin gene from the gram negative soil bacteria ( Bacillus thuringiensis Hubner) represents a significant technological land mark in the global cotton research. India adopted this technology i n 2002 -03. Last few decades bollworm attack on cotton was a serious problem but, with the introduction of Bt varieties of cotton this problem has been solved to some extent and a significant change in cropping scheme in the cotton growing areas has been observed (Ahsan & Altaf, 2009). But the problem of sucking insect pests attack is remained unsolved still now. Among them thrips is most destructive sucking pest. Thrips attack cotton crop early in the season, but high population densities can be seen during second fortnight in September (Gupta et al., 1997, Khan et al ., 2008). Both nymph and adult stages of thrips damage the tissue and destroy leaves by sucking cell sap. Due to the attack of this pest, leaves curl up and in the case of several atta ck, plant remains stunted at initial stage. This insect is widely distributed in northern area. The chemical control is the one of the rapid methods to reduce the losses caused by sucking in sect pests to the cotton crop ( Gogi et al., 2006). Many new chemical insecticides are introduced in the market for management thrips therefore, the present study was undertaken to evaluate the various insecticides for management of thrips ( Thrips tabaci ) in Bt cotton.
Conclusion
Thrip population was significantly low in all the plots treated with insecticides over control. Our results suggested that, Acephate 75% SP and Imidacloprid 17.8% SL were proved to be the most effective insecticide resulted in significant reduction of thrip populations as compared to all other insecticides . Both the treatments were at par and significantly superior over the other treatments. The phytotoxic effect on crop could not be observed during the experimental period.