Evaluation of pyriproxifen 10 EC against sucking insect pests of cotton.

An investigation was conducted to evaluate the bioefficacy of pyriproxifen 10 EC against sucking insect pests of cotton. At 125g a.i./ha pyriproxifen exhibited very good protection of the crop against sucking pests in both the years(2009-2010 and 2010-2011). The population of leafhoppers, aphids, whitefly and thrips was brought below ETL with 3 sprays of pyriproxifen at 10 days interval at different doses(75,100 and 125 g a.i./ha.). Significant highest seed cotton yield (1331 and 1327 kg/ha) was picked by pyriproxifen @ 125 g a.i./ha during both the years, proving it better than commercial check acetamiprid 20 SP @ 20g a.i./ha and difenthiuron 50 WP @ 300g a.i./ha. Key words; Aphids, cotton, leafhoppers, pyriproxifen, thrips,whitefly The increasing problem of pest resistance to pesticides and environmental pollution due to large scale use of broad spectrum synthetic pesticides necessicitated the use of effective and bio degradable pesticides. Further, new generation insecticides of neonicotinoides group viz., imidacloprid, thiamethoxam and acetamiprid etc have gained importance and are widely used in cotton. For better management of sucking pests in cotton, intervention with newer compounds particularly biorationals is essential. (Richardson and Lagos, 2007). Pyriproxifen 10 EC is one of such biorational and has been proved effective against whitefly (Crowder et al., 2006 ), California red scale(Eliahu et al., 2007), green house whitefly (Trialeurodes vaporariorum), cotton leafworm (Nasr et al., 2010) and tomato leafminer (Tuta absoluta) (Tome et al., 2012). Pyriproxifen 10EC,with lower mammalian toxicity, has been evaluated for its efficacy against sucking insect pests of cotton. MATERIALS AND METHODS The present study was carried out under All India Co ordinated Cotton Improvement Project at College of Agriculture, Indore during kharif, 2009-2010 and 2010-2011 under rainfed conditions, in medium black soil. The experiment was planned in randomized block design, replicated 4 times with 6 treatments in homogenous block with respect to fertility. Pyriproxifen 10 EC was used at 3 dosage i.e. 75,100 and 125 g a.i. /ha in comparison with acetamiprid 20 SP (20 g a.i./ha.), difenthiuron 50 WP (300 g a.i./ha.) and untreated control. The insecticides were sprayed at 10 days interval. The cotton hybrid bunny (NCS 145 Bt) was sown with a spacing of 60×60 cm in a plot size of 6.0×5.2 m. Test chemicals alongwith standard checks were spayed at early stage of infestation i.e. 2 to 5 insects / leaf. Observations on incidence of thirps (Thrips tabaci Lind), Aphids (Aphis gossypii Glover), leafhopper(Amrasca bigutulla bigutulla Ishida) and whitefly (Bemisia tabaci Genn.) were made a day before and 10 days after third last spray. Sucking pests of cotton require many sprays to make their population below ETL. Hence, last observation was considered to observe the effectiveness of insecticides. In each plot 5 plants and 5 leaves / plant (2 lower,2 middle and 1 upper) were randomly selected for observations. In each year, 4 blanket sprays were given to manage the bollworms in all treatments. The seed cotton yield was obtained from each plot and converted into kg/ha. Impact of these chemicals on predators (Coccinellids) activity was also recorded at 10 days after last spray. The data on each parameter have been subjected to statistical J. Cotton Res. Dev. 29 (1) 99-102 (January, 2015)