Impact of Weather Parameters on the Incidence of Pink Boll worm, Pectinophora gossypiella (Saunders) on Bt and non-Bt Varietal Cottons

摘要

Studies on impact of weather parameters on the incidence of pink bollworm, Pectinophora gossypiella (Saunders) on Bt and non-Bf varietal cottons were carried out under Department of Entomology, Agricultural College, Bapatla at Regional Agricultural Research Station, Lam, Guntur during two seasons, kharif20Q9-0 and kharif '2010-11. Pink bollworm larval population and their damage to locules was completely absent on stacked Bt cotton hybrids (RCH 2 BGII and Mallika BG11) compared to high larval population (0.50-11.50 larvae/25 green bolls) and locule damage (0.51 -18.59% 125 green bolls) in non-Bt (L 604) during 49* (Dec. 3-9)- 8* (Feb. 19-25) std. weeks with its peak (11.50 larvae and 18.59 per cent) during 8* std. week. The favourable weather parameters that influences the build up of high population of pink bollworm (6lh to 8* std. weeks) are in the range of maximum and minimum temperatures 31-33 and 17-19°C, morning and evening relative humidities 82-92 and 42-56 per cent, and the rainfall 0-4mm. Maximum temperature and evening relative humidity exerted significant positive (r= 0.673**) and significant negative influence (r= -600*) on the pink bollworm incidence in L 604 non-Bt, respectively. All the weather variables (viz., maximum and minimum temperatures, morning and evening relative humidities, and rainfall) together contributed to 68.7 per cent variation in pink bollworm larval population significantly (RMJ.687*) in L 604 non-5r. Of the five variables, minimum temperature was found to have significant influence on variation of larval population.