Population dynamics of major sucking pests of Bt cotton

The population dynamics of major sucking pests of Bt cotton along with their correlation with weather parameters were studied during kharif 2007–2008 and 2008–2009, at the Experimental Farm, Department of Agricultural Entomology, Marathwada Agricultural University, Parbhani. During kharif 2007–2008 the incidence of aphids was highest (86.45/aphids/3 leaves) during 37th MW. Jassid's highest population (13.80/3 leaves) was observed during 40th MW and thrips reached highest incidence (110.10 thrips/3 leaves) in 40th MW. Highest incidence of whitefly (52.75/3 leaves) was noticed during 45th MW while mealybug's highest incidence (42.40 mealybugs/2.5 cm shoot length) was observed in 51st MW. During kharif 2008–2009 the peak incidence of aphids (75.40/3 leaves) was observed in 35th MW while jassid‘s peak (13.75) was recorded in 39th MW. The peak incidence of thrips (107.65/3 leaves) was recorded in 40th MW and whitefly (63.00 whiteflies/3 leaves) in 45th MW. The peak incidence of mealybugs at 2.25 mealybugs/2.5cm shoot length was noticed in 49th MW. Simple correlation studies revealed that weather parameters viz., rainfall, rainy days, morning RH and evening RH showed significant and negative correlation with aphids and whitefly population while maximum temperature showed significant positive correlation with jassids, thrips and whitefly populations. All weather parameters showed significantly negative correlation with the infestation of mealybugs except maximum and minimum temperatures during kharif 2008–09.