SOUJANYA P.L., PRASAD N.V.V.S.D. AND ARJUNA RAO P.

The seasonal occurrence of sucking pests was similar on Bt, stacked Bt and non Bt cotton hybrids and the population means did not differ significantly. The initial incidence of aphids was recorded on 34th standard metrological week (SMW) and the peak incidence was observed during 39th SMW to 46th SMW. The incidence of leafhoppers showed an increasing trend from 39th SMW onwards crossing the ETL during 42nd to 47th SMW; while the peak incidence was during 35th to 37th SMW for thrips and 44th to 48th SMW week for whiteflies. The incidence of aphids recorded in the Bt, stacked Bt and non Bt hybrids had a positive correlation with most of the weather factors except maximum temperature with which it showed a significant negative correlation. The total influence of all the weather parameters was high and significant on the leafhoppers (59.10 per cent) and thrips (80.5 per cent), while it was non–significant on aphids and whiteflies.