Population dynamics of leafhopper, Amrasca devastans Distant in Cotton and its relationship with weather parameters

Field trial was conducted to determine the effect of ecological factors on the incidence and development of leafhopper, Amrasca devastans at five different dates of sowing on three varieties of cotton. The pest population was started from third week of February on third weeks old crop and acquired its peak in second week of March on six weeks old crop. Maximum pest population (9.30/3 leaves) was build up at temperature ranged from 21⁰ to 31⁰ C, relative humidity ranges from 82 and 55%, zero rainfall, wind velocity 4.5 km/hr, total sunshine hours (9.00 hrs/week), evaporation (56.10 mm) and dewfall (1.491 mm). The highest incidence of leafhopper population was recorded in cv. MCU 7 followed by SPCH 22 and SVPR 3. Leafhopper population was build up showed a significant and positive correlation with morning and evening relative humidity and rainfall whereas, it was significant and negative association with minimum temperature, wind velocity and dewfall. The determination of effects of different weather factors on population of leafhoppers in cotton was essential for effective pest management.