Abstract

A field experiment was conducted during 2004-05 and 2005-06 to study the effect of weather
factors on aphid population in cotton. Aphid population was recorded for the first time in 28th
standard week, which remained active up to Ist standard week having its peak density (18.15/
leaf) in 37th standard week. Weather parameters namely maximum and minimum temperature
and relative humidity showed positive correlation with aphid population and also increased at
the rate of 1.3181, 0.5406 and 0.1939 per leaf with 1o C increase in minimum and maximum
temperature and 1 percent increase in relative humidity, respectively. About 43.71 per cent
variation in the population of aphid were influenced by the all weather parameters including rain
fall. The direct contribution of minimum temperature was substantially positive and highest
(0.510) followed by maximum temperature (0.281). Most of the weather parameters exerted
their indirect contribution to the aphid population through minimum temperature.