author(s)
Zarina Abbasi, Riffat Sultana and Muhammad Saeed Wagan

abstract
Investigations were conducted on the effects of abiotic factors such as temperature, humidity and rainfall on population dynamics of aphid on five different wheat varieties such as TD-1, Benazir, TJ-83, QS-4 and NIA Amber at Abbasi farm and Qauid-e-Awam Agriculture Research Institute Larkana Sindh, Pakistan, during 2017 and 2018. The aphid population starts to appear in the first week of January (0.3 aphids/leaf), the aphid count was low in January because of cold but gradually it starts to increase and reached its peak in mid March (mean aphid 54.9 per ten leaves/ear) during 2017 and (mean aphid 44.6 per ten leaves/ear) during 2018. Correlation analysis of aphid population with abiotic components shows that the temperature had a positive effect (r= 0.261), during 2017 and (r= 0.253), during 2018, while the relative humidity played a negative role (r= -0.125) and (r= -0.164), during2017 and 2018, respectively. The cloudness was negative (r= -0.270), during 2017 and positive (r= 0.202), during 2018. Similarly, rainfall had a negative effect (r= -0.282) and (r= -0.035), during 2017 and 2018, respectively. The wind speed showed positive correlation during years, 2017 and 2018 (r= 0.956) and (r= 0.267), respectively.This study suggests that the early sowing of wheat showed the least aphid infestation. The study of the environmental factors and their effects on aphid population is also important for effective pest management.