Effect of meteorological parameters on population dynamics of rose aphid

The incidence of aphid Macrosiphum rosae was studied on thirty rose cultivars during winter and summer seasons. The pest build up started in the third week of January, which increased gradually, reaching its peak (149.2 aphids/shoot) in the fourth week of February and declined thereafter. Maximum temperature (T_max), minimum temperature (T_min), relative humidity in morning (RH-I) and in the afternoon (RH-II) and bright sunshine hours (BSH) were in the range of 30.3 to 31.5°C, 9.7 to 11.7°C, 85 to 91%, 29 to 31%, 9.6 to 10.1 hrs, respectively which prevailed during February month, appeared to be congenial for multiplication of aphids. Increase in aphid population was found to be positively and significantly correlated with T_max and T_min in phase I, while they were found to have negative and highly significant correlation in Phase-II.