Population dynamics of major insect pests of castor, Ricinus communis L. as influenced by weather variables in south-west Haryana

The population dynamics of major insect pests of castor was studied during 2018–19 at CCSHAU RRS, Bawal on castor hybrid DCH 177. Among the major insect pests, castor semilooper, Achaea janata was the first to infest the crop reaching its peak population of 6 larvae per plant in 35^th SMW. The peak population of Spodoptera litura was 3.4 larvae/plant during 41^st SMW. Peak nymphal population of leafhopper was in 44^th SMW. Maximum capsule damage by castor shoot and capsule borer, Conogethes punctiferalis was during 50^th SMW of 2018. The rainfall (r= 0.688) and relative humidity were positively (r= 0.836) related with A. janata larval population. Maximum temperature (r= 0.900) and bright sunshine hours (r= 0.737) exhibited a positively significant correlation with the larval population of S. litura. Leafhopper nymphal population and capsule damage by C. punctiferalis were negatively influenced by evening relative humidity (r= -0.775) and rainfall (r= -0.505) and maximum (r= -0.698) and minimum temperature (r= -0.828), respectively. Regression analysis revealed that the weather variables exhibited a significant effect on the population dynamics of the pests with adjusted coefficients of determination to the tune of 0.67, 0.90, 0.58 and 0.67 for A. janata, S. litura, E. flavescens and C. punctiferalis, respectively.