Population dynamics of major insect pests of cowpea (Vigna unguiculata L. Walp) and its correlation with different abiotic factors under south Gujarat conditions

Abstract

Investigations were carried out to know the population dynamics of major insect pest of cowpea (Vigna unguiculata L. Walp) and its correlation with different abiotic factors under south Gujarat conditions at Navsari Agricultural University, Navsari during summer 2018. The results revealed that aphid, jassid and whitefly population started from 3 rd week of March reached to a peak level of 3.0 aphid index, 4.66 jassids/leaf and 4.06 whiteflies/leaf respectively. The incidence of cowpea pod borer and spotted pod borer initiated from 4 th WAS i.e. 3 rd week of April (16 th SMW) with the initiation of the flower and pod formation occurs pest population reached to a peak level 2.82 larvae/plant and 2.70 larvae per plant during 8 th WAS (19 th SMW).Then after the pest population declined throughout the cropping period. Almost all the insect pests were found abundant in 2 nd week of May, i.e. 8 th week after sowing. Among various weather parameters, rainfall showed a significantly negative influence on population of almost all pests and morning relative humidity showed a significantly negative influence on population of almost all pests except jassid and H. armigera.