SEASONAL INCIDENCE AND SPATIAL DISTRIBUTION OF THE COTTON APHID APHIS GOSSYPII GLOVER AND ITS COCCINELLID PREDATORS ON BRINJAL

Abstract

 Studies on the seasonal incidence and spatial distribution of a pest and its associated predators aTC a prerequisite in formulating effective measures for management of the pest. The incidence and distribution pattern of Aphis gossypii Glover and its associated coccinelid predators were evaluated on brinjal (Solanum melogena L. var. Pusa Purple Long) in the experimental field of Life Sciences Department of the University, Various indices of dispersion such as variance, variance to mean ratio, Lloyd's index of Patchiness and mean crowding were evaluated to study their distribution. The distribution of 4 gossypii started during second week of April and extended till first week of August. The coccinellids appeared during first week of May in the field and continued their activities till end of July. A gossypii was observed to follow contagious distribution on the host plant. The coccinellid predators initially followed random distribution but later on followed contagious distribution with increase in density,