Effect of abiotic and biotic factors on incidence of pests and predator in cowpea[Vigna unguiculata (L.) walp.]

Field experiments were conducted during Kharif season of 2007-2008. The pest population was recorded in cowpea field aphids, jassid, thrips and pod borer and its highest population 116.20/15 cm shoots tip, 8.6/compound leaves, 5.87/flower bud and 0.73/flower bud and 1.8/pod, respectively. Abiotic factors like temperature, relative humidity, extent and distribution of rainfall, sunshine hour etc. influenced the infestation and stabilization of various insect pests in cowpea. The populations of aphids and pod borer influenced positively relative humidity while those of jassid was affected by temperature and sunshine hour. The negative correlation was found between aphid and maximum temperature, sunshine hour and wind speed; jassid and thrips with relative humidity and pod borer with maximum temperature and wind speed. Coccinella septempunctata was the most abundant predator of cowpea aphid and negatively correlated with aphid population.