Abundance of Heliothis armigera and its natural enemies in cotton intercropped with cereals or legume

A significantly lower number of eggs and larvae was observed on cotton intercropped with corn and sorghum than on cotton monoculture or those with soybean or peanut intercrop at 77 days after planting. Heliothis armigera damages on squares, flowers, and bolls were generally lower on cotton intercropped with corn and sorghum than on those with other intercrops or monoculture. The highest yield of cotton was obtained from cotton intercropped with corn and peanut in dry and wet seasons, respectively. Aphis gossypii, Amrasca biguttula and Anomis flava were the earliest insect pests recorded during the dry and wet seasons. The population of cotton aphids, A. gossypii, was high at the early growth stages of cotton. Population of cotton leafhopper, A. biguttula, as a major pest increased continuously as the cotton plant reached the flowering stage and bolling formation in the dry and wet seasons, respectively. The highest population of semilooper, Anomis flava, was observed at 56 and 42 days after planting in the dry and wet seasons, respectively. Nazara viridula and Dysdercus cingulatus were encountered at 56 days after planting in the dry season while Sylepta derogata and Earias fabia at 35 days after planting in the wet season. The first colonizer predators, Menochilus sexmaculatus and syrphid flies, were present from 28 to 42 days after planting.The most abundant predator was Campylomma livida and its population was high at squaring and boll formation in dry and wet season, respectively. Other insect predators identified with considerable population were Metioche vittaticollis and Anaxipha longipennis and spiders. Two species of parasitoids were found during the wet season: Trichogramma chilonis on eggs and tachinid flies on larvae. However, no parasitoids were found during the dry season. Percent parasitism was higher in cotton intercropped with corn and sorghum. In the laboratory, Harmonia ectomaculata was the most promising predator observed, having consumed the highest number of eggs and larvae. Trichogramma chilonis was so far the most effective egg parasitoid of H. armigera among the four Trichogramma species.