Effects of host sterols on the development and sterol composition of Microplitis demolitor (Hymenoptera: Braconidae) in Heliothis zea (Lepidoptera: Noctuidae)

Investigations were conducted on how changes in the sterol composition of Heliothis zea (Boddie) affected the growth, development, and sterol composition of its hymenopterous endoparasitoid, Microplitis demolitor Wilkinson. When the amount of sterol in the hemolymph of the H. zea larva was decreased by the addition of cholestyramine to its diet, the growth of the hemolymph-feeding parasitoid was inhibited. In contrast, when the amount of sterol in the hemolymph of the H. zea larva was increased by the addition of niacin to its diet, the growth of the parasitoid was normal, probably because its essential dietary sterol was readily available. Such changes in the tissue sterols of the host did not affect the growth and development of M. demolitor , although the sterol composition of the parasitoid was also altered.