The biology ofApanteles medicaginisMuesebeck (hymenoptera: Braconidae)

Abstract

Apanteles medicaginis Muesebeck is an important parasite of the alfalfa caterpillar, Colias philodice eurytheme Boisduval. This small braconid parasite oviposits inside the early host instars and the larva completes its development by the time the Colias caterpillar reaches the late third or fourth instar. At maturity the parasite larva emerges from the caterpillar, spins a small yellowish cocoon and pupates. The wound inflicted by this emergence causes death of the host caterpillar in a very short time. Since the caterpillars are killed before they can feed heavily, this parasite can effectively prevent damage to alfalfa. The genus Apanteles is made up of many species, all of which are endoparasitic on lepidopterous larvae. Throughout the world a large number of species have been reported as parasites of legume-feeding Colias. In North America there are two important species that attack members of the Colias philodice complex; because the two are closely related, Apanteles medicaginis was not separated from A. flaviconchae Riley until 1947. Although morphologically similar, the two are biologically distinct, A. medicaginis being a solitary parasite emerging from the third- or fourth-instar Colias larva, and A. flaviconchae a gregarious species emerging from the fifth instar.