The biology and early stages of Acampsis alternipes (Nees), with comments on the relationships of the Sigalphinae (Hymenoptera: Braconidae)

Abstract

Details of the biology of the braconid subfamily Sigalphinae, based on rearings of Acampsis alternipes (Nees), are provided for the first time. A. alternipes is a solitary, koinobiont larval endoparasitoid of the geometrid moth Alsophila Hubner, though there is an external feeding phase prior to spinning a cocoon and pupation. Two features are of potential phylogenetic significance indicating a close relationship with the subfamily Agathidinae: (1) eggs are deposited in the host's nerve ganglia, and (2) the first instar larva is polypodiform. A. alternipes completes development in the autumn and overwinters as a fully eclosed adult within its cocoon, enabling it to emerge and search for hosts early in spring. The posterior of the eclosed adult within the cocoon is immersed in a viscous liquid that also surrounds the meconium. Chemical analysis of this liquid revealed that it comprises at least 25% glycerol and a further 25% consists of various fatty acid derivatives. Oviposition and developmental stages are illustrated. The overwintering behaviour of the agathidine braconid Earinus elator (Fabricius) is described and compared.

Keywords:

• Parasitoid Biology Classification Overwintering