The natural history and behavior of Hymenoepimecis argyraphaga (Hymenoptera: Ichneumonidae) a parasitoid of Plesiometa argyra (Araneae: Tetragnathidae)

摘要

Larvae of the koinobiont ectoparasitoid Hymenoepimecis argyraphaga Gauld used a series of different adaptations as they matured to hold onto the abdomen of their host spider. Plesiometa argyra, its web, and the larval cocoon: the first instar did not leave the egg chorion, which was glued to the spider by the female wasp when she oviposited; the second instar used two pairs of ventral abdominal protuberances to help hold onto both the first larva's molted cuticle and to what was probably a sheet of coagulated spider hemolymph that adhered to the larva and to wounds that it made on the spider's abdomen; the early final instar grasped the shed second instar cuticle that remained attached to the coagulated hemolymph with the ventral surface of is abdomen; and the late final instar used a row of mobile dorsal protuberances with sharply curved spines that grasped lines of a unique web that the larva induced the spider to spin just before killing it, and then the larva'a own cocOon silk. The pupa used a pair of toothed protuberances at the tip of the abdomen to stay at the upper end of its cocoon. Other aspects of the wasp's biology that are described include infanticide by adult females; aculeate-like lack of use of the ovipositor to oviposit; manipulation of host web-spinning behavior, apparently by means of a fast-acting larval secretion with long-term effects; manipulation of host bleeding; alternative tactics in attacks on spiders; use of pheromones by females to attract males; cocoon spinning behavior; and a bias to parasitize female rather than male spiders.