Differing Success of Defense Strategies in Two Parasitoid Wasps in Protecting their Pupae Against a Secondary Hyperparasitoid

Abstract

During their larval development, endoparasitoids are known to dispose of host resources in several different ways. Some parasitoid wasps consume most or all tissues of the host, whereas others consume a small fraction of host resources and either ensure that the host moves away from the pupation site or allow the host to remain close to the parasitoid cocoon(s). Using a single host species, Mythimna separata Walker (Lepidoptera: Noctuidae), this study compares the success of the two pupation strategies in the solitary parasitoids Microplitis sp. and Meteorus pulchricornis Wesmael (Hymenoptera: Braconidae) against attack from a secondary hyperparasitoid, Gelis agilis F. (Hymenoptera: Ichneumonidae). The caudal appendages of M. separata caterpillars parasitized by Microplitis sp. remain physically attached to parasitoid cocoons and the caterpillars behave aggressively when disturbed. However, after Me. pulchricornis larvae emerge from caterpillars of their host, M. separata, the parasitoid larvae pupate in cocoons that are suspended by a single thick thread that hangs 1–2 cm from under a leaf. In choice tests conducted in petri dishes, significantly fewer cocoons of Microplitis sp. attended by caterpillars than unattended cocoons were hyperparasitized by G. agilis. By contrast, Me. pulchricornis cocoons that were hanging from corn, Zea mays L., plants were hyperparasitized as frequently as those which were attached to leaves. We discuss the potentially different selection pressures generated among natural enemies such as predators and hyperparasitoids in determining optimal pupal defense strategies in primary parasitoids.

Convergent development of a parasitoid wasp on three host species with differing mass and growth potential

“…The cocoons are constructed at the end of a thread and dangle from the leaf. This provides protection against predators like ants (Shirai & Maeto, ), but not against hyperparasitoids (Harvey et al., ).…”

The Biology and Ecology of Parasitoid Wasps of Predatory Arthropods

“…Despite lacking wings, they are apparently capable of parasitizing egg sacs of spiders that have been suspended via threads (89). For example, Gelis agilis females descend head-first down single threads of silk to reach the cocoons of the primary parasitoid Meteorus pulchricornis suspended at the end of them (60). Adult geline females, which attack primary parasitoid hosts, generally have very low fecundity (158) and produce large, yolky anhydropic eggs (92) that require proteins that are generally obtained by host-feeding by the adult female wasps (72).…”

Is direct bodyguard manipulation a parasitoid-induced stress sleep? A new perspective

“…In another system, Thyrinteina leucocerae (Geometridae), parasitized by the parasitoid, Glyptapanteles sp., stops feeding and guards the parasitoid's pupa against predators through violent head swings [16]. Microplitis mediator, a solitary Microgastrinae parasitoid of Mythimna separata (Noctuidae), makes its parasitized host defend hyperparasitoids from their pupae [17,18]. Another species of Microplitis, Microplitis pennatulae, makes its parasitized host Psalis pennatula (Erebidae) guard its pupa against its hyperparasitoid, Brachymeria lasus (Chalcididae) (electronic supplementary material, video file S1) .…”