Suppression of orb-web building behavior of the spider Metazygia laticeps (O. Pickard-Cambridge, 1889) (Araneae: Araneidae) by a new parasitoid wasp

Abstract

Parasitoids may change host behavior in order to improve their survival during the pupal stage. This has been observed in some ichneumonid wasps (Polysphincta genus group), which are able to induce modifications in the movements of host spiders during web construction. These changes usually result in web patterns distinct from those of normal webs of spiders. In this study, we describe the behavioral change in the orb-weaver spider Metazygia laticeps (Araneidae), parasitized by a new species of parasitoid wasp, Polysphincta sinearaneasp. n. (Ichneumonidae), which has a high prevalence in M. laticeps populations. This parasitoid induces behavioral changes in M. laticeps that result in the complete suppression of the normal orb-web structure. The absence of the orb probably reduces accumulation of debris and interception of insects by the webs (factors that could result in the rupture of threads that hold the shelter of the web) during the period from cocoon construction to the emergence of the adult wasp. Also, the suppression of the normal orb-web structure implies that resources that would have been invested in the web will be available to the larva wasp.