Induction of cocoon webs in the spider Anelosimus jucundus (Araneae: Theridiidae) by the Darwin wasp Zatypota baezae (Hymenoptera: Ichneumonidae)

The larvae of parasitoid wasps of the Polysphincta genus group (Ichneumonidae: Pimplinae), in addition to exploiting their host spiders as a food resource, often also change the web-building behavior of spiders to favor their chances of survival in the pupal stage. In this study, we find that the spider Anelosimus jucundus (Araneae: Theridiidae) is a host of the wasp Zatypota baezae Pádua & Sobczak, 2019 (Hymenoptera: Ichneumonidae), and describe the cocoon webs built by this spider species under the influence of wasp larvae. The cocoon web induced in A. jucundus by Z. baezae consists of an outer web that is closed on almost all sides. Only some areas of the upper, lateral or lower region of the outer web present some openings that lead to the inner region of the web where the wasp's cocoon is built vertically. The construction of the cocoon web occurs gradually, two days before the death of the spider. These behavioral changes induced in A. jucundus are similar to those observed in other species of spiders of the genus Anelosimus induced by other wasps of the genus Zatypota.