Survival of the Fittest: Predator Wasps Breed at the Expense of Spider Juveniles

Feb. 4, 2013 — Two wasp species, Calymmochilus dispar and Gelis apterus, have been recorded as parasitoids on ant-eating spiders in a study published in the open access journal ZooKeys. The host spider, Zodarion styliferum, belongs to the largest genus of predominantly ant-eating spiders. Their distribution area includes Europe, Asia and North Africa, significantly with at least 35 species reported for the Iberian Peninsula only, marking a record in numbers in Portugal, where this study was conducted.

Available data on the biology of the host spider shows that all species of the genus Zodarion are compulsory ant eaters. What is interesting is that these spiders perform aggressive mimicry, i.e. disguise as ants to help them in their hunt and to capture their prey. These crafty hunters are often nocturnal wanderers and mainly active in twilight.

During the day, these spiders remain hidden in carefully built igloo-shaped stone retreats that are attached to the underside of rocks or dead wood. The igloos provide protection against unfavourable environmental conditions and enemies such as ants.

Despite these evolutionary advancements in the fight for survival, however, the Z. styliferum spider turns out to be an easy victim for wasp species in their strive for reproduction.

Continued: http://www.sciencedaily.com/releases/2013/02/130204102432.htm