First Record of Tromatobia sp.1 Associated with the Egg Sacs of Neoscona oaxacensis 2 in Mexico

Tromatobia sp. (Hymenoptera: Ichneumonidae) is reported for the first time associated with Neoscona oaxacensis (Araneae: Araneidae), a spider that exhibits prolonged maternal care of its egg sacs or ovisacs, in Toluca, State of Mexico. The ichneumonid infested 24% of individual ovisacs. The presence of ichneumonid eggs was not documented in the infested ovisacs. Larvae of Tromatobia sp. consumed all the eggs of N. oaxacensis and, close to pupating, built individual cocoons, placing them side by side. For each individual ovisac infested of N. oaxacensis, two to three pupae and/or adults were counted. Adults left the interior of the cocoons through 2 mm diameter holes. This study represents the first trophic interaction occurring between Tromatobia sp. and N. oaxacensis in Mexico.