Nest Defense Behavior Against the Attack of Ants in Colonies of Pre-emergent Mischocyttarus cerberus (Hymenoptera, Vespidae) by Olga Coutinho Togni 1, 2 & Edilberto Giannotti 1, 3, * ABSTRACT he study was carried out at the UNESP Rio Claro campus (SP), where biotests consisting of simulating ant attacks were performed in colonies of Mischocyttarus cerberus. he behaviors of the wasps were recorded with a camcorder, for further analysis. his analysis was done using the Mann-Whit- ney U test and the Principal Component Analysis. In the pre-emergence development stage, colonies with a single foundress defend the nest only ater the irst larvae appear. When there are only eggs in the nest, the wasp abandons the nest. Before leaving, the wasp rubs its gaster against the nest, releasing the ant repellent secretion. When the nest contains larvae or larvae and pupae, the foundress defends the colony, vibrating its wings, pumping her abdomen and biting the ant. Keywords: ants; defense of nest; Mischocyttarus cerberus; pre-emergence stage INTRODUCTION M. cerberus is a primitive eusocial wasp, with no morphological distinc- tion in its castes, whose colonies, of independent foundation and typically monogynic, have an annual biological cycle, which is partially asynchronous regarding the seasons (Giannotti, 1998). Colonies of M. cerberus remain very small through their biological cycle, increasing in size only during a short time period, before leaving the nest in order to start the foundation of new colonies (Giannotti, 1999). Any study on colony defense must comprehend the analysis of predator-prey or host-parasite interactions. Within this context, the vespidae have developed 1 Departmento de Zoologia - Instituto de Biociencias, Universidade Estadual Paulista, Caixa Postal 199; 13506-900, Rio Claro, Sp, Brazil. 2 olguinha@rc.unesp.br 3 edilgian@rc.unesp.br *corresponding author