A behavioral guard caste in a primitively eusocial orchid bee, Euglossa viridissima, helps defend the nest against resin theft by conspecifics

Defense castes are know from highly eusocial insects yet have rarely been described in social species with a small colony size. In nests of Euglossa viridissima, an orchid bee exhibiting primitively eusocial behavior, we recorded one subordinate female per nest to specialize in guarding in the presence of a dominant and a second subordinate who specialized in foraging. Guarding may have arisen as a response to cleptobiosis by conspecifics, as nests with a guard more successfully avoided intrusion and resin theft.