Swarming Behavior of Two Parasitic Wasps, Leurus caeruliventris (Hymenoptera: Ichneumonidae) and Conura sp. (Hymenoptera: Chalcididae), at the Same Site

Abstract

Swarming behavior, in which individuals of one sex form groups at sites lacking resources but where they are likely to encounter receptive individuals of the other sex, is common in some orders of insects such as Ephemeroptera and Diptera (Thornhill and Alcock, 1983; Sivinski and Petersson, 1997). For reasons that are unclear it is less common in others, such as Hymenoptera (except, again for apparently unknown reasons, in Formicidae). In the family Braconidae, males of several species of Blacus form swarms (van Achterberg, 1975, 1977). There are scattered reports of swarming in several other species of parasitoids (Godfray, 1994). Because nothing is known of the mating behavior of most species of Ichneumonidae and Chalcididae, especially in the tropics, it seems worthwhile recording brief observations of swarming in two species, Leurus caeruliventris (Cresson) (Ichneumonidae: Metopiinae), and Conura sp. (Chalcidae) in Costa Rica. Leurus are endoparasitic koinobionts of microlepidopterans; L. caeruliventris is a common, widespread species ranging from the United States to Argentina (I. D. Gauld, pers. comm.). Conura is a huge genus (estimated 250–300 species in Costa Rica, .1000 species in the Neotropics) that are parasitoids of the pupae of Lepidoptera, Chrysomelidae, and their primary parasitoids (Delvare, 1995), and also of ichneumonid wasp pupae (Eberhard, 2000).