Parasitoids of Drosophilids in the Brazilian Savanna: Spatial-temporal Distribution and Host Associations with Native and Exotic Species

Host-parasitoid interactions may have a relevant role not only in ecological processes but also in human procedures such as biological control and the management of invasive species. Although the Drosophila-parasitoid system has been widely used for investigating all aspects of host-parasitoid relationships, it is still poorly understood in tropical areas. Here, we investigate the richness, spatial-temporal distribution, and host associations of parasitoids attacking drosophilid flies in the core region of the Brazilian Savanna, a hotspot of biodiversity. Using different methods, we collected wasps on several occasions over 7 years and found 13 species representing families associated with drosophilid larvae (Figitidae, Braconidae) and pupae (Pteromalidae, Eurytomidae, Dipriidae). The dominant species infesting larvae and pupae were Dicerataspis grenadensis Ashmead and Pachycrepoideus vindemmiae (Rondani), respectively. Spalangia simplex Perkins was recorded for the first time in the Brazilian Savanna. Although our study was not designed to evaluate collection methods, we observed that they captured different subsets of the wasp community. The spatiotemporal distribution of wasps followed those of drosophilids: they were more abundant in forests and during the rainy season, suggesting that the abundance of hosts, especially native drosophilids, is an important factor determining the assemblage structure and population dynamics of parasitoids. Common parasitoids and drosophilids were associated with more than one host/antagonist species, suggesting that caution should be used for the selection of biological control agents. This study confirms the role and relevance of natural vegetation in preserving biodiversity and ecosystem services, especially in a biome severely threatened by agricultural expansion.