Interspecific competition between the invasive species Zaprionus indianus and two Drosophila species (Diptera: Drosophilidae) in their natural hosts

The history of biodiversity is closely related to the history of the evolution of species interactions. Diversity can be reduced by competitive exclusion in species with similar ecology that live in the same spatial region. Zaprionus indianus Gupta is a pest species that has colonized the American continent in the last 20 years. The expansion of this species in Argentina can generate competition, a major event of the ecology of insect communities exploiting ephemeral and fragmented resources. Zaprionus indianus has shown an overlapping in the breeding and feeding resources and in the distribution with Drosophila melanogaster Meigen and D. simulans Sturtevant in north-eastern Argentina. In this study, we analyzed the effect of interspecific competition between larvae of these species reared in cultured media prepared from three natural fruits. Our results revealed that D. simulans has a lower competitive ability with respect to the other species. On the other hand, both the successful colonization of Z. indianus and the differences observed in nature in the relative abundance of these three species between samples of collected and emerged adults cannot be attributed only to effects of interspecific competition.