Genetic structure, species limits and evolution of the parasitoid wasp genus Stenocorse (Braconidae: Doryctinae) based on nuclear 3RAD and mitochondrial data

Stenocorse (Braconidae: Doryctinae) is an ectoparasitoid wasp genus widely distributed from southern U.S.A. to central Argentina, which is known to attack over 60 bruchine beetle species that feed on a variety of legumes. This genus currently comprises a single described species, S. bruchivora (Crawford, 1910), though it is probably composed of additional, morphologically similar species. In this study we investigated genetic structure, species limits and evolutionary relationships of sampled populations of Stenocorse obtained along its known geographic distribution, with an emphasis on the Mexican territory. For this, we generated DNA sequences from both the mitochondrial (mt) barcoding locus and nuclear genome data obtained with the 3RAD technique. The Bayesian phylogenetic reconstructions based on the two datasets were mostly congruent, both showing clear geographic structure. Four clusters were recovered with nuclear data, which were also congruent with the geographic distribution of the samples and the species delimitation analyses. We delimited six evolutionary lineages with the two data sources, and three additional species were also delimited with the COI locus alone. Stenocorse probably originated during the mid- to early Miocene, and the diversification events that led to its current species distribution probably occurred between the early Pliocene and late Pleistocene. Our species delineation analyses, phylogenetic reconstructions and rearing records suggest that the species of Stenocorse have generalist feeding habits, contrary to what was expected due to host plant specialization of the bruchine species and the cascading effect that this could have in the species diversification of their parasitoids.