Detection of Centistes sp. (Hymenoptera, Braconidae) from intercepted Diabrotica undecimpunctata (Coleoptera, Chrysomelidae) using CO1 DNA barcodes and larval morphology

Abstract

Globalized trade has resulted in the incidental translocation of numerous insect species, some of which have become invasive in their expanded ranges. While rigorous inspection programs are a regular part of commodity importation, rarely if ever are the internal contents of intercepted insects examined. As part of a genetic diversity project on intercepted Diabrotica undecimpunctata beetles, we detected CO1 DNA that closely matched sequences from Centistes parasitoid wasps in 9% of our samples. The presence of internal parasitoids was confirmed through dissections and imaging, wherein the samples were morphologically consistent with Centistes larvae. Such a discovery suggests that insect translocation as part of trade can be more diverse than initially thought. The case of Centistes in imported Diabrotica may present a positive benefit specifically to agroecosystems through the biological control of pest beetles like Diabrotica. However, drawbacks from such introductions include off-target parasitism of non-pest beetles and resultant impacts to insect populations in undisturbed ecosystems. Thus, examination of intercepted insects beyond the initial species identification is warranted to better understand the potential impacts of human mediated insect translocations. Methods employing high-throughput sequencing and metabarcoding are well suited for such broad-scale identification projects where Diabrotica would be an excellent candidate for this work.