Integrative species delimitation and preliminary study of host specificity of encyrtid parasitoids associated with psyllids in China

In the family Encyrtidae (Hymenoptera, Chalcidoidea), many species attack psyllids (Hemiptera, Psylloidea) and, thus, are instrumental in controlling populations of those hosts. However, successful biological control requires accurate identification of encyrtid parasitoids and a clear picture of specificity in host-parasitoid interactions. Taxonomic classification, species delimitation and host affiliation remain challenging for researchers due to their the small size of parasitoid wasps, morphological complexity, and the prevalence of cryptic species in the family. In the present paper, we conducted a DNA barcoding study of encyrtid parasitoids of psyllids collected from many provinces throughout China over the past two decades. We analyzed host specificity within an integrative taxonomic framework that combined both morphological data and DNA barcodes. Multiple species-delimitation analyses (ABGD, ASAP, GMYC and bPTP) were used, with a range of 32 to 47 Molecular Operational Taxonomic Units (MOTUs) returned, indicating cryptic diversity among morphological forms. By integrating morphological evidence with molecular species-delimitation results, we recognized 32 species in our samples. Host specificity analysis indicated more than 80% of parasitoid species were strictly monophagous, each parasitizing no more than a single psyllid species. This study provides a preliminary clarification of the species status of Chinese encyrtids parasitoids of psyllids and establishes a DNA barcode database covering their diversity.