DNA barcoding and phylogenetics of selected hymenopteran species from Gozo

Abstract

DNA barcoding and phylogenetic and morphological analyses have proven to be essential tools in correct species identification, especially for poorly studied taxa or taxa containing a high level of cryptic morphological diversity, such as those found in the order Hymenoptera. In this study, bees, wasps and sawflies (order Hymenoptera) were sampled during a total of 46 fieldwork sessions taking place in Gozo. A total of 179 specimens were morphologically identified down to the lowest taxon possible. Various ecological data, such as the hymenopterans sampled per habitat type, were also evaluated. DNA was extracted from all the sampled specimens during the genetic analyses, and a partial sequence of 658 bp from the cytochrome oxidase subunit 1 gene (COI) was amplified. PCR amplification was confirmed through gel electrophoresis. PCR products were sequenced, and the sequences generated were compared to publicly available data on BOLD and GenBank to confirm species identity. The 179 specimens were genetically confirmed to represent 59 species from 17 families belonging to 8 superfamilies within Hymenoptera. The genetic dataset compromising all the studied specimens was aligned and used to produce a phylogenetic tree using Bayesian Inference. Specimens from the same species grouped with high posterior probability values, confirming that they genetically belong to the same species. While locally some morphological studies focused on Hymenoptera, genetic work on this order for the Maltese Islands is minimal, whilst this is the first genetic study on hymenopterans from Gozo. Only 12% of the studied species were previously scientifically recorded from Gozo, including species such as Xylocopa violacea. Therefore this work contributes highly to the knowledge gap reduction for hymenopteran species in Gozo. Additionally, out of the 80 haplotypes recorded in this study, 42 novel haplotypes belonging to 35 out of 59 studied species were also discovered, further contributing to the genetic resources available on these species at an international level. This study also paves the way towards a better understanding of the conservation needs of identified bees, wasps, and sawflies. These species are increasingly recognised for their valuable ecological roles as pollinators or predators of pest insect species.