Morphological and molecular characterization of common European species of Adialytus (Hymenoptera: Braconidae: Aphidiinae) based on the mtCOI barcoding gene and geometric morphometrics of forewings

Abstract

In this study three common European species of the genus Adialytus Forster, 1862 were examined: Adialytus ambiguus (Haliday, 1834), Adialytus salicaphis (Fitch, 1855) and Adialytus thelaxis (Starý, 1961). Molecular analysis involved the DNA barcod- ing of a region of the mitochondrial gene cytochrome oxidase I (COI). The genetic difference based on Kimura's two-parameter model for computing pairwise distances showed that A. thelaxis differs from both A. ambiguus and A. salicaphis by 4.9 and 6% on average, respectively. The genetic distance between A. ambiguus and A. salicaphis was 1.5% on average, suggesting that barcodes based on the COI gene are insufficiently informative for separating these two species. Geometric morphometrics analysis of forewing size and shape revealed statistically significant differences. The R1 vein on the forewing of A. ambiguus is more elongated than on the wings of A. salicaphis and A. thelaxis. The geometric morphometrics analysis of the forewings also revealed that A. salicaphis and A. thelaxis have much broader forewings, suggesting strong flight ability associated with their parasitizing arboricolous aphids. The distal part of the forewing of Adialytus ambiguus is narrower, which in this case suggests poor flight ability associated with parasitizing Sipha aphids on grasses. An illustrated key for identifying the European species of Adialytus is provided.