Species status of two populations of Pnigalio soemius (Hymenoptera: Eulophidae) reared from two different hosts: an integrative approach.

Pnigalio soemius is a polyphagous ectoparasitoid of late instars of leafminers or gallmaking larvae belonging to different orders of holometabolous insects. The aim of this work was to determine whether two populations of P. soemius obtained respectively from two lepidopteran hosts (Cosmopterix pulchrimella and Holocacista rivillei) represent a single species or two sibling species. Different complementary approaches were used: (1) uni- and multivariate analysis of morphological characters; (2) reproductive compatibility tests; (3) evaluation and comparison of different behavioral and biological traits; (4) karyological analysis (chromosome number, morphology and NORs); (5) molecular characterization of mtDNA (COI) and RFLP-PCR. Our results demonstrate the existence of two reproductively isolated cryptic species, even though their two karyotypes could not be distinguished and the morphometric analysis was only partially able to discriminate the two populations (86% with analysis of ratios and 92% with analysis of Burnaby size-adjusted data). These results point out that the broad concept of P. soemius may include cryptic species whose correct characterization plays a decisive role when evaluating the effects of field-margin habitats.