Abstract: The Hessian fly Mayetiola destructor Say and the barley stem gall midge Mayetiola hordei Kieffer are two sibling phytophageous species causing, annually, important losses to cereals in Tunisia. Damage to wheat has usually been attributed to Mayetiola destructor but there is no strict association between the cereal species (wheat or barley) and the Mayetiola species ( destructor or hordei ). An effective pest management program requires an accurate analysis of the midges' genotypes. In the present study, we used the RAPD technique in conjunction with mating bioassays and mitochondrial DNA typing, to assess the extent of genetic variability and taxonomic relatedness, within a Mayetiola population infesting wheat in the North of Tunisia. Phylogenetic analysis inferred from the RAPD showed that the studied population had a variable genetic background that could be due to a complex epidemiological situation where wheat samples would be co-infested by both M. destructor and M. hordei. Although mating assays did not result in oviposition in a few cases (2/14), mitochondrial typing based on the Cyt b gene restriction analysis showed that all samples were M. destructor ones. Our results are additional evidence that RAPD variability is not a reliable criterion for taxonomical inference and provide support for allopatric distribution of M. destructor and M. hordei species, in Tunisia.

Key words: Diptera, Mayetiola, species, cytochrome b gene, RAPD, PCR-RFLP, mating