Abai, MR

6th International Congress of DipterologyBehavior, ecology, and genetics of Dasineura folliculi(Diptera: Cecidomyiidae) - another case of host-raceformation in goldenrod gall midges?Dorchin, N., W.G. Abrahamson & S. JordanDepartment of Biology, Bucknell University, Lewisburg PA, 17838, USAHost-race formation is considered to be the first step toward sympatricspeciation in phytophagous insect species, a concept that keeps gainingsupport from behavioral and genetic studies in different insect taxa. Gallinducinginsects in particular serve as ideal models for such studies due totheir close and highly specific interaction with their hosts. In recent years,several insects associated with goldenrods (Solidago altissima and S.gigantea) in North America have offered evidence for host-race formationbased on ecological and genetic data. In two of these cases, involvingparasitic wasps and predatory beetles, it has been found that the naturalenemies differentiate on the two plants following the gall inducers, in aprocess known as sequential radiation.We are currently studying host-race formation and sequential radiation inthe gall midge Dasineura folliculi, which induces loose bud galls on S.gigantea and S. rugosa, and in an inquilinous gall midge that is associatedwith the galls. As host preference in herbivorous insects is frequently linkedto mate choice, the requirement for simultaneous mutations leading to hostshifts may be alleviated. Preliminary mate-choice experiments indicatedsignificant preference for mates from the same host-associated populationamong the gall inducers. However, host-preference experiments wereinconclusive and will be repeated in an improved setting this summer.One of the factors that may facilitate shifts to new hosts is the acquisitionof enemy-reduced space, in which the rates of enemy attack are lower on thenovel host. Documenting inquiline infestation in galls on S. gigantea and S.rugosa showed inquilines are significantly more common in the latter,suggesting S. gigantea might be the more recent host. Molecular analyses ofthe COI mitochondrial gene of the gall inducer and the inquiline, currently65