Oviposition preferences of Gephyraulus lycantha (Diptera: Cecidomyiidae) females with respect to three Lycium spp. host plants.

[Objectives] To investigate the oviposition preferences of gall midge, Gephyraulus lycantha Jiao & Kolesik (Diptera: Cecidomyiidae), females with respect to three different Lycium spp. host plants, and thereby clarify the effect of semiochemicals on host selection. [Methods] Oviposition preferences for three host plants, L. barbarum, L. chinense and L. ruthenicum, were determined in both choice and no-choice experiments. The preference of gravid females for specific volatiles emitted from these three different host plant species was measured in a Y-tube olfactometer under laboratory conditions. Dynamic headspace collection and gas chromatography-mass spectrometry were used to analyze differences in the composition of volatiles emitted from the three different host plant species. [Results] L. barbarum was the preferred host species with a significantly (P<0.05) higher oviposition selection rate and number of eggs laid on the young flower buds of this species than on L. chinense or L. ruthenicum. The results of Y-tube olfactory experiments showed that females also significantly (P<0.05) preferred volatiles from bud-bearing branches of L. barbarum to those of the other two species. There were significant differences in the volatiles emitted from healthy flower buds of the three Lycium species. Volatile components of L. barbarum and L. chinense were relatively similar in that both contain a higher proportion of esters, whereas L. ruthenicum volatiles were low in esters and high in ketones. [Conclusion] G. lycantha significantly preferred ovipositing on L. barbarum to L. chinense or L. ruthenicum. Differences in the volatiles emitted from flower buds of L. barbarum might be responsible for this preference. [ABSTRACT FROM AUTHOR]