Host acceptance and larval development of the gall midge <i>Dasineura tetensi</i> (Diptera, Cecidomyiidae) on resistant and susceptible black currant

Abstract

The gall midge Dasineura tetensi is a widespread pest of cultivated black currant. Females oviposit on shoot apices, and larvae form galls on leaves which then fail to expand normally. Genetically based resistance to the midge is known to occur among black currant genotypes. In the present laboratory study, larval performance on a susceptible black currant genotype (cv. "Öjebyn") was compared with that on a resistant (cv. "Storklas") genotype and oviposition preferences were investigated. On the susceptible genotype, infested leaves were consistently galled, and larvae developed successfully. On the resistant genotype, there was considerable variation in larval performance, ranging from no development to successful, but slow, development. This variation in expression of resistance occurred also in the field. Leaves of the resistant genotype that were infested with larvae that grew were not as densely galled as corresponding leaves of the susceptible genotype. Individual females offered the two black currant genotypes in sequence, did not show any tendency to discriminate against the resistant genotype.