HOST ACCEPTANCE AND LARVAL DEVELOPMENT OF THE GALL MIDGE DASINEURA TETENSI (DIPTERA, CECIDOMYIIDAE) ON RESISTANT AND SUSCEPTIBLE BLACK-CURRANT

The gall midge Dasineura tetensi is a widespread pest of cultivated bl ack currant. Females oviposit on shoot apices, and larvae form galls o n leaves which then fail to expand normally. Genetically based resista nce to the midge is known to occur among black currant genotypes. In t he present laboratory study, larval performance on a susceptible black currant genotype (cv. ''Ojebyn'') was compared with that on a resista nt (cv. ''Storklas'') genotype and oviposition preferences were invest igated. 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 re sistant genotype that were infested with larvae that grew were not as densely galled as corresponding leaves of the susceptible genotype. In dividual females offered the two black currant genotypes in sequence, did not show any tendency to discriminate against the resistant genoty pe.