Biotypes of Dasineura tetensi, differing in ability to gall and develop on black currant genotypes

• Published in: Entomologia Experimentalis et Applicata
• Main Author: Hellqvist, Sven
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2001
• Subjects: Ribes; Northern Sweden
• Online Access: http://dx.doi.org/10.1046/j.1570-7458.2001.00760.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1046%2Fj.1570-7458.2001.00760.x; https://onlinelibrary.wiley.com/doi/pdf/10.1046/j.1570-7458.2001.00760.x

Abstract Variation in damage levels on certain black currant, Ribes nigrum L., genotypes, caused by the black currant leaf midge, Dasineura tetensi (Rübs.) (Diptera: Cecidomyiidae), has been observed in northern Sweden. I investigated whether this variation is due to variation in virulence among midges. From a field population of midges, I successfully selected for virulence and avirulence, respectively, on the resistant black currant genotype cultivar ‘Storklas’ (called resistant genotype). The performance of avirulent and virulent midge larvae on two black currant genotypes were studied in experiments where first or second instar larvae were artificially transferred. There were no differences in larval survival and developmental rate between the two midge types when transferred to the susceptible currant genotype ‘7801–31’ (called susceptible genotype). Larvae of the virulent strain established galls and developed on ‘Storklas’ but development was initially slower there than on the susceptible currant genotype. Larvae of the avirulent strain suffered high mortality or remained in first instar on that same currant genotype when transferred alone, but developed readily if transferred together with virulent larvae. Larvae transferred in second instar to host plants susceptible to the larvae resumed feeding and developed further to maturity. Second instar larvae were also able to establish new galls even though these galls were not as well developed as those caused by first instar larvae. Black currant plantations in northern Sweden were surveyed and local midge populations were found to be composed of either avirulent, virulent or a mixture of both midge types. Virulent midges were not restricted to plantations where resistant currant genotypes were grown. I conclude that, at least, two biotypes of the midge exist, and that those two are distinguished by the ability to gall and survive on ‘Storklas’.