Control of frit fly ( Oscinella spp.) in newly sown grass using a combination of low doses of pesticide, resistant grass cultivars and indigenous parasitoids

Abstract

Larvae of dipterous stem-borers (e.g. Oscinella frit) can cause considerable damage in newly sown grass. Damage can be reduced by the use of resistant cultivars, by applying various pesticides and by naturally occurring hymenopterous parasitoids. To test a combination of these factors as an IPM strategy, three pesticides were used at three-quarters of their recommended dose on a susceptible and a resistant cultivar. On the susceptible and resistant cultivars, respectively, the maximum increase in tiller numbers was 129% and 50%, the maximum reduction in numbers of larvae was 94% and 87%, the decrease in parasitism was 28% (combined cultivars), and the maximum increase in dry-matter yield was 17% and 4%, compared with the untreated plots.