No abstract

The population dynamics of tortricid pests and their parasitoids and the impact of vegetation management in the orchard by mulching, on both the pests and the parasitoids, was investigated in eight ecological apple orchards in two regions of Southern Germany. Differences in pest and parasitoid abundance and species composition could be shown between the regions and the single orchards. Extensive mulching regimes seemed to enhance diversity of leafroller species whereas Adoxophyes orana F.v.R., the most dangerous leafroller species in this region, was less abundant in those orchards. Most important parasitoids of A. orana were Teleutaea striata Grav., Pseudoperichaeta nigrolineata Wlk and Colpoclypeus jlorus Wlk. The last species occurred only on the summer generation and in autumn on the overwintering larvae.Polyphagous parasitoids such as Cotesia xanthostigma Hal. or Meteorus ictericus Nees were found on A. orana in the orchards with high abundance of this species, and on other species in the orchards with low abundance of this species and higher abundance of other species. Thus, the leafroller species of minor economic importance, such as Rhopobota naevana Huebner and the gelechiid species, Recurvaria leucatella Clerck, may constitute a parasitoid reservoir for A. orana. This may be one of the reasons for the lower abundance of A. orana in extensively mulched orchards.