Effects of flowering groundcover vegetation on diversity and activity of wasps in a farm shelterbelt in temperate Australia

Significant worldwide interest in conservation biological control in agricultural systems currently exists but little information is available on the usefulness of this approach in farm forestry. In a field experiment conducted in a native vegetated shelterbelt in central-west New South Wales, we measured the diversity of wasps in plots comprising Eucalyptus blakelyi Maiden (Myrtaceae) trees with and without a groundcover of Lobularia maritima (L.) Desv. (Brassicaceae). Vacuum samples revealed a greater abundance and species richness of parasitic wasps in the plots comprising trees surrounded by the L. maritima groundcover. Cotesia sp. (Hymenoptera: Braconidae), Pteromalus sp. (Hymenoptera: Pteromalidae), Anagyrus sp. (Hymenoptera: Encyrtidae), Entedoninae sp. and Eulophidae sp. 1 (Hymenoptera: Eulophidae) were the most common taxa. These were more abundant also in the trees with the L. maritima groundcover. Ardozyga stratifera (Meyrick) (Lepidoptera: Gelechiidae) larvae, that were naturally infesting the E. blakelyi trees, were significantly more parasitized in the trees with the L. maritima groundcover. Results indicate that parasitic wasps associated with a native-tree shelterbelt in Australia were amenable to manipulation via groundcover vegetation.