Establishment of Platygaster tuberosula, an introduced parasitoid of the wheat midge, Sitodiplosis mosellana

Abstract

AbstractWheat midge, Sitodiplosis mosellana (Géhin) (Diptera: Cecidomyiidae), was first detected as early as 1901 in Western Canada. The first major outbreak in Saskatchewan was recorded in 1983. In 1984, Saskatchewan wheat midge populations were found to be parasitized by the egg parasitoid Macroglenes penetrans (Kirby). Parasitism levels vary from year to year but, on average, 33% of wheat midge populations are parasitized by M. penetrans. In 1993 and 1994, Agriculture Canada and the International Institute of Biological Control in Delémont, Switzerland, collaborated to release Platygaster tuberosula Kieffer into Saskatchewan to augment biological control of wheat midge. Platygaster tuberosula individuals were recovered at low numbers in follow-up monitoring programs in each of the last 5 years. In 2001, the parasitoid population density increased fivefold at the release site and showed signs of migrating into the surrounding area.