Aphids (Homoptera, Aphididae) and their natural enemies occurring on Sonchus spp. (Compositae) in the Mediterranean region.

Surveys were carried out in the Mediterranean areas of France, Greece, Turkey and Iraq in 1981-84 to study the distribution of aphids infesting sowthistles (Sonchus spp.) and the incidence of their natural enemies. Hyperomyzus lactucae and Uroleucon sonchi were constant and abundant at all the sites studied. Nine primary parasites were reared from H. lactucae, and the total rate of parasitism was 1-19%. Many of the natural enemies found during the study constituted new records for the country and/or region in which they were collected, and the aphidiid Monoctonus crepidis was a new parasite record for H. lactucae. The parasite complex of H. lactucae was dominated by Aphidius sonchi in southern France and Praon volucre in the other countries. These 2 aphidiids caused over 90% of the total parasite-related mortality, and have only been recorded from this aphid on sowthistles at the sites surveyed. Strains of these 2 species have been forwarded for release in Australia in an attempt to control H. lactucae there, since it is of economic importance in that country.