Relative population levels of citrus thrips Scirtothrips aurantii on commercial citrus and adjacent bush

Citrus thrips Scirtothrips aurantii Faure is a serious economic pest in southern Africa. It is indigenous, breeding on many wild hosts as well as on citrus. In this northern Transvaal lowveld study, bush containing known host plants of S. aurantii was not the source of early infestation of a navel orange orchard by adult citrus thrips during September and October. Early-season damage therefore resulted from the activities of citrus thrips which had overwintered in the orchard. In contrast, S. aurantii populations on wild hosts could possibly boost orchard populations later in the season and contribute to late damage on the fruit. This is because, in one of the years, adult thrips numbers were higher in the bush than in the orchard during November and December.