Colonization and predation of thrips (Thysanoptera: Thripidae) by Orius spp. (Heteroptera: Anthocoridae) in sweet pepper greenhouses in Northwest Italy

Frankliniella occidentalis (Pergande) and Thrips tabaci Lindeman (Thysanoptera: Thripidae) are major pests of sweet pepper for direct damage and tospovirus transmission. To control their infestations, Orius laevigatus (Fieber) (Heteroptera: Anthocoridae) is produced by many commercial insectaries and widely used on IPM vegetable crops of Europe. This predator is naturally widespread along the Mediterranean and Atlantic coasts, and not in more continental areas, where other Orius spp. are more common. Research was conducted in a continental area of Northwest Italy in 2002–2003 to assess the natural presence of anthocorids on pepper, and to compare their colonization and predatory ability with those of the species artificially introduced. Experiments were conducted in 12 sweet pepper greenhouses, in six of which O. laevigatus release was made. From late May to early October, thrips and anthocorids were sampled on pepper by collecting flowers; Orius spp. were also collected on neighboring wild flora. Independently of the releases, Orius specimens were found in all surveyed greenhouses, but O. niger Wolff, also captured on various wild plants, was the most abundant species. It naturally colonized crops from late June and proved to be the most efficient predator on sweet pepper in the surveyed area, if not disturbed by pesticide application. Contrarily, O. laevigatus was rarely found and only in the greenhouses in which it had been released. However its introduction resulted in thrips control before natural colonization by the native species occurred.