Predatory thrips as biological control agents of exotic thrips in greenhouse ornamental crops

Abstract: Within the order Thysanoptera, some species are predatory, targeting other thrips and small arthropods. For many years, these predatory thrips have been overlooked in biological control strategies due to limited biological and ecological data and high production costs. Here, the predatory thrips Franklinothrips vespiformis Crawford and Aeolothrips intermedius Bagnall were evaluated as biological control agents against exotic thrips species. Franklinothrips vespiformis was tested in the laboratory. Both species were compared in cage and field experiments. Field trials were conducted in commercial greenhouses against Echinothrips americanus Morgan on potted Monstera plants and in cut-flower crops of Gerbera, as well as against Chaetanaphothrips orchidii Moulton in cut-flower crops of Anthurium. Our results show that both natural enemies are able to prey upon and reproduce on exotic thrips species. Field trials in Monstera indicated that both predatory thrips established and reduced pest thrips populations, with F. vespiformis occurring at higher densities. In the other crops, both predators were only sporadically detected, despite the provision of Ephestia kuehniella Zeller eggs as an additional food source. Further research is needed to clarify the role of predatory thrips in integrated biological control programmes for greenhouse ornamentals.