Biological control of the invasive pest Echinothrips americanus by Macrolophus pygmaeus

Abstract: The poinsettia thrips Echinothrips americanus Morgan is a relatively new pest that has spread rapidly worldwide and causes serious damage in both vegetable and ornamental plants. In this study we investigated if and how effective this pest can be controlled by the omnivorous predator Macrolophus pygmaeus (Rambur) in Gerbera. Since herbivores on plants can interact through a shared predator, we also investigated how this control was affected by the presence of the greenhouse whitefly Trialeurodes vaporariorum (Westwood), a pest that commonly co-exists with E. americanus in Gerbera. In a greenhouse experiment, densities of both pests on single Gerbera plants were reduced to very low levels by their shared predator M. pygmaeus either with both pests present together or alone. This study shows that omnivorous predators can be important for controlling invasive pest species.