Compatibility of the parasitoid Aphidius matricariae with BotaniGard for the control of greenhouse aphids

The simultaneous use of multiple biological control agents can be effective in suppressing pest populations, but the intraguild interactions that occur between biological control agents can disrupt biological control. I hypothesized that the combined use of the parasitoid, Aphidius matricariae, and the entomopathogenic fungi Beauveria bassiana (in the form of commercialized product, BotaniGard) for controlling the greenhouse aphid pest, Myzus persicae, would have a positive effect on pest control. Experiments were conducted in the laboratory over short periods and in greenhouses over multiple generations. Although BotaniGard had negative interactions with the parasitoids in short time scale experiments, over an extended time the combined use of BotaniGard and parasitoids had synergistic effects on aphid suppression. The number of parasitoids present at the end of the experiments in longer-scale experiments was higher in treatments with BotaniGard application than in treatments with parasitoids alone.