Exploring opportunities to induce epizootics in greenhouse aphid populations

Aphids are a huge problem in organic greenhouse production systems of sweet pepper, eggplant and cucumber in northern Europe. Biological control with arthropod natural enemies is often not effective, resulting in large crop losses yearly. Entomopathogenic fungi of the order Entomophthorales are known for their ability to cause epizootics and reduce host populations dramatically in a short time. These abilities make them potentially more effective biological control agents of pest species than commercially available entomopathogens of the order Hypocreales (e.g., fungi of the genus Beauveria, Metarhizium, Lecanicillium and Isaria). However, a major stumbling block to utilizing these fungi as biological control agents has been the difficulties encountered in growing them in vitro, which is one of the reasons why the biocontrol industry did not develop commercial products based on these fungi. Another approach in utilizing these fungi could be to try inducing epizootics by introducing inoculum of infected aphids into the crop. Here we present our attempts to induce such epizootics with banker plants of wheat with grain aphids infected by the entomophthoralean fungi Pandora neoaphidis. The system of introducing "Pandora bankers" has now been applied by 8 organic greenhouse growers in The Netherlands with various results. The requirements for causing a successful epizootic with this fungus will be discussed.