Mode of action
Entomopathogenic fungi parasitise insects, either killing or disabling them. Fungi of the genera Beauveria (white muscardine) and Metarhizium (green muscardine) are the best studied. Entomopathogenic fungi occur naturally in the soil and, depending on the species and strain, infect different species of insects. Fungi that parasitise grubs can be cultured in the laboratory, providing an efficient method of biological control.
The fungal strains are cultured on sterilised barley grains, on which the fungus forms its spores. The inoculated barley kernels are applied to the infested areas using a no-till seeder. Timing of the application has to be adjusted to the developmental cycle of the target species. In addition, the soil needs to be dry enough to drive on, but moist enough to provide suitable growing conditions for the fungus. Grubs coming into contact with the inoculated barley kernels are infected and killed by the fungus. The fungus forms spores on the grubs’ bodies, multiplies in the soil and goes on to infect further grubs in a chain reaction. This amplifies the effect of treatment, which persists for several years.
The long-lasting effectiveness of the treatment offsets the high initial costs. In addition, in cases of regional mass infestations, the Swiss cantons often participate in the organisation and funding of grub control.