Control of western flower thrips (Frankliniella occidentalis) pupae with Metarhizium anisopliae in peat and peat alternative growing media

The entomogenous fungus Metarhizium anisopliae V275 was more efficacious than chemical insecticides (imidacloprid, fipronil) in killing pupae of the western flower thrips (70–90% versus 20–50%) in a range of horticultural growing media (peat, coir, bark and peat blends with 10% and 20% composted green waste). Premixing inoculum of M. anisopliae into the growing media gave better control than drench applications in coir and peat blended with 20% composted green waste. Use of M. anisopliae with sublethal dose of the insecticides gives slightly better control than the individual control agents but no clear cut additive or synergistic effects. Overall our study shows that M. anisopliae is efficacious in all growing media and compatible with conventional insecticides and offers much promise for the control of thrips as part of an integrated pest management program.