Chemical insecticides are used to protect stored grain from infestation by stored product insects and mites. In the UK only a limited number of products are available for application and there are concerns about safety, pest resistance and environmental impact of these conventional pesticides. Biological control offers an alternative to the use of chemical insecticides. The potential for biological control of storage pests in the UK using an insect-specific fungus, Beauveria bassiana, to treat the structure of the stores, has previously been established. However, this study also highlighted areas where improvements were needed; specifically to improve the uptake of the fungal conidia by the pests and to improve their germination and penetration into the pests. In addition it was necessary to ensure that potential formulations had a good shelf-life and to develop a mass production method to consistently produce high quality fungal conidia. A four year project has recently been completed examining these areas in detail. The work has concentrated on two different fungal isolates of B. bassiana, both of which were found from insects in UK grain stores. Optimisation of production methods, formulation and delivery systems has resulted in prototype formulations that exhibit good viability over periods up to one year and that have good efficacy against a range of storage insect pests under conditions that are likely to be found in UK grain stores. Pilot scale trials using three species of stored product beetle have shown that significant levels of control can be achieved. An overview of the key findings is presented. The study has made a significant contribution to the development of a biopesticide as a structural treatment for grain storage areas in the UK.Keywords: Biological control; Beauveria bassiana; Oryzaephilus surinamensis; Structural treatment; Biopesticid
