Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 28, 2004
Publication Date: November 15, 2004
Citation: Throne, J.E., Lord, J.C. 2004. Control of sawtoothed grain beetles (Coleoptera: Silvanidae) in stored oats using by using an entomopathogenic fungus in conjunction with seed resistance. Journal of Economic Entomology 97: 1765-1771. Interpretive Summary: Stored oats are susceptible to infestation by insects, and residual insecticides are used to control insect pests of stored oats; however, alternative control strategies are desirable. We investigated the use of resistant oat cultivars in combination with an insect-pathogenic fungus for control of an insect pest of stored oats, the sawtoothed grain beetle. Adding 150 milligrams of fungus spores/kg to cracked or whole oats resulted in a 70 and 98% reduction, respectively, in number of beetles produced. No further reduction in progeny production was obtained by adding 200 mg of fungal spores/kg of cracked or whole oats. The results of the study indicate that use of the fungus may be a commercially viable option for control of insect pests of stored oats. Studies to determine effect of the fungus on other species of insects that infest oats are required, and field-scale studies will be required before commercial use.
Technical Abstract: We tested the hypothesis that the entomopathogenic fungus Beauveria bassiana would be more efficacious on oat cultivars that prolonged the immature development period of the storage pest, Oryzaephilus surinamensis (L.), the sawtoothed grain beetle. However, percentage reduction in progeny production was similar on whole Don and Paul oats treated with fungus, even though immature development time was longer on whole Don than on Paul oats. In our initial test at 10 mg of conidia/kg of oats, the number of beetle progeny produced was reduced by 38 to 67% in whole oats, and there was no effect of the fungus on insects developing on cracked oats. Therefore, we conducted two dose-response studies that showed that adding 150 mg of conidia/kg to cracked or whole Paul oats resulted in a 70 and 98% reduction, respectively, in number of progeny produced. No further reduction was obtained by adding 200 mg of conidia/kg of cracked or whole Paul oats. Presence of the fungus did not affect development time in any of our tests. A previous study showed that cleaned oats should limit insect population growth to allow long-term storage of oats without insect damage. However, the current study shows that if the oats are not cleaned, and not cleaning oats is the normal storage practice, then the fungus Beauveria bassiana could be used to help control sawtoothed grain beetles.