Is there a role for spinosad in protecting Australian grain from insects?

The potential for using spinosad to protect Australian grain from storage insects is discussed. Spinosad is produced from the metabolic by-products of a soil-dwelling bacterium, and is active against a range of insect species. Studies on relevant susceptible and resistant strains of a range of beetle and psocid pests indicate that spinosad efficacy varies greatly between species. Among the five beetle species tested, spinosad was most effective against Rhyzopertha dominica and least effective against Oryzaephilus surinamensis. In contrast, spinosad failed against all four psocid species tested. These preliminary results suggest that the most promising use of spinosad would be against R. dominica, which has proven very successful in developing resistance to grain protectants. Laboratory experiments suggest that an application rate of 1 mg/kg in wheat may be suitable for controlling R. dominica strains that are resistant to organophosphates, pyrethroids or the insect growth regulator methoprene. Studies are needed to establish the efficacy of spinosad during long-term storage. 1 Corresponding author: .