Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/7/2002
Publication Date: 6/1/2002
Citation: FANG, L., SUBRAMANYAM, B., ARTHUR, F.H. EFFECTIVENESS OF SPINOSAD ON FOUR CLASSES OF WHEAT AGAINST FIVE STORED-PRODUCT INSECTS. JOURNAL OF ECONOMIC ENTOMOLOGY 95(3): 640-650. 2002.
Interpretive Summary: Chlorpyrifos-methyl (Reldan), the only conventional insecticide currently registered for use on stored wheat, may be lost through implementation of the Food Quality Protection Act (FQPA). We evaluated Spinosad, a reduced risk-low toxicity biological insecticide, by conducting tests on different wheat classes using several important stored-grain insect pests. Spinosad applied at 1.0 part per million (ppm) killed all lesser grain borers and Indianmeal moths, while survival of other species varied among the different classes. Rates in excess of 1.0 ppm may be necessary to give complete control of all species tested. It may also be possible to combine Spinosad with aeration or biological control to improve control.
Technical Abstract: The efficacy of spinosad, a commercial reduced-risk pesticide that is naturally derived, was evaluated on four classes of wheat (hard red winter, hard red spring, soft red winter and durum wheats) against adults of the lesser grain borer, Rhyzopertha dominica (F.); rice weevil, Sitophilus oryzae (L.); sawtoothed grain beetle, Oryzaephilus surinamensis (L.); red flour beetle, Tribolium castaneum (Herbst); and larvae of the Indianmeal moth, Plodia interpunctella (Hubner). On all untreated wheat classes, adult beetle mortality ranged from 0-6%, and P. interpunctella larval mortality ranged from 10-19%. The effects of spinosad on R. dominica and P. interpunctella were consistent across all wheat classes. Spinosad killed all exposed R. dominica adults and significantly suppressed progeny production (84-100%) and kernel damage (66-100%) at both rates compared to untreated wheat. Spinosad was extremely effective against P. interpunctella on all wheat classes at 1 mg/kg rate, based on larval mortality (97.6 - 99.6%), suppression of egg-to-adult emergence (93-100%), and kernel damage (95-100%) relative to similar effects on untreated wheats. The effects of spinosad on S. oryzae varied among wheat classes and between spinosad rates. Against S. oryzae, O. surinamensis and T. castaneum, spinosad was effective at the 1 mg/kg rate only on durum wheat.