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Title: Efficacy of deltamethrin against stored-product beetles at short exposure intervals or on a partially-treated rice mass

item KAVALLIERATOS, NICKOLAS - Agricultural University Of Athens
item ATHANASSIOU, CHRISTOS - University Of Thessaly
item Arthur, Franklin

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/25/2015
Publication Date: 4/1/2015
Publication URL:
Citation: Kavallieratos, N.G., Athanassiou, C.G., Arthur, F.H. 2015. Efficacy of deltamethrin against stored-product beetles at short exposure intervals or on a partially-treated rice mass. Journal of Economic Entomology. 108(3):1416-1421. doi: 10.1093/jee/tov060.

Interpretive Summary: Normal procedures for treated grain as it is loaded into storage involves treatment of the entire grain mass. Alternative methods include treated only the top portion of the grain mass because it is assumed that most insects are in this top portion. However, this provides a means whereby insect pests can escape the treatment by moving to the untreated grain. We conducted study by exposing stored product beetles for short time periods on brown rice treated with the insecticide deltamethrin or by exposing the insects on mixtures of treated and untreated rice. Insects were able to recover from exposure when moved from treated rice to untreated rice and insect mortality was limited. Entire treatment of the rice provided the most effective control for most of the species evaluated in our study. Results show optimal insect control is achieved when the entire grain mass is treated with an insecticide, instead of treating only the top portion. Incorporation of these results into management practices will enable managers of stored grain to reduce economic losses caused by stored product insects.

Technical Abstract: Stored product insects can potentially be exposed to grain protectants for variable time periods. Adults of six species, the lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae), the granary weevil Sitophilus granarius (L.) (Coleoptera: Curculionidae), and the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) were exposed for 0, 1, 4, 8, and 24 h on brown rice treated with the pyrethroid deltamethrin at the label rate of 0.5 ppm, then removed and placed on untreated rice. Adults of these same species were also exposed on treated brown rice mixed with varying amounts of untreated rice to assess progeny production. Immediate and delayed mortality of exposed adults did not exceed 7% for any exposure interval, but progeny production for T. castaneum was generally lower in comparison with that for the other species. Increasing the amount of treated grain decreased progeny production of R. dominica but not for any Sitophilus species. Mixed results were obtained for T. castaneum and T. variabile. Results show that long exposure times and treatment of an entire grain mass may be necessary to give complete control of stored product beetles.