Milling Journal - Q4 2008 - (Page 38) Keeping Insects Out of Flour KSU tests ability of meshes to exclude flour beetle larvae Red and confused flour beetles are common grain storage pests that prefer the fine particulates of milled grain, such as wheat flour. They can be present throughout the mill flow. These pests entry to the mill is accomare most dreaded by millers, Pest Management plished by closing doors and and mill fumigations and heat windows and using plastic treatments are directed to strips or air curtains. Preventmanage these pests. ing entry to the product To complement external stream is accomplished by use insecticide inputs—such as of sieves with specific mesh crack/crevice treatments, sizes to prevent insect eggs, fogging, fumigation, or heat larvae, and adults from endtreatment—practices such as ing up in the milled product. sanitation and exclusion tacHowever, very little retics are used to manage flour search has been done in this beetles. Dr. Bhadriraju area, because in my opinion, Exclusion tactics are deSubramanyam there are sieves of different signed to prevent insects sizes used throughout the mill from entering a facility or enflow, and the primary purpose is for partering the product stream. Preventing Figure 1: PVC cylinders used in laboratory tests. ticle size reduction, with the secondary purpose being for insect exclusion. Mesh Sieve Experiment In 2006, my graduate students conducted laboratory experiments looking at the ability of sieves of 150 and 180 micrometer mesh size to exclude young larvae (larvae that hatch from eggs) under static and dynamic (moving) conditions. In this article, I report findings on how the experiments were done and what we observed. Some of these findings can be extrapolated to sieves of different mesh sizes currently used in the milling process. Insects used in tests were obtained from colonies established by the Stored Product Entomology Research and Education Laboratory in the Department of Grain Science and Industry, Kansas State University, Manhattan. The species included in the tests were red flour beetle and confused flour beetle. Both of these species are commonly associated with flour mills worldwide. Sieves were glued between two equal halves of PVC cylinders of 4 cm internal diameter, so that the total height of the PVC cylinder was 10 cm (see Figure 1). Eight PVC cylinders were fitted with a 150-micrometer sieve and eight with a 180-micrometer sieve. Four sieves of each mesh size were designated for red flour beetles and four for confused flour beetles. Exactly 60 eggs of each species laid within 24 hours of pairing were added to separate rings above the sieve of each ring. 38 Fourth Quarter 2008 Response No. 381 MILLING JOURNAL http://www.diamondbacktechnology.com http://www.diamondbacktechnology.com
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