EARLY DETECTION OF INSECTS IN STORED WHEAT USING STICKY TRAPS IN BIN HEADSPACE AND PREDICTION OF INFESTATION LEVEL

Insect populations in 14 bins of newly harvested wheat on eight farms in Kansas were monitored with sticky traps in the bin headspace and with grain samples. Sticky trap catches during the first 3 wk of storage were used to provide an estimate of the species and densities of insects that were present in the headspace. Grain samples were taken every 2 wk during the first 3 mo of storage to provide an estimate of population growth under the grain temperature and moisture conditions in the bins. The sticky traps correctly predicted whether lesser grain borer, Rhyzopertha dominica (F.), and rusty grain beetle, Cryptolestes ferrugineus (Stephens), would be found in the grain samples in 85.8 and 78.6% of the bins, respectively. Traps were less reliable for foreign grain beetle, Ahasverus advena (Waltl), and hairy fungus beetle, Typhaea stercorea (L.), with correct predictions in 57.1 and 42.9% of bins, respectively. Indianmeal moth, Plodia interpunctella (Hubner), was found in both traps and grain samples in only one bin and red flour beetle, Tribolium castaneum (Herbst), and sawtoothed grain beetle, Oryzaephilus surinamensis (L.), were not found in both traps and grain samples in any of the bins. The traps in the center of the bin caught 4.7-14.2 times more beetles than those on the bin walls, but only 1.3 times more P. interpunctella adults. The total numbers of C. ferrugineus adults in the grain samples could be predicted better from the product of mean grain temperature times maximum grain moisture than from sticky trap catch.