Monday, December 11, 2006 - 4:20 PM

Temperospatial distribution of psocids in stored wheat

George Opit,, James Throne,, and Paul Flinn, USDA-ARS Grain Marketing and Production Research Center, 1515 College Avenue, Manhattan, KS

Psocids are an emerging problem in stored grain and in grain processing facilities in the U.S. We conducted a study in steel bins containing wheat to determine temporal and spatial distribution of Liposcelis entomophila in the wheat. Using data obtained, we compared use of cardboard refuges and grain trier samples for sampling psocids in the wheat. We found infestation levels before the bins were filled with wheat to be low, but some psocids were present in the empty bins. Numbers of psocids caught on sticky traps on the outside of bins dropped quickly as ambient temperatures dropped in autumn. Numbers of psocids in cardboard refuges on the wheat surface were low immediately after bins were filled in July, peaked in late September, dropped to almost zero in December as temperatures dropped during autumn and winter, and then remained at low levels until the study was ended in mid-March. Significantly more psocids were found at depths of 1.12-1.96 m compared to 0-0.84 m. During periods when psocid numbers are high, significantly more psocids appear to be found closer to the bin wall (0.15 m) than farther away (0.76 m). Numbers of psocids in cardboard refuges was indicative of number of psocids in grain samples. The results indicate that cardboard refuges may provide an efficient method for sampling psocids in bins of wheat, and that psocid populations can increase quickly to high levels during storage even though they are low early in the storage period.

Species 1: Psocoptera Liposcelidae Liposcelis entomophila (psocid, book lice)

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