Temporospatial distribution of the psocids Liposcelis entomophila and L. decolor (Psocoptera: Liposcelididae) in steel bins containing wheat.

We studied the temporospatial distribution of psocids in steel bins containing 32.6 tonnes of wheat in 2005 and 2006 in Manhattan, KS. Psocids were sampled in the top 0.9 m of wheat using a 1.2-m open-ended trier; samples were taken from the bin center and in the four cardinal directions at 0.15 and 0.76 m from the bin wall. In addition, a 2.4-m partitioned grain trier with 16 compartments was used to sample psocids from a 2-m-diameter circle in the center of the bins and to a depth of 1.96 m. Only two species of psocids were identified in the study: Liposcelis entomophila in 2005 and L. decolor in 2006. Densities of psocids were low immediately after bins were filled in July 2005, peaked in October, dropped to almost zero in December as temperatures decreased, and remained at low levels until the study was ended in March. In 2006, densities of psocids increased gradually from August to mid-October and declined until the study was ended in early November. During the fall, psocids were more abundant at the center of the bin and at lower depths. In October to November of both years, the temperatures and moisture contents of grain in the center also were higher than that in other locations. This is the first report of temporospatial distribution of psocids in steel bins of wheat.