Seasonal abundance and distribution of psocids in an animal feed warehouse


Abstract: In the last 15 years, psocids (Psocoptera) have risen to prominence worldwide asserious pests in stored grain, grain processing facilities, and food-product warehouses. In theU.S., no previous studies have been conducted in food-product warehouses to determine thespecies, abundance, and distribution of stored-product psocids. Therefore, we sampled psocids ina 1,800m2 animal feed warehouse located in Stillwater, Oklahoma from May 21, 2008 to March25, 2009 to determine the species present and their abundance and distribution. Walls in all fourcardinal directions (east, north, south, and west) of the warehouse were sampled using 8.9 x12.7cm corrugated cardboard refuges. Biweekly sampling was conducted using five refuges ineach cardinal direction. Refuges in each cardinal direction were placed next to the wall, at equaldistances from each other, for one week. Temperature and relative humidity (RH) data wererecorded in each cardinal direction. We found seven psocid species, namely, Lepinotusreticulatus Enderlein (Trogiidae), Liposcelis decolor (Pearman) (Liposcelididae), Liposcelis rufaBroadhead, Liposcelis bostrychophila Badonnel, Liposcelis entomophila (Enderlein), Liposcelispearmani Lienhard, and Liposcelis paeta Pearman. Liposcelis decolor comprised 96% of the totalnumber of psocids sampled. The numbers of psocids found in each of the five positions withineach cardinal direction and in each cardinal direction were highly variable. Percentages ofpsocids found in the north, west, east, and south were 2, 5, 11, and 82%, respectively. In thesouth, 97% of all psocids found were L. decolor. Relative humidity and food availability had themost influence on psocid abundance. Psocid populations in the south began to increase in mid-May and had two peaks in June and September which coincided with RH peaks. The number ofpsocids remained low during winter before starting to increase in the spring.

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