Stored products insect pests in combine harvesters on the Darling Downs

Abstract

In 4 surveys of combine harvesters on the Darling Downs, Queensland, in 1976-78, insect pests were found in 66 of the 72 headers sampled. Tribolium castaneum (Hbst.), Rhyzopertha dominica (F.) and Sitophilus oryzae (L.) together accounted for 91.7% of the insects found. Three headers were cleaned once, and 6 others twice. The average weight of residue found in previously uncleaned headers was 46.4 kg, containing an estimated 3238 adults of major pests. During grain harvests, most insects in the inside parts of the header were flushed into the newly harvested grain, but about 250 remained in protected areas. Cleaning headers was effective in reducing populations; in one survey, uncleaned headers contained mean major pest populations of 2142 plus or minus 842, as compared with 77 plus or minus 32 in cleaned headers.