Ecology and IPM of Insects at Grain Elevators

Authors: HAGSTRUM, DAVID - Collaborator; Flinn, Paul; REED, C - Kansas State University; PHILLIPS, T - Kansas State University

Submitted to: Biopesticides International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/25/2010
Publication Date: 7/5/2010
Citation: Hagstrum, D.W., Flinn, P.W., Reed, C.R., Phillips, T.W. 2010. Ecology and IPM of Insects at Grain Elevators. Biopesticides International. 6: 1-20.

Interpretive Summary: It is estimated that economic losses caused by insects to stored wheat in the USA range from 5 to 10% per year, or about 1.25 to 2.5 billion dollars. Alternative, economically viable methods for controlling these insects and reducing losses to raw commodities are required because of loss of available insecticides due to insect resistance or regulatory changes. An insect ecology study was conducted in commercial grain elevators and flat storages in Kansas. The study showed that grain may become infested soon after it is stored. Residual insect infestations at the elevator appear to be the most common source of infestation. In stored wheat in commercial elevators, the rusty grain beetle was the most common insect species from June-September, but was often surpassed by the lesser grain borer after 3-4 months of storage. The red flour beetle was the third most common insect species. Insect populations in wheat increased from June to October, then leveled off and declined as fall and winter temperatures cooled the grain. The insect density decreased with increasing depth below the grain surface. In corn in flat grain stores, 90.9% of the insects were weevils, 7.3% were red flour beetles, 0.7% were lesser grain borers and 1.1% were rusty grain beetles. In wheat, 74.7% of the insects were weevils, 17.0% were lesser grain borers, 6.1% were red flour beetles and 2.2% were rusty grain beetles. Insect populations in wheat in flat stores generally peaked in March and then declined. Insect populations in corn in flat storages generally peaked in June and then decreased. The findings from this study will be used to improve insect pest management programs for stored grain.

Technical Abstract: Cost-effectiveness of insect pest management depends upon its integration with other elevator operations. Successful integration may require consideration of insect ecology. Field infestation has not been observed for grain received at elevators. Grain may be infested during harvest by residual insect infestations in the combines or may be infested from residual insect infestations soon after grain is loaded into bins at the elevator. A total of 61 species of insects in 26 families and 6 orders have been reported at elevators or in flat storages. At grain elevators, the species composition in grain residues differed from that in the wheat stored in bins. Insect populations in wheat increased from June to October, then leveled off and declined as fall and winter temperatures cooled the grain. Often less than 20% of the bins had economically important insect infestations and generally the bins with high insect densities were close to other highly infested bins. The numbers of insects at elevators decreased with the depth below the surface as they did on farm. Insects are moved through the marketing systems with grain, but low sampling rates result in few of the infestations being discovered. Wheat with high test weight was less likely to be discounted for insects than wheat with a lower test weight. Pest management practices were very effective for 20 out of 25 flat storages and infestations in others were not allowed to reach densities which would result in an infested designation on the grade certificate.