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POST-HARVEST GRAIN TEMPERATURE, MOISTURE, AND INSECT INFESTATION IN STEEL GRANARIES IN MANITOBA

Published online by Cambridge University Press:  31 May 2012

S. R. Loschiavo
Affiliation:
Agriculture Canada, Research Station, Winnipeg, Manitoba R3T 2M9

Abstract

Post-harvest grain temperature and moisture were consistently higher at the center than at the edge roof openings of steel granaries in Manitoba in 1982 and 1983. In 1982, temperatures at the center were significantly higher in infested than in uninfested granaries and declined only slowly during a 2-week period. Several kinds of insects were found in grain samples or in beetle-detection traps inserted into grain at the center location but none was found in grain or in traps at the edge. The heaviest infestations coincided with the temperatures and moistures at the center. In 1983, initial temperatures at the center and edge roof openings were high when the granaries were filled but declined rapidly, particularly at the edge, during the next 2 months. Between late August when the granaries were filled and early November, moisture content increased at the center and edge roof openings. It was significantly greater at the surface than at a depth of 20–130 cm. Insects were found in traps inserted 1 m into the grain at the center location. The results indicate that the most likely place to find insects in filled granaries is at the center near the surface and the most opportune time to begin checking the grain is 2 months after the granaries have been filled.

Résumé

Au Manitoba en 1982 et 1983, la température et la teneur en eau du grain après la récolte étaient régulièrement plus élevées aux ouvertures du toit situées au centre des réservoirs d'acier qu'aux ouvertures situées près des parois. En 1982 les températures au centre étaient sensiblement plus élevées dans les réservoirs infestés que dans les réservoirs non infestés, et elles n'ont baissé que très lentement durant une période de deux semaines. On a trouvé plusieurs sortes d'insectes dans des échantillons de grain et des pièges à coléoptères insérés au centre des réservoirs, mais on n'a découvert aucun insecte dans le grain ou les pièges placés le long des parois. Les infestations les plus prononcées coïncidaient avec la température et la teneur en eau au centre. En 1983, la température initiale aux ouvertures du centre et de la périphérie du toit était élevée à l'époque du remplissage des réservoirs, mais baissa rapidement, particulièrement le long des parois, durant les deux mois suivants. Entre la fin août lors du remplissage, et le début de novembre, la teneur en eau a augmenté aux ouvertures du centre et de la périphérie du toit. La teneur en eau était significativement plus élevée à la surface qu'à une profondeur de 20 à 130 cm. On a détecté des insectes dans des pièges introduits à 1 m dans le grain au centre des réservoirs. Selon les résultats obtenus, le site d'échantillonnage le plus suceptible de révéler la présence d'insectes dans des réservoirs à grain remplis, est au centre près de la surface; et l'époque la plus opportune pour commencer à examiner le grain se situe deux mois après le remplissage des réservoirs.

Type
Articles
Copyright
Copyright © Entomological Society of Canada 1985

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