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Title: COMPARISON OF TWO MODELS OF GRAIN TEMPERATURES AND INSECT POPULATIONS IN STORED WHEAT

Author
item MANI, S - UNIV OF MANITOBA
item Flinn, Paul
item MUIR, W - UNIV OF MANITOBA
item JAYAS, D - UNIV OF MANITOBA
item WHITE, N - CEREAL RESEARCH CENTRE

Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2001
Publication Date: 9/1/2001
Citation: MANI,S., FLINN,P.W., MUIR,W.E., JAYAS,D.S., WHITE,N.D., COMPARISON OF TWO MODELS OF GRAIN TEMPERATURES AND INSECT POPULATIONS IN STORED WHEAT, TRANSACTIONS OF THE AMERICAN SOCIETY OF AGRICULTURAL ENGINEERS 44(3): 655-660. 2001.

Interpretive Summary: The objective of this research was to compare two different methods of predicting insect growth in stored grain, with the ultimate goal of providing grain managers with a better method of predicting when insects will become a problem in stored grain. The two models were a hot spot model and a spatial model. Basically the two models are similar, the main difference is that the hot spot models allows for heat that is generated b an insect aggregation to be simulated, whereas the spatial model does not simulate insect-generated heat. We found that when both models were started with high numbers of insects in the bin center, and the grain was relatively cool (77 C), the hot spot model tended to predict higher insect numbers than the spatial model. However, when the grain temperature was warmer (86 F), the spatial model tended to predict slightly higher numbers than the hot spot model. What this means in real world conditions is that hot spots will not influence how fast populations grow in the grain unless the grain is cool and there is a very high number of insects located in a small region of grain.

Technical Abstract: Grain temperatures and insect populations predicted by a hot spot model, which includes feedback from the insect model to the temperature model, and a spatial model, which does not include that feedback, were compared. The hotspot model predicted a maximum of 120 adults/kg of wheat at the centre of the grain bulk towards the end of fall and reached a maximum temperature of 39 C, while the spatial model predicted an adult population of 500 adults/kg of wheat and no increases in temperatures for an initial grain temperature of 30 C, an initial Cryptolestes ferrugineus population of 10,000 adults, and Winnipeg, Canada storage conditions. For the same simulation conditions but using weather data for Topeka, Kansas the hot spot model predicted a maximum of 150 adults/kg of wheat at the center of the bulk in fall while the spatial model predicted a maximum of 800 adults/kg of wheat. Due to the warm ambient temperatures in Topeka, Kansas the insect populations predicted by both the hot spot and spatial models were higher and insect development was earlier than those predicted under Winnipeg storage conditions.