Movement of Rhyzopertha dominica in response to temperature gradients in stored wheat

Authors: Flinn, Paul; HAGSTRUM, DAVID - Retired ARS Employee

Submitted to: Journal of Stored Products Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/4/2011
Publication Date: 9/24/2011
Citation: Flinn, P.W., Hagstrum, D.W. 2011. Movement of Rhyzopertha dominica in response to temperature gradients in stored grain. Journal of Stored Products Research. 47(4):407-410. http://dx.doi.org/10.1016/j.jspr.2011.08.003.

Interpretive Summary: The lesser grain borer is one of the most common and damaging insect pests of stored wheat in the USA. In the autumn, the periphery of the grain bulk cools faster than the center, and this allows grain insects to continue to reproduce in the center. Very little is known about the movement of the lesser grain borer in temperature gradients in stored grain. ARS researchers in Manhattan, Kansas, studied the movement and temperature preference of the lesser grain borer in wheat using two temperature gradients. Beetles preferred moderate temperatures but avoided the highest and lowest temperature regions. Compared to other stored grain beetles, such as the rusty grain beetle, the lesser grain borer appears to move more slowly through the grain into preferred temperature regions, which could affect the beetle’s ability to overwinter in bins of stored grain because they may die from cold temperatures on the periphery of the bin before they have a chance to move toward warmer grain in the center of bins.

Technical Abstract: The movement and temperature preference of Rhyzopertha dominica was determined in a 56 cm diameter cylinder with 9 cm high sides containing 19.9 kg of hard red winter wheat. Two temperature gradients were tested over a 24 h period: 42 to 20°C and 24 to 20°C with the cooler temperature being on the periphery of the cylinder. No preference existed when there was no temperature gradient. Beetles preferred the moderate temperature region of the cylinder in the 42 to 20°C gradient, but avoided the highest temperature region. In the 24 to 20°C gradient, insects did not move very much during the 24 hour period. When a longer duration was used (96 h) for the 24 to 20°C gradient, there were significantly more insects in the warmest center region of the gradient compared to the middle or outer regions. Compared to other stored grain Coleoptera, such as Cryptolestes ferrugineus, R. dominica appears to move more slowly through the grain into preferred temperature regions.