Rhyzopertha dominica movement and spatial pattern formation in wheat
Erick M. G. Cordeiro1, James F. Campbell2, Thomas Phillips1, and Kimberly A. With3
1Department of Entomology, Kansas State University, Manhattan, KS 66506, USA
2USDA, Agricultural Research Service, Center for Grain and Animal Health Research, 1515 College Ave., Manhattan, KS 66502, USA
3 Laboratory for Landscape and Conservation Ecology, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
Stored grain is a highly homogenous resource, but stored-product insects within a mass of grain are often patchy in distribution. Insect movement patterns and interactions with each other within this homogenous resource may generate non-random spatial distribution, but this process is not well understood. Rhyzopertha dominica movement behavior and feeding spatial pattern formation was evaluated within a mono-layer of wheat simulating a grain mass. Single adults tended to revisit certain areas generating a spatially patchy distribution. Differences in feeding strategy, mating behavior, and competition have a strong impact on behavior and ultimately in spatial distribution patterns. Although same sex conspecifics tend to maintain the same distance from each other, females in the presence of another female had a higher daily displacement and a more tortuous path than males, whether alone or with another male or female. The presence of a female increased the tortuosity of the male’s path. Comparing two strains – one recently collected from the field and one kept in culture for many generations – revealed differences in spatial pattern of distribution. These experiments provide insight on how spatial patterns may be formed within homogenous patches through movement, feeding behavior, and interactions with conspecifics.
