Factors affecting vertical movement of Rhyzopertha dominica (Coleoptera: Bostrichidae), lesser grain borer, in the grain mass

Vertical moviment of Rhyzopertha dominica (Coleoptera: bostrichidae), the lesser grain borer, in the grain mass: factors affecting dispersal behavior

Erick Cordeiro¹, James Campbell², Thomas Phillips¹

 

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

 

Grain in storage facilities forms suitable but temporally and spatially discontinuous resource patches in the agricultural landscape for stored-product insects. Insects residing in a particular patch are able to contribute to population grow and eventually to disperse; the colonization of the new patch depends on the ability to reach the surface of the natal site, take flight, move through the environment, and to find a new resource patch.  The causes for stored-product insects to disperse from stored grain is not well understood, but this process is critical for population establishment and colonization of new resource patches. This research focused on the dispersal behavior within the grain mass of Rhyzopertha dominica.  To address this question we measured the movement of individual adults in a vertical mono-layer of wheat to determine when they move to the grain surface based on age since adult emergence from an infested kernel (1, 7, and 14 days), sex, and strain. Three week-old adults tended to stay closer to the surface compared to one or two week-old insects. Also, females tended to be more active and to explore a wider area compared to males. Explored area and daily displacement were also significantly strain dependent. These experiments have provided important information regarding what drives lesser grain borers to leave stored grain and can be used to improve trapping and monitoring of lesser grain borer in grain storage sites.