THREE DIMENSIONAL DISTRIBUTION OF SITOPHILUS GRANARIUS (L.) (COLEOPTERA: CURCULIONIDAE)IN WHEAT INFLUENCED BY THE SYNTHETIC AGGREGATION PHEROMONE

Authors: Plarre, Ruediger

Submitted to: Journal of Stored Products Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: The grain weevils, as well as several other grain feeding beetles, produce chemicals called pheromones that enable them to communicate in their normally dark environments. The practical use of pheromones in integrated management of stored-grain insects has not been fully explored. Research on the application of the environmentally safe compounds would help in the management and control of grain insects. The distribution pattern of the granary weevil, as influenced by the pheromone, was determined. In the absence of the pheromone the insects were active at the surface of the bin, as determined by surface traps. In the presence of the pheromone the insects were more active within the inter-kernel spaces of the grain, rather than on the surface, and were trapped by probe traps. An understanding of the behavior modifying character of the pheromone will lead to an improvement in monitoring systems for grain insects and result in reduced usage of pesticide chemicals.

Technical Abstract: The distribution pattern of Sitophilus granarius in a large bulk of ca. 350 kg wheat was investigated using a three dimensional trapping grid of pitfall- and probe-traps at eight different trap locations. Baiting just a single trapping-location with ca. 6000 ng of the synthetic aggregation pheromone sitophilate, considerably changed the distribution behavior of the weevils. In the presence of the pheromone the overall catch of all trap sites combined was reduced while the proportional catch of the baited trap location increased slightly. The insects tended to stay in the inter-kernel space beneath the surface. The aggregation pheromone was expressed more as an arrestant than an attractant chemical. The weevils' reaction to the pheromone can be described as an orthokinesis. The sex specific effects and the behavior modifying character of sitophilate in the granary weevil is discussed in relation to the aspect of practical application leading to improvement of monitoring systems in the field of stored product protection.