Upwind flight of Prostephanus truncatus is mediated by aggregation pheromone but not food volatiles

Abstract

Flight bioassays were carried out to investigate the response of Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) to maize volatiles in comparison to the male-produced aggregation pheromone. Upwind attraction of flying P. truncatus is mediated by the male-produced aggregation pheromone. In contrast, beetles showed no response to maize grains or volatiles, and no interactions between aggregation pheromone and maize volatiles were recorded. This absence of upwind flight to food volatiles, or any synergism between pheromone and food volatiles suggests that the male-produced aggregation pheromone is the only known long-range semiochemical used by P. truncatus for dispersal and host-selection. These results are in contrast with those on several other stored-product species, and suggest that P. truncatus may not use maize volatiles as long-range host finding kairomones in nature. We propose a hypothesis for the process of dispersal and host colonisation by P. truncatus.