Trees or stores? The origin of migrating Prostephanus truncatus collected in different ecological habitats in southern Benin

Migrating Prostephanus truncatus (Horn) (Col.: Bostrichidae) were collected weekly with pheromone-baited funnel traps at three different sites in southern Benin for 12 months. One site was located in a primary forest, one in a peri-urban area, and one in a region with intensive agriculture. The sex of the trapped beetles was determined. The gut-content of the specimens was analyzed for remains of lignin and starch, the former indicating recent feeding on woody, the latter on a starchy substrate, such as stored maize or dried cassava. At all locations, the sex ratio of migrating P. truncatus was significantly female-biased, with the greatest proportion of females trapped at the peri-urban site. At the forest site, most beetles had lignin in their guts, while the proportion of beetles containing starch was highest in the peri-urban site. Approximately equal proportions of beetles with either starch and lignin were trapped in the region with intensive agriculture. The results are discussed with regard to the population dynamics of P. truncatus in different habitats and the flight activity of the beetles.