Nonagricultural Hosts of <I>Prostephanus truncatus</I> (Coleoptera: Bostrichidae) in a West African Forest

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Prostephanus truncatus (Horn) is an important insect pest on stored maize, Zea mays L., and cassava, Manihot esculenta Crantz, in Africa, but weekly pheromone-baited trap catches in West and East Africa exceeding 1000 individuals suggest that this insect is also well established in nonag- ricultural areas. The magnitude of pheromone-baited trap catches on the African continent empha- sizes the importance of looking into the nonagricultural hosts of P. truncatus, because wild P. truncatus populations may be a threat to nearby food storage systems. In this study, we used a combination of 1) laboratory no-choice rearing tests on forest branches, roots, and seeds; 2) a behavioral experiment; 3) a review of published studies on the spatial ecology and host range of P. truncatus; and 4) a comparison of estimated P. truncatus production from potential forest hosts with the magnitude of pheromone trap catches, to discuss the possible role of different hosts in the P. truncatus ecology in West Africa. In no-choice tests, we evaluated the ability of P. truncatus to attack and reproduce on 1) fresh branches from 26 plant species, 2) dry branches from 13 species, 3) fresh roots from 18 species, 4) dry roots from two species, and 5) seeds from four species. Heavy attacks occurred on fresh branches from 11 tree species and fresh roots from four tree species. High reproductive rate was found on branches from four species and on roots from two species, and P. truncatus reproduction was also observed on teak, Tectona grandis Linn. F., seeds. We provided rough estimates of P. truncatus populations from different forest hosts and compared them with the spatial distribution pattern and the magnitude of pheromone-baited trap catches in a West African forest. The results from this study underscored the importance of further research into the possible role of girdled branches of Lannea nigritana (Sc. Elliot) Keay (Anacardiaceae), forest seeds, and roots in the P. truncatus ecology in West Africa.