Submitted to: Annals of the Entomological Society of America
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/1/2004
Publication Date: 3/1/2004
Citation: Nansen, C., Meikle, W.G., Tigar, B., Harding, S., Tchabi, A. 2004. Non-agricultural hosts of prostephanus truncatus (horn) (coleoptera: bostrichidae) in west african forests.. Annals of the Entomological Society of America. Interpretive Summary: Pheromone traps in West African forests yield more larger grain borer beetles (pests of stored maize and cassava) than do traps in agricultural areas, but the specific tree species serving as refuges are unknown. Beetles were found to feed and reproduce at various rates on branches, roots, or seeds of several tree species out of 26 tested in the laboratory. One lead was that teak seeds in the forest may be a resource providing a potential reservoir of pest beetles. The impact of this study was to provide a hypothesis requiring further work in the field to either confirm or deny. The results will ultimately influence management of the insect pests to protect stored grain in Africa.
Technical Abstract: Prostephanus truncatus is an important insect pest on stored maize and cassava in Africa, but it is also believed to be well established in savanna and forest habitats. However, fairly little is known about potential hosts of P. truncatus in non-agricultural habitats. In no-choice experiments, we evaluated the ability of P. truncatus to attack and reproduce on the following potential forest hosts: (1) fresh branches from 26 tree species, (2) dry branches from 13 tree species, (3) fresh roots from 18 tree species, (4) dry roots from two tree species, and (5) seeds from four tree species. Heavy attacks on fresh branches were recorded in 18% of all infestations, and they occurred on 11 different tree species. Heavy attacks also occurred on fresh roots from four tree species. High reproductive rate was found on branches from four species (Delonix regia, Ceiba pentandra, Manihot esculenta, and Ficus exasperata) and on roots from F. capensis and F. exasperata. In behavioral experiments, a substantial proportion of P. truncatus individuals chose to burrow into the soil when free flight was allowed. Seeds from four tree species Afzelia africana, Vitellaria paradoxa, Elaeis guineensis (oil palm), and Tectona grandis (teak) were also tested as potential forest hosts, and P. truncatus reproduction was obtained on teak seeds. Based on estimates of P. truncatus production in the Lama Forest and surrounding teak plantations from branches and seeds of tree species shown in laboratory tests to be susceptible to P. truncatus, we estimated that even a very low rate of successful reproduction by P. truncatus on these seeds would yield several magnitudes more P. truncatus than would be expected from branches, including the only previously identified host, branches of Lannea nigritana previously girdled by cerambycids. We therefore suggest that seeds and roots may be important non-agricultural hosts for P. truncatus in West African savanna areas.