Untersuchungen zur Biologie von Prostephanus truncatus (Horn) (Col., Bostrichidae) auf Holz

Abstract

Studies on the biology of Prostepbunus truncatus (Horn) (Col., Bostricbidue) on woodThe adult survival period and the lifetime progeny of Proste banus truncutus were investigated on the wood of Manzbot esculenta and Poincinza regia. O n M . escuinta there was a slight mortality from the beginning of the trial which caused a slow decrease of the population. The maximum survival period lasted between 40 and 44 weeks. O n P. regia the population of P. truncatus decreased faster than on M . esculenta. The maximum survival period was between 24 and 30 weeks. The survival curves of male and female adults had a similar shape on both media. The number of eggs laid in average per female during lifetime was 186 on M . esculenta and 52 on P. regia. The determination of the larval instars by measuring the width of the frontoclypeus was practicable on M . esculenta. The measures were separated into 3 distinguishable classes which could be expected as the 3 larval instars. O n P. regia and 3. trugucuntba there were no distinguishable classes of measures, though a clear determination of the larval instars was not possible.

Flight initiation in Prostephanus truncatus: influence of population density and aggregation pheromone

“…The ecology of P. truncatus beyond maize and cassava stores remains ill-defined; however, there seems to be strong evidence that the insect occupies a transient niche in degrading branches of trees and shrubs (Nang'ayo et al, 1993) specifically those girdled by cerambicids (Ramírez-Martínez et al, 1994), which may have enriched nutritional status (Forcella, 1981;1982). This is also consistent with the observation that P. truncatus is only able to reproduce in wood with a high starch content (Helbig & Schulz, 1994). In these circumstances, it may be advantageous for most of the population to remain in a patch of substrate, even if it is already heavily exploited.…”

Studies on predation of Prostephanus truncatus (Horn) (Col., Bostrichidae) and Sitophilus zeamais Mots. (Col., Curculionidae) at different densities on maize by Teretriosoma nigrescens Lewis (Col., Histeridae)

“…Experiments at the cob level were designed to compare T. nigrescens foraging success in the presence and absence of adults of P. truncatus or S. zeamais through one generation. The initial ratios of the different insect species among the treatments approximated those reported in the West African storage environment ( Helbig 1993).…”

“…In West Africa, many aspects of P. truncatus and T. nigrescens behaviour and ecology are unknown and the pest complex of traditional African grain stores makes it difficult to determine the efficacy of an introduced predator. Several studies ( Rees 1985; Leliveldt 1990; Helbig 1993; and Pöschko 1993) have shown that T. nigrescens is an effective predator on P. truncatus in laboratory settings, and studies by NRI, the Ghana Ministry of Food and Agriculture, GTZ and the International Institute of Tropical Agriculture in Benin, have been conducted to assess the ecological and economic impact of T. nigrescens in Ghana, Togo and Benin (e.g. Boxall 1996) but fundamental biological questions remain.…”