Emmanuel Opuni Frimpong

The mahogany shoot borer, Hypsipyla robusta (Moore) (Lepidoptera Pyralidae), is a serious pest insect in the tropical forests of Africa, Asia and Australia. This insect causes multiple branching of young shoots in indigenous mahogany plantations. Gravid insects are attracted to oviposition sites by volatile organic compounds (VOCs) released by their hosts. Therefore, in this study, we aimed to (i) identify and characterise the VOCs released by the shoots of Entandrophragma and Khaya mahogany and (ii) to determine the electrophysiologically active VOCs which could influence the olfactory response of H. robusta. Volatile samples were collected from shoots of Entandrophragma angolense (Welwitsch) de Candolle, Entandrophragma utile (Dawe et Sprague) Sprague, Khaya anthotheca (Welwitsch) de Candolle and Khaya ivorensis Chevalier by closed-loop-stripping-analysis. The VOCs were identified by gas-chromatography mass-spectrometry (GC-MS) and characterised by comparing their retention times ...

Hypsipyla robusta Moore (Lepidoptera: Pyralidae), like many other moth species, shows selectivity when choosing host plants for its eggs. Four Meliaceae species (Khaya grandifoliola, K. ivorensis, Swietenia macrophyla, and Entandrophragma cylindricum) were established in a moist semideciduous forest in Ghana to study this selectivity at 12 and 21 months after planting. The analysis of variance (ANOVA) at aP-value of 0.05 was used to test the significance of differences in infestation by H. robusta between the species. H. robusta attacks were recorded by month 12 after planting in the field, and only Khaya spp. was attacked, with attacks evident on 15.5% of K grandifoliola and 6.6% K. ivorensis. Saplings in blocks closer to an older H. robusta infested K. grandifoliola stand had more infestation compared to saplings further away. The mean percentage of K. grandifoliola attacked was 38.9%, 38.9%, 13.3%, and 7.4% in 4 different plots located increasingly further away from the older inf...

We conducted a year long survey of the fruit-feeding butterfly fauna of sacred forest groves and forest reserves of Ghana. About one-third of all fruit-feeding species recorded for Ghana were trapped, but our total sample had not yet reached the point of species saturation. Rarefied species richness was higher in the larger forest reserves than in the small sacred groves, as predicted by species-area relationship theory. Bebearia and Euriphene showed the greatest decline in species richness across sites, demonstrating that common, wide-spread species can be vulnerable to fragmentation.

Leaf area, IBA concentration and age of stockplants were all found to be important factors for successful rooting for vegetative propagation using single-node cuttings of the two main African mahogany species: Khaya anthotheca and K. ivorensis. Cuttings with leaf area of 30–50 cm2 had the best rooting percentage and cuttings with about 30 cm2 had the most number of roots per cutting in K. anthotheca. Khaya ivorensis, cuttings with 10–30 cm2 leaf area had the highest rooting percentage. Cuttings collected from 1-year-old stockplants recorded the highest rooting percentage and largest number of roots per cutting. Cuttings from 3-year-old stockplant of the same seeds sources had the lowest rooting suggesting aging negatively impacted rooting ability. The effect of auxin concentration, on rootability was examined with cuttings of K. anthotheca. An IBA concentration of 0.8% was the best exogenous auxin concentration for percentage rooting, number of roots per cutting and the length of the longest root per cutting.

Sacred forest groves in Ghana are centuries old protected areas that were once part of continuous forest cover but now mostly exist as relict forest patches embedded in an agropastoral landscape. We conducted a year-long survey of the fruit-feeding butterfly fauna of four sacred groves and two forest reserves in the moist semi-deciduous forest zone of Ghana to characterize resident species diversity and complementarity among communities. Joint analysis of frugivorous butterfly diversity at these six forest fragments, which ranged in size from 6 to 5000 ha, was used to evaluate the conservation potential of these ancient indigenous reserves. A total of 6836 individuals were trapped across all sites, representing 79 species and five subfamilies. Community diversity was characterized in terms of, (a) number of species accumulated versus sampling effort, (b) rarefied species richness, (c) nonparametric richness estimates, (d) species evenness, (e) Simpson’s Index of Diversity, and (f) complementarity of communities. Diversity of the fruit-feeding butterfly communities, quantified in terms of both species evenness and rarefied species richness, was higher at the larger forest reserves than at the small sacred forest groves. Additionally, although all sites had species trapped only at that site, the 5000-ha forest reserve harbored a resident community that was clearly distinctive from and more diverse than the other communities including the other forest reserve. Hence, our findings add to the burgeoning body of data that indicates large reserves are the foundation of successful conservation programs. Nonetheless, we found these small forest patches contribute to biodiversity conservation in at least three ways and these are identified and discussed. We also identify a number of species that appear more or less vulnerable to dynamics of forest fragmentation based on changes in their relative abundance across sites and we interpret these data in the context of potential indicator species and theoretical predictions of at-risk species.