Pollinator decline, driven primarily by habitat degradation, has the potential to reduce the quantity and quality of pollinator-dependent crops produced across the world.  Vitellaria paradoxa, a socio-economically important tree which grows across the sub-Saharan drylands of Africa, produces seeds from which shea butter is extracted. However, the habitats in which this tree grows are threatened with degradation, potentially impacting its ability to attract sufficient pollinators and to produce seeds. The flowers of V. paradoxa are insect-pollinated, and we investigated flower visitors in six sites in southern Burkina Faso and northern Ghana and tested whether plants were capable of fruit set in the absence of pollinators. We found that the majority of flower visitors (88%) were bees, most frequently small social stingless bees (Hypotrigona gribodoi), but native honey bees (Apis mellifera adansonii) were also common visitors to flowers early in the morning. The number of fruit produced per inflorescence was significantly lower when insects were excluded during flowering by bagging, but any fruits and seeds that were produced in bagged treatments were of similar weight to un-bagged ones. We conclude that conservation of habitat to protect social bees is important to maintain pollination services to V. paradoxa and other fruit-bearing trees and cultivated crops on which local livelihoods depend.

Shea (Vitellaria paradoxa C.F. Gaertn.) is a multipurpose tree species indigenous to the Sudano Sahelian zone of Africa and occurs as the most abundant economic tree species in northern Ghana. The edible oil (shea butter) extracted from shea kernel is ranked as the most economic product of the species. Although fruit set and yield of shea are known to be influenced by insect pollination, the actual contribution of insect pollinators to its reproductive success has rarely been studied. This study estimated the percentage insect pollinator dependence and monetary value of insect pollination per bag of shea kernel (85 kg) in the Guinea savanna zone. Open pollination and insect exclusion treatments were applied to the flowers of 18 randomly selected matured shea trees and observed from the onset of flowering to fruit maturity. Proportion of total production value attributed to insect pollination approach was used in estimating the monetary value of pollination per bag of shea kernel with the average market price as proxy. The study revealed an insect pollinator dependence of 77% and 73% for fruit set and dry kernel yield, respectively. Mean number of fruit set per inflorescence varied significantly between insectexcluded and open-pollinated inflorescences (p < 0.05). The monetary value of insect pollination was estimated at GH₵ 73.21 (US$ 18.67) per bag of kernel as of August 2016. Shea is a high insect pollinator-dependent species and the conservation of insect pollinators would be critical to the sustainability of yield.

Detarium microcarpum Guill and Perr is a multipurpose tree species indigenous to semi-arid regions of Sub-Saharan Africa. It is being exploited to local extinction due to high dependence for fuelwood and other uses. The present study explored different pre-treatment methods for enhancing seed germination and growth of D. microcarpum in the Guinea savanna zone of Ghana. The experiment employed a 4 × 4 factorial design with seeds subjected to four pre-treatments (50% sulphuric acid concentration, 98% sulphuric acid concentration, cold water and hot water) at four pre-treatment time durations. Percentage germination varied significantly between pre-treatments (p < 0.05) with cold water treatment recording the highest mean germination (73.06%) and the 98% sulphuric acid concentration recording the least (47.72%). Germination rate had a moderate positive relationship with plant height (r xy = 0.49) and collar diameter (r xy = 0.54). The study recommends seed immersion in cold water for 48 h as the most efficient pre-treatment for D. microcarpum.

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