Insect pollination improves yield of Shea (<i>Vitellaria paradoxa</i> subsp. <i>paradoxa</i>) in the agroforestry parklands of West Africa

Abstract

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.

Insect pollinator dependence of shea (Vitellaria paradoxa C.F. Gaertn.) in the Guinea Savanna zone of Ghana

“…5). This significant difference in mean weight agrees with Lassen et al (2018) and Stout et al (2018) who recorded heavier nuts under open pollination as compared with bagged inflorescences. This could be due to the ability of pollination to mediate the production of growth hormones in plants (Klatt et al 2013).…”

Local‐scale tree and shrub diversity improves pollination services to shea trees in tropical West African parklands

“…Flowers are born on inflorescences located at the tips of branches. The flowers are short lived, but buds, receptive flowers and older blooms occur simultaneously over a long flowering period (Stout et al, 2018). The flowers are protogynous, with the stigma emerging from the bud and becoming receptive before the sepals part to reveal the petals and stamens (Hall, Aebischer, Tomlinson, Osei-Amaning, & Hindle, 1996).…”

“…The nuts and butter are commercially valuable: traded locally providing women with a rare source of cash income and internationally for use in the cosmetics and confectionary industries (Pouliot, 2012). Shea is heavily dependent on bees for pollination, and a range of bee species have been recorded visiting flowers, although honeybees are thought to be more effective pollinators than smaller bees (Lassen, Nielsen, Lompo, Dupont, & Kjaer, 2016;Stout et al, 2018).…”

“…Given the intensification of agriculture and encroachment on natural areas in West African shea parklands, and the association between habitat loss and fragmentation with decreased pollinator abundance and diversity, pollination services in shea parklands may be negatively affected by human activities. As shea relies heavily on bees for pollination (Lassen et al, 2016;Stout et al, 2018), changes in agricultural practices may have a negative effect on pollinating insects, which could contribute to threats to food security and the economic well-being of an estimated 45.1 million rural people living in the shea belt (Naughton, Lovett, & Mihelcic, 2015). We aimed to quantify the relationship between species diversity in fields in shea parkland, the area of semi-natural habitat in the wider landscape and provision of pollination services to shea trees by testing the following hypotheses:…”

Action before certainty for Africa's European migrant birds

“…Empowering African conservationists to develop schemes is likely to provide more sustainable long-term solutions. The Birds, Bees and Butter initiative, for example, aims to improve productivity of native shea trees (Stout et al, 2018) and to benefit insects and birds, and has built in socio-economic and biodiversity assessments. In the Sahel the re-creation of traditional bocage areas of fields surrounded by hedges and woodland, to improve the sustainability of crop and livestock management, could provide valuable habitat for both resident and migrant birds.…”