Bush mango (Irvingia spp.)

by Verina Ingram, Abdon Awono and Sarah Laird

Species scientific and trade names

Irvingia robur, I. grandifolia, I. wombulu, I. excelsa, I. smithii and I. gabonensis (Eyog et al. 2006) Klainedoxa gabonensis, Klainedoxa trillesii and Desbordesia insignis (Gallois, van Andel et al. 2020) are all commonly known under the collective name of Bush mango in anglophone Cameroon, mangue sauvage and andok in Francophone Cameroon in the Centre, South and Littoral regions, and peké in the East region. It is also known in local dialects as payo (Baka), bojep (Boki), ogbono (Igbo), geluae (Anyang), kelua (Basho), elueh (Ovande), and uyo (Effik and Ibibio) (Sunderland et al. 2010). Some ethic groups distingish specifc species (Gallois, van Andel et al. 2020). The primary species for subsistence and commercial use are Irvingia gabonensis and Irvingia wombulu.

Origin of species, ecology, habitats 

Irvingia gabonensis and Irvingia wombulu are both found in the lowland tropical humid forests. I. gabonensis is found from eastern Nigeria to the northern Congo Basin, and I. wombolu has a wider range through West Africa, reaching as far west as Senegal, and south to Angola (Sunderland et al., 2002; Tchoundjeu et al., 2005; Vivien and Faure, 1985). Irvingia gabonensis and Irvingia wombulu are very similar, and often difficult to differentiate (Ainge et al, 2001). The fruit of I. gabonensis has a juicy and fragrant flesh that produces a sweet juice, while I. wombulu (known as dry season mango) has a bitter and smaller fruit (Tchoundjeu and Atangana, 2007; Oyen, 2007). Irvingia gabonensis is a larger tree of up to 40 meters in height and 120 centimetres in diameter, Irvingia wombulu trees reach 25 meters in height and 80 centimetres in diameter (Eyog et al. 2006, Awono et al. 2009, Ainge et al. 2001).

Commercial use

Marketed primarily as African Mango (also Agbono, Bread tree, Dika Nut, and Bush Mango), extracts of the kernel are promoted to contribute to weight loss, as an appetite suppressant, lower cholesterol, treat type 2 diabetes, and, to a lesser extent, as a treatment for diarrhoea, pain and an anti-microbial. The nuts are marketed as high in fibre and fatty acids. Dozens of small companies sell bush mango products on the internet, alongside mainstream herbal medicine companies (e.g., Nature’s Way, Vitamin Shoppe) selling products in retail stores. For more on the medical applications of the bark see Okolo et al., 1995, and on the seed extract Olorundare et al., 2020. New uses and applications for bush mango are being researched and developed, given its unique chemical structure and physical properties, which allow for a variety of applications, such as acting as a cocoa butter substitute, which has a similar chemical composition (Yamoneka et al., 2018).

Traditional use

Bush mango is one of the most widely used forest tree species in Cameroon, and in West-Central Africa. The fruits have been harvested and used for subsistence, and sold as a condiment and medicine for centuries. The most important product comes from the kernels, which yield an important food additive popular to thicken soups and stews and as a condiment (Sunderland et al., 2003; Ndoye et al., 2001; Ofundem et al., 2017). It is widely valued for its ‘drawability’ (Bello et al. 2011) – a quality important in local cuisine. 

Bush mango kernels are processed by grinding and crushing, and are sometimes made into a cake called ‘dika (or odika) bread’ to preserve it for easy use in thickening soup. Dika bread is also sometimes used for animal feed. Edible oil is extracted from the seed and used in cooking, and as a substitute for cocoa butter, and for soap making, cosmetics, and medicinal products (Ejiofor et al, 1987; Silou et al, 2004; Leakey and Newton, 1994; Vivien and Faure, 1995). The fruit of Irvingia gabonensis is juicy and sweet and is eaten fresh. It is rich in Vitamin C (Eyog et al 2006) and can be used for the preparation of juice, jelly, jam and wine (Ejiofor, 1994; Okolo et al. 1995). The pulp has also been used to prepare a black dye for cloth (Tchoundjeu and Atangana, 2007). The kernels are rich in protein, calcium, iron and fat (FAO, 2014). Bush mango wood is used locally for the construction of frames, the manufacture of mortars, pillars and to make poles, stakes, walking sticks and thatched roof supports, and dead branches are used as firewood (Eyog et al 2006; Tchoundjeu and Atangana, 2007; Ayuk et al, 1999).

Traditional medicinal uses are numerous and include the astringent nut paste used for burns (Eyog et al. Op. cit.) and grated bark to treat diarrhea and dysentery (Walker and Sillans, 1995). The bark is used as a pain reliever for wounds, toothache, diarrhea, hernia, yellow fever and as an antidote for poisoning (Ewane et al. 2009; George, 2007). The shell of the fruit is a talisman brought to small children to ensure their good health (Eyog et al. 2006).

Use of traditional knowledge in commercial products

New product development for weight loss by companies does not rely on traditional knowledge, however any new developments derived from traditional uses should require benefit sharing through ABS agreements. 

Local and regional markets

Bush mango is one of the most widely traded NTFPs in the humid forest zone of Cameroon (Ndoye et al, 1997; Ndoye and Tabuna, 2016). From a study analyzing the marketing of four non-timber forest products (NTFPs) sold in 28 markets in the rainforest area, 45% of traders reported that bush mango was their most marketed product (Ndoye et al., 1997). It was the second most traded NTFP, after Gnetum (Ingram, 2013). Tabuna (1999) estimated the value of bush mango marketed in 7 large markets neared $1 million and by 2016 in Cameroon this was estimated at $9,428,710 US (Ingram et al 2017). It is also one of the most widely traded NTFPs in the region – with a large trade between Cameroon and neighbouring countries including Nigeria, Gabon, Central African Republic and Equatorial Guinea (Awono et al., 2016). Awono et al (2016) found that the highest volumes of bush mango, 2,400 tons, are traded to Nigeria.

In 2007 an estimated 2,390,920 kg was exported from Cameroon to Nigeria, and 302,050 kg to Equatorial Guinea and Gabon, with a commercial value of CFAF 3.6 billion (USD $7.2 million) and CFAF450 million (USD $900,000) respectively. An estimated 3125 tons are exported annually to Nigeria, via Bamenda in the Northwest, and Kumba, Mamfe, Idenau, and Limbe in the South-West. Approximately 2,391 tons flowed from the South via Mbalmayo, Sangmélima and Ebolowa to Equatorial Guinea and Gabon (302 tons) and via exporters in Messock, Akom, Kye-Ossi and Abang Minko (Ingram et al. 2017). Exports from Cameroon to West and Central Africa have steadily increased since mid 1990s (Ndoye, 1995, Ndoye et al, 1997, Eyog et al, 2006, Ingram et al 2017).

Hirai (2014) shows in the Southeast region of Cameroon that Baka communities utilize the majority of the bush mango harvested for their own personal consumption. However, this is also attributed to the fact that the relative benefit they receive from increased commercialization is lower than for other actors, thereby not incentivizing the sale of all their supply.

Global markets 

Two global markets exist: One for the consumption of bush mango in the traditional manner as a soup and stew thickener by the ex-patriate African community. Kernels have been traded since at least the 1970s from Cameroon, when it was estimated to be worth 50 million US$, and have been exported, notably to Nigeria, Gabon, and Equatorial Guinea, and onwards in West and Central Africa (Ingram et al. 2010, Clark and Sunderland 2004). In 2016 the Cameroonian market was estimated at 2700 tons a year with a value of 6480 million CFA (Awono, Eba'a Atyi et al. 2016).

Second, since the new millennium, nuts have increasingly processed in the USA and Europe as the active ingredient in nutraceutical and herbal medicine, weight-loss and appetite-suppressant supplements and cosmetics (Sun and Chen 2012). The first category of use appears greater than the second although data is lacking. For the second, national export figures are unreliable and global figures are not available as there is no international product code classification, but the largest markets for bush mango based on internet adverts appear to be USA, EU and India. There appears to have been an increase in the quantities of bush mango exported to Europe from Cameroon, from 5 tons per year prior to 2000 increasing to over 100 tons in 2005 (Ingram, Ewane et al. 2017). Increased sales are attributed due to the continued domestic demand, increased size of the African diaspora in Europe, and stronger links between the EU and Africa (Tabuna, 1999, Tabuna, 2016, Ingram 2014).

Researchers reported that the industrial potential of bush mango includes kernels used for wine (Akubar, 1996), as a cooking oil, margarine, perfume, soap (Joseph, 1995), gum (Ndjouenkeu et al. 1996), obesity and diabetes management (Oben, et al. 2008), pest management (Dudu et al. 1998) and binding agent in tablet formulation (Odeku et al. 1998).

Employment or scale of livelihoods involved

Ingram et al. (2017) indicated that approximately 5190 people work in the Bush mango value chain ending in 24 markets in southern Cameroon, with an estimated 4109 tons harvested on average annually in the period between 2007 and 2010. Bush mango income contributes on average 31% of harvester's annual income, with dependence on Bush mango income increasing for those further from the forest. Ndumbe et al. (2022) show that the contribution of bush mango to collectors’ NTFP income was statistically significant and could on average contribute around 18%. Within areas of high commercialisation, in the Southwest and Littoral provinces NTFPs contribute around 33% of household incomes (Ndumbe et al., 2022). However, levels of reliance on NTFPs in general, and specifically bush mango, fluctuate significantly each year, depending on geography and weather.

Management

All the species sold as bush mango are found wild in forests, with I. wombulu, I. gabonensis and Desbordesia insignis semi-domesticated - commonly left in farmers’ fields and fallows (Ainge and Brown, 2004; Iponga et al, 2016; Lowe et al. 2000, Tchoundjeu et al. 2005, Ewane 2010, Ingram 2014, (Gallois, van Andel et al. 2020). Sweet Bush mango trees are selected for the sweetness of their fruit pulp and the sliminess of its kernels, while bitter Bush mango is selected for the sliminess of its kernels alone. Kernel quality outweighs the taste of the fruit pulp in selecting sweet Bush mango (Kengni et al. 2011). Differences in socio-cultural groups have been associated with the cultivation status of bush mango trees in West Africa which are key factors influencing their abundance and conservation (Vihotogbé, Kakaï et al. 2014). In contrast to Irvingiaceae in the forest, of which the fruits are available for everyone, trees growing on or near agricultural fields are generally property of the owner of the field, who may prohibit fruit collection by others (Ainge and Brown, 2004; Iponga et al, 2016; Lowe et al. 2000, Tchoundjeu et al. 2005, Ewane 2010, Ingram 2014, (Gallois, van Andel et al. 2020).

Conservation status

The IUCN Red List classified Irvingia gabonensis as lower risk/near threatened, but this classification needs updating. Irvingia wombulu is not listed (World Conservation Monitoring Centre, 1998; The IUCN Red List of Threatened Species, 2016). Increased logging of natural forests produces collateral damage to bush mango, a species not of interest for the industrial timber trade. Deforestation due to agriculture and degradation of lowland forest is putting pressure on these species and has raised concerns about the sustainability of the trade (Ainge and Brown, 2004; Iponga et al, 2016; Lowe et al. 2000, Tchoundjeu et al. 2005, Ewane 2010, Ingram 2014, (Yobo, Awono et al. 2020). Additionally, fallen fruits are often over-harvested, negatively impacting regeneration, particularly since fruit yield varies by year (Ingram, 2014; Awono et al, 2009).

Regulatory framework

Governance of bush mango (as with other wild edibles) is a hybrid and dynamic adaptation of multiple statutory measures, customary law, international conventions, project-based systems, voluntary market-based systems, and corruption – the complexity and disorder tend to undermine sustainability and local livelihoods.

Bush mango or the specific species are not classed as a ‘Special Forestry Product’ according to Decision No 336 of 2006, which sets annual exploitation quotas for products of economic and/or environmental interest by the Ministry of Forestry and Wildlife. From 2005 to 2010, quotas were granted for 120 and 100 tons to one company in each year and agreements (gré à gré) were granted by Ministerial orders to seven companies for a total of 111 tons in 2004 and for six companies for 60 tons in total in 2005. These permits are demand based and do not reflect the supply of bush mango, as despite the requirement of the 1994 Forest Law there has never been an inventory of stock. Way bills, the administrative paperwork used to track Special Forestry Products and the permit allocation, do not match the volumes nor the quotas allocated, indicating a large discrepancy between practice, the regulatory framework and its enforcement. Current land tenure and forestry law gives local community usufruct rights to resources in their forests only for subsistence use, and they are prohibited from selling bush mango in local and regional markets without applying for onerous and expensive permits. Permitting and taxation associated with bush mangos NTFPs are currently arbitrary, expensive and bureaucratic for small scale producers and traders, leading to illegal trade and exposure to corruption.

There is widespread corruption during transport nationally and at border posts by police officers, forestry officials, customs, council, commerce and quarantine officers. Wholesalers generally do not have permits, and even when they do possess, corruption is prevalent. So called ‘informal taxes’ amounted to 4% of trader's costs and 15% of exporter's costs to Guinea and Gabon (Ingram et al 2017).

Customary tenure and ownership rules dominate governance arrangements concerning access to the species in practice. Ewane (2010), found that in South-West and East Cameroon fees are paid to traditional authorities to gain access to wild Bush mango in the region, with resources extracted for free by community members, and fees paid to traditional councils or chiefs in neighbouring villages by commercial harvesters. However, systems of land tenure, including the absence of effective land titles, even while maintaining customary rights, can create conflicts and precarity (Kimengsi & Balgah, 2021). The harvest of bush mango often exists in a grey area within the statutory land tenure and resource rights system which does not formally recognize ownership but also does not enforce non-ownership through dispossession. In doing so, it creates a plural system and allows actors the ability to craft their own response. The issue of land tenure also extends to the legal zonation of land use. Hirai and Yasuoka (2020) argue that the harvest of bush mango is not primarily an ecological issue but rather an access issue. Zonation is often strict (on paper) and typically does not allow for multiple uses, which can limit community access to NTFPs.

Certification

No voluntary certification either as timber or wild species (eg Fairwild) of the species is known in West Africa. A few companies make claims about their bush mango products being sustainably wild harvested, fair trade, or organic, although these are usually not independently verified.

Discussion

The sale of kernels and processed products from wild and semi cultivated bush mango (Irvingia spp.) makes a substantial contribution to the livelihoods of actors throughout the value chain in southern Cameroon. Because the majority of stakeholders use revenues to meet basic household needs, the development implications of this trade are significant. Increasingly, however, this commerce appears unsustainable, indicated by declining wild resources reported by experienced harvesters travelling longer distances, combined with continuing high demand, clearance of the species' natural forest habitat, low levels of managed cultivation, and a lack of consistent regulatory control and enforcement. This situation has arisen despite long running concerns of over-exploitation.

Strategies to address the problems include (1) revising the regulatory framework to better capture and monitor bush mango permits, particularly at major markets and border crossings, (2) government promotion and guidance on sustainable harvesting techniques, and (3) collaboration with customary authorities who could help enforce regulations in forest areas. Together with private sector, research and development partners, other ways to implement a more sustainable policy include furthering collective action, particularly at the harvester level, improved market information, disseminating more efficient and safe processing and storage techniques, promoting domestication and cultivation, and support to strengthen producer associations and enterprises, with a focus on vulnerable ethnic groups and remoter communities. Pilots show such measures to be effective (Tieguhong et al., 2009; Awono, 2005; Awono et al., 2013; van der Goes and Ngueko, 2009; Leakey, 2011; Degrande et al., 2006). Improved coordination between the Ministries of Agriculture, Forestry and Wildlife, Commerce and Customs with direct stakeholders in the chain, and indirect actors such as research and development NGOs concerning trade and distinguishing cultivated from wild species in permitting could further enhance sustainable governance.

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Additional resources

References

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