African mountain honeybees in the light of climate change and threats to honeybees’ diversity
Honeybees are major pollinators of both native flora and agriculturally important crops. The crucial services rendered by both wild and managed bees is said to be responsible for the pollination of about 33% of agricultural and other pollinator-dependent crops. However, general opinion within the realm of science, politics and the general public is of a looming crisis that threatens agricultural productivity as a result of declining pollinator numbers. This is coming despite reported increases in global numbers of managed honeybee hives since 1968. However, a reported increase (about 300%) in demand for pollination services as a result of large scale agriculture is exerting strong pressure on global pollination capacities.
The regional decline in densities of honeybees and beekeeping has been attributed to losses resulting from diseases and parasites, pesticides, climate change, land transformation and abandoned beekeeping operations due to the emergence of these and other challenges that are making beekeeping no longer lucrative.
Africa is often described as a hotspot of honeybee evolution and diversity. This is supported by the fact that the continent is home to eleven of the twenty-four known sub-species or races of the western honeybee Apis mellifera. However, this assertion may change if we are not careful, according to a recent review article titled ‘Honeybees health in Africa: A review’ published in a special issue of Apidologie by researchers from the Social Insects Research Group at the University of Pretoria. This publication mentioned that, aside from threats faced by honeybees globally, African honeybees are facing serious threats that are unique to the continent.
Research on honeybees found around the Afromontane regions has quite an interesting history, starting with their first description by Smith in the 1960s. Smith referred to the ‘large and dark bees’ he collected from the slopes of Mounts Kilmanjaro and Meru in Tanzania and Kenya as ‘monticola’. Other authors, including Ruttner and Hepburn, maintained that monticola are found all over the Afromontane regions, from the east up to Mozambique and Malawi in the southern part of Africa. This suggests a geographical spread analogous to the Afromontane flora as a result of climate differences. However, this often presents a challenge when dealing with mountain honeybees in Africa since the refugia hypothesis does not hold for the simple fact that these bees form at least six morphoclusters (not relating to each other genetically aside from having similar body sizes). The refugia hypothesis is also critiqued from the point of how related mountain bees are to their neighbours in the surrounding lowlands. In 2013, Gruber and colleagues lent their voice to the refugia hypothesis and proposed that bees found around East African mountains are not genetically different from those in the savannah. They concluded that the morphological differences are simply phenotypic plasticity used to adapt to the mountains. Although we cannot categorically say that this is true for all Afromontane honeybees, this brings forth an interesting question as to what will happen if there are altitudinal displacements resulting from changes in temperature. Will the bees occupying mountains adapt or will they be displaced by bees from the surrounding savannahs? These and other key questions need to be answered in order for us to understand and predict the plight of African mountain bees. Needless to say, these bees are under-studied and their taxonomy and status are still hotly debated.
Why are honeybees an important part of the mountain ecosystem?
For the majority of people living around mountain regions, agriculture is one of the main sources of livelihood. This is despite the fact that land resources are often limited, resulting in small holdings and meagre returns, among other constraints. Most of the cash crops cultivated are often sterile, thus requiring pollination. Pollinators (bees, flies, butterflies, beetles, moths) play critical roles in improving food security in mountain regions. Bee products are also used as a source of additional income through the sale of honey, beeswax and royal jelly.
Although we have no detailed and long term data on how Afromontane honeybee populations are faring in light of global climate change and other challenges, we can draw an indication from what is happening in other mountain regions like the Hindu Kush-Himalayan (HKH) in South Asia. The HKH is an important mountain region that stretches through countries like Pakistan, Afghanistan, India, China, Nepal, Bhutan, Myanmar and Bangladesh. Most of the inhabitants of the HKH are farmers with 91% dependence on agriculture as a major source of livelihood. However, in the year 2001 a study of five countries within the valleys showed declining numbers of pollinators and a consequent decline in the yield of cash crops like apple. This was a serious concern and caused farmers in the Maoxian area to resort to pollinating their crops by hands, serving as ‘human pollinators’. Human pollinators pollinate apple trees by moving pollen from one flower or tree to another by hand, and extremely arduous and time-consuming task.
A decade later, hand pollination is still practiced in the region by apple growers and has become more expensive due to labour costs. As a result, farmers who can not cope with this additional burden have been forced to abandon apple farming for other crops that do not require pollination. Of interest here are the different approaches that were adopted by farmers in the HKH region. While farmers in China resorted to hand pollination, Pakistani farmers who were not aware of pollinator deficiency as a cause of declining apple production started cutting down ‘non-viable’ trees. Their counterparts in Himachal Pradesh India resorted to using honeybees to pollinate their orchards. In Himachal Pradesh, both farmers and government institutions are working together to conserve and utilise indigenous honeybees species like Apis cerana and Apis mellifera. As at 2011, these efforts had increased crop yield and fruit quality by 20-30%. Other trickle-down effects of using honeybees as pollinators include increased employment opportunities and extra income through renting and managing honeybee colonies. These successes were recorded due to the concerted efforts by fruit growers and by national and regional research and development institutions.
To conclude, there is a strong need for proactive research approaches towards understanding and conserving honeybees in the montane regions of Africa. These efforts should include detailed studies of their ecology, and as well as efforts to predict what will happen if/when the bees are displaced by changes in climate and other threats. Support should be provided to human communities living within the mountain regions so that they adopt sustainable beekeeping practices that will help conserve indigenous honeybees and preserve the pristine ecosystems within the mountain regions. For the time being, ALL HOPE IS NOT LOST for the Afromontane honeybees! We just have to be proactive rather than reactive.
This blog was contributed by Yusuf Abdullahi Ahmed, PhD, University of Pretoria, Social Insects Research Group (SIRG), Department of Zoology and Entomology
Email: aayusuf@zoology.up.ac.za or ayusuf@daad-alumni.de
Tel: +27 12 420 2533/4627
Skype: abdullahiahmedyusuf
https://www.researchgate.net/profile/Abdullahi_Yusuf2