The literature on African pollination biology is reviewed. It is found that relatively little work has been done on pollination biology in Africa, and a very small proportion of pollination relationships has so far been studied. Much of the research which has been done is of an evolutionary nature. Very little work has been conducted at the community level and comparatively little applied work, either to agriculture or conservation, was encountered. Most research has been conducted in South Africa, in particular, from the Cape region, which is the only part of Africa for which a reasonably comprehensive body of work on pollination biology exists. In a number of instances results of African studies challenge conventional understanding of pollination biology. It is argued that as more work on pollination is done in Africa, more differences between African systems and the rest of the world, particularly the North temperate regions will be found and changes to the overall conceptualization of pollination systems in different ecosystems are likely to ensue. A more thorough understanding of pollination biology would also make an important contribution to food security and conservation of biodiversity on the continent. Scientists working in fields other than pollination biology, and amateurs, should be encouraged to contribute to the groundwork of African pollination biology by the documentation of pollination relationships.

There is now considerable evidence for disruption of plant–pollinator mutualisms in fragmented landscapes. The causes can be myriad, and vary from lack of nesting sites for key insect pollinators, to a decline in pollinator visits when plant population sizes are reduced by fragmentation. One important and well-documented consequence of disruption in pollination systems is reduced seed production in plant populations in fragments as a result of pollen-limitation. When reduced seed production, in turn, has a negative effect on seedling recruitment, populations may enter a spiral towards extinction. Some pollination systems, on the other hand, are surprisingly resilient to anthropogenic changes, and pollen flow between trees in fragments separated by several kilometres has been reported recently. Understanding how reproductive attributes of plants, such as breeding systems and specificity of pollination systems, affect the outcome of habitat fragmentation remains a key challenge.

A particularly rich array of pollination systems is represented in the flora of southern Africa. Hopliine beetles, long-proboscid flies, satyrine butterflies, hawk moths, birds and rodents appear to assume greater importance as pollinators than they do in other temperate regions. These ‘alternative’ pollination systems may have developed because the bee-fauna of southern Africa is not particularly rich relative to the flora. Pollination by moths, for example, is relatively frequent in the eastern half of southern Africa where bee diversity is lowest. Pollination systems in southern Africa are relatively specialized and shifts between pollinators have been shown to be an important driving force in plant diversification and speciation. Changes in land-use, particularly afforestation and ploughing of grasslands, invasion of alien plants, overgrazing and urban developments have disrupted these mutualisms with mostly unknown consequences for ecosystem functioning. Future research will be directed at expanding our knowledge of pollination systems, with a strong focus on the conservation of mutualistic ecological interactions.

Pollination in the genus Ceropegia L. (Apocynaceae: Asclepiadoideae–Ceropegieae) in East Africa is discussed based on field observations and herbarium studies. All inferred or confirmed pollinators are small, mostly female dipteran flies, c. 2.5mm long, which carry pollinaria on their proboscis. Identified putative pollinator flies belong to families Milichiidae, Chloropidae and Ceratopogonidae. The most important factors for an insect to effect pollination appear to be the appropriate overall size, i.e. small size of c. 3×;3mm at most, and appropriate mouth parts, i.e. extendible probosces with suitable surfaces and adjacent pads on which a pollinarium can attach. The complex and diverse floral morphology of the tubular flowers and their disposition as well as other commonly occurring features namely, diverse interior and exterior coloration, diverse scents, secretions such as nectar and water droplets, vibratile corolla lobes and hairs, specialized hairs, interior sculpturing, sliding zones and differential lighting within the flower are important mechanisms for attracting and detaining insect pollinators.

Pollination ecology was investigated in Citrullus lanatus (Thunb.) Matsum. & Nakai, which is a species vulnerable to pollinator loss. It was found that this species depends heavily on the honeybee, Apis mellifera L., as the main pollinator. Other pollen vectors identified include Xylocopa bees, halictid bees, Hypotrigona bees, flies and beetles. Phenologically, the plant was found to promote male fitness by producing numerous male flowers, which serve as pollinator attracting structures. Blooming sequence and A. mellifera visitation rates to these flowers are presented. This will enable farmers and pollination managers to better understand visitation patterns and to safeguard pollinators during pesticide application schedules.

The study reported examined mechanisms of pollen transfer within the genus Lagenaria, including insect vectors in the natural and cropped field environment. The major flower visitors to Lagenaria were observed for 10 months, from June 2001 to April 2002 at five sites, namely the Botanic Garden of the National Museums of Kenya, three farmers' crop fields in Dungicha village in Kilifi District, Katitika and Wayowani villages in Kitui District and the home garden of one of the authors, in Westlands, Nairobi, Kenya. Twenty-two species of insects represented in four orders belonging to 10 families were found to be the major visitors of L. siceraria flowers. From the foraging patterns of the flower visitors, visiting frequencies and development of fruits, four groups of flower visitors comprising hawkmoths (Hippotion celerio, Agrius convolvuli), moths A–D (Noctuidae spp.), skipper butterfly (Gorgyra johnstoni) and honeybee (Apis mellifera) were considered active flower visitors. Hawkmoths were suspected to be the major pollinators of this plant in the locations surveyed.

Honeybees are of critical importance in Africa for both ecological and economic reasons. Their contribution to floral biodiversity and conservation, by virtue of their pollination of indigenous flowering plants is unknown, but certain to be considerable. Economically, honeybees are critical for the pollination of a host of commercial crop plants as well as being the source of energy and livelihood for many thousands of mostly small-scale beekeepers. In the past, honeybee pests and problems have been of limited importance in Africa. More recently, however, an increasing number of exotic diseases and pests as well as home-grown problems threaten honeybees, beekeeping and honeybee-pollination in Africa. Two problems in South Africa, the capensis problem and varroa mites, have severely curtailed beekeeping in that country and may well have impact on bees and beekeeping throughout the continent.

A study was conducted to investigate whether a lack of pollinators, pollination and therefore, a shortage of fruit set of perennial plants is more likely to occur in overgrazed land than farmland without grazing pressure, as this could have considerable effects on the reproduction of certain plant species. The study was conducted at two adjacent BIOTA biodiversity observatories (<url>www.biota-africa.org</url>) in Namaqualand, South Africa. Individuals of certain plant species of the family of Aizoaceae were measured and flower and fruit production recorded. Malaise traps and transect walks were used to document insect diversity. Preliminary results indicate that not all plant species show reduced flower production but that fruit set is indeed compromised on overgrazed land. Insect diversity and abundance is partially reduced under heavy grazing pressure, especially in locations where the vegetation cover is low and dominated by unpalatable plant species.

Investigations into the potential impacts of selectively managing Apis mellifera on pollination ecology were carried out in several sites in Tsavo National Park of southern Kenya, a typical arid African environment. Temperature alone contributed significantly to the foraging patterns of both managed honeybees and wild bee species within the acacia–commiphora community. Honeybees, vulnerable to heat stress, foraged earlier in the day than wild bee species. Foraging patterns of the latter ranged from oligolectic to broadly non-specialized. Floral biology and adaptations were also considered in the analysis of divergent foraging trends. Observations suggest that honeybees potentially out-compete highly specialized wild bee species for scarce seasonal floral resources. No evidence was found of direct interaction on abundant seasonal floral resources such as the mass synchronous flowering of Acacia spp. at current managed honeybee densities. Investigation of visitors revealed a high diversity of potential insect pollinators, particularly high in wild bee species (Apoidea) diversity. Suggestions for the improved management of honeybees in arid African environments include shading of hives, providing access to water with protection from predators, and cultivation of indigenous, nectariferous plants close to hive colonies.

Stingless bees are little-known organisms but important plant pollinators in Bwindi Forest. They risk disappearance, as with other pollinators and seed dispersers, as a result of pesticide and herbicide poisoning, habitat alteration, invasion by alien species (plant and animal) and insularization of habitats. Bwindi Impenetrable National Park forest has five species of stingless bees in two genera (Meliponula and Hypotrigona). The conservation of pollinators in Bwindi needs to be urgently addressed, and among the required measures are studies on plant–pollinator relationships. The study also demonstrated the accuracy of Abayanda indigenous systematic knowledge.