Summary

Honey bees are not the only bee species that are significant for human wellbeing. Lasioglossum bees are a group of native bee species that do not produce honey but are important pollinators of crops and wild plants. These small black bees are not aggressive but can sting for defence. They have a mild sting that is much less painful than that of a honey bee.

They live independently of others (i.e. they are solitary) or in small groups and build their nests in the ground. This fact sheet provides information about these bees to encourage farmers to understand and protect them to help ensure that their crops are effectively pollinated.

From a conservation and agricultural standpoint it is not necessary to recognise all the different bee genera. However, it is important to know that there is a large bee biodiversity. Different bee genera pollinate different plant species, although there is some overlap that acts as a buffer as bee populations wax and wane. For healthy ecosystems, including agro-ecosystems both diversity and abundance in the bee fauna is important.

Common Name (Language)

Sweat bees, mining bees (English)

Scientific Classification

Kingdom: Animalia

Phylum: Arthropoda

Class: Insecta

Order: Hymenoptera

Family: Halictidae

Subfamily: Halictinae

Tribe: Halictini

Genus: Lasioglossum Curtis, 1833

Species in the Genus

About 280 species from all over the world have been described from this genus, making Lasioglossum one of the bee genera with the highest number of species. In Africa it is possibly the genus with the most species in it.

Species in Kenya, Tanzania & Uganda

Over 30 Lasioglossum species have been recorded in Kenya, Uganda and Tanzania . This genus is in urgent need of revision and the numbers of species and distribution information will certainly change.

Description

Lasioglossum bees are not well known by local people (including farmers) inEast Africa. These insects are usually not recognised as bees by local people in East Africa , where the name bee is generally thought only to apply to honey bees. Lasioglossum bees (commonly known as sweat bees) are small black bees (smaller than honey bees) known to have bands of light hairs at the base of their abdominal segments, but this is not always the case. They also have the distal veins (i.e. those furthest away from the body) in the front wing that are more weakly developed than the proximal veins (i.e. those nearest to the body). Species in this genus are very varied in terms of their size, colour and physical appearance. The genus contains species with different social behaviour; some solitary and others social or communal.

Possible Causes of Confusion

These bees can be confused with some flies that have similar black colouring and size. Flies can be distinguished from Lasioglossum bees in that they have only two wings while bees have four wings. These bees are very closely related to those in the genera Halictus and Patellapis. Lasioglossum bees  can be distinguished from Halictus species which are metallic but Lasioglossum and Patellapis species may be difficult to distinguish from each other apart from under a microscope.

Distribution in Kenya, Tanzania & Uganda

There is little information about the distribution of these bees within the East Africa countries. However, considering their habitats and some previous studies (e.g. Martins 2008, Eardley and Urban 2010), representative species of these bees are likely to be found in all ecologies, farmed and protected areas, from coastal lands to highlands. Farmers can assist in reporting the presence of these bees in their neighbourhood. This would improve our knowledge of their distribution in the region.

Habitats

Lasioglossum bees can be found in all agricultural habitats (agro-ecologies) and natural habitats in the East African region extending from the low coastal lands to the highlands. Representative species can be found both in dry and wet lands.

Nesting

These solitary bees construct their nests in soils.

Crops Visited

These bees are known to visit crop plants in the families; Asteraceae (Compositae) e.g. sunflowers, Convolvulaceae (e.g. sweet potato), Cucurbitaceae (e.g. cucumbers and melons), Liliaceae (e.g. asparagus), Malvaceae (e.g. okra), Papilionaceae (the pea family) and Rosaceae (e.g. strawberries).

Other Plants Visited

Wild relatives of the crop families listed above are visited by these bees. There is also a wide range of plants belonging to many different families that provide pollen to Lasioglossum bees in natural habitats.

Economic / Ecological Importance

Little information exists on the usefulness of these bees to the lives of the people in East Africa. However, they are pollinators and thus they are likely to contribute to increased agricultural productivity and the conservation of the natural biological diversity of the region.

Threats

InEast Africa, Lasioglossum bees and other bee taxa are threatened by factors such as habitat degradation, agricultural intensification (e.g. replacing hedges with barbed wire fences, and increased use of herbicides which can affect wild flower numbers), the misuse of insecticides and trampling of nests by livestock and people. Farming practices that involve over-digging of soils are likely to threaten populations of these bees since they nest in the ground. Lasioglossum bee populations in East Africa are likely to be affected by pests and diseases but information on this subject is lacking. The lack of knowledge of about these bees and their economic importance by people (de facto custodians of nature) is significant as their conservation and management practices implemented at the farm level will depend to a large extent upon the value that people attach to them.

Conservation and Management Practices

There are now concerted research efforts in the region to develop best practices for conservation and management of bees that are compatible with other good farm practices, to enhance crop production. Theoretically, bee conservation and management is inexpensive and adopted activities can also improve the aesthetic value of the landscape. Such practices involve setting land aside (e.g. a 1-metre strip) in the farmland to host all year round food resources for the bees, as well as safer sites for nesting, mating, resting and refuge from natural enemies. During flowering, farmers should manage pesticide usage carefully to avoid poisoning flower-visiting bees. Farmers should also minimise pesticide drift from the field to adjacent areas. Laws governing registration and use of plant protection products indirectly play a major role in the protection of pollinators. Trampling by people and livestock and tilling should be managed to conserve the nesting sites of soil-nesting species such as Lasioglossum bees. KARI (the Kenya Agricultural Research Institute) is developing protocols for mass rearing of different species of solitary bees. Any successful results from this research will be freely communicated to the public. In addition, KARI is collaborating with other stakeholders to ensure in situ conservation and management of bees for pollination purposes. Much of the work of conserving native bees will be underpinned by raising public awareness of the importance of these species.

Legislation (National and International)

There is not yet any legislation in East Africa that explicitly addresses pollinators. However, there is scattered legislation for the protection of biodiversity particularly that covering environmental protection, protection of wildlife and heritage sites, protection of forests and natural resources such as water catchments. In addition, laws governing registration and use of plant protection products also indirectly play a major role in the protection of pollinators Such legislation, together with market-based mechanisms such as the Good Agricultural Practices (GAPs) codes and practices may help to protect bees albeit incidentally. At the international level, the Conservation on Biological Diversity (CBD) is spearheading strategies to enforce bee management for pollination purposes within the member countries, which include Kenya, Tanzania and Uganda. Farmers should lobby their governments to develop Integrated Pest Management policies that would protect bees and other insects of importance in agriculture.

References