Apis mellifera scutellata
(africanized bee)

A. mellifera scutellata was imported from Africa to Brazil in 1956 to increase honey production, and 26 swarms accidentally escaped into the countryside where the queens mated with drones of the European honey bees. The subsequent poly-hybrid bees were named ‘Africanized honey bees’, and over a period of 50 years, they colonized most of South America and all of Central America. In 1990, they entered the USA through Texas, and they are now established throughout the south-western states and southern California.

A. mellifera scutellata is native to eastern and southern Africa, from Ethiopia to South Africa. In Ethiopia, A. mellifera scutellata occupies the west, south and southwest humid midlands. Other morphoclusters in Ethiopia included A. mellifera jemenitica in the northwest and eastern arid and semi-arid lowlands; A. mellifera bandasii in the central moist highlands; A. mellifera monticola from the northern mountainous highlands; and A. mellifera woyi-gambell in south western semi-arid to sub-humid lowland parts of the country (Amssalu et al., 2004). Honey bees of Uganda represented an important biogeographical gap, defining the population structure of A. mellifera scutellata; however, morphometric analysis of worker honey bees has resolved this issue. At lower altitudes <200 m), honey bees formed one distinct morphocluster typical of A. mellifera scutellata throughout the continent. In comparison, those at higher altitudes (>2000 m) formed a separate distinct cluster of large, dark bees as mountain ecotypes (Radloff and Hepburn, 2001). The distribution of honey bee subspecies, including A. mellifera scutellata, in Taita Taveta District, Kenya, also appears to be related to altitude, with A. mellifera monticola found to be most widespread in the highlands and A. mellifera litorea was most common in lowland areas (Oden, 2001).

A. mellifera scutellata was introduced to Brazil in 1956 and from there it and its hybrids with European honey bees have spread to much of South America, to Central America and to the southern parts of North America.

A. mellifera scutellata is an aggressive invader, and its spread is facilitated by a high adaptability to variable ecological conditions (Piereira and Chaud-Netto, 2005), indicating that further spread is likely. See Kaplan (2004) and Schneider et al. (2004) for a discussion of traits and behaviours that are responsible for making this species a successful invader.

A. mellifera scutellata form colonies in tree hollows, rotted logs and man-made structures, such as wood and rock piles. A list of known nesting places of Africanized honey bees in the USA includes: trees and shrubs; wood pike or trash piles; flower pots; old tyres; ground holes; chimneys; storage sheds; wall cavities; attics and crawl spaces; roof overlaps and building eaves; underground utilities; water meters and sprinkler control boxes; old mine shafts or rock crevices; and evaporative coolers (UDAF, 2008). They can be found wherever such sites are found, most commonly in urban areas, agricultural land, forests (natural and managed), but also in riparian areas, coastal areas and occasionally in many other habitat types.

According to Oliveira and Cunha (2005), Africanized honey bees in the Americas are limited to regions of low altitude and cool winters, and principally occur in urban areas, and open or disturbed vegetation in Brazil, as opposed to the interior of dense forest, such as the Amazon. It was observed that Africanized honey bee workers did not visit baits in continuous forest or forest fragments, but were observed in deforested or open areas. This indicates that there is no possibility of source competition between Africanized and native bees within the Amazon forest, and also that large-scale beekeeping is unlikely to succeed in the region because the forest is not explored by Africanized bees.

Genetics

Small hive beetles (Aethina tumida) are pests of honey bees and can damage combs, stored honey and pollen. A study by Neumann and Hartel (2004) showed that A. mellifera scutellata remove unprotected eggs and larvae of the beetles and this behaviour plays an important role in the apparent resistance of African honey bees towards infestations by small hive beetles. They are also affected by the mite Varroa destructor in the same way as other bee subspecies

A number of bacteria are associated with honey bees and in a study of those associated with A. mellifera capensis and A. mellifera scutellata by Jeyaprakash et al. (2003), Lactobacillus and Bifidobacterium were found. These have also been reported from other honey bee subspecies; however, other sequences were found associated with honey bees for the first time, e.g. Bartonella, Gluconacetobacter; Simonsiella/Neisseria; and Serratia. Another bacterium, the parasitic microbe Wolbachia, is found in workers and drones of A. mellifera scutellata and hybrid workers of A. mellifera capensis and A. mellifera scutellata (Hoy et al., 2003).

Gene sequencing of a microsporidium from honey bees in Zimbabwe has found Nosema apis, a fungal parasite of honey bees, causing nosemosis or nosema (Fries, 2002; Fries et al., 2003).

Environmental

• Commercial pollinator

Human food and beverage

• Honey/honey flora

Medicinal, pharmaceutical

• Traditional/folklore

A. mellifera is similar to A. mellifera scutellata, and it is very difficult for the layperson to positively distinguish Africanized honeybees from common European honeybees, as apart from genetic analysis, a comparison of up to as 20 different body measurements is the only way to distinguish subspecies with any certainty (Kaplan, 2004). Also, the Africanized honey bee is more defensive around its nests than the European bee and has a tendency to sting in large numbers. A. mellifera can withstand colder temperatures compared to A. mellifera scutellata. A. mellifera scutellata is slightly smaller than A. mellifera and less selective in habitat selection.

Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.

Prevention

Early warning systems

Behavioural studies of A. mellifera scutellata have been undertaken with the aim of creating informed strategies for dealing with Africanized honey bees and educating the public (Mello et al., 2003). The removal of bee colonies and swarms in Sao Paulo, Brazil was positively correlated with average temperature and degree of insolation, and negatively correlated with relative humidity and rainfall, and it was shown to be likely that colonies nested in artificial constructions, whereas wandering swarms tended to nest in trees. Such results can be used to predict times of the year when people should be more alert for activity of the bees. State Agricultural Departments in the USA have been tracking and studying Africanized honey bees since their introduction, and in particular, the Utah Department of Agriculture and Food has been setting traps since 2003 as an early warning line (UDAF, 2008).

Public awareness

Public awareness facilitated by studies such as that by Mello et al. (2003) will hopefully lead to the removal of structures seen as potential nesting sites for the bees and avoidance of areas possibly harbouring swarms. Africanized bees are much more likely to attack to defend their colonies compared to European honey bees and attacks are provoked by vibration, noise or motion within 50 feet of the nest. Offending origins of such sounds include lawn mowers, leaf blowers and hedge trimmers, and the odour of freshly cut grass or citrus may also be a source of provocation. Animals and humans may be pursued for up to a quarter of a mile and bees remain agitated for up to 8 hours after disturbance (UDAF, 2008).

Control

Biological control

Chemical control

22/05/08 Original text by:

Claire Beverley, CABI, Nosworthy Way, Wallingford, Oxon OX10 8DE, UK