Monday, May 29, 2023

The buzz about bees

The world is abuzz with talk about bees. It is virtually impossible to scroll through a social media feed without seeing an article on the global decline of bees and what the threatened extinction of this important pollinator could mean to food production and the planet’s people.

The agricultural industry is only too aware of the fact that without bees, certain food crops will disappear. Robotic bees have been developed, but they are far from able to replace actual bees as pollinators.

But exactly how serious is the situation, especially in a South African context?

Bee reports

According to a report from the United Nations Environment Programme (UNEP), humans are dependent on bees for the pollination of many fruit, nut, vegetable, legume and seed crops. The Food and Agriculture Organization (FAO) of the United Nations states that approximately one third of all the plants people eat are directly or indirectly dependent on bee pollination and could disappear without these pollinators.

A study that included 200 countries found that fruit, vegetable and seed production from 87 of the leading global food crops depends on pollination, while only 28 crops are self- or wind pollinated. The study estimated that 90% of global food production comes from 100 crop species, 71 of which are pollinated by bees. There are 4 000 vegetable varieties dependent on bee pollination. Furthermore, close to 75% of the world’s fruit and grain producing crops depend, at least in part, on pollinators for sustained production, yield and quality. For example, the flowers of fruit crops that are not properly pollinated will deliver fruit that is not well-shaped.

According to a 2010 UNEP report titled Global honey bee colony disorders and other threats to insect pollinators, beekeepers, primarily in the United States (US) and Europe, have been reporting annual hive losses of 30% or more. According to the report, this is substantially more than is considered normal or sustainable.

Many factors influence the decline of bees, including pests and diseases, habitat loss, increased use of neonicotinoid pesticides, pollution, climate change and an increase in agricultural production.

The importance of bee species

Of the 20 000 species of pollinators, the European (or Western) honeybee, Apis mellifera, is the most commonly domesticated for honey production and for pollination services. A. mellifera is native to Europe, Asia and Africa; it was introduced to the Americas and Australia by European settlers. Each country has its own unique indigenous bees. The US has more than 4 000 native species. Before the introduction of A. mellifera, native pollinators did all the work and were more efficient pollinators of native plants such as blueberries.

According to the South African National Biodiversity Institute (SANBI), there are two indigenous subspecies of the European honeybee in South Africa, namely the Cape honeybee (A. mellifera capensis) and the African honeybee (A. mellifera scutellate). The Cape honeybee is found in the fynbos biome in the winter rainfall regions of South Africa. It is darker than other honeybees and displays the typical yellow and black striped abdomen. Cape honeybees are sometimes called ‘black bees’. The African honeybee is native to central and southern Africa and to the northern summer rainfall regions of the country.

There is also a hybrid zone where the two regions overlap and the subspecies hybridise. Since the honeybee subspecies in South Africa are indigenous to the region, it is not easy to distinguish between wild and managed honeybees since there is essentially no bee breeding; colonies in managed hives are trapped from wild populations. Swarms from managed colonies also commonly return to the wild.

There is some need to distinguish between domesticated and wild bee populations when discussing the decline in global bee populations. Pollination services are provided by both wild (free-living) and commercially managed bees. Although bees, especially the honeybee, are the dominant and most economically important of the pollinators, it is worth noting that some plants are pollinated by other insects such as butterflies, moths and flies, and by vertebrates such as bats, birds and rodents.

Causes of bee decline

The most commonly cited culprit of bee decline is pesticides, specifically neonicotinoids. Although pesticide use has been recognised as a contributing factor, there are a number of other factors that play a role in bee decline. Here are some of the main causes of bee decline as discussed in the UNEP report:  

Chemical applications

Studies have found that neonicotinoids, the world’s most widely used type of pesticide, are harmful to bees, especially when used in combination with fungicides, which increase the toxic effects. The effects of neonicotinoids on bees have been recognised by legislation, leading to the ban of certain pesticides in the EU and in some states in the US. Chronic or sub-lethal exposure to pesticides can weaken the honeybee’s immune system and make it less able to fight infection. The use of neonicotinoids is suspected of links to higher incidences of a disease that has become increasingly common among bees, known as colony collapse disorder (CCD).

Insecticides used to coat seed have also been found to affect pollinators since the chemicals migrate from the roots through to the flowers. Studies have shown that chemicals can cause a loss of the sense of direction, can impair memory, brain metabolism and reproduction, and cause mortality.

Chemicals such as herbicides affect the habitat, eliminating nectar sources and destroying larval host plants. The chemical destruction of habitats can have long-term consequences on the distribution of pollinators in agro-environments. Ironically, some chemicals used to control common bee pests and diseases could be contributing to the decline. Antibiotics and miticides are widespread in beehive management.

Pests and diseases

Many pests and diseases occur naturally among bee populations in the wild and have made their way to domesticated bees. The Varroa mite, an ectoparasite, is the most serious threat to global apiculture. The Varroa mite was discovered on honeybees in 1904 in Southeast Asia but is now found worldwide. The mite feeds on the circulatory fluids of bees, and vectors viral and bacterial diseases. If left uncontrolled it leads to the premature death of colonies within three years.

Important bee diseases are CCD and American foulbrood (AFB). AFB is internationally considered to be the most serious disease and is caused by the spore-forming bacteria Paenibacillus larvae, while CCD is a phenomenon that involves the sudden disappearance of worker bees from a hive, leaving behind the queen and the nurse bees to care for the immature bees. CCD has been occurring with greater frequency.

Diseases are spread rapidly throughout the hive by the bees themselves. Beekeepers may also spread diseases by moving equipment from contaminated hives to healthy ones.

Unhealthy ecosystems can facilitate the development of parasites that may affect both managed and wild bee populations.

Habitat loss

Human activities have changed the natural habitat of bees through fragmentation, degradation and destruction. They have also created new man-made ones. These changes affect pollinators by reducing food sources, and bee populations decline so drastically that they no longer serve plant communities. Insufficient forage also leads to nutritional deficiencies in bees, causing weakened immune systems and increased susceptibility to disease. Researchers have observed that insufficient access to forage correlates with increased likelihood of CCD. Wild pollinators also need an undisturbed habitat for reproduction.

Pollution and climate change

Air pollution affects pollinators and flowers. Although bees rely mostly on vision to find forage, pollution has been shown to decrease the scent that flowers produce to attract insects. Electric and magnetic fields may also influence bee behaviour, as bees are sensitive to such fields.

Climate change plays a role in various ways, such as fluctuating flowering periods, shorter growing seasons and altered distribution of flowers. Following natural disasters such as fires, for example, bee colony formation is closely linked to the recovery of flowering plants. Climate change also leads to decreased precipitation and shifts in seasonal rainfall. This reduces plant vigour and delays plant maturation.

Increased agricultural production

It is crucial that we consider the impact of an agricultural industry that continuously produces more food to support the growing global population. Agricultural production has increased globally and has become increasingly dependent on pollinators not just due to larger areas requiring pollination, but also due to the types of crops dominating the agricultural landscape.

The production of crops requiring pollination has increased fourfold, while the number of crops that do not rely on pollinators has doubled. Farmers that grow pollinator-dependant crops in areas where wild bee numbers are insufficient for pollination rely on managed bees to prevent losses in crop yield and quality. This means that bees and hives must be transported to farms to help with pollination.

In the US, over two million colonies in travelling hives cross the continent every year. A single truckload can carry more than 20 million bees. While it serves crop farmers, this tradition also has a negative impact on bee health as the prolonged confinement and temperature fluctuations inside the hives can be stressful to bees. It further contributes to increased susceptibility to disease. Not only does stress lead to a weaker immune system, but the bees are exposed to foreign pests and diseases. Longer periods of confinement also have negative sanitary effects. It is common for mortality rates to increase by up to 10% following colony transportation.

The South African situation

In 2017, role-players in the beekeeping industry published a report about the sustainability of the honeybee population and beekeeping in the Western Cape to determine if there will be enough bees to pollinate important crops as the agricultural industry continues to expand. For example, the current pollination needs required by the deciduous fruit industry is 65 000 pollination units; this will likely increase by at least 30 000 pollination units over the next decade due to new cultivars and general intensification of the agricultural landscape. Although the report centres around the bee industry in the Western Cape as most beekeepers are based in this province, the issues discussed apply to other areas as well.

According to the report, honeybees in South Africa and the rest of Africa are the primary pollinators on the continent. Not only are they important to the agricultural industry, but they also pollinate 40% to 70% of the indigenous flowering plants. In the Western Cape the Cape honeybee is an essential pollinator for the fynbos biome, of which 83% of plants are insect pollinated. It is better adapted for flying under cooler and windier conditions than the northern sub-species of honeybee.

As previously mentioned, the wild honeybee population is interlinked with the managed honeybee population. Most beekeepers in the Western Cape and the rest of South Africa regularly trap honeybee colonies from the ‘wild’ to sustain beekeeping enterprises and pollination in the agricultural industry. As commercial and pollination demands for managed bees increase, there is a risk of over-harvesting from the wild honeybee population. Thus, actions by beekeepers and those that make use of pollination services directly impact the wild honeybee population. The spread of disease is also affected by this. Therefore, the management of a healthy wild honeybee population means a sustainable apiculture industry and vice versa. Both will ensure that the country’s unique biodiversity, as well as the yield and quality of agricultural crops, are maintained.

The following factors also impact the sustainability of bee populations in South Africa.

Insufficient forage

Although the list of factors contributing to bee decline are also applicable to the South African context, the sustainability report emphasises the need for enough forage to maintain bee colonies. Due to the differences in geographical distribution the various bee species depend on a variety of flowering plants as forage. In the Western Cape, bees mostly search for indigenous fynbos flowers such as Proteas and Ericas, whereas in the Eastern Cape aloes provide a large portion of bee forage. In the northern regions, during the winter, indigenous thorn tree flowers serve as forage when little else is in bloom. Indigenous and alien weeds also provide forage in the various provinces. In addition, agricultural crops such as canola, sunflower, lucerne and fruit trees play an important role in ensuring there is enough forage for bees throughout the year.

Research has shown that beekeepers in all provinces rely on Australian eucalypts as a forage resource for their honeybees. Eucalyptus trees provide a reliable food source because different species flower at various times of the year. However, these trees are considered an invasive species that utilities a large amount of water. In recent years, the Department of Agriculture, Forestry and Fisheries (DAFF) has embarked on a large-scale project to remove eucalypts. Although water resources are vital to sustain the agricultural industry, the removal of these trees has also contributed to the reduction of bee forage.

Natural disasters

Natural disasters such as fires and drought pose a major risk to the beekeeping industry. The 2017 Knysna fires, for example, had devastating effects on the local beekeeping industry and major losses were reported. The forage loss will take at least five years to recover. The ongoing drought in most provinces has also had a detrimental effect on bee forage.

Theft and vandalism

Theft and vandalism are major problems affecting beekeepers as they continuously struggle to find secure sites for their hives. There is a significant link between forage and vandalism. Good bee forage may exist, but if the bees are not safe on the specific site, having good forage is meaningless.

While man-made vandalism is the biggest concern, other natural predators, such as baboons, ants and honey badgers, also cause a significant threat to honeybees. Less than 5% of beekeepers own their own land. Beekeepers are therefore reliant on the goodwill of other landowners for their beekeeping activities. Hives are often quite exposed and beekeepers are discouraged as they struggle to make ends meet with the great impact of theft and vandalism.

According to the UNEP report, honeybee hives have increased globally by close to 45% in the last 50 years; declines have mostly been reported in North America and Western Europe. However, human activities and other environmental impacts do affect bees and it is our duty to promote the stewardship of bees and other pollinators. – Ursula Human, FarmBiz