• Wild Cousins of the Honey Bee

    Diligent Pollinators

    show caption

    Distant relatives of the honey bee: Wild bees form a large and diverse group.

Wild bees, like honey bees, are important pollinators of many cultivated plants in agriculture. Scientists worldwide have therefore joined forces to gain a better understanding of how we can support them to increase pollination of crops.

Story check

  • Herausforderung:
    Approximately 5 to 8 percent of agricultural production is dependent on pollination by bees or other insects. Wild bees, which until now have been rarely studied, also play a major role in this process. The international research community is working to find out more about this group of insects.
  • Lösung:
    Researchers all over the world are undertaking a variety of projects to investigate the biology of wild bees, the role that they play in pollination and how they interact with honey bees.
  • Nutzen:
    The findings of this research will improve pollination efficiency as a whole and promote species protection. Farmers will be given the information they need to be able to strike the right balance between nature conservation and agriculture.

The honey bee is one of humanity’s favorite insects. Since being domesticated by humans at least 6,000 years ago, honey bees have played an important role in honey production and later also crop pollination. But while the Western Honey Bee is the best-known bee species, you may be surprised to learn that it is only one of more than 20,000 different bee species worldwide, including other honey bees, bumble bees, solitary bees and stingless bees.

Bees vary greatly in appearance, size and preferences. While some wild bees such as the different kinds of stingless bees and many sorts of bumble bees live in colonies, most of them live on their own (solitary). And whereas managed honey bees live in beehives, wild bees rely on a variety of nesting places. Eighty percent nest in the ground, some species burrow in wood and some nest in empty snail shells, while others look for holes in stone walls. For their food, they have adapted to forage on different plant species to varying extents, with some of them specializing to forage only on certain plants.

Super pollination powers
To reproduce, plants must either self-pollinate or use external vectors to carry their pollen from one flower to another, fertilizing the female parts in each flower. While wind and water carry some pollen, animals help to pollinate an estimated 87.5 percent of flowering plant species. As many as 200,000 animal species are thought to act as pollinators, and they come in many shapes and sizes. Around 1,000 are vertebrates, including small mammals, bats and birds, yet insects are by far the largest group, comprising bees, flies, butterflies, beetles, wasps, moths, midges and ants, among others.

In agriculture too, insects are the dominant pollinators – and bees top this list, providing pollination services for many of our crops. The global economic value of insect pollination has been estimated at up to US$ 577 billion. Around 5 to 8 percent of agricultural production depends on pollination by bees or other insects. Not all bee species are important for agricultural pollination. In fact, just two percent of all bee species are responsible for 80 percent of crop pollination, and threatened or rare species are rarely observed in crop fields. Nor do some of the important staple crops, like cereals, corn or potatoes, require pollination by insects, such as bees. However, without the help of bees, our diet would become a lot less colorful and vitamin-rich, as many of our fruits, vegetables and nuts rely on them to some extent.


Bumble bees

Foraging: Bumble bees are not picky and collect nectar and pollen from various plants.

Ecological features

  • Mostly wild-living insects
  • Most species live in colonies (size: 50–500 bees)
  • Various nesting sites: most bumble bees prefer dry, dark cavities

Life and social organization

  • Specialization of tasks and cooperative care of the young (eusocial)
  • Queen: egg laying, colony foundation (1 year)
  • Workers: various duties – brood care, foraging, defense (5–6 weeks)
  • Drones: reproduction (multiple weeks)
  • Only queens overwinter

Food

  • Generalists: most species forage on a broad range of plants
  • Needed: nectar (carbohydrate source) and pollen (protein source) – food storage is limited
  • Foraging radius: typically < 1.7 km

Relevance for humans

  • Pollination

Both wild and managed bees contribute to crop pollination in their own ways, across crop types and regions. In many places, they complement each other and enhance pollination overall, yet in others there may be negative ecological effects due to competition for food. Besides honey bees, growers are increasingly relying on managing other bee species to pollinate their crops; bumble bees are used in greenhouses, mason bees are used in orchards and leafcutter bees are preferred for alfalfa. Unmanaged wild bees also provide pollination services, playing a significant role in certain landscapes. As Professor David Kleijn from Wageningen University in the Netherlands, who conducted a five-continent study on pollination, found out, “Wild bees contribute US$ 3,000 per hectare annually to the production of insect-pollinated arable crops.” This is about the same as managed honey bees.

For the farmer, the advantage of wild bees is that, as the group is so big and diverse, there is every chance that there may be a pollination specialist for his region and crops. Wild bees are also freely available to him, provided that crop and landscape offer a suitable habitat for them. And most species of wild bee are solitary, thus not living in colonies and, as such, they are less prone to, for instance, diseases that can afflict managed bee populations. Yet farmers may find that local, wild pollinators do not provide the level of pollination service they need. For example, wild bees are often too sparsely distributed in intensively farmed landscapes to pollinate crops adequately. Accordingly, many farmers opt for the convenience of buying or renting managed pollinators. These can provide pollination services in a more reliable way and are easier to ‘steer’ than wild populations.

“For crop production, at the end of the day, it’s all about getting the balance right,” says Christian Maus from Regulatory Landscape and Intelligence at Bayer’s Crop Science Division in Monheim, Germany. Having the right number of managed and wild pollinators in an agricultural region is key as, for many crops, a mix of both is the ideal scenario.

Wild bees can be much more efficient pollinators than their honey bee relatives. For example, when different apple varieties are planted in rows in plantations, honey bees almost always remain with the same variety. Many wild species, on the other hand, fly from one row to the other, which can be important when blossoms of one variety have to be pollinated with pollen from another variety in order to obtain optimum results, and they are even more precise pollinators than honey bees. The Red Mason Bee, for example, does not stick pollen together to transport it but carries it in a dry state. This makes its pollination work more effective.


Solitary bees

Loners: Solitary bees live alone. Many species prefer nesting sites in the soil.

Ecological features

  • Wild-living insects
  • Nesting sites: mainly in the ground (80%), various other nesting sites, e.g. dead wood

Life and social organization

  • Solitary
  • no queen
  • Females: lay eggs, forage, prepare nesting site, brood care
  • Males: reproduction
  • Lifespan: ranging from weeks to months
  • Overwintering: many species overwinter as pupa

Food

  • Many specialists: forage specifically on certain plants
  • Needed: nectar (carbohydrate source) and pollen (protein source)
  • Foraging radius: species-dependent (0.1–1.2 km)

Relevance for humans

  • Pollination (roughly 2% of all wild bee species act as pollinators in 80% of crops worldwide)

Wild and managed bee interactions
Moreover, wild bees sometimes and in some crops also function as “influencers” of honey bee behavior, on occasion driving them away from their favorite plants and thereby forcing them to deviate from their route. Maus explains this phenomenon using sunflowers as an example: “Research on hybrid sunflowers in California found that behavioral interactions between wild bees and honey bees increased pollination efficiency by up to five times.” When wild bee numbers were low, honey bee pollination produced three seeds per visit, on average. When wild bees were abundant, the number increased to 15 seeds. “This increased pollination”, explains Maus, “results from a greater activity of honey bees, induced by wild bees disturbing them.”

Research is now being conducted to better understand wild bees’ biology and their potential contribution to crop pollination. This includes projects established by Bayer researchers to identify whether some wild bee species could become managed pollinators for different crops. “Currently, for example, we are running three projects in Thailand, Brazil and Africa to assess the pollination efficiency of stingless bee and other bee species in crops like mangoes, greenhouse vegetables, macadamia nuts, cashew nuts and coffee,” says Maus.

Increasing wild bee populations
To safeguard wild bees in the future, Bayer is working hard to promote their conservation. For example, Bayer scientists are working together with external researchers on a project called “Ecological enhancement of arable land in the Upper Rhine valley” to foster wild bee species in test areas located at two farms in southwest Germany, in a region where the landscape is dominated by corn and cereal crops. As Arno Schanowski, one of the project members and a research associate at the Institute for Landscape Ecology and Nature Conservation in Bühl, Germany, explains, “The increase in farmed land has resulted in fewer and fewer areas remaining where wild bees can find a nesting site and habitat with sufficient food.” In order to support and increase wild bee numbers, the project is therefore focusing on finding ecological enhancement measures such as flowering strips to boost the diversity and abundance of wild bees and butterflies. The aim is to find the optimum combination of wild flowers and the best sowing time. “We initially worked with annual mixtures that are sown in spring, and then ploughed over again in the fall and re-sown the next year. In the following years we learned to use different mixtures and to apply a combination of annual, biennial and perennial plants, some of which were sown in the fall,” explains Schanowski. This method proved to be successful. “With this optimization of the flowering mixtures and management of the area, the number of species has increased significantly – from 30 wild bee species in 2011 to a total of around 130 species in 2017.” In fact, this positive achievement led to the project being extended beyond 2019. “I very much welcome this decision. With continuity, we can transfer robust, long-term ecological know-how from the project to wider groups of farmers and other stakeholders involved in agriculture, which is invaluable for the maintenance and promotion of biodiversity in our countryside,” Schanowski adds.


Stingless bees

Nest guards: Stingless bees have clearly defined jobs.

Ecological features

  • Wild-living or managed insects
  • Live in colonies (size: 300–80,000 bees)
  • Nesting sites: mostly in plants or soil cavities

Life and social organization

  • Specialization of tasks and cooperative care of the young (eusocial)
  • Queen: reproduction
  • Workers: various duties – build combs, process food, prepare nesting site, foraging, defense
  • Drones: reproduction

Food

  • Mostly generalists: forage on a broad range of plants
  • Needed: nectar (carbohydrate source) and pollen (protein source)
  • Foraging radius: from 400 m to 1.5 km

Relevance for humans

  • Pollination and honey production

Agriculture and bees: a crucial partnership
To conclude: There is no doubt that bees and other pollinators play an important role in agriculture around the world. Their importance makes it vital that we increase our knowledge about which crops need which pollinators and establish how best to protect and enhance both wild and managed species, something Bayer is actively engaged in. Bayer is convinced that management measures, whether to increase pollination or to conserve pollinators, will become more refined and targeted, providing farmers with the information and tools they need to achieve the right balance between agriculture and nature conservation on their farms.