This article explains how pollination works and why it is so important for plants and the human food chain. We also cover how the main pollinators, like bees and wasps are under threat due to pesticides, land-use change and climate change events.
How Does Pollination Work?
Flowers create pollen, a fine powder usually yellow in colour – the stuff that can make you sneeze! Flowers use this pollen to make seeds. Pollen is made in the anther of the stamen, the male part of the flower.
It needs to be moved from the stamen to the female part of the plant, the stigma in the pistil, in order for pollination to occur. Once this happens, the pollen can then be used to make seeds which enables the plant to reproduce or form fruit.
How Is Pollen Transported?
So how does the pollen move from the stamen to the pistil? Most often it is carried from plant to plant by small animals. Plants use sweet scents, bright colours and the lure of a sweet nectar meal to lure their pollinators in. In the process, pollen sticks to the animal’s fur or skin. This is why pollinators provide such a crucial ecosystem service.
Flies and beetles were the original pollinators, going back to when flowering plants first appeared 130 million years ago. Today, as well as flies, bees and wasps are the primary pollinators.
Less frequently, pollen it is carried in the wind, wind being an abiotic vector, or non-living process. If there were no insects, plants would have to rely on unpredictable winds for reproduction.
You may have heard about a pollen count. This is the measurement of the number of pollen grains in the air. When pollen counts are high, it can cause hay fever and other allergic reactions in some people. Pollen counts tend to be higher when it is windy and lower when it rains.
Did you know: The study of pollination by insects is known as anthecology.
Who Are The Main Pollinators?
Somewhere between 78 and 94 percent of all flowering plants need help with pollination 1. Flowers in hotter tropical parts of the Earth, like the Amazon Rainforest tend to rely slightly more an animal pollination. Most pollinators are wild species, but some are reared for economic reasons, like the honey bee. These ‘farmed’ species are known as managed pollinators.
List of The Main Pollinators
The following are some of nature’s most active animal pollinators:
– Flies, including the hoverflies
– Birds, including hummingbirds
– Small mammals, like monkeys, lemurs, rodents, possums and lizards
The Animal-Pollinator Relationship
Without a rich biodiversity of pollinators, many plants could not set seed and reproduce. At the same time, without plants to provide nectar and other enticing food rewards, many animal species would decline, with consequent knock‐on effects for other species within the biome or wider community.
The Human Relationship
Plants are important to us, for three main reasons:
1. Plants are a key component in the oxygen cycle, producing the oxygen we and all animals breathe.
2. Plants are the foundation of the food web, creating food energy from sunlight and carbon dioxide (CO2).
3. During photosynthesis, plants absorb carbon dioxide, thus helping to regulate our climate system.
Plants create their own food energy through photosynthesis, a process unique to the plant kingdom. We consume plants for nutrition, and we eat the animals that rely on plant based-diets, like cows and sheep. In addition we rely on those animal products for milk, clothing and other reasons.
Without pollinators the world would struggle to sustain a human population of 7 billion – never mind the expected 11 billion by 2100. Our supermarkets would have half the usual amount of fruit and vegetables. 3
Despite this, humans continue to chop down trees in true Anthropocene style, robbing pollinators of their natural habitat. The effects of deforestation on climate change has been much reported, but its effects on our little pollinator friends have been largely ignored.
Why Bees Are So Important
Bees are important pollinators, pollinating 70 of the 100 types of crops that feed 90 percent of the world. The European honey bee (Apis mellifera) is the most important managed species for agricultural pollination across the world. Before commercial farms became so big, farmers did not need to manage pollinators. They were all around because the landscape was naturally diverse. Now, they need to bring in beekeepers with an army of pollinators, to get the job done.
The problem is, industrial scale farming is wearing down the health of bees by exposing them to pesticides (those containing neonicotinoids are the worst), disease and poor nutrition. Managed honey bee colonies are dying in huge numbers, typically between 30 and 40 percent in North America and Europe. Beekeepers are lifting the lids of their hives, only to find a queen and a few stragglers. This crash of hives has been named colony collapse disorder and remains a major problem.
Pesticides also have serious adverse effects on certain birds of prey, destabilizing ecosystems across the Indian subcontinent.
Will We Starve Without Bees?
One in three bites of your food includes a bee-pollinated product. While we are not likely to starve without bees, our diet will be very limited and dull. Here is a list of just some of the foods we would have to do without, if bees died out:
Blueberries, squash, watermelon, strawberries, pears, apples, coconut, pumpkins, carrots, onions, potatoes, celery, cauliflower, broccoli, chillies, brazil nuts, cashews and almonds.
Cotton and flax would also be affected, so we would have to make clothes out of different materials.
Wasps: The Less Appreciated Pollinators
Wasps are not exactly the most-loved creatures, but they are just as important as bees when it comes to pollination. They pollinate figs for example, which more than 1,000 types of tropical birds and mammals depend upon for food.
Wasps are a key predator in the food web and they protect plants from spiders, caterpillars and flies. Without wasps you would see fewer flowers, and a big rise in spiders and other unwanted creatures in your home!
Wasps face a similar threat to bees, they just don’t capture the public imagination as much.
There are thousands of types of wasps out there, quietly getting on with their business. Only 1 percent of those are the type that buzz around your picnic. Yet, studies show that people associate bees with more cuddly images like honey, pollens and flowers whereas wasps evoke negative feelings like pain, stinging and rage.
Did you know that a wasp sting, contains a toxin which has cancer fighting properties? And the venom of a honeybee sting could hold the cure for breast cancer. 4 Scientists are researching how this could be turned into a safe drug for humans.
What Are The Main Risks To Pollinators?
The main risk to bee and other pollinators include:
- Pesticide misuse and drift in aerial spraying can harm the health of pollinators. It can also cause impaired navigation, flight disorientation and reduced production of offspring.
- Habitat loss due to urban development, commercial agriculture and resource extraction including fracking and mining for fossil fuels.
- Rising temperatures associated with global warming are harming the complex relationship between plants and the insects they rely on for reproduction. It is modifying flowering times and pollinators behaviours, as well as introducing the emergence of diseases and pathogens. Heatwaves are causing a decline in (or extinction) of plant species on which pollinators depend for food and nesting.
- The planting of non-native shrubs that threaten the wildflowers needed by certain pollinators like butterflies for nectar or larval food.
- Man-made air pollution is a real problem for bees and other pollinators which rely on scent trails to find flowers.
- Deforestation reduces pollinators natural habitats. Large scale tree planting has been a positive public response.
How Are Pollinators Linked To The Economy?
According to the United Nations, between US$235 billion and US$577 billion worth of annual global food production relies on direct contributions by pollinators. 5 In addition to food crops, pollinators contribute to crops that provide biofuels like palm oils and canola, as well as fibres for clothes (cotton), medicines, forage for livestock and construction materials.
Honey bees contribute nearly US$20 billion to the value of U.S. crop production. 6 Honey is used for food, anti-aging lotions, skin creams and medical wound dressings. In Africa, Australia and South America, a type of fly known as the midge is key to pollinating the cacao plants. Valued at over US$100 billion, the chocolate industry depends on that little midge.
What Can Be done?
The solution is to give pollinators more of what they need, and less of what they don’t need.
- Reduce the use of pesticides and seek alternative forms of pest control.
- Encourage farmers to cultivate flora surrounding their farms to solve habitat problems. Grow wild flowers along long roads and farm yards. Plant hedgerows and flowers that bloom at different times of the year.
- Support traditional farming practices that allow for insect diversity, like crop rotation. Listen to indigenous local knowledge.
- Maintain or create greater diversity of pollinator habitats in urban landscapes, as part of the sponge city design. Did you know, there are 450 species in New York State alone? 7
- How many flowering plants are pollinated by animals? Jeff Ollerton et all, 2011.
- Special Report 15/2020: Protection of wild pollinators in the EU — Commission initiatives have not borne fruit: https://www.eca.europa.eu/Lists/ECADocuments/SR20_15/SR_Pollinators_EN.pdf
- BBC Future May 4, 2014.
- Honeybee venom ‘kills some breast cancer cells’ BBC News 2020
- “Pollinators vital to our food supply under threat.” Food and Agriculture Organization of the United Nations. 2016.
- American Beekeeping Federation
- Natural Resources Conservation Service New York