A photo has been circulating for a while that suggests our grocery stores will look like this in a world without bees. Is that true? Will our food choices be radically limited, come the future Beepocalypse?
We already know what raising fruit without honey bees looks like. In a remote area in China, humans pollinate 100% of fruit trees by hand. Armed with pollen-loaded paintbrushes and cigarette filters, people swarm around pear and apple trees in spring. The reason why they hand pollinate is not what you think, though. Honey bees are still present in these areas of hand pollination, and many fruit growers also keep bees for honey.
Hand pollination in China has as much to do with economics and fruit biology as it does with bees. In the early 1990s, farmers of marginal lands in the Hindu Kush Himalayan region--an area spanning parts of Nepal, China, Pakistan, and India--realized that apples could be a major cash crop. Their land was mountainous and hard to farm, so tree fruits were ideally suited to the region. A major shift occurred from subsistence farming to fruit crops. The payoffs were large -- in some areas, farmers quadrupled their income. Now they had cash on hand to send kids to school and build roads. Quality of life improved.
With that early success, farmers found that certain varieties of apples and pears sold better than others. As new orchards went in, more and more of the same cultivars of apples were planted. And that is when things started to go wrong.
Delicious plant genitals
A fruit is a plant ovary with embryos (seeds) inside. It's how plants reproduce. Bees and other pollinators serve as plant sexual surrogates by spreading pollen (plant sperm!) around to flower ovaries. A flower has to be pollinated to "set fruit" or begin to create the juicy ovaries that will become apples.
Some fruits are self-pollinating, and can fertilize themselves without any bees involved. The Navel Oranges seen in the photo at the top are a good example of a fruit that can self-pollinate. Most fruit trees -- pears and apples in particular -- are self-sterile for their own pollen. If you plant all Royal Delicious apples, for example, you won't get fruit, with or without bees. Just as we don't often marry our cousins, apple and pear trees require cross-pollination with "pollinizer varieties" that are not closely related to produce a full crop of fruit.
Clearing marginal lands for agriculture destroyed nesting and food resources native pollinator species needed. The problem with insects as commercial pollinators is that they can't just appear for 2 weeks, pollinate your plants, and disappear. They have to have something to eat the rest of the year, and a place to live. Clearing mountain forests got rid of habitat that pollinators needed.
Farmers planting new trees in their orchards also made a logical economic choice: plant just tree varieties that make marketable fruit. The consequences of that choice, though, were that fruit set was radically reduced. Because the trees planted were the same variety, they were self-sterile.
Farmers did plant a few of what are called "pollinizer" trees--trees that serve as pollen donors. Pollinizer varieties usually don't have pretty fruit, which means that farmers give up potential income when they plant them. The recommended mix of fruiting trees and pollinizer trees in orchards is 70:30 for proper fruit set. In most fruit orchards in the Hindu Kush Himalayan region, less than 10% of the trees were pollinizer varieties in the late 1990s. There just wasn't enough plant sperm to go around.
To make things even more complicated, a farmer can't just randomly pick two different kinds of apple or pear trees and have them be cross-fertile. (This compatibility matrix gives you a sense of just how complex choosing two pear cultivars to grow can be.) A pollinizer variety also must bloom at the same time as your fruit variety--pollen needs to be used while it is fresh, and can't be stored. So even with plenty of bees, fruit production was very low, and in some areas crops failed completely.
Another perfectly sensible economic decision made by farmers was to spray pesticides often to have better looking fruit, which got a higher price. Just as in cultivar selection, this had unforeseen biological consequences. Poor pollination due to pollen incompatibility was made worse by killing off pollinating insects.
In 1999, the problem of poor fruit set was widespread throughout the Hindu Kush regions of Nepal, China, Pakistan, and India. Hand pollination was widely practiced through the entire region. However, by 2011, only apple growers in the Maoxian region of China were still hand pollinating.
What was different about China that made hand pollination persist?
In Nepal, India, and Pakistan, government and non-governmental organizations provided support to help promote using native pollinator species, as well as provided training and education about managing pollination. Planting of native host trees that provided nectar to support colonies through the harvest year was encouraged. Bees are now an important part of local economies, and hand pollination is rare.
In China, officials promoted and offered training in hand pollination, rather than offering information about native pollinators. That's not the reason hand pollination persisted, though -- 100% of apple crops in the Maoxian region are pollinated by hand because it makes economic sense. By using humans as pollinators, the number of pollenizer trees that have to be planted can be minimized, and valuable land isn't used up for non-productive trees.
Fruit set is much higher with human pollinators -- every flower is fully pollinated and can become fruit. A person can pollinate 5–10 trees a day, depending on the size of the trees. In 2010, farmers paid their human pollinators US $12–19/person/day, if they pay them at all. There is a social benefit of having your neighbors help pollinate your orchard, and reciprocating in kind.
The cost of renting a Maoxian bee colony for pollination in 2010 was $46.88/day. Why is renting a hive so expensive? Economics tells us that scarcity should drive prices up, but honey bees are still present. In fact, up to 50% of the fruit farmers surveyed in the Maoxian region in 2011 also kept honey bees. Farmers in this region of China are uninformed about the effects of pesticides on bees--half of apple farmers surveyed did not know that pesticides would kill bees. The Maoxian region also sprays pesticides more often than other regions where pollinators have recovered. Maoxian beekeepers will not rent their hives to orchards at anything less than a premium price, since pesticide sprays continue during bloom season and they risk losing their entire hive.
One last additional factor is making things difficult for farmers: Global Climate Change. Frequent rains, fluctuating temperatures, and cloudy weather affect the number of days that plants flower and the times that pollinators can fly. Changes in flowering time also means that fruit trees and their local pollinators may not be in sync, which makes a mismatch between pollinator and plant timing more likely in an already strained system. Humans are more effective pollinators than insects under adverse conditions.
What can North Americans learn from China's pollination failure?
The story of hand pollination in China illustrates what a failure to understand ecosystem services looks like. Ecosystem services are things the earth does for us for free: oxygen is produced; water is filtered; and plants are pollinated. When parts of an ecosystem are removed, it stops functioning the way it has in the past. Agriculture is an ecosystem, even if it's not a very diverse one.
Some of our foods are hand pollinated right now; cherimoya and vanilla are examples. They are hand pollinated because their specially-adapted native pollinators are missing, and honey bees can't pick up the slack.
Problems with bees, agriculture, and pollination are deeply related to issues of habitat loss and basic plant biology. Pesticides are a problem in bee deaths--for all bees, not just honey bees. But just getting rid of all pesticides will not solve our bee problems, and pesticides are only part of the story of human pollination.
While the chance of honey bees (Apis mellifera or Apis cerana) going extinct is pretty much nil, native bees and other pollinators are threatened. Incredible losses in native bee diversity are happening--in one study, 50% of Midwestern native bee species disappeared over a 100 year period. When scientists study who does pollination, it turns out honey bees are... kind of slackers. In a study of 41 different crop systems worldwide, only 14% had yield increases with honey bees present. Who did all the pollination? Native bees and other insects.
Is China's experience a picture of our future without bees? Probably not. But preserving our pollinators and pollinator habitat will be critical to keeping our food choices diverse and affordable in the future. Consider planting some food for bees, or setting aside nesting space. Check out this huge resource center for North American plant lists, nesting guides, and more.
References:
- Burkle L.A., Marlin J.C. & Knight T.M. (2013). Plant-Pollinator Interactions over 120 Years: Loss of Species, Co-Occurrence, and Function, Science, 339 (6127) 1611-1615. DOI: 10.1126/science.1232728
- Garibaldi L.A., Steffan-Dewenter I., Winfree R., Aizen M.A., Bommarco R., Cunningham S.A., Kremen C., Carvalheiro L.G., Harder L.D. & Afik O. & (2013). Wild Pollinators Enhance Fruit Set of Crops Regardless of Honey Bee Abundance, Science, 339 (6127) 1608-1611. DOI: 10.1126/science.1230200
- Partap U. & Ya T. (2012). The Human Pollinators of Fruit Crops in Maoxian County, Sichuan, China, Mountain Research and Development, 32 (2) 176-186. DOI: 10.1659/MRD-JOURNAL-D-11-00108.1
- Partap U. (2010). Innovations in revival strategies for declining pollinators with particular reference to the indigenous honey bees: Experiences of ICIMOD’s initiatives in the Hindu Rush-Himalayan region, Pest Management and Economic Zoology, 18 (1) 85-95.
- Tang Ya, Xie Jia-sui, & Chen Keming (2001). Hand pollination of pears and its implications for biodiversity conservation and environmental protection — A case study from Hanyuan County, Sichuan Province, China, FAO Case studies on pollinators and pollination.
- Warning Signals from the Apple Valleys of the Hindu Kush-Himalayas: Productivity Concerns and Pollination Problems (2002). Kathmandu, Nepal: International Centre for Integrated Mountain Development. 116pp.
- Case Study #10: Cash Crop Farming in the Himalayas.
- The Parable of the Bees: Beyond Proximate Causes in Ecosystem Service Valuation. (2012). John Gowdy, Lisi Krall, Yunzhong Chen. Rensselaer Working Papers in Economics, Number 1202.
