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Saturday, January 21, 2017
- Pollinators, whose role is essential in a third of what the world eats, are at center stage after a landmark new United Nations report warned that many of the 20,000 species are threatened by human behaviour.
For the first time, a truly global study has looked at honey bees, bumble bees and butterflies, with an eye both to their survival and their role in boosting the nutrient value of food.
That highlights the increasing amount of work done on the subject in Asia, where honey exports have doubled in the past decade according to FAOStat.
The report from the Intergovernmental Science Policy Platform on Biodiversity an Ecosystem Services comes on the heels of another research publication led by several experts at the Food and Agriculture Organization of the United Nations in Rome. They both note that almost all flowering plants depend on bees and their brethren, including 75 percent of the world’s food crops, ranging from almonds to okra.
The Western media regularly run stories about collapsing honeybee hives in North America and Europe. Yet globally the hive count has doubled in the past half century, even as the volume of farm output that relies on it has quadrupled.
Given strong public awareness of the European honeybee – a highly industrious type willing to focus on a single crop before being driven to another – it is salient to note that there are tens of thousands of animals that can help plants reproduce. “Birds, flying foxes, lemurs, even snails or geckos, can and do function,” notes Dharam P. Abrol, a professor at Sher-e-Kashmir University of Agricultural Sciences and Technology and author of a new book on pollination biology which takes a close look at the major species and crops in India.
Beekeeping is an intriguing entrepreneurial option in developing countries, as honey is not perishable, producing it does not require land ownership, equipment is basic and it promotes desirable plant biodiversity. On the other hand, managed European honeybee colonies are not as effective as a healthy array of wild pollinators, and while the tropics offer them a more friendly year-round nectar supply, bees also require energy there than in temperate regions, according to scientists at FAO.
Beyond concerns of bees’ demographic survival is the role of quality pollination services in improving human food systems, especially in terms of addressing widespread “hidden hunger” or micronutrient deficiencies.
It turns out that this depends on local diets, which vary in terms of how much and which pollinator-dependent foods are on the menu. A recent study found that children’s intake of iron, zinc, folate and calcium mostly derive from other kind of foods, while vitamin A is highly dependent on bee-visited fruits, which proved especially true in Bangladesh.
That makes mangos even more important. Ruhul Amin and fellow scholars studied insect foraging behaviour in a mango-growing area and found that pollinator richness was well behind that of pests and other insects such as hoppers and ants. Fortunately, there was substantial diversity among pollinators, which turns out to be a major factor in their effect on fruit sets.
While fragile and in need of support, this fact is important. One key finding, demonstrated again in a recent British study, found that plants tend to have higher seed production when grown in urban gardens – where decorative flowers tend to be varied and abundant – compared to arable farmland – in this case mostly oilseed rape subject to monoculture.
Oilseed rape now accounts for around 15% of British farming, and while the plants’ nectar and pollen likely vastly outstrips that provided by all other flowers combined, it comes fast and furious over a few weeks, which doesn’t foster the abundant year-round habitat of an English garden. Somewhat ironically, urban areas were also more likely to offer safe hiding places than mono-cropped fields subject to mechanized ploughs.
This is one reason why farmers are increasingly looking at devoting the edges of their fields to other plants, to cultivate biodiversity. Such practice amounts to offering a “bed and breakfast for pollinators” as opposed to a migrant factory job, according to Geoff Coates, an expert on sustainable agriculture at Syngenta.
Honeybee visits in fact have only a modest effect on fruit production, while wild pollinators- including insects – have an impact twice as powerful, according to a study of 41 crop systems across all the continents that are home to farming.
“Improving pollinator density and diversity – making sure that more and more different types of bees and insects are coming to your plants – has a direct impact on crop yields,” according to Barbara Gemmill-Herren, one of the FAO authors of that report. She and her colleagues estimate a more diversified pollination ecology, meaning more flower types, would narrow the yield gap of smallholder farmers by a quarter.
Chemical insecticides are widely seen as detrimental to bees. One Bangladeshi research team in Dinajpur studying cotton found that wild pollinators were superior to the managed European honeybee, but suggested insecticide be sprayed at night. Cotton flowers bloom in the morning, turn pink in the afternoon and close at night, never to reopen. A. Hasnat and others from Sher-e-Bangla Agricultural University in Dhaka offered similar practical advice after looking at okra. They also found that while okra can pollinate itself, it tends to have half against as much luck with outside help – including by human hand.
Human pollination is not a myth, but its use is widely exaggerated. The classic citation in the field is of apple orchards around Maoxian in China where it was widely practiced in the 1990s due to local circumstances. However, it was obviously very costly – one person can pollinate five to 10 trees a day, but that now costs $19 in pay – and is fading away. Apples are no longer the valley’s main crop, according to Uma Partap, whose research first brought the practice to light.
Natural insect pollinators were scarce in the region due to widespread insecticide use and to farmers’ reluctance to devote enough of their orchards to different kinds of less profitable trees to keep pollinators alive. Local farmers have rapidly shifted to plum trees, whose fruits command prices ten times higher than apples. Somewhat ironically, farmers who made the shift also adopted more intercropping of vegetables to round up their incomes, thus improving pollinator habitat.
U.S. almond farmers worried by a bee apocalypse have also experimented with mechanical pollination. But while blowing pollen is cheaper – around $300 an acre, or the cost of just 15 apple trees in China – it doesn’t work as almond flowers are not open all the time, according to Elizabeth Fichtner of the University of California.
It may depend on the type of fruit, however. A more recent study from Washington State in the U.S. found a sophisticated approach to spraying pollen on apple trees could beat what bees do. A South African study found that hand pollinating apple flowers – with a paintbrush, as in China – actually outperformed the work of honeybees in terms of fruit set. But wild rather than managed pollinators were better than both.