Despite popular reports that pollinators are crucial for food security and human health, no scientific studies have actually tested how pollinator declines may impact nutritional health - until now, say researchers.
The study, published in PLoS One, has, for the first time, connected what people actually eat in four developing countries to the pollination requirements of the crops that provide their food and nutrients.
"The take-home is: pollinator declines can really matter to human health, with quite scary numbers for vitamin A deficiencies, for example," said Taylor Ricketts from the University of Vermont - who co-led the new study.
Indeed, Ricketts noted that vitamin A deficiencies can lead to an increased risk of blindness and increases in death rates for some diseases, including malaria.
“Continued declines of pollinator populations could have drastic consequences for global public health," said the authors – noting that ‘hidden hunger’ associated with vitamin and mineral deficiencies is already estimated to harm more than 1 in 4 people around the globe.
"We find really alarming effects in some countries for some nutrients and little to no effect elsewhere," Ricketts added.
While the plummeting level of bees has gained much publicity, researchers around the world have also observed a ‘worrisome’ decline of many pollinator species, threatening the world's food supply.
Indeed, recent studies have shown that these pollinators are responsible for up to 40% of the world's supply of nutrients, say the authors.
The new research takes the next step by showing that in some populations, like parts of Mozambique, the disappearance of pollinators could push as many as 56% of people over the edge into malnutrition.
"This is the first study that quantifies the potential human health impacts of animal pollinator declines," said study co-author Samuel Myers of the Harvard School of Public Health, who noted that earlier studies have shown links between pollinators and crop yields - and between crop yields and the availability of food and nutrients.
"But to evaluate whether pollinator declines will really affect human nutrition, you need to know what people are eating," Myers explained.
The new study examined the full pathway from pollinators through to detailed survey data about people's daily diets in parts of Zambia, Mozambique, Uganda and Bangladesh.
According to Ricketts, the team looked in to how each population’s dietary patterms, questioning how much of each food group they ate.
“How much mango? How much fish?" said Ricketts. "From that kind of data we can find out if they get enough vitamin A, calcium, folate, iron and zinc."
From this, the scientists were able to examine the likely impact a future without pollinators would have on these diets.
On the bleak end of the spectrum, the team projected little difference in Bangladesh, since so many people there are already malnourished. While at the other end of the spectrum, Zambia should be relatively insulated from this risk, said the team – noting that there is so much vitamin A in the diet in Zambia already that even reductions from pollinator declines “that it didn't push very many people below the threshold.”