Ecosystems and interdependence · System
Pollinators and food security
Bees and other insects carry pollen from flower to flower. If they all vanished, what would the world actually lose?
Start here
“If bees disappeared, humans would have four years to live.”
You have probably seen this on a poster, usually attributed to Einstein, who never said it. It is repeated because people want a reason to care about bees. The real reason is more interesting than the invented one, and it survives being checked.
If you had to guess, with no bees or other pollinating insects, would people starve?
Fair guess. That is what the poster says, and it sounds right. But wheat, rice and maize are pollinated by the wind, so most of the world's calories would carry on.
Good guess. Wheat, rice and maize are pollinated by the wind, and they give most of the world's calories. What would go is most of the fruit, nuts and vegetables.
Enough to eat is not the same as a healthy diet. Next: twelve foods on a supermarket shelf, and what happens to each with no pollinators.
At the bench · empty the shelves
Which foods survive?
shelf intact
Twelve foods from an ordinary shop. Watch the two numbers underneath — because they do not fall by the same amount, and that is the whole lesson.
Bread (wheat)
wind-pollinated
Rice
wind-pollinated
Sweetcorn (maize)
wind-pollinated
Potatoes
grown from tubers
Milk
cattle feed partly insect-pollinated
Apples
insect-pollinated
Strawberries
insect-pollinated
Tomatoes
bumblebee-pollinated
Almonds
entirely insect-pollinated
Broccoli
insect-pollinated
Coffee
partly insect-pollinated
Chocolate (cocoa)
pollinated by midges
The shelf as it is. Four of these twelve foods need no insect at all, and between them they carry most of the calories.
Who actually does the pollinating
Mostly not the insect on the poster.
Farmed, not wild
Honeybees
Kept in hives and moved to crops by lorry. Numerous, useful, and not the group that is disappearing — there are more managed colonies now than fifty years ago.
The ones in trouble
Wild bees
Around 250 solitary bee species in Britain, plus the bumblebees. Several are better at pollinating crops than honeybees, and several are in serious decline.
Overlooked
Hoverflies, moths and beetles
Hoverflies work in colder weather than bees will, moths pollinate at night, and cocoa depends on tiny midges. Pollination is not a bee monopoly.
What they need
Flowers, nests, fewer sprays
Flowers across the whole season rather than one crop’s brief bloom, rough ground and hedges to nest in, and insecticides used sparingly.
Key fact
Insect pollination is a service one group of organisms provides to another, and human food supply depends on it. Wind-pollinated cereals supply most of our calories; insect-pollinated crops supply most of the variety, the vitamins and the minerals.
Think again
“No bees, no food — we would starve within a few years.”
Overstating a real problem is not a harmless way of getting people to care, because the overstatement is the part that gets checked. Wheat, rice, maize, barley and oats are wind-pollinated and between them provide most of the calories eaten on Earth; they would be entirely unaffected. What the exaggeration hides is a genuine and more specific problem: the crops that do depend on insects are the fruit, nuts and vegetables that supply vitamin C, vitamin A, folate, iron and calcium, and losing them means a population with enough energy and widespread deficiency diseases — the situation When diet goes wrong describes. That is worth acting on, it is defensible against anyone who checks it, and it does not need a fake quotation from Einstein attached to it.
“Save the bees — keep a hive of honeybees.”
Honeybees are a farmed animal. There are more managed honeybee colonies in the world now than there were fifty years ago, and a beekeeper adding a hive is doing roughly what a farmer does by keeping chickens — useful, but not conservation. The pollinators actually in decline are the wild ones: solitary bees, of which Britain has around 250 species, along with bumblebees, hoverflies, moths and beetles. Several studies find these wild insects pollinate crops more effectively than honeybees do, and a dense hive in a poor landscape can compete with them for the few flowers there are. What wild pollinators need is flowers through the whole season, undisturbed ground and hedges to nest in, and fewer insecticides. Those are landscape decisions, which is why this appears in a lesson about food security rather than a lesson about pets.
Mastery ladder
Not started yet.
Rungs 3 and 4 you mark yourself.
Rung 1 · Which crops depend on insects
Which of these would be least affected if all insect pollinators disappeared?
Rung 2 · The one that catches people
A poster says losing bees would mean worldwide starvation within four years. What is wrong with the claim?
Rung 3 · Explain the two numbers
On the bench, removing insect pollinators takes far more from the vitamin bar than from the calorie bar. Explain why, and say what a population living on the remaining food would suffer from.
Rung 4 · Take it somewhere new
A farm grows one crop across every field — oilseed rape, which flowers for three weeks in spring and is insect-pollinated. The farmer cannot understand why wild bee numbers on the land keep falling despite so much blossom. Explain the problem, and suggest two changes.
Key note
Many crops depend on insects to transfer pollen between flowers, and without it those plants set little or no fruit or seed. Cereals are wind-pollinated and supply most of our calories, so a loss of pollinators would not cause starvation — it would remove most of the fruit, nuts and vegetables, and with them most of the vitamins and minerals in the diet. Wild pollinators, not managed honeybees, are the ones in decline.
Going further
In parts of Sichuan in China, apple and pear growers have pollinated their orchards by hand for decades, climbing the trees with pots of pollen and brushes made from cigarette filters and chicken feathers. It works, the fruit sets, and it takes a person a day to do what a few hundred bees would do in an afternoon. Why it started is disputed — heavy pesticide use, loss of wild habitat and the profitability of hand pollination in a region with plentiful labour all appear in different accounts — and it is worth being careful with the story rather than using it as a simple parable. What it does establish is a price. Insect pollination is a service that has always been free, and where it has been lost, the replacement cost has been measured in human working days per hectare. That is what makes it a food security question and not only a wildlife one.
Before this lesson
Connects to
At GCSE this becomes
- Food security, the biological factors threatening it, and the trade-offs in intensive and sustainable farming.
Where to next
Ask MrBadmus
Want to check a claim you have seen about bees?
The shelf is a teaching model. The calorie and nutrient bars are illustrative proportions for these twelve foods, not a calculation for a real diet or a national food supply, and crops differ in how completely they depend on insects — many set a reduced crop rather than none. Published estimates of the share of global food production that depends on animal pollination vary widely with how the question is asked.
Lesson content © MrBadmus.