WCBA & Industry News

The Great Onion Pollination Mystery

What lies behind the failure of honeybees to pollinate onion seed crops in certain years?

Onions have been a staple in diets around the world for thousands of years. With their sharp smell and pungent taste, they’re ideal for adding flavour to our food. You’ll be hard-pressed to find a recipe that doesn’t call for them.  But some of us detest onions, and that’s not only because they often make our eyes water when slicing or dicing them.

There’s a condition called “alliumphobia”.   The word is derived from Allium, which refers to the large genus of bulbous herbs of the lily family, including onion, garlic, chives and leeks.  People who suffer from alliumphobia are said to experience panic attacks or other forms of anxiety triggered by the sight, scent or contact with alliums, such as onions.

It seems honeybees are also picky when it comes to onions. Honeybees are essential for the onion seed industry, accounting for between 98% to 100% of pollination.  Crucial as they are, honeybees sometimes disappear when the onion flowers are in full bloom.

In 2012, onion seed growers in the Little Karoo – a world hub for the propagation of onion seeds – were shocked when they lost an estimated R70 million because of what was deemed to be a poor pollination season. 

But worse was yet to come. In 2021, the crop was a near flop, with a staggering loss of R150 million to R200 million, also blamed on the indifference of the honeybees brought in to pollinate the flowering onion plants. This was a massive hit for a niche agricultural industry, centred around Oudtshoorn, and which has a sprawling customer base in North America, Europe and Asia.

Honeybees are essential for the onion seed industry, accounting for between 98% to 100% of pollination.

Baffled why usually reliable pollinators can behave so unpredictably, seed growers, experts from the Department of Agriculture and representatives of the Western Cape Bee Industry Association have been meeting to try to tackle the conundrum.

David Malan, Managing Director of Little Karoo Seed Production, can’t stress the importance of honeybees in the production of onion seeds enough. He says “if the bees aren’t working during the three to four weeks of flowering it can ruin the entire harvest”.

Mike Allsopp, senior honeybee researcher at the Agriculture Research Council, the ARC, says it’s a problem that puzzles experts around the world. Although it was “episodic”, he said there was “surprisingly limited research into the issue”.

Onion seed pollination can be challenging at the best of times. Red onions, for example, have very dominant pollen and need to be grown at least five kilometres from white and yellow onions to prevent bees from cross-pollinating them.

Speculating on why bees may suddenly abandon an onion pollination job, Mike Allsopp said his best guess was that there was better forage around at the time the onion plants were flowering.  However, he cited other possible causes ranging from the use of certain fungicides which may drive bees out of pollinations blocs, environmental factors such as high temperatures and low humidity, lower nectar levels than usual, to the presence of certain minerals and phenolics in the nectar that bees might find unattractive.

Allsopp added that “baseline research was needed to find out nectar levels, sugar content and other components in the nectar of onion plants”.  The other possibility was to cultivate new onion varieties that might be more attractive to bees. A multi-disciplinary team is being assembled to investigate the erratic behaviour of honeybees on onions. With a new pollination season looming, it’s unlikely answers will be found in time. But findings from the research will be much anticipated by onion growers and onion lovers alike, who can’t have the bees buzzing off when they are needed most.

David Malan, MD of Little Karoo Seed Production.

Discover More