If you were to believe many reports in the media in recent years, you would probably think that honey bee numbers in New Zealand are plummeting and that we are about to be plunged into a food supply crisis as a result.

Yet if you have read any articles about the manuka honey boom, you probably would have also learned that hive numbers in New Zealand have doubled over the last 10 years.

So, what's going on here? Which news stories should you believe?

Although we don't have any reliable data on some introduced and native bee populations, any claims that honey bee numbers are currently in decline in New Zealand are false.


New Zealand now has more managed honey bee hives than ever before.

So why do we hear stories about a drastic decline in the honey bee population?

Honey bees are not native to New Zealand, but were introduced by early European settlers.

They spread beyond managed hives to establish feral colonies in the bush.

As far as we can tell, when the destructive Varroa mite arrived and spread through New Zealand in the early 2000s, we lost all these feral honey bee colonies and numbers of managed hives dipped down for about four years.

Varroa means that, for all practical purposes, honey bees only survive now thanks to human intervention in managed colonies.

Varroa is still the primary threat to honey bees worldwide.

Varroa and other health threats have led to increases in annual hive loss rates globally, with some countries like the USA reporting an overall loss of 45 per cent of hives per year.


However, these loss rates don't mean an overall decline.

Even in the US, hive numbers have been increasing, not decreasing.

The continued growth of beehive numbers in the US and New Zealand is possible because beekeepers routinely split single hives into two, mimicking the natural process of new colony formation.

Like any population of animals, it is the balance between death and reproduction that matters, rather than the death rate on its own.

In New Zealand the significant increase in the value of manuka honey has driven demand for hives.

Beekeepers have been able to split their hives at a sufficiently high rate to result in a phenomenal increase in total hive numbers.

While it is encouraging that the value of honey has been sufficient to keep hive numbers on an upward trajectory, the high hive loss rate is still a concern, because it requires an increasingly large effort and cost to keep up with producing new hives.

Thus, scientists around the world have been working to understand the relative importance of a multitude of factors that affect hives, including parasites and disease, stress and nutrition, and the impact of a range of pesticides.

But these honey bees are just one species of bee.

When most members of the public read the word "bees", they are probably thinking about the European honey bee.

By some estimates there could be over 20,000 species of bee worldwide.

Bees are an incredibly successful group of insects that have evolved special relationships with flowers for about 100 million years.

They range from the large black and yellow striped bumble bees we see in our gardens here in New Zealand to the metallic green orchid bees in Central and South America, and the tiny colony-forming stingless bees that are managed for pollination on a small scale in Australia.

There are even other species of honey bee, and some Asian honey bee species are also managed in similar ways to the familiar European honey bee hives.

It is wild bees, such as bumble bees, that are a major cause of concern for bee scientists around the world.

Managed honey bees are owned by a human who is able to advocate for their protection, and hives can be easily moved out of harm's way if need be.

In contrast, wild bees nest in the ground or in the environment surrounding the farm.

There isn't the option of moving them away from pesticides, for example.

One study looked at the effects of neonicotinoid pesticides on bees in a real-world agricultural environment, and found negative effects on bumble bees and solitary bee species, but not on managed honey bee colonies.

But bees, in the broadest sense, are not the only pollinators out there.

With just under 30 species of native bees, native plants in New Zealand rely on a wide range of other pollinators too.

These include flies, beetles, moths, birds, lizards and bats.

Different plants rely on these different groups to varying degrees.

Our native plants never used to be pollinated by honey bees or bumble bees, nor do these bees effectively pollinate many of our native plant species.

So the loss of honey bees would probably not have negative consequences for New Zealand forests.

Crop plants are different.

We don't have any important crop species that are native to New Zealand.

Our crops originate in Europe, the Americas and Asia.

Honey bees are important pollinators for these crops, because they readily visit all sorts of flowers.

Managed honey bee hives can be brought in when you need large numbers to provide a degree of certainty about the level of pollination service.

But even with honey bees present, there are many other species that also visit flowers and make a contribution to pollinating these crops.

Global studies have shown that this extra contribution from wild pollinators can be critical for crop production.

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Increasing the numbers of these species can increase crop yields, while increasing honey bee numbers doesn't always add more pollination.

This means there is a base level of pollination service that is provided by honey bees, but the wild pollinators can often provide an extra pollination service that honey bees cannot.

This could be due to different activity patterns between insect species. While honey bees prefer warm, still, sunny days, other species are happier at dusk, dawn or even at night, and are often still foraging when the weather is gloomy or damp.

Having a wide range of species pollinating your flowers means that you may achieve better pollination even if conditions are not ideal for honey bees.

So what would happen if we lost honey bees?

A quote attributed to Einstein, quite possibly incorrectly so, is floating around the internet which says we'd only have four years to live if we lost the services of honey bees. Could this be true?

All the evidence says that it is not true.

Even if we lost all pollinators, we wouldn't starve, as most of our staple grains, starches and proteins do not require pollination by insects.

While some people estimate that pollination is required for up to two-thirds of our fresh produce, it is less clear about the exact contribution of honey bees.

The loss of honey bees might make the production of some crops, such as kiwifruit, unprofitable and we would probably see a decrease in the availability and affordability of many of the fresh produce items that give us diversity of nutrients and flavours.

But many crops could still be pollinated by other bees, flies, beetles, and moths.

Given the incredible diversity of pollinators out there, we're not likely to see a wholesale loss of all pollinator species.

So what does this mean for you, and your vegetables and fruit trees in the garden?

Take a look next time you see a bug on a flower.

Is it a honey bee? Or is it actually a native bee, or a fly or something else?

Before you spray for pests, stop and think about what beneficial insects you might also be affecting.

Be aware of bees, both native and introduced, and be aware of all the other creepy crawlies that could be important for pollination of your favourite plants.

And continue to care passionately about European honey bees.

They remain the backbone of our crop pollination service and produce one of our fastest growing export products - manuka honey.

While hive numbers are at an all-time high, so are the threats to colony health.

If we want to maintain our ability to increase honey production while also pollinating our increasing area of crops, then we will need to invest significant energy and ideas into overcoming the new and emerging challenges to honey bee health.

Meeting these challenges is at the heart of the research we're leading at Plant and Food Research in collaboration with industry.

Dr David Pattemore is a pollination scientist at Plant and Food Research.