environment

Are honey bees good for our native species?

New Zealand’s honey bee population has exploded in recent years and increasingly beehives are being placed on public conservation land. Farah Hancock reports on the introduced species' effect on our native flora and fauna.

Rachel Nepia wants people to imagine native forest as a dinner table filled with pollen and nectar from natives plants. Guests seated at the table are indigenous birds, moths, lizards and our native bees and flies.

There's also a visitor from abroad at the table, the honey bee.

With the help of the Lucy Cranwell Grant fund the Waikato University PHD student has been researching what effect introduced honey bees are having at the native forest dinner table.

“We’re not really sure what their table manners are like. How they’re going to interact with other guests at the table, or how much food they’re going to consume,” said Nepia.

She also wants to understand if honey bees are dining out on the sweet nectar of native flowers without doing the important task of spreading pollen.

Her research comes at an important time.

Introduced in 1839, the number of honey bees hives in New Zealand has skyrocketed to over 800,000. In the 2016/17 period, pure honey exports earned $329 million. Despite this, little research has been done to understand honey bees' effect on New Zealand’s ecosystem.

Source: Apiculture New Zealand

More than 25,000 hives are on Department of Conservation (DOC) land, and a 2015 review of what conservation land might be suitable for hives found capacity for up to 500,000 hives.

There are controls over how many hives are in one site and each application is assessed individually, however, the dearth of knowledge makes it hard to know what the true impact is, or whether they pose a risk and transport disease, like myrtle rust from plant to plant.

Nepia’s research focused on two plants, the tāwari and kāmahi, to understand how introduced honey bees are interacting with plants and other creatures, and if there’s enough food for the natives and the honey bees.

The tāwari flower has an open structure with large gaps between the nectar and pollen. Photo: Ang Wickham CC BY-SA 2.0

She’s still crunching the numbers on the data she gathered over two summers of fieldwork but already there are interesting results.

It appears honey bees are poor pollinators of tāwari flowers. Through hours of video footage, Nepia found honey bees treat tāwiri flowers like a restaurant drive-through.

Ninety percent of the time they head straight to the nectar and leave without venturing near the pollen.

For a flower like the tāwari, which is large and has a considerable area between the nectar and pollen, not surprisingly, Nepia found birds are the most effective pollinators, followed by large beetles.

Size wasn’t the only factor though. While honey bees dine and dash, native bees are eat-in customers who like to linger and leave a tip of pollen.

“Native bees, even though they are smaller than honey bees, they have a very different behaviour to honey bees at the flower. They will go to the anther, collect pollen and crawl up and down over the flower. I saw one spend five minutes on one flower.”

For the smaller flowered kāmahi, where the nectar and pollen is closer together, Nepia said honey bees seemed to be doing a good job of pollination.

Pollen and nectar in kāmahi flowers is closer together. Photo: Rachel Nepia

Nepia also looked at the sugar content of nectar over two summers and found it to be different between two summers, with different average temperatures. During the wet 2016 summer the average temperature was 17 degrees; in 2017 it was 21 degrees.

“What was really scary was the available sugar per flower between those summers. In that cooler weather summer, we had more than double the amount of sugar per flower for tāwari and kāmahi.”

She also counted flowers each week of the summer.

“What we really need is a hive management system that is as dynamic as the flowers it relies on.”

“I found the same trend. The number of flowers in 2016 was more than double what I saw in 2017. In 2017 not only did we have half as many flowers per tree, but we have half as much sugar per flower. That’s a big change in resource availability.”

The effect of millions of honey bees being added to an area in years where food is limited could impact native species.

“What this highlighted to me is the availability of floral resources is hugely dynamic. It changes a lot from year to year, but the process we use to manage hive numbers doesn’t really reflect those changes in available resources."

Varroa mite has wiped out most wild honey bee colonies, so the majority of honey bees in New Zealand are from managed hives and are effectively livestock.

“What we really need is a hive management system that is as dynamic as the flowers it relies on.”

How DOC manages hives

In the year to June 2018 DOC, earned $428,784 from concession fees for the 25,000 beehives placed on conservation land. Divided equally, this would work out at $17.15 per hive.

The company holding the largest number of hives is The True Honey Co with 2600 hives. According to their website, prices for their mānuka honey range from $260 to $68.90 for a 250 gram jar.

In an Official Information Act (OIA) request response, DOC said rates at different sites were calculated differently.

“For example, beehives placed at sites with high numbers of manuka will pay more than beehives placed at sites without mānuka.”

The fees are made up of an activity fee for having the beehive on conservation land, as well as a management fee. Management fees are used to cover the cost of department staff reviewing hives and compliance.

The land review, from 2015, followed an application to place 58,000 hives on public land.

“Prior to 2015, there was very little demand for beehive concessions … the growth of the NZ honey industry has resulted in a substantial increase in applications to place hives on public land. This has meant most land suitable to host hives [is] now occupied by concessionaires.”

DOC said the behaviour of concession-holders was also growing fierce and increasingly anti-competitive. Hives were being placed illegally, and theft and vandalism was occurring. Concessions were being requested with no intention of placing hives on the land, simply to lock out competitors.

Source: Department of Conservation 2018 submission to the Inquiry into Honey

In 2018, DOC decided that once a concession expired, the site would be assessed for ecological and cultural suitability to continue housing hives. If suitable, it would then be open to a tender process and advertised on DOC's website.

DOC's said it’s taking a precautionary approach due to the limited amount of information available about honey bees’ impact on native ecosystems, according to its OIA response.

“[W]hen the effects of an activity are unknown, the Department will move towards refusing an activity on public conservation land. In support of this, the Department no longer approves beehives to be placed in EMUs (ecological management units), areas of significant ecological importance.”

DOC has also moved to place controls to reduce the spread of disease. In 2018, Plant & Food research confirmed honey bees transport myrtle rust spores into their hives. With a foraging range of around 5 kms, the likelihood of honey bees spreading spores where wind doesn't wasn't high. However, apiarists moving hives several kilometres to new areas could potentially spread the disease. Hive movements on some areas of conservation land are now restricted, and will be reviewed annually.

A DOC document submitted to the Primary Production Committee’s 2018 Inquiry into Honey says while the department is taking a proactive approach to protecting biodiversity, it's also attempting to maximise revenue:

“As the mānuka honey industry grows, the Department is committed to ensuring Crown revenue from the use of conservation land is maximised. As industry knowledge of the value of other honey variants also increases, we expect to see that value also translate to Crown revenue.”

In its Inquiry into Honey submission, DOC pointed out the lack of knowledge about the impact of honey bees on native species. One reason given was that the research was hard to do. Another was “the research funding environment is very restrictive in NZ”.

When it’s complete, research like Nepia’s - though based on two plant species - may help DOC understand how the honey bees’ table manners are impacting the indigenous biodiversity it’s responsible for.

Read more:

The dark side of New Zealand's honey bee

The unloved Cinderella of science

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