The buzz on bees

Dr Pattemore, who leads the Productive Biodiversity & Pollination group at Plant & Food Research, and his team wanted to understand how bumble bees picked their nesting sites. Using an automated tracking system to monitor the bees, the researchers hoped the transmitters would allow them to track which particular landscape features the wild queens found attractive, information that could help to develop methods to encourage more bees to nest. The ultimate goal behind this interest in bumble bees? To harness them to pollinate crops — not as a replacement for the ubiquitous European honey bee, but as a complementary force.

The bumble bee work is part of a Government-funded six-year investigation into alternative pollinators by Pattemore’s group. There are compelling New Zealandspecific reasons why developing a pollination “plan bee” makes sense — the tension between the needs of crops such as kiwifruit and the lucrative mānuka honey industry being just one.

Native bees are under threat. In Ireland, almost a third of native bee species are threatened with extinction, and elsewhere are other stories of decline. Although honey bees are not threatened with extinction, it requires more effort to keep colonies alive.

And it’s not just bees: the so-called “Insect Apocalypse” may have been overstated, but many pollinating species are declining. The reasons are likely to be multiple, and include the increased use of insecticides (the EU banned neonicotinoids in 2018; however it’s not yet clear that the products used to replace them are less harmful), habitat loss, the loss of honey bee colonies from the Varroa destructor mite (varroa), and climate change.

Should the worst happen — a mass decline in pollinators — the world won’t starve, but it would certainly affect food supplies and damage the ecosystem. Bees, and other pollinating insects, are involved in the production of one in every three bites we eat, critical pollinators for 70 out of 100 crop species that feed 90% of us.

And the impacts will extend well beyond food. Jane Stout is a Professor of Botany at Trinity College Dublin and an initiator of the All-Ireland Pollination Plan, aimed at reversing decline in Ireland, where wild bees are struggling.

“Crop production is just one of many benefits we gain from healthy populations of wild pollinators,” she says. “They also pollinate wild plants that contribute to ecosystem function. They contribute to cultural and spiritual services, health and wellbeing, a sense of peace, et cetera.”

To sustain crop pollination in future, we need both to protect wild pollinators and also to ensure we have a healthy population of managed honey bees to use for crop pollination.

At Plant & Food Research, much of the research into the health of managed honey bees is focused on varroa, which was discovered here in April 2000 and rapidly wiped out our feral honey bee colonies (honey bees are not native to New Zealand). Thanks to management techniques and synthetic chemical controls, however, varroa wasn’t the hammer blow to managed bees it might have been — in fact, the number of colonies has climbed from 300,000 in the early 2000s to nearly 900,000, largely thanks to the mānuka honey bonanza.

Yet the challenge remains, says Pattemore. “We are seeing more viruses associated with varroa, and varroa also develop resistance to treatments,” he says. “It’s a mission to keep ahead.”

One area being investigated by Plant & Food Research is whether bee breeding can contribute to varroa control. The research focuses on assessing in New Zealand honey bees the value of genetic markers described for a behavioural trait known as “varroa sensitive hygiene” (VSH), where honey bees detect and remove bee pupae infested with the mite. The more VSH exhibited, the better a colony is able to withstand a varroa assault.

“We’re involved in a DNA-based queen selection programme,” says Dr James Sainsbury, the leader of Plant & Food Research’s Bee Biology and Productivity team.

“The question is this: if we look at the DNA of a queen before she produces a colony, can we work out how much of this anti-varroa behaviour that colony will have? We have run a controlled research trial, and this coming year we’re running a citizen science project with beekeepers to test the idea of DNA-assisted selection for varroa resistance.”

If it pans out, it could be a useful tool in managing varroa in New Zealand, he says. “We do not expect it to replace the need for synthetic chemical treatment completely, but it opens the door for us not to rely on them so much.”

Plant & Food Research is also exploring how bees might be made into more effective pollinators. As Pattemore points out, “New Zealand doesn’t have a problem of lack of honey bees; the issue is where the bees are going. It’s much more profitable for a beekeeper to produce a good mānuka honey crop than to put their colonies in for pollination.” Achieving more bang for your pollinating buck has become a priority.

As part of its research, Pattemore’s group has developed an automated pollen dispenser that “pre-loads” bees as they leave the hive, to maximise pollination. The device is now being commercialised.

Meanwhile, Plant & Food Research has been subcontracted, as part of the University of Otago’s “Future Bees” programme (funded by MBIE), to develop pollination effectiveness measures that could be incorporated into breeding. “They’re not planning to breed a super bee, but they’re trying to set up a breeding index such as you have for livestock,” says Plant & Food Research bee scientist Dr Ashley Mortensen.

The team is looking at colony-scale parameters such as the amount of food a colony provides to its larvae. When that is high, so too is the protein demand on worker bees, which the researchers suspect will drive them to collect more pollen.

“We’re also looking at individual bee parameters. For example, we want to see if there’s variation between colonies in the hairiness of workers; if that hairiness correlates to a change in electrostatic charge; and if that change influences pollination efficiency – which we assume it would,” says Mortensen.

Behind all of this is a possibly surprising insight: while the European honey bee is the world’s number one pollinator of crops, pound-for-pound it’s by no means the most efficient. Bumble bees, for instance, forage in ways that make them individually far more effective. And there’s growing understanding of the importance of other pollinators – including some seemingly unlikely species.

For example, this Plant & Food Research group has discovered that in some Australian regions avocado orchards are almost entirely pollinated by flies. It reinforces a point Pattemore makes about the importance of knowing exactly who is pollinating your crops – if those Australian growers had sprayed for flies, they would have endangered their livelihoods. But it also highlights the rich potential for harnessing pollinators other than honey bees.

Dr Romina Rader, a Senior Lecturer in Community Ecology at the University of New England, in New South Wales, is involved in a new three-year study into the role of flies as pollinators. “Wild pollinators have a big future in Australia for some crops,” she says. “For other crops, a mixed system with both managed and wild pollinators is definitely possible – it’s already happening in many regions.”

As noted, Pattemore is particularly interested in the potential of bumble bees for crop pollination. “There’s the potential to see them sit alongside honey bees as our number one and number two managed pollinators,” he says. “It’s something we’re very motivated to see.”

One stumbling block is economic. Commercial bumble bees are expensive, and for various reasons you need many more bumble bee colonies than honey bee colonies to pollinate an open orchard. Pattemore’s group has been trialling a new rearing system that could dramatically cut the cost.

The New Zealand researchers are also interested in the pollinating role played by flies and other insects.

Pattemore stresses the importance of developing many complementary pollinating options, noting that even in crops where honey bees do 80% of the work, it’s often the “top-up” by other species that makes that crop economically viable. “And the more diversity you have, the more chance that you’re going to achieve pollination regardless of weather conditions or the shape of your flowers.”

At the end of the day it all comes down to fostering biodiversity.

“The dominant theme here is understanding the role played by these alternative species that are in the landscape, but which go under-recognised and under-utilised. It’s about understanding how we should manage farms and orchards as ecosystems, and how we can protect those beneficial species.”