Save the bees!

You’ve heard this before. Yet, most of us are either scared to be stung, or worse, are allergic to them. So, it can be difficult to grasp the thought that we should protect their wee bee lives. But, since we often hear about their distressing decline, they must be important, right? But, why?

Pollination is how plants sexually reproduce. There is a pollinator (the bee) and the plant to be pollinated, resulting in seed and fruit/veg production. In return for this good deed, pollinators receive food – nectar. Pollination is an ecosystem service that humans benefit from, e.g. food and fibre.

Globally, bee pollination is valued at $153 BILLION. Bees are responsible for pollinating 30,000 plant species, and a THIRD of human food consumption. New Zealand (NZ) relies heavily on agriculture that depends on the pollination of horticultural/agricultural crop and pasture species. Without bees, NZ agriculture would not be as productive as it is today!

An ‘effective’ pollinator is determined by how well it can transfer pollen, its abundance, and its flower visitation rate. They are especially important if few other pollinators are available, and if the pollinator can be transported in managed situations.

There are two categories of pollinators – managed and unmanaged.

Managed pollinators, introduced to NZ, include the European honey bee (Apis mellifera) and four bumble bee species (Bombus spp.). Honey bees are the superior pollinator due to their rapid growth of large colonies (up to 80,000 individuals) and ability to be transported to crop pollination sites. Honey bees contribute $5 billion to NZ’s Gross Domestic Product (GDP) from horticultural/agricultural crops, whilst contributing further to meat and dairy exports via pollination of pasture species, alongside honey products. That’s some hard mahi*. Makes me break a sweat just thinking about it! Bumble bees are less abundant. They are short- or long-tongued, large and hairy, and are popular for use in glasshouses.

Unmanaged pollinators include some flies as well as native and the aforementioned introduced bees, the latter being populations that have escaped to the wild as self-sustaining ‘feral’ populations. Flies are ‘effective’ crop pollinators, with the ability to carry as much pollen as honey bees, but more research is needed to be sure. Furthermore, our few native (mostly endemic) bee species exist in small populations, are challenging to commercially manage, or aren’t as ‘effective’ at pollination.

Consequently, NZ agriculture is dependent on managed and feral bee pollinators. ‘Background pollination’ is the term given to the ‘free’ ecosystem services provided by feral pollinators, and is what NZ agriculture is most reliant on, feral honey bees especially.

BUT. This is where we sound the alarms and enter crisis mode.

Since 2000, feral honey bee populations have almost entirely disappeared due to parasitic varroa mites (Varroa destructor). These mites cause blood loss and microbial infections to adult honey bees, as well as reduced vitality, deformities, and death of honey bee larvae. Feral honey bee colonies can re-establish, although they don’t survive more than a year unless they are treated for varroa mite.

This isn’t the only issue.

Bee populations are in decline, globally, due to habitat loss and the use of agricultural pesticides – the former reported as the #1 cause. Although there are schemes in Europe and the U.S.A that incentivise the creation of flower-rich habitat on agricultural land, no such schemes exist in NZ.

NZ agriculture depends on managed populations of honey and bumble bees. However, varroa mites are developing resistance to treatments. Therefore, the future of managed honey bees depends on new treatment development as the genetic base for breeding varroa-resistant bees is small. All of this is a significantly large pressure to put on the small New Zealand beekeeping industry. The poor folk.

What can be done to help the situation?

Restoring floral diversity within agricultural landscapes is a straightforward strategy to boost bee health. It allows bees to obtain high-quality food to give them the vitality to withstand varroa mites and agricultural pesticides, whilst providing them with a home. The key is to plant floral diversity that supplies food year-round.

During a bee’s life cycle, the most crucial times are winter-early spring and autumn-early winter, as agricultural crop species typically flower in summer. If the colony doesn’t have a consistent supply of quality pollen (pollen-dearth), the population won’t reach it’s peak size or fatten before winter, causing colony collapse disorder. Beekeepers can provide supplementary artificial feed, however this is costly and of low quality, so it doesn’t aid bee resilience against stressors.

But, we can’t plant flowers on farms willy-nilly.

Trees for Bees NZ have produced bee plant guides identifying bee forage species that can be planted on farms, flower in critical pollen-dearth times, and provide quality nutrition. These help farmers to increase floral diversity in various ways; e.g. non-crop buffer strips, hedgerows, or restoration of native areas to aid our native bee populations – despite their lower contribution to NZ’s agricultural pollination, boosting their populations will reduce reliance on honey and bumble bees.

Increasing floral diversity generates an initial monetary cost to farmers. However, there are a multitude of secondary benefits to be reaped: increased biological pest controls (reducing pesticide use), decreased erosion and runoff due to covered soil, weed suppression (further reducing agri-chemical use), greater rural landscape aesthetic, reduced nitrogen leaching, and improved soil structure and fertility. Realistically, NZ’s agricultural production literally depends on these pollinators – the secondary benefits are just a bonus!

Varroa mites and their treatment resistance, pesticide use, a narrow genetic base for breeding varroa-resistant bees, and loss of habitat/floral resources, are the four main threats to NZ’s pollinators. The latter can be remedied by planting nutritious bee forage species that flower during pollen-dearth times. This boosts bee vitality to combat stressors whilst also providing secondary benefits, some of which positively feed back to the reduction of agri-chemical use.

The challenges faced by managed and feral populations, alongside our low diversity of native species, causes New Zealand to be extremely vulnerable to a pollination crisis. Urgent action is critical within agricultural landscapes, but also on public and private land. It all helps. The bees’ and our own livelihoods depend on it.

So, get planting!

Greer Manderson is a postgraduate student completing her Bachelor of Science with Honours. She wrote this article as part of her assessment in ECOL608: Research Methods in Ecology.

*mahi = work, in Māori.

This article was based on work done by these Lincoln researchers:

Wratten SD, Gillespie M, Decourtye A, Mader E, Desneux N. 2012. Pollinator habitat enhancement: Benefits to other ecosystem services. Agriculture, Ecosystems and Environment. 159:112-122.

Newstrom-Lloyd LE. 2013. Ecosystem services in New Zealand: John Dymond Ed. Lincoln, New Zealand: Manaaki Whenua Press. 2.11, Pollination in New Zealand; p. 408-431.