The not so sweet side of honey bees

By Athayde Tonhasca

Our honey bee – more precisely, the Western or European honey bee, Apis mellifera – is the world’s most important crop pollinator. Thanks to an ancient history of domestication, farmers can count on a work force of up to 60,000 bees per hive, which can be managed and moved from place to place to pollinate flowers of many shapes and sizes. Unlike the vast majority of bee species, honey bees live in highly social, organised colonies that last for many years. They fly long distances in search of food, and are quite effective in collecting pollen and nectar. Depending on the floral abundance, season and density of colonies in the area, a single hive may consume 10 to 60 kg of pollen and 55 to 400 kg of nectar per year.

A honey bee displaying its skills in pollen gathering. ©Phonon.b, Wikipedia Creative Commons

Honey bees are efficient pollinators that have been introduced to many parts of the world to improve the yield and quality of crops. But their presence can be bad news for other pollinating species.

Bees can be infected by several viruses and other pathogens such as microsporidia (fungus-like single cell parasites). Every time a bee visits a flower, it risks being contaminated by a pathogen left by a prior visitor. The transmission can go from honey bees to other bees – and even flies – or the other way around, but honey bees are the most likely source of diseases: they are known hosts of many viruses and other pathogens. Besides, large numbers and communal, crowded living arrangements are not the best conditions for keeping diseases at bay, as we humans have recently and painfully learned. Indeed, studies have confirmed pathogen transmission from honey bees to bumble bees and solitary bees. Infections in the opposite direction have been less documented.

A honey bee on a dandelion: risk of diseases for the next visitor. ©Juan Carlos Fonseca Mata, Wikipedia Creative Commons

Honey bees are good at what they do, and the figures prove it: the amount of nectar and pollen collected by a large apiary is sufficient to support 102 bumble bee colonies; during high season (June–August), a 40-hive apiary collects as much pollen as four million wild bees: that means that one hive gathers enough pollen for an average solitary bee species to produce 100,000 offspring. It is difficult to measure whether this level of industriousness has any effect on honey bees’ wild counterparts: bees are highly mobile and cover a huge area while foraging, so it is not easy to set out experiments. Despite this, we have a great deal of circumstantial evidence to suggest there is not enough food to go around when honey bees are in the neighbourhood. 

Every spring, Tenerife beekeepers temporarily move up to 2,700 beehives to Teide National Park to take advantage of the seasonal bloom. A research team saw this cyclical invasion as a great opportunity to evaluate the impact of honey bees. So for three years, they monitored the area before and after beehives were brought in. They observed a clear reduction in the number of pollinator species and diversity of flower visitors when honey bees were present. In other studies in different countries, wild bees switched to less abundant and less rewarding plant species when honey bees were present. Or they became scarcer, gained less weight, and produced fewer and smaller offspring. In other instances, wild bee numbers increased once honey bee hives were removed. In Spain and another 13 countries in the Mediterranean basin, honey bees have become more abundant over the years and are gradually replacing wild bees as visitors of wild and cultivated plants. We don’t know what the consequences are for the 3,300 or so bee species in the region, but it does not bode well. 

Teide National Park, a natural habitat altered by honey bees. ©Mike Peel, Wikipedia Creative Commons

Competition between species happens when food is a limited resource, as is the case for small or isolated areas. That helps explain why native bees have become endangered after honey bees were introduced in New Caledonia (south Pacific), New Zealand, Japan and Tasmania. But competition is not a problem for islands only; it is likely to happen whenever flowers are scarce, such as at the beginning or end of bees’ foraging period, or during unusually cold or dry years.

All of this suggests it is wise to keep honey bees apart from native bees. Introducing or enhancing beekeeping in sensitive areas – that is, those already occupied by scarce or threatened bee species, of semi-natural habitats, or where flowers can be in short supply any time during the season – can put our bee fauna at risk.  

The importance of beekeeping and honey bee pollination is unquestionable, but our wild bee species are important as well, as pollinators and components of our biodiversity. Despite the recent panicked reports in the media about the imminent demise of the honey bee and supposedly mankind, beekeeping around the world has increased by ∼45% during the last 50 years (numbers from America and North Europe are exceptions). Meanwhile, many wild bees have declined for many reasons, including the presence of honey bees.

There are plenty of opportunities for all bees to coexist in our planet: it’s a matter of recognising their potential, limitations, risks and proper place.

Nectar network

The Irvine to Girvan nectar network boasts many projects. One interesting task centres around Belleisle and Seafield golf courses, particularly on making the rough more pollinator-friendly.  The courses have been surveyed recently by the Scottish Wildlife Trust working in partnership with South Ayrshire Council’s Golf Service, and the findings make for an interesting read.

Extensive scarification work was undertaken on the roughs in September 2018 .  Many of these areas were sown with wildflower in October 2018. With any project it is always a telling experience to revisit the site to see what has worked and what has struggled. And hence the golf course areas which were sown in 2018 were revisited in July 2019 to look for successes and challenges.

Red clover

Red clover

The surveys at the two golf courses was to prove valuable and given that there was also an intention to note the presence of any pollinating insects there would be a good insight gained into habitat and species.

Yellow rattle

Yellow rattle

At Seafield golf course several patches were inspected, and 50 plant species were noted in 9 distinct sites. It was interesting to note that of 17 species which were present in the seed mix that was used, 12 occurred on the ‘inspection visit’ and three of the 12 were widely evident (pignut, wild carrot and yellow rattle).  Red clover, bird’s-foot trefoil and lesser knapweed. fared relatively well but there was no sign of the devil’s-bit scabious or vetches that had been planted.

A few items which were flourishing at Seafield hadn’t actually formed part of the mix – including white clover, yarrow and harebell.  12 species of pollinators were noted whilst visiting Seafield, including three species of butterfly, three of bee and two types of hoverfly.  The digger wasp was one of the star finds.

Digger wasp

A digger wasp

When the team moved on to Belleisle they found rough that was more densely vegetated, and isolating the ‘sown’ areas was a deal trickier. Again three species in the mix that was sown thrived — lesser knapweed, yellow rattle and pignut. Five elements know to have been sown did not show, including red campion, devil’s-bit scabious and common vetch. Lesser stitchwort, which did not form part of the mix, had done well as had ribwort plantain and creeping buttercup. Four different species of butterfly and 3 kinds of bee were noted during the survey – others may have been present.

One of the Seafield plots that was analysed

One of the Seafield plots that was analysed

The surveys at the two golf courses were useful for gaining a picture on the success, or otherwise, of the mix sown. There was a sense that it might have been more economic, and more productive, to have narrowed the list in the mix. Given that plenty of non-sown items were evident it might be that simply sticking to the highly beneficial yellow rattle would be a good approach, particularly on light, well-drained soils.

The team have also concluded that more scarification would be a good thing — allowing the build up of grass to be cleared and helping move to a one-cut per year scenario. But overall their findings are fascinating and help prove that you never quite know beforehand what will thrive and what will disappear when sowing seeds.

Further reading:

Fnd out more about the Irvine to Girvan nectar network on the Scottish Wildlife Trust website.

Marvellous meadows

East Dunbartonshire Council are one of a number of councils converting much of their bland amenity grassland into wildflower meadow.  Under the expert influence of Jackie Gillespie they have made great strides, and as I found out recently, they aren’t finished yet.

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I visited four locations around the Strathkelvin area and saw at first-hand how they are slowly but surely delivering a transformation that is going to be great news for pollinators. And I rather suspect that people are going to like it too.

I started my tour at Lennoxtown in the shadow of the Campsie Fells and the popular cycling challenge that is the famous Crow Road.  Bathed in sunshine down by the River Kelvin I came across a stunning wildflower meadow. This rich meadow is just a few  years old and in summer a glorious technicolour feast for pollinators. The ever-popular John Muir Way runs alongside the meadow and the area is well noted locally. Asking for directions revealed a degree of local pride in ‘our meadow’

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During my visit I saw red-tailed bumblebee, various hoverflies and a generous smattering of butterflies. It was clear that as a source of food the meadow was doing a great job.

A quick hop along the road and I found myself in Bearsden’s Cluny Park. Here a four-year old meadow was perhaps going over, but had,  judging by the comments I heard, made a huge impression locally. Sandwiched between the Bears Way cycle route and busy A81 and has become something of a local landmark. The weather was sunny and fine, the mix of grasses were swaying in the gentle breeze and cyclists were gliding past … all in all a most tranquil scene on the fringes of Scotland’s largest city.

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If the Bearsden meadow is highly visible then the equivalent in Torrance could accurately be described as being ‘tucked away’. This is a new meadow so at the moment the planting has just been completed. As anyone who knows about meadows will testify, you need patience. It isn’t much to look at just now, just a series of pock marks on the grass but given time an array of wildflowers will pop through.  No two meadows are alike, no single meadow is the same year on year … and always there are challenges. Here the challenge might be the proximity to the River Kelvin and the banks of rosebay willow-herb patiently poised for areas to spread into.  Time will tell.

My final port of call was Milton of Campsie, where like Torrance, works are at an early stage. I feel the folks of Milton of Campsie are on the verge of being spoiled, for the ambitious folks at East Dunbartonshire Council have gone for not one, not two, but three meadows. The new meadows promise to give pollinators some great forage in addition to the plethora of gardens that are a proud hallmark of this community.

Creating meadows is a sure-fire way to help pollinators.  Tackling historic loss of habitat, and a shortage of food, is an incredibly practical step to take to help deliver Scotland’s pollinator strategy.   It hasn’t been easy, and it may not look at its best yet, but in time what East Dunbartonshire Council have done will be mightily well-received – by people and pollinators.