The heath bumble bee: Crime and nourishment in the heathlands

The heath bumble bee is widespread in the north and west of Scotland. Despite its name, it is not restricted to heathland: it is also found on moorland, grasslands, coastal dunes and in gardens, where it visits a variety of flowers. It nests in different places, from old birds’ nests, small mammal burrows, or among moss and leaf litter.  Athayde Tonhasca’s latest blog takes a closer look at this intriguing species.

A heath bumble bee (Bombus jonellus). © Wikipedia Creative Commons

The heath bumble bee is a short-tongued bee, which means it cannot reach the nectaries of flowers with long and narrow corollas. The bee solves this problem by using its strong mandibles to pierce a hole at the base of the corolla to access the nectar. This behaviour is known as nectar robbery, and it is common among other bumble bees, many insects and birds. Indeed, almost all flowering plants with tubular flowers are victims of nectar larceny.

If flowers have been robbed, they will usually have a hole near their base, close to where the nectar is produced. After the robber has left, smaller bees, ants and other insects may come along to take their share: these are known as secondary robbers.

The relationship between plants and pollinators is considered mutualistic because plants benefit from the pollinators’ transport of pollen, whereas pollinators benefit from a reward (usually nectar or pollen). Because nectar robbers bypass the usual pollinating process, they can be seen as cheaters who harm flowering plants, which spend a lot of energy and resources to produce nectar. For Darwin, ‘all plants must suffer in some degree when bees obtain their nectar in a felonious manner’. Indeed, studies have shown that nectar robbery may damage the flower or reduce its attractiveness to ‘legitimate’ pollinators. But there is also evidence that robbing sometimes is neutral or even beneficial because robbers frequently touch the reproductive parts of the flower, pollinating the plants they visit. But in reality, although nectar robbing is widespread in nature, we know little about its ecological implications.

‘Nectar robbers’ is a well-established term among ecologists, but just like other labels based on human values such as ‘killer bees’, ‘assassin bugs’ and ‘cow killer’ (a wingless wasp), they are invariably exaggerated, biased and misleading. Nectar robbing is simply a more efficient means of extracting food than a normal flower visit; through natural selection, the heath bumble bee is doing what it takes to survive and reproduce. Insect robbery is not immoral, because nature is amoral.

Tee-ing things up for nature

When it comes to helping nature you have to hand it to John Milne, head greenkeeper at Rothes Golf Club. He was recently nominated for the Conservation Greenkeeper of the Year by the Golf Environment Awards, and prides himself on making his course as pollinator-friendly as possible.

John is well-travelled and has experience of golf courses stretching from Scotland to Cyprus, Mallorca and Australia. Now settled near his home town of Elgin he knows the Rothes course particularly well –  he played it as a boy and worked here back in 2003.

What measures has he taken to help pollinators?  The main step has been to ease back on mowing some areas around the rough. This has allowed a host of native wildflowers to gain a foothold and the species count has soared as a result. For example last summer John could celebrate an attractive blaze of yarrow and harebell in an area where the small change of just stopping continual mowing was creating a big impact.

A glance at the Rothes green keeping facebook page shows an impressive array of flowers and insects.  Bumblebees of various varieties, hoverflies, moths, orange-tip butterflies and goodly number of ringlets vie for attention in what is a homage to golf and nature. Some of those species you might expect. Perhaps less so the regular seasonal sighting of mining bees.

If you were to list the pollinator-friendly plants on John’s golf course you would be compiling a lengthy list – thistles, ladies smock (cuckoo flower), devil’s bit scabious are just a few of the plants that now flourish here.

By embedding a bug hotel into the building of a new tee John was hoping to snatch an opportunity to create a home for wildlife, and the inclusion of softer touches like the bird feeders within clear view of the clubhouse are another welcome addition. As with anything in life there are few guarantees of success, but by being willing to try different approaches John increases his chances of helping biodiversity and engages others with the subject.

Creation of good habitat is one thing, managing it is another aspect. Cutting and lifting, excessive sunshine or rain, these are typical challenges in improving the ecological performance of rough grass areas. And of course John is all the while balancing improving the aesthetics of the golf course, with seeking to increase biodiversity and maintaining a sound level of play-ability.

Aggressive grass growing conditions, and a lack of equipment, can mean that John has to step back in time and revert to traditional man-hours and hard labour to tackle the rough.  It was a herculean exercise of this nature that has got John considering the merits of planting yellow rattle in order to tackle the sward more naturally (yellow rattle being a native plant which is parasitic on grass roots, known as a ‘meadow-maker’,  and will suppress grass growth).

 

 

With these levels of commitment and planning it is little wonder that John was highly delighted to get a glowing ‘well done’ when  Rowan Rumball, a Sports Turf Research Institute Ecologist, visited last September to judge the environmental and ecological improvements at Rothes.

The north-east is proving a hot-bed for progressive golf course management. Of the four nominees in the Conservation Greenkeeper of the Year category three are from this region of Scotland (Rothes, Banchory and Montrose) with a course in East Anglia’s Ipswich making up the quartet. Richard Mullen at Banchory gained a further mention in the Operation Pollinator category.

The 2020 Golf Environment Awards are celebrating their 25th anniversary in 2020, and continue to recognise golf clubs and individuals that strive to undertake environmental best practice. Past finalists’ projects have ranged from simple but effective, to grand scale schemes.

Head of Ecology at STRI, Bob Taylor, said: “I cannot believe it’s twenty five years since we first set up the Golf Environment awards. Moreover, the awards have become the leading accolade for ecological and environmental excellence within the golf industry. Many golf greenkeepers tell me the awards represent something to aspire to, they provide an opportunity to market the good works they do. For me the awards represent a growing community that all come together at the awards celebrations discussing works and passing on ideas. Anyone is welcome to attend the awards, and one thing is certain you will leave inspired by the great work clubs are doing.”

The award to the Conservation Greenkeeper of the Year will be made in Harrogate on 22 January and, no matter the outcome, John is a winner as far as nature is concerned.

Further reading

You can find out about Richard Mullen’s work at Banchory in our earlier blog @ https://scottishpollinators.wordpress.com/2019/09/04/on-course-for-nature/

 

 

 

 

 

 

The pink hawks sampling our lilacs (Vladimir Nabokov)

The elephant hawk moth (Deilephila elpenor) is not yet common in Scotland, but its range is expanding, writes Athayde Tonhasca in our latest blog. This colourful moth flies at dusk and night, feeding on honeysuckle and other sweet-smelling flowers that open and produce nectar at night-time. 

Elephant hawk moth © Wikipedia Creative Commons

Hawk moths (family Sphingidae) are large and strong flyers. They can swerve with great agility, producing a soft whirring sound as they pass by. While most nectarivore (nectar-eating) insects land on the flower to feed, the elephant hawk moth hovers in front of the flower and extends its long, straw-like proboscis to suck its nectar. Stationary flight is quite demanding energetically, so the moth must be efficient when searching for food. But it has a special power: it can see colour at very low light levels, in conditions in which we humans are completely colour-blind. This ability allows the moth to quickly recognize rewarding flowers regardless of changing light conditions.

The elephant hawk moth pollinates the greater butterfly-orchid (Platanthera chlorantha) and the lesser butterfly-orchid (P. bifolia). However, as it is the case for moths in general, we don’t know much else about its pollination services. Hawk moths use their long tongues to access flowers with long corollas, which typically are out of reach for other pollinators. These moth-plant interactions are important for evolutionary biology because moth tongue length seems to coevolve with plant corolla length, a phenomenon first postulated by Charles Darwin. So the elephant hawk moth may have a greater ecological role in Britain – we just don’t have the data yet.

Elephant hawk moth caterpillar. It is usually dark brown, but there are bright green forms. © Wikipedia Creative Commons

The caterpillar – which inspired the species name by its resemblance to an elephant’s trunk – feeds mostly on rosebay willowherb (Epilobium angustifolium) in a variety of habitats. The caterpillar is quite big and conspicuous, so it relies on a ruse to reduce the risks of being eaten. When disturbed, the caterpillar retracts its head, which expands a pair of eye-like markings (eyespots) on the first two abdominal segments. Eyespots are found in a variety of Lepidoptera and other animals, and they have been shown to intimidate predators. This could happen because they resemble the eyes of the predators’ own enemies, or merely because they look startling and bizarre.

Either way, the caterpillar has a chance to live another day.