Too hot to handle – climate change and insects

By Athayde Tonhasca

The body temperature of most insects is approximately the same as that of their surroundings. They are poikilothermic, or ‘cold-blooded’, animals. So the warmer it gets, the more active insects become; they feed more, mate more frequently and lay more eggs.

You can see where this is going. Could global warming be good for insects? To a point, yes. In a warmer planet, diapause (the period of suspended development) will terminate earlier, winter mortality will be lower, spring will come sooner and summers last longer. Most insects will have more time for developing and dispersing.

But before you start singing the Ode to the Coal Power Station, remember that less desirable insects may benefit as well. Numbers of crop pests with high reproductive potential such as aphids and thrips could explode; forests in Scandinavian countries are already facing severe damage by insect outbreaks. Invasive disease-carrying species – affecting humans, livestock and plants – may no longer be killed by the cold weather.

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Mild winters allow more pine beetles to survive and kill large swathes of forest in Colorado, USA. The image is in the public domain.

Most insects benefit from higher temperatures, but not all: some, like bumble bees, apparently already live close to their upper levels of tolerance. As temperatures rise, these species are forced to follow shifting cooler habitats by moving towards the poles or to higher altitudes. Indeed, the abundance of many butterflies, beetles, dragonflies, grasshoppers – and plants as well – have contracted at low latitudes and elevations, and increased in more northern and elevated regions. Species incapable of dispersing or which are isolated in pockets of habitats are stuck, and eventually may vanish. In Britain, local populations of cold-adapted butterflies with narrow temperature tolerances have disappeared. As far as we know, no species has gone extinct because of increasing temperatures, but the risk is real.

As the overwhelming majority of reputable climatologists have predicted, the rise of greenhouse gases in the atmosphere is not only turning the world warmer, but also changing precipitation patterns and increasing the frequency of extreme weather events. There will be more and stronger droughts, floods, tornadoes, cyclones and other dangerous, traumatic and costly weather-related phenomena.

Scientists have been looking for possible consequences of these factors to insects, particularly agricultural pests, and they have come up with a maze of scenarios. Plants suffering from water stress during droughts are more vulnerable to damage by herbivore insects, but some of these pests do not survive droughts. A rise in atmospheric CO2 enhances crop photosynthesis thus plant growth and crop production, but it also increases the carbon to nitrogen (C:N) ratio in plant tissue. Insects need nitrogen for protein, so herbivore species have to eat more to compensate for plants’ reduced nitrogen content. But higher C:N ratios slow their development, making them vulnerable to natural enemies for longer. On the other hand, higher temperatures reduce the length of larva and nymph stages, which are the periods of greater exposure to predation. So plant feeders may have a greater chance of escaping natural enemies. The life cycles of plants, the insects that feed on plants, and those insects that feed on the plant feeders, may get out of sync if they respond differently to higher temperatures, with unknown and unpredictable consequences.

Does all of this sound complicated? Well, there’s more.

Diapause is one the most important events in an insect’s life – it allows it to survive unfavourable conditions, which happens during the winter in temperate regions. Diapause is regulated mostly by photoperiod, which is the daily period of light. When the days shorten, insects start to prepare for the onset of winter; when the days lengthen, insects become active again. Photoperiod is a reliable clue because it does not depend on the weather; it follows a stable pattern. The problem is that for many species, photoperiod is not the only trigger for diapause: they may respond to temperature and sometimes to precipitation as well. As we have seen, this is risky in a world changed by climate. The mismatch between temperature and photoperiod cues may induce insects to enter or leave diapause too soon or too late, with potentially disastrous consequences for their development, reproduction, and survival.

We have a vague, unsatisfactory grasp of the effects of climate change to insects, but the few data available tell us that trouble is brewing. And risk to insects means risk for us, since we depend on so many of their ecological services such as maintaining the food chain, decomposition, and recycling of organic matter.

And how about the effect of climate change on pollinators?

We will leave that for next time.

(This is the first in a trio of articles by Athayde looking at climate change, insects and pollinators)

Marmalade hoverflies, the unbeatable frequent flyers

Soon during a stroll in your garden or local park, you will see lots of flies striped orange and black hovering over flowers like tiny helicopters, writes Athayde Tonhasca. These are marmalade hoverflies (Episyrphus balteatus), which are some of the most conspicuous and familiar insects in gardens and indeed many other habitats. They are widespread throughout Europe, North Asia and North Africa.

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The marmalade hoverfly and related species (family Syrphidae, aka syrphid flies) are mimics of bees and wasps; in fact, is not uncommon for people, tricked by the flies’ ruse, to step back from these harmless insects.

Adults feed on pollen, nectar and honeydew from a range of plant species, while larvae feed on aphids – entomologists say they are aphidophagous. Females smell aphid colonies and lay their eggs in the middle of them. The larvae hatch immediately, and each devours up to 300 aphids per day until pupation. So you could say these flying morsels of marmalade are important allies of gardeners and farmers.

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A marmalade hoverfly larva © Entomart, Wikipedia Creative Commons.

Some people will be surprised to know that these fragile insects embark on migrations that may cover thousands of miles. Each autumn, marmalade hoverflies and other migratory syrphids head south to spend the winter in southern Europe and the Mediterranean. Their offspring move northwards in the spring, lay their eggs, and the new generation sets out the cycle again. To survive these hazardous journeys, hoverflies climb to high altitudes, where strong tailwinds take them to their intended destination.

Some years, they arrive in Britain in large numbers. And “large” is an understatement. By using specialised radars designed for monitoring insects (Vertical-Looking Radars or VLRs), researchers have estimated that up to four billion marmalade hoverflies along with the aptly named migrant hoverfly (Eupeodes corollae) cross the English channel to and from Great Britain every year. This represents 80 tons of biomass. If you are impressed by these figures, you should know that hoverflies account for a fraction of insects’ latitudinal migrations known as “bioflows”: about 3.5 trillion insects, or 3200 tons of biomass, migrate into southern Britain annually. Insect bioflows pour vast amounts of nutrients (particularly nitrogen and phosphorus), energy, prey, predators, parasites, herbivores and pollinators into our ecosystems. But we have only a vague understanding of their impact on food webs and local species.

The marmalade hoverfly does not stand out as a particularly efficient pollinator. It is small and not very hairy, a negative mark for joining the pollinators club because pollen transport depends on abundant body hair. Even so, this fly is known to improve the yield of strawberries.

Each marmalade and migrant hoverfly carries an average of 10 pollen grains from up to three plant species in their journey into Britain. These are not impressive figures when compared to bees, which return to their nests loaded with pollen. However, considering the massive number of flies and the wide range of flowers they visit, a grain of pollen deposited on a flower here and there must add up quickly. We just haven’t paid much attention to these unpretentious pilgrims.

On the verge of success

During the recent pandemic one thing that people have noticed, and increasingly appreciated, is the fact that so many of our verges haven’t been cut. This has been good news for flowers, bees and butterflies. What’s more many verges have become a visual feast which we can all enjoy.

The way we manage our verges is clearly changing.

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Riverside Drive, Dundee

Social media was awash with images of floral diversity during lockdown as many councils directed their resources to other areas, or simply couldn’t follow their usual cutting regimes. Of course this may have simply emphasised a change that was already underway, Across the UK a number of councils are have been altering their mowing regimes in a way that maximises opportunities for flowers and pollinators to thrive.

Historically the primary driver behind mowing verges seems to have been linked to seeking to comply with the Highways Act. There was also, in the minds of some, a perception that an unmown verge looked untidy or messy. So the safety angle got mixed in with a notion of civic pride, and hence verges were often mown when really they could have been managed with an annual cut and lift regime. That would undoubtedly have helped nature and saved councils money, and if explained as such quelled any notions of civic abandonment.

But change is gathering apace, and complementing a reduction in mowing of verges there has also been a shift away from 100% mowing of amenity grassland in cities, towns and villages.  A more selective approach is gaining momentum. Thus it is increasingly common to see a mown strip around the edge of urban patches of grass, or a mown path emphasising a desire line through an area of longer grass. Both actions taken in a spirit that is practical for ease of use, sensible in terms of cost of management, and a benefit for biodiversity.

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University of Strathclyde, showing a short mown area for ease of access.

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A narrow strip either side of the Perth cycle path near Muirton

Taken as individual approaches these are great advances. Viewed in aggregate they can help build up to a wildflower corridor approach.

In the Perth & Kinross Local Authority area the council have gone a step further.  Working with the Tayside Biodiversity Partnership and the Perth and Kinross Biodiversity Ambassadors, they are looking to survey the difference between areas of grass normally cut by the council against those which have not been cut during the Covid-19 crisis.  This will give them a clearer measure of what the differences in management styles deliver for biodiversity.

The survey is easy yet comprehensive. Preferably participants should select two area of grass, each over 1m square. They should aim for one area which has not been cut during the Covid-19 crisis, and one area which has continued to be mown. If they cannot find an area which has been mown, they are encouraged to concentrate on a site that is unmown.

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A series of questions are presented in an easy to follow table. To illustrate some of the findings the public are encouraged to submit photographs as part of their submission.  This visual approach will complement the short, yet cleverly crafted, survey form in which around a dozen questions are listed. These range from noting wildflowers present, counting the variety of flowers, stating bees and butterflies seen, through to noting the perceived appearance of the area.

That latter point is an important one. There is a perception with some members of the public that unmown areas can look abandoned and unkempt, almost unmanaged.  That’s why at Scottish Natural Heritage the Pollinator Team produced a ‘Managed for Wildlife sign’.  These are free for any council to display in unmown areas to let the public know that the area is indeed being managed for the benefit of wildlife.

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It is a great credit to the Perth and Kinross that they are going down this route in such an engaging and open fashion, but perhaps not a surprise. Visitors to the River Tay who walk north towards the meeting of the River Almond with the Tay will have noticed how flower-rich the river defences are. Here the defensive banks are not nutrient rich and as a result a host of wildflowers have flourished. What’s more the banks are sensitively managed for nature; allowed to flower through summer and set some seed, before receiving an autumn cut.  This programme ensures the banks continue to look good year on year.

The twin threats of climate change and biodiversity loss coincide with a period in which we are increasingly realising that we need to have a nature rich future if a green recovery is to take place. We are also enjoying the mental and physical benefits that a healthy natural world can offer.

How our local authorities manage their areas of grassland has the potential to play a small yet very visible role in this process, and in taking actions on our doorsteps they can both help wildlife and galvanise increased support for helping nature.

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The old joke used to say that “Perth is the smallest place in Scotland. Why?  … because it lies between two Inches!”  Clearly however this is an area where the biodiversity team think big, and that’s a wonderful punchline for nature.

 

Participants in the survey should email their completed sheets and photos to JoannaDick@pkc.org.uk

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Seizing opportunities, big and small

Recent months have been a sobering experience. Many of the things we took for granted suddenly disappeared.  The view outside our window, the greenspace in our local community, filled a huge void. Simultaneously, an appreciation of the role of nature in improving our mental and physical wellbeing became mainstream.

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Meadow sown in derelict sewage works tank (Pictures courtesy of Mark Brand)

Whilst the Covid crisis has been in everyone’s mind, lurking in the background are the twin threats of climate change and biodiversity loss, and they won’t play second-fiddle for long. Scotland’s Local Authorities are responding to these two issues, and their biodiversity work has produced encouraging social benefits.

In speaking to Mark Brand, a Planning Officer with East Renfrewshire Council, it is heartening to hear of the strides his Local Authority has made in developing new approaches to tackling biodiversity loss. The way that they manage green spaces in particular has been under near constant review and progress can be measured both in the short and the long term.

Take a small project just completed in the village of Waterfoot (which lies between Eaglesham and Clarkston). A community greenspace has been created next to an area of new housing. At first glance the space looks conventional, with the typical mix of play equipment, benches and a small AstroTurf area you might expect.

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A five hectare derelict site two years after sowing.

However, the Council has sown a short meadow mix instead of the usual ryegrass amenity seeds. This will provide a feeding stop for a host of pollinators and, managed sympathetically, it may do so for years to come. What’s more, it will be nice to look at, thus creating a joint ‘for people and pollinators’ benefit.

And it isn’t just the creation of a valuable foraging area for pollinators that impresses. It’s the realisation that managing sites for the long run can make for an easier journey. By following a relaxed mowing timetable the grassland flourishes during spring and summer, and the flowering season is maximised during pollinators active-lifecycle. And cutting the grass annually makes the area less likely to become dominated by a few species.

Changing mowing regimes is a hot-topic these days, as is cutting short grass-paths for easy access whilst letting meadows thrive.   Hand-in-hand with introducing these pragmatic approaches comes an education and information role which lets the public know that relaxed mowing isn’t down to untidiness or laziness, rather it’s about making a choice in favour of giving biodiversity a helping hand and better managing our assets for the nature we love and need.

Phil Collin’s famously sung about how you ‘Can’t Hurry Love’ and certainly people promoting these sorts of greenspace changes would sympathise. They know that good things don’t always happen overnight. Instead there usually has to be a period of conversation and persuasion before there is acceptance of a change of tack. One point however may prove the clarion call for change – reduced mowing results in financial savings.

In the same vein, East Renfrewshire Local Authority deserves credit for swapping the usual mix of landscape trees for fruit trees in Waterfoot. In doing so they created a small community orchard space with about 20 varieties of fruit trees. These can provide an early source of nectar and pollen for emerging insects in spring. And there’s more. The subsequent fruit is a welcome bonus for local residents (and birds!). It’s a classic ‘win-win’ scenario.

And good news spreads.  Mark recently noticed that house builder Taylor Wimpey will be using the same ‘Waterfoot’ Scotia seeding mix for the greenspaces in their latest development in Barrhead.

There was a time when Barrhead was associated with large industrial sites belonging to the likes of Armitage Shanks and Nestle. Now, as a post-industrial future takes shape, land is being converted to different uses, some of which are rich in opportunities. Sometimes those opportunities are temporary.

With that in mind, back in 2016, just over five hectares of meadow were sown on derelict land on the edge of Barrhead.  The land had been vacated by Nestle’s Purina Factory, but being relatively flat and enjoying good access was always likely to be earmarked as a development site. Nevertheless, as a vacant site it was an interim opportunity for helping nature. Development looks likely next year but this temporary greening project has had a good run.

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Sowing gets underway in 2016

The moment was seized, and a fleet-footed project saw seed sown on a crushed demolition substrate (which had been farrowed to break up compaction). There was never any certainty as to how long it would last, but a full five years on it is a source of comfort that this short-term opportunity was snapped up. On a hot summer’s day it positively vibrates with insect noise and is a vital refuge for all sorts of wildlife.

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Kidney vetch is dominant on very rubbly crushed demolition ground

The value of outdoor space, for nature and people, has rarely been higher on the agenda. In East Renfrewshire, the Local Authority has seized opportunities with considerable imagination. It bodes well for the future, and the new normal.

 

The birds and the beetles: the rowan tree’s facts of life

The rowan tree (Sorbus aucuparia) has deep roots in Celtic folklore, thanks mostly to its bright red berries, which have long been associated with spirits and all things magic. But never mind the myths; the rowan is a ubiquitous feature of the British landscape, and has an important ecological role to play, writes Athayde Tonhasca.

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Rowan berries © Lorne Gill

The rowan is found in most parts of Britain, reaching altitudes close to 1,000 m in the Scottish Highlands. It is not finicky about its habitat, as long as the soil is well-drained; it grows on abandoned mines and wasteland, as well as rocky slopes and cliffs, crevices in rock outcrops and on top of boulders.

The sweet, heavy smells of rowan flowers are quite attractive to insects, particularly flies. But this tree may be an oddity; it appears to be primarily a cantharophilous species. Cantharophily, from the Greek kántharos (beetle) and philos (loving), means pollination by beetles. Not many plants are fully cantharophilous, although beetles were important pollinators for the earliest flowering plants during the Mesozoic (about 200 million years BC), long before bees came along. Today, many primitive species such as Magnolias are pollinated by beetles.

Beetles do not have the subtle approach of bees, flies and moths. They plough through flowers eating nectar, pollen, petals and leaves, defecating as they go. They often spill more pollen than they eat. That’s why they are called “mess and soil” pollinators. Click beetles (Elateridae), scarab beetles (Scarabaeidae), sap beetles (Nitidulidae), leaf beetles (Chrysomelidae), rove beetles (Staphylinidae), blister beetles (Meloidae), and long-horned beetles (Cerambycidae) are known to feed on flower parts.

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Click beetles visiting flowers © gailhampshire, Wikipedia Creative Commons

The pollen attached to their bodies fertilises quite a few rowan berries, which are eaten by a variety of birds. In fact, the rowan is one of the most important food sources for fruit-eating birds in northern Europe.

Rowans produce large crops of seeds in some years (plant ecologists call it ‘masting’), and very little to almost none in others. The availability of rowan berries affects the annual distribution and migratory behaviour of birds on large scales. For example, the location and abundance of bullfinches in parts of the Fennoscandian region (Norway, Sweden, Finland, and Denmark) are synchronized with rowan masting episodes, and the arrival of fieldfare and redwing flocks to Britain is regulated by the onset of winter and the dwindling supply of rowan berries in Scandinavia and continental Europe.

Messy they may be, but the beetles that pollinate rowan flowers have quite an influence on the life of the rowan tree and the birds that feed on its juicy berries.

 

As easy as A-bee-c with an app

A wildlife app launched today by the Bumblebee Conservation Trust gives users a new view of bumblebees through an augmented reality 3D function.

The free ‘What’s that Bumblebee’ app lets people engage with nature in a different and fun way. It brings a three-dimensional bumblebee to virtual life in the user’s own garden or living room, for studying in detail and with the option of capturing images to send to family and friends.

The app also makes it easy for bumblebee-beginners to identify which of the UK’s most common eight species of these important pollinating insects may be buzzing around their garden or local park.

“In these difficult times, lots of people have been appreciating nature and wanting to find out more. What’s That Bumblebee makes it easy for people of all ages to discover and identify different bumblebees visiting their gardens, outdoor spaces, parks or window boxes,” said Andy Benson, the Bumblebee Conservation Trust’s Education Officer.

The app is available for Apple and Android, and works on compatible phones and tablets. It was developed by the Trust, with National Lottery Heritage Fund support.

In total there are 24 bumblebee species in the UK, but the most common ‘Big 8’ that people are most likely to see in their garden or park are the Buff-tailed bumblebee, Common carder bee, Early bumblebee, Garden bumblebee, Heath bumblebee, Red-tailed bumblebee, Tree bumblebee and White-tailed bumblebee.

What’s That Bumblebee offers a brief description of these eight species, and allows users to compare similar species side-by-side.

“We’ve received lots of enquires from people who’ve had more time to notice bumblebees because of the lockdown and want to find out more, and this app is a great way of doing that. Kids and adults will love seeing a virtual bumblebee in their front room or outdoor space, and being able to capture a photo of it to study – while also being able to go out on their own local mini-safaris to discover our ‘Big 8’ bumblebees in real life,” said Gill Perkins, Chief Executive of the Bumblebee Conservation Trust.

People are being encouraged to share images from the app on social media using the hashtag #whatsthatbumblebee.

Anne Jenkins, Director, England, Midlands & East at The National Lottery Heritage Fund, said: “It’s wonderful to support this educational and interactive app thanks to the generosity of National Lottery players, and we’re sure it will inspire people to discover more about our precious bumblebees!”

Furry and brightly coloured, bumblebees are icons of the British summer. These important pollinators of our fruit and veg contribute a huge amount to the British economy. One in three mouthfuls of food are due to the hard work of pollinating insects.

But UK bumblebee populations have crashed, and two species have become extinct in the last 80 years. Loss of flower-rich habitat is the biggest threat to their survival, with 97% of our wildflower meadows lost since the 1940s. Climate change, disease and pesticides may also be major threats. The Trust encourages people to make gardens, parks and green spaces bumblebee-friendly.

What’s that Bumblebee can be downloaded for free at the Apple App Store or Google Play.

To find out more, visit bumblebeeconservation.org.

Godly food and pesky midges

Theobroma cacao. Named after the Greek theos (god) and broma (food), the cacao plant is, as any chocoholic would agree, the’ food of the gods’, writes Athayde Tonhasca.

Cacao beans made their way to Europe as medicine, as the cocoa drink cacahuatl (bitter water) of the Maya and Aztec peoples was considered a palliative to abdominal pains and other illnesses. When someone thought of sweetening the paste made of cacao beans, chocolate left the apothecary’s shelf for the kitchen and then for the factories. Joseph Fry – who created the first chocolate bar and Easter egg – Henri Nestlé, Rodolphe Lindt, Milton Hershey and many others helped build an ever growing industry that changed the world. Today, Americans and Europeans consume more than US$100 billion worth of chocolate annually, produced mostly in West Africa.

Not many people know that chocolate production, and by extension the livelihoods of countless small-scale cacao farmers in the developing world, depend on the finicky pollination requirements of the cacao flower.

Flowering occurs in explosions of buds that cover the trunk and main branches, a feature known as cauliflory: a mature tree may produce over 5,000 flowers at a given time.

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Cacao flowers sprouting from a tree trunk © Daderot, Wikipedia Creative Commons

The flowers cannot self-fertilize, so they are entirely dependent on pollinators. But the blooms are small, with a convoluted hooded shape and face downwards. So bees, hoverflies and other common flower visitors do not bother with cacao flowers, or just can’t reach their pollen and nectar.

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A cacao flower © Björn S., Wikipedia Creative Commons

If flowers are not fertilized, they abscise (drop off) the next day. Only 1 to 5% of all flowers develop into a pod. This apparently inefficient reproductive apparatus makes no sense until we consider that the cacao plant originated from the rainforests of Central and South America. These are hot, dense, dark and moist environments, chocked with rotten wood and decomposing leaf litter. This type of habitat is hostile to many sun-loving pollinators, but it is perfect for one group of insects – the biting midges.

These are ceratopogonid midges (family Ceratopogonidae), of which the 1,000 or so species from the genus Forcipomyia are particularly important for our story. They spend most of the day hidden in the forest’s shady spots, coming out in swarms of enormous numbers in the early morning and late afternoon. Adults live for about a week, but there are about 12 generations per year. Male and female flies visit cacao flowers to collect nectar and pollen. They are 1 to 3 mm in length, so can squeeze their way into the pollen-producing anthers of the small, hooded flowers. Pollen grains attached to the thoracic hairs of a massive number of midges ensure that many flowers are pollinated. So the cacao flower has no use for bees, moths, bats or birds. All it needs are these tiny flies.

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A male Forcipomyia midge © Christophe Quintin, Wikipedia Creative Commons

Traditionally, cacao has been grown in shaded areas intercropped with forest trees that were spared when the forest was cleared for cultivation. Today, cacao trees often grow in open plantations, which do not have the damp and shady conditions required by biting midge larvae. As a consequence, on average only three out of 1000 flowers become pollinated and produce seed pods. Also, within commercial plantations, the time of peak flower abundance is out of sync with the peaking of midge populations. The loss of midge habitat explains in part why cocoa production has been decreasing, even though demand has increased annually.

There are more than 5,000 species of ceratopogonid midges. Some of them pollinate orchids and possibly many other plants: we just don’t know. A few species transmit animal diseases, and some have ruined many a picnic in the Highlands. But next time you are mobbed by midges while hiking in the woods or gardening, think chocolate. You will immediately become more judicious and forgiving.

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Chocolate, ‘food of the gods’. © André Karwath, Wikipedia Creative Commons

Thistle cafe open for business

After many months of staying within walking distance of the house, I finally managed a visit to Taynish NNR on Sunday, writes Caroline Anderson.   Arriving early in the morning I had hoped to catch some of the pollinators before they became too active. 

 

The first thing that struck me when I got out the car was the glorious heady smell of the honeysuckle which was in bloom.  One of my very favourite perfumes – I wish it could be bottled!   The very next thing I noticed was the sound, birdsong and buzzing everywhere – this was the Taynish I know and love and it felt SO good to be back.

First a stop at the lochan boardwalk where damselflies and dragonflies flitted from plant to plant, their wings shimmering in the sunlight.

Speckled wood butterfly

Speckled Wood butterfly

Down the path, and through the wood, the Speckled Wood butterflies alighting for only a split second before taking off again.

Next stop the picnic area at the mill.  This area is normally strimmed to allow easy access to the picnic tables, however due to lockdown only essential work has been done on the reserve, for example feeding the cattle, so the grass and wildflowers have grown which meant more insects than usual.

The thistle café was open for business!  They were positively teeming with bees, beetles and flies of all sorts – all covered in pollen doing what they do best!

Tree bumblebee on Thistle

Tree bumblebee

Early bumblebee 1

Early bumblebee

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Early bumblebee

tree bumblebee

Tree bumblebee

Then on one of the thistles, a new record for the vice county, a Ctenicera pectinicornis – check out these antennae!

Ctenicera Pectinicornis

Ctenicera pectinicornis

Black spotted longhorn beetle

Black-spotted longhorn beetle

Not to be outdone and strutting its stuff nearby was a Longhorn beetle

Even the route marker post had an occupant – a little Forest Bug in all its glorious colours, blues, pinks and oranges – amazing!

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Forest Bug

Then joy of joys, a Marsh Fritillary in all its glory,  still a little sleepy it sat and allowed me to photograph it for some time.

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Oh Taynish! – it’s been too long, but it definitely won’t be as long until the next visit I promise!!

 

It’s great to welcome Caroline back to our pollinator blog, and we hope to carry regular updates from Taynish as summer progresses.

Eggs-and-bacon, boots-and-shoes, to bees are good news

Eggs-and-bacon, boots-and-shoes, lady’s slipper, hen-and-chickens and bird’s-foot-trefoil are all popular names for Lotus corniculatus, which is all over the landscape: grasslands, meadows, rock ledges, sand dunes, roadside verges and derelict sites. This perennial herb, a member of the legume family (Fabaceae, which includes peas, vetches, broad beans and clovers) is valued in many countries as pasture, hay, and silage, although it has become invasive in some parts of North America and Australia. By Athayde Tonhasca.

 

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Bird’s-foot-trefoil © Robert Flogaus-Faust, Wikipedia Creative Commons

The bird’s-foot-trefoil is food for the larvae of several butterflies and moths, and a valuable nectar source for many other insects. And, like other legumes, it produces nutritious pollen.

However, it is not advantageous for the plant to make its pollen available to all that want it; pollen grains, which are full of proteins, amino-acids and vitamins, require a lot of energy to produce. To restrict pollen access to those insects more likely to act as pollinators, the bird’s-foot-trefoil and its relatives evolved a special type of flower. It has an irregular corolla with two lateral petals and two lower ones, which are united at their edges to form a landing platform.

As you can see in this short film clip, a bee has to alight on a flower’s platform and prise the lateral petals apart to get access to the pollen. The bee’s intention is to take all pollen to its nest and store it as food for the larvae, but some grains will become attached to the bee’s underside and released in the next flower visited, ensuring pollination.

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Bird’s-foot-trefoil flower © Wilson44691, Wikipedia Creative Commons

 

Only some insect species, mostly solitary bees and bumble bees, are able to deal with the complex flower morphology of legumes. As a consequence, some bees became highly specialized on these plants; in fact, the decline of several bumble bee species has been linked to the reduced availability of clover, bird’s-foot-trefoil and other legumes. In Britain, three of our scarcest bee species are believed to be completely dependent on bird’s-foot-trefoil’s pollen; the pine-wood mason bee (Osmia uncinata), the mountain mason bee (O. inermis) and the wall mason bee (O. parietina).

Because of its ability to grow almost anywhere, the bird’s foot trefoil can be seen as a weed when it thrives in lawns, gardens and other places where it is not wanted. But before you reach for the weed killer bottle, have a thought about the importance of this plant for our bees and other insects.

 

 

The unfairly maligned wasps

I saw a wasp upon a wall

And did not like his face at all:

And so the creature had no time

To wonder whether he liked mine.

‘Plain Murder’, A.G. Prys-Jones.

 

The common wasp (Vespula vulgaris) and its close relative, the German wasp (Vespula germanica), are not likely candidates for the most loved insects, but many people are not aware of their ecological value, writes Athayde Tonhasca.

Wasps feed mostly on high-energy sugars and carbohydrates from foods such as nectar and fruit. Because they are not covered with fuzzy hairs, wasps are much less efficient pollinators than bees. Even so, they are thought to be the main pollinators of ivy, which flowers late in the year when the number of bees diminishes and wasps require more nectar to produce males and queens. Because of their high energy content, ivy fruits are important for many farmland and garden birds, so wasps contribute to their food supply.

Wasps for Jim _m204018

Vespula sp. © Caroline Anderson

Adult wasps feed on sugars, but their larvae need protein. Adults provide it by hunting soft-bodied invertebrates such as caterpillars, flies, spiders and beetle larvae.

Researchers in New Zealand estimated that wasps capture ~0.8 to 4.8 million prey items per hectare per season (1.4 to 8.1 kg of prey/ha), which is equivalent to what is taken by all insectivorous birds in the same area. The figures for Britain are likely to be lower, but nonetheless it is evident that wasps are voracious predators, and thus gardeners’ allies.

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A common wasp captures a horsefly.   © Robert Goossens, Wikipedia Creative Commons

Wasps may spoil your picnic, but without them, your hamper could have been deprived of bread, beer and wine. Yeast – especially Saccharomyces cerevisiae – has been fundamental to baking, brewing and winemaking throughout human history. In nature, yeast cells are found primarily on ripe fruits during the summer months. Since yeast is not airborne, it must rely on vectors to move from plant to plant. For years it has been assumed that birds or bees were responsible for transporting yeast cells, but nobody could explain how they survived the winter. Italian researchers suspected that wasps were involved, because they feed on yeast-harbouring grapes, and their nests are hibernation havens for microorganisms.

The research team analysed samples from vineyards around Italy to find several species and hundreds of strains of yeast in the wasps’ guts. Some were related to wine strains of S. cerevisiae, others were similar to bread strains. Also, yeast survived the winter in the insects’ guts, and was transferred to the larvae via the food regurgitated by the queen. Other organisms such as birds may be involved in the life cycle of yeasts, but wasps seem to be especially important.

Common Wasp nest

Common wasp nest © Richerman, Wikipedia Creative Commons

Wasps are also master engineers. They build their nest with a strong, lightweight and waterproof paper-like material produced by a mix of saliva and scrap wood, which is chewed to a pulp. The queen kick starts it by building a column and coating it with a chemical that repels ants. Then she builds cells around it, all in clusters of hexagonal units. Workers expand the nest by building more cells, ventilating them by vibrating their wings. The cells’ hexagonal configuration maximises strength and efficiency, as this design demands the least amount of energy and building material.

So next time someone asks you what’s the point of wasps, you can say they are fundamental for nature and for us, and they are fascinating creatures with complex social organisation and efficiency. They may be a nuisance now and then, but possible clashes with us are easily avoided.

Wasps are not aggressive outside the nest; when they hover persistently over your bottle of lemonade or sandwich, they are only interested in the food and will not deliberately attack you. The best strategy to avoid a close encounter is by minimizing the chances of attracting them. Do not leave food exposed; keep it in sealed containers and put away any rubbish into lidded bins. If a wasp flies towards your food, wait for it to fly away; flailing your arms increases the chances of entrapping the wasp, which could then sting you.

However, wasps will defend their nest aggressively if disturbed or threatened. If you find yourself near a nest, retreat without producing much vibration or noise. Take care with lawnmowers and other motorized equipment because they may trigger a defensive reaction.