If bumblebees are exposed to heat stress during their development (they go through four stages : egg / larva / pupa / adult or imago) their bodies develop asymmetries.  The wings in particular are affected, so the left and right wing are shaped differently.  This asymmetry can be measured and has been used by a team from the Natural History Museum and Imperial College to investigate how changing climate over time has affected bees. They investigated four species of bumblebee [Bombus hortorum, B. lapidarius, B. pascuorum and B. muscorum] in museum collections that dated back to 1900 CE.  The bees were ‘held’ in collections at various museums  [Natural History Museum (London), National Museums Scotland (Edinburgh), Oxford University Museum of Natural History, Tullie House Museum and Art Gallery Trust (Carlisle) and World Museum (Liverpool)].   [caption id="attachment_38920" align="alignleft" width="300"] Landing[/caption] Using digital images of many bees collected at different times over the last 130 years, they measured the asymmetry of their wings.  The data from these measurements were then correlated with information about annual rainfall and mean annual temperature in the year the bee was collected.  It became clear that wing asymmetry was associated with hotter and wetter years; and that each of the bee species displayed greater asymmetry, hence stress, in the second half of the twentieth century.  As hotter and wetter conditions are predicted to become more frequent with climate change, it is probable that bumblebees will experience greater stress, indeed they may be in for a ‘rough time’ as this century progresses. Apart from investigating wing asymmetry, the team used a leg from some of the historical specimens to analyse the DNA / genetic make-up of the bumblebees (B. lapidarius).   With the DNA data from these bees (dating aback over a century),  the Natural History Museum and the Earlham Institute were able to construct a ‘reference genome’ - a standard against which they can see how bee genomes change over time.  This may ultimately reveal how bees are adapting (or not) to a changing climate / environment.

The decline in insects numbers, especially pollinators is a cause for concern.  Insect numbers have fallen as natural ecosystems have been lost or disrupted by the expansion of farming and urbanisation, plus the increased use of pesticides and herbicides. The loss of insects not only affects the pollination of many commercially important plants, but also affects the animals and birds that feed upon insects.  So, there are knock on effects throughout food chains and ecosystems. Plantlife has launched a number of initiatives, such as  No Mow May,  Transforming Road Verges Saving Meadows to help offset the decline in insect numbers.  Now work done in Professor Goulson’s laboratory at Sussex Univeristy by Janine Griffiths-Lee (a PhD student) suggests another approach to increasing insect / pollinator levels in urban settings.  Her research has demonstrated that creating a small patch of wild flowers in gardens can go some way to address this fall in insects numbers.    She and colleagues managed to enlist the help of some 150 volunteers distributed across the UK (many were members of the Buzz Club*). Each volunteer set aside a wild flower area  - a mini-meadow (two metres by 2 metres).  Some  of the volunteers then sowed the mini-meadow area with a commercial seed mix of wild flowers, others sowed a seed mix designed / thought to be ‘beneficial to pollinators’. A third group did not receive wild flowers seeds but were asked to set insect traps and record insects in their gardens in the same way as the two ‘wild flower seed groups’. The results were interesting and revealing. The mini-meadows proved to be resource-rich habitats, with an increased numbers of wild bees, more bumblebees, solitary bees and also wasps (when compared to the control group with no wild flower seed sowing).  There were differences in the insect populations for the two groups of seed.  The commercial mix attracted more solitary bees and bumblebees, whereas the ‘designer mix’ of seeds attracted more solitary wasps.  There was no difference in the number of hoverflies that visited the two types of wild flower rich mini-meadows.  Solitary wasps, whilst not pollinators, are important in that they prey on a number of insect pests of fruit and vegetables. Clearly, the planting of small areas in gardens with wild flowers could do much to encourage the numbers and variety of insects / pollinators visiting (or possibly help control the damage done by insects pests).   * The Buzz club is a citizen science initiative.  The UK has a tradition of using the enthusiasm of volunteers to collect data for ecology research.  The Buzz Club projects are focused on gardens - see here.  Membership of the Club is free and the research projects are generally involve no cost.  You might be asked to supply simple equipment or to cover the cost of sending samples back to the club based at Sussex University. Should you sign up then you will receive : A ‘thank you’ email from the team! Information direct to your inbox of new projects being planned. A newsletter about what your data is telling us.  Professor Goulson has previously written a blog about bumblebees for woodlands.co.uk

It would seem that pollinators have ‘favourite plants’.  Research centred on the National Botanic Garden of Wales has looked in some detail at the foraging habits of bees, bumblebees, hover flies and solitary bees - our most important pollinators. Dr Abigail Lowe identified the plants that the insects were visiting by analysing the DNA from pollen grains on their bodies (a process known as DNA barcoding). It is clear that the ‘preferences’ of the insects change with the seasons and indeed the availability of particular flowers.  In Spring, nearly all the pollinators frequent buttercups, lesser celandines and dandelions (all brightly coloured yellow flowers).  Come the summer, honey bees and bumblebees tend to favour thistles, knapweeds and brambles, whilst hover flies may be seen on hogweeds and angelica plus thistles and knapweeds.  In autumn, the bumblebees can be see visiting asters (Daisy family flowers) and brambles. Full details of her work can be found here : https://botanicgarden.wales/press/plants-for-pollinators-new-dna-research-reveals-fascinating-insights-into-the-plants-used-by-bees-and-hoverflies/ There are also suggestions on how to help pollinators in your garden, such as encourage buttercups and dandelions by reducing mowing (in the Spring) plant late flowering daisy type flowers encourage some bramble (you might get some blackberries, in return) reduce the use of chemicals (especially pesticides and herbicides) hoverflies can be encouraged by damp, wet areas and rotting wood and these suggestions would also work in a woodland.   [caption id="attachment_38320" align="aligncenter" width="700"] Marmalade hover fly[/caption]

In recent decades, signs of Spring have occurred earlier and earlier, indeed the early flowering of crocuses and daffodils in our gardens is one such sign. Now a detailed analysis of such ‘signs’ has been undertaken by using the information held in Nature’s Calendar.  This is an enormous database * of records of seasonal changes; it has records of some 400+ species of plants, from trees, to shrubs and herbs. Nature’s Calendar includes records from organisations like the Royal Meteorological Society, plus those of scientists, naturalists and gardeners. Recording when things happen (such as when horse chestnut and ash trees come into leaf, or when the first swifts or bumblebees are seen) is known as phenology. These timings vary from year to year.  Phenology is not a new discipline. One of the first phenologists was Robert Marsham, who recorded ‘indications of spring’ starting back in 1736. He catalogued some 27 different natural events on his family’s estate in Norfolk.  In 1875,  the Royal Meteorological Society set up a national recorder network.  Nature’s Calendar includes thousands of these historical observations and enables scientists to look for trends and see if they correlate with changes in temperature, rainfall, weather phenomena. The research team from Cambridge University looked at FFDs - first flowering dates and temperature records. They found a difference in flowering dates from the 1750s and the most recent years of almost a month.  Professor Ulf Büntgen has said that rising global temperature has brought Spring forward by several weeks.   This raises concerns. For example, if a plant grows and comes into flower earlier in the year what happens to insects that are dependent upon it? For example, some bees collect from only one species of plant.  Or to put it another way, suppose the plant flowers earlier but its pollinating agent (an insect such as a hover fly) is not about, has not emerged from its over-wintering stage? What if there is a ‘late’ frost?   * Nature’s Calendar : The Woodland Trust joined forces with the Centre for Ecology & Hydrology to collate phenology records into Nature’s Calendar; this has some 3.5 million records- some going back to eighteenth century.  

Reports in the papers and electronic media have made us aware that many forms of wildlife are under threat.  This threat is wide ranging - from the destruction of tropical rain forests, coral reefs, the loss of species-rich meadows, the insect apocalypse - indeed where does this loss of plant and animal species end? One small positive observation amidst the doom and gloom is the findings of The Biodiversity in Urban Gardens project [BUGS] at the University of Sheffield.  The original study focused solely on Sheffield and finished in 2002, but  it was then extended to five cities across the U.K.    Professor K Gaston who led the study is now working at the University of Exeter.  The original study was important in that it revealed within Sheffield city, there was 33 km2 of wildlife habit was available within the city 360000 trees in the city limits 45000 nest boxes 25000 ponds and  50000 compost heaps Furthermore, there were in excess of a thousand plant species (flowering plants, ferns and conifers) and a diverse collection of invertebrates (bumblebees, hoverflies, beetles and spiders).  Whilst the diversity was in no way comparable to that of an ancient woodland (with veteran oak trees etc) or indeed of wetlands, it is significantly better than that found on farmland - particularly in those areas where the farming is intensive and characterised by monocultures (e.g. oil seed rape extending to the horizon).  Farmland now occupies some 70% of the landscape. Gardens, parks and urban areas are therefore an important resource for wildlife.  It is important as house building proceeds, on both brown and green field sites, that the associated gardens continue to provide ‘sanctuaries’ for wildlife, for example, by avoiding large areas of hard standing for cars (which also encourage  rain / water run off - which can overwhelm the drainage systems).  Professor Gaston has emphasised the importance of ‘dimensional complexity’ in gardens; that is a variety of trees, shrubs and plants of different shapes and sizes.  This provides a range of different niches / habitats for wildlife.  Of course,  in gardening to promote wildlife, there are the additional benefits (for householders) of physical and mental well-being.   Remember later this month, there is the Big Garden Birdwatch, organised by the RSPB. For further information, click on the image below:- [caption id="attachment_36525" align="aligncenter" width="670"] Ladybird 'stalking' aphids[/caption]

Climate change is affecting all parts of the world, from the melting of the ice caps in Antarctica, to droughts in Australia and California.  On a more local level, we may see changes in our rainfall pattern.  Certainly for many parts of the UK, it has been a very dry start to the Spring, coupled with some very cold nights. Cold and dry weather affects plant growth in significant ways.  Warmth is needed for a plant’s enzymes (catalysts) to work, speeding up reactions and allowing growth.  Similarly, if water is in short supply, growth is stunted; plants do not realise their full ‘potential’. They are smaller overall as is the number and size of flowers that they produce.  Flowers attract visitors by colour, size and scent; or combinations thereof.   Smaller and fewer flowers, in turn, have ‘knock-on effects’ for their pollinators - bees, bumble bees, hoverflies etc. The effects of drought on pollination has been recently investigated by researchers at Ulm University in Germany.  They studied the effect of drought on field mustard (aka Charlock) : Sinapsis arvensis.  This is an annual plant that is to be found in fields, waysides and field margins across Europe.  It has bright yellow flowers, with four petals.  It is visited by many different pollinators (it cannot self-pollinate).   The researchers compared the number of visits by bumblebees (Bombus terrestris) to drought-stressed plants to well-watered ones.  The data showed that as the number and size of the flowers decreased so did the number of pollinator visits.  [caption id="attachment_21589" align="aligncenter" width="600"] Bumblebees also favour the teasels[/caption] The ‘attractiveness’ of the plants / flowers to pollinators was reduced, and it is possible that the smaller flowers were more difficult for relatively large pollinators (like the bumblebees) to ‘deal with’.  If pollen movement is reduced, then fewer fruits / seeds will be set and (insect pollinated) plant populations could decline.  The effects of reduced rainfall and water stress need to be considered alongside the declining number of pollinators.  The reduction in pollen movement has lead some to speculate that it might lead to a selective pressure for self-pollination / self-fertilisation, with plants dispensing with the need for visiting insects.  Other Woodlands blogs have reported on the falling numbers of insects / pollinators. Featured image : garlic mustard.

In a previous woodlands.co.uk blog, Professor  Dave Goulson (University of Sussex) has written about the problems that bees and bumblebees face.  Recently, he joined with Clipper teas (who produce organic tea products) to again emphasise the problems that bees and other pollinators face, and to explain how our lives would be affected if they were to be lost.  Bee, bumblebee and other pollinator populations are at risk or in decline.  Professor Goulson estimates that there are some 6,000 different species of pollinating insects in the U.K alone, but they face risks as a result of Habitat loss Pollution Climate change Use of pesticides (insecticides, herbicides, fungicides) [caption id="attachment_36158" align="aligncenter" width="650"] Hoverfly foraging[/caption] Whilst it is true that insecticides such as neonicotinoids are directly toxic to bees and bumblebees, many other compounds used as herbicides and fungicides are also harmful to these insects.  Obviously herbicides get rid of weeds, but weeds or wild flowers are a food source for these pollinators.  Pesticides can have what are termed  ‘sub-lethal effects’, so that the learning ability of the insects is reduced.  Bees and bumblebees can learn which flowers are best as food sources, they can navigate to and from their nests / hives through open countryside.  Also these compounds can affect their resistance to disease, and their fertility / reproduction. It is a concern that that bees’ honey stores may contain a cocktail of several pesticides that the bees have encountered during their foraging.  In collecting pollen and nectar, a single bee may visit / pollinate four thousands flowers in a day. Not only are many thousands of  wild flowers species dependent on bees for pollination but some three quarters of our food crops also need bees and other insects.  Without them, the range and availability fo fruit and vegetables in our supermarkets would be substantially reduced. Whilst going organic and reducing reliance on the many forms of pesticide agriculturally is great help to pollinators, there is also good news in that small growers and even domestic gardeners can have a positive impact on the numbers of bees and others pollinators, such as : Planting a range bee-friendly plants in their gardens Creating a wild flower area in the garden or Allowing the lawn to grow up to form a small meadow like area Reducing the use of all pesticides - insecticides, herbicides, fungicides etc.

Silwood Park is part of Imperial College, a postgraduate campus, located some 25 miles west of central London, near Ascot. It is a centre for research and teaching in ecology and allied disciplines. The campus includes areas of wet woodlands, acid grasslands, traditional orchards and parkland. The veteran and ancient trees support an significant number of rare species of insects, lichens and fungi that depend on decaying wood. Silwood is the heart of the wildlife corridors for the surrounding area.  Read more...