Blog - bumblebee
Promoting wildlife in gardens
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]
Drought and pollinators
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.
Heat, bumblebees and foraging
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...
In praise of sunflowers.
The vibrancy and gaudiness of sunflowers is one of the delights of summer. The common name "sunflower" generally refers to Helianthus annuus, whose round flower heads look like the sun. Sunflowers are cultivated as food crops for humans, cattle, and poultry, and also for the garden. They typically grow during the summer and into early autumn, with the peak growth season being mid-summer. A field of sunflowers is a welcome relief from the acres of oilseed rape. The flower of a sunflower is not a flower but hundreds of small flowers (florets) massed together the better to attract pollinators. The structure so formed is known as a capitulum. The inner florets are arranged in spirals that conform to fibonacci sequences. The pattern of these florets has been described mathematically by Helmut Vogel and it allows for the most efficient ‘packing’ of the florets in the ‘flower’ head. Before the flowers open, the plants tilt during to face the sun, gaining more light for photosynthesis. This movement is known as heliotropism and continues for a while when the flower head opens. This may help to attract pollinators. Frequent visitors to sunflowers are bumblebees. Sadly, like honey bees, bumblebees face a number of problems which include parasites. However, recent research in the United States suggests sunflowers can help certain species of bumblebee. If sunflower pollen is included in the diet of the common eastern bumblebee then it helps reduce infection by a parasitic protozoan Crithidia bombi. This is a parasite that lives in the gut of bumblebees. When they pass out of the gut in cysts, they can be ‘picked up’ by the next passing bumblebee (or another insect, as the parasite is not too fussy). Once established in a bee, the parasite can affect the ovaries. If a queen is infected then the reproductive success of the colony is affected. Giacomini et al. have found that good nutrition is vital for bumblebee health and that sunflower pollen can be a huge benefit when it is included in the diet. They noted that the majority of the bees that consumed sunflower pollen had no detectable infection a week later. The pollen* significantly reduced infection by the parasite. So sunflowers are a visual feast for us, and an edible one for bumblebees and bees. They also provide us with seeds. The seeds are rich in monounsaturated and polyunsaturated fats, notably linoleic acid. The seeds also contain phytosterols which may contribute toward lowering the level of blood cholesterol. The seeds may be pressed releasing sunflower oil, and the remaining ‘cake’ can be used as a protein rich animal feed. The Ukraine and Russia are the top producers of sunflower seed. A somewhat different use of sunflowers is phytoremediation; using plants to remove toxic organic or inorganic compounds from soil. After the disaster at the Chernobyl nuclear reactors in 1986, an exclusion zone with a radius of 30 km centred on the nuclear power plant was created. This was later expanded to include other heavily irradiated areas. Even now, no one lives in the exclusion zone, but scientists and others may ask for permits to allow them to enter for short periods. Fields of sunflowers were planted to ‘harvest‘ the radioactive metals (notably caesium-137 and strontium-90) from the soil. The sunflowers accumulated these elements in their tissues. When the sunflowers had completed their growth, they were harvested and burnt, leaving only the radioactive ash behind. This material could then be vitrified (incorporated into glass) and stored underground in a shielded container. In Brazil, a study looked at the ability of different sunflower cultivars to remove nickel, copper and lead from contaminated soil. Though phytoremediation with sunflowers proved to be an efficient and low-cost method for the treatment of contaminated soils, the cultivars varied in their ability to take up particular metals. “Cleaning up’ with sunflowers was tried after a tsunami hit the Fukushima Daiichi nuclear power station in Japan. However, it was not very successful. As different cultivars vary in their capacity to hyperaccumulate, so it is important to match the cultivar to the situation. Planting sunflowers in this case did little to improve the situation. This could be in part due to the sunflowers but also be associated with the soil type and the time that the caesium has had to bind to the soil particles. Understanding the mechanisms and detail of hyper accumulation is critical if sunflowers are to be used for phytoremediation in the future. Pollen is rich in secondary plant metabolites e.g. flavonoids, terpenoids, alkaloids, amines, and chlorogenic acids [caption id="attachment_35695" align="aligncenter" width="650"] field of sunflowers[/caption]
“tropical nights’ and greening our cities
Much of England experienced a series of ‘tropical nights’ last summer, when night time temperatures were 20oC or above. These tropical nights were associated with the heat wave that affected most of south east England. Central London experienced its longest stretch of extreme daytime temperatures since the 1960’s - temperatures of 30+oC were recorded on six consecutive days. A number of experts have said that such heatwaves and associated tropical nights are likely to become more common as a consequence of climate change. We were not alone in experiencing high temperatures by day and night, much of western Europe sweltered in the heat this August. The problem was most marked in urban areas and large cities. Some three-quarters of the population of Europe now live in urban areas. Extreme heat affects our health causing general discomfort, malaise, respiratory problems, headaches, heat stroke, heat cramps and heat-related mortality. Read more...
Urban Foxes – updated.
Urban foxes are sometimes in the news as they get noticed with their roaming through urban gardens, and occasionally entering houses. Indeed, attacks on people and pets have been reported. More often foxes come to attention when people are disturbed at the night by the strange, ‘metallic' screams of the foxes, especially during their mating system (December through to February). There are significant numbers of foxes in our cities. Estimates vary but it is thought that there may be 150,000 or more urban foxes or ‘townies’ and perhaps 400,000 foxes in total throughout the U.K. The average life of an urban fox has been estimated at about eighteen months to two years, partly because many are killed on the roads (often the younger foxes). In the wild, a fox can live for up to 8 years. In Scotland, a fox’s territory can range over several miles but in towns their territories are much smaller. They survive, in part, because we are careless in terms of the disposal of our waste food; and also because some people put out food for foxes. In the country, their diet would include small mammals, bird eggs, insects, earthworms, wild fruits / berries and carrion. It has been suggested that the high populations of rats and mice in London are a 'big draw' for urban foxes, and they help in keeping numbers of rats down in the city. Read more...
Rewilding Britain’s report : connectivity and biological corridors.
Sadly, the number and range of various species in the U.K. is decreasing, biodiversity is falling. Our wildlife-rich areas are actually separated and fragmented, by tracts of intensively-farmed land, by motorways and roads, and the ever increasing spread of urban areas. The dispersion and isolation of wildlife areas makes it difficult for both plant and animal species to move. The ability to move around is ever more important as a result of climate change. Rainfall patterns and average temperatures in different regions are changing, extreme weather events are more common. For a species to stay in its ‘comfort zone’, it may need to move ‘northwards’ as climate change continues. According to a report released by Rewilding Britain, the speed at which species need to migrate in order to stay in their ‘comfort zone’ is approximately some 5km / year Read more...