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]  

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 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...

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...

The loss of pollinators, particularly honey bees, may bring about a synergy between pollinators such as hover flies and artificial intelligence technology.  Honey bees (and indeed bumblebee)s have been hit hard by habitat loss, pollution, the  extensive use of pesticides and the spread of viruses and varroa.  Bees provide an important ecosystem service, namely pollination.   bees provide the majority of plant pollination world-wide but the bees are fighting a losing battle and this represents a threat to food supplies.  In the United States, bee hives are 'bussed around' in a somewhat 'cavalier manner', indeed "Hives may be moved multiple times and several thousand miles per year" Read more...

Gill Perkins is one of those people you can't help liking - there's a smile in her voice when she speaks and we found her to be generous with her time and knowledge.  She arrived early for our woodland meeting and had come equipped - a small plastic tube with a plunger (costing about £5) allows her to catch bumblebees as they graze on flowers and she can trap them for long enough to tell us that "this one's a queen of the buff-tailed type and you can see she's very freshly minted as her wings are so undamaged ... a lovely specimen ...".    She releases the bee and it seems quite unphased as it quickly goes back to collecting nectar. Gill loves to get out into the woods and see the bees first-hand - most of the rest of the time she's in her office with the 40 or so staff employed by the Bumblebee Conservation Trust, and despite being the Trust's CEO she's often teaching groups about bumblebees and working with various sponsors including a big housebuilder and a big London law firm. Read more...

In Spring, or earlier if winter has been mild, queen bumblebees emerge from ‘hibernation’, from their nests.  They then need to feed, having more or less exhausted their bodily reserves during the cold of winter.  Their food comes in the form of nectar and pollen - both of which can be in short supply in early Spring. Whilst the bumblebees may need food, flowers also have a ‘need’-  pollinating agents - particularly bumblebees.   The inter-dependence of flowering plants and insects probably evolved many millions of years ago, back in the Cretaceous Period. Read more...

The latest WoodlandsTV film features some insects that you might see whilst wandering through a woodland this Spring.    One of the earliest to be seen, possibly even in February, is likely to be the bumblebee, which in recent years, has often seen mild periods.  However, the bees may suffer if there is then a particularly cold spell - such as The Beast from the East, which occurred in late February / early March of 2018. Bumblebees and solitary bees are important pollinators. The woodlands blog has often written about bumblebees and the threats that they face due to viruses, pesticides, and habitat fragmentation.  Another woodlands insect - the bee fly is a parasite of their young (larvae).  Read more...