Blog - Flora & Fauna
Viruses, Varroa and honey bees.
Honey bees are often infected by the mite - Varroa. Mites are small arachnids. The varroa mite is an external parasite, attaching to the body of the bee and feeding from it. It also infects honey bees with various viruses, which further harm the bees. One such virus is the deformed wing virus. Bees that are severely infected with this virus die within days, some have such poorly developed wings that they cannot properly forage for nectar and pollen. The virus also affects their ability to learn, so that if they forage they may not be able to find their way ‘home’. Lost bees die, the colony is deprived of food collected by such bees and the colony may collapse. Eliminating the mite is difficult and the use of chemicals risks contaminating any honey collected from treated colonies / hives. However, researchers at the National Taiwan University have found a naturally occurring compound that may help alleviate the effects of the virus. The compound in question is sodium butyrate Na(C3H7COO). In a series of experiments, the research team found that bees that were fed sugar-water laced with butyrate were better able to resist the effects of subsequent viral infection. Compared to a control group that did not have butyrate, some 90% were still alive five days after infection whereas 90% of the control group died. The butyrate treatment also improved the bees’ ability to forage and return to the hive. Further details of this work here. Sodium butyrate is an inexpensive chemical, and if its benefits are substantiated then it could provide an affordable solution to the mite and virus problem that honey bees face.
opening and closing – flowers, leaves …..
Some flowers are open during the day, ready to receive visitors (pollinators) but close up each night at dusk; for example, crocuses, tulips, poppies. Other plants move their leaves in response to light and dark. Such movements of flowers and leaves are known as nyctinastic movements. The reasons for these movements are not particularly clear / obvious. A number of suggestions have been advanced : The closing of the petals at night might serve to keep pollen dry. When wetted, pollen is heavier and less easy for insects to distribute. By closing at night, the nectar and pollen is protected from unwanted visitors. Some insects are nectar robbers that is they take nectar but do not contribute to pollination. Darwin made the suggestion that the closing might help protect the floral organs from the chill of night time temperature. Leaves may move to help capture rain, closing down at night to allow water to trickle down to the roots (?). Different explanations may apply to different plants but these movements have a common underlying mechanism, namely phytochrome. Phytochrome is a blue-green light absorbing pigment. It responds to red (in the region of 660 nM) and far red light (>730 nM). Red light is generally abundant during the day, but the balance between red and far red shifts towards the end of the day. This change is detected by phytochrome and it directs the plant’s circadian / daily rhythm. Phytochrome is involved in many processes during a plant’s life cycle from germination to flowering. The nyctinastic movements of plant parts is, however, largely controlled by the movement of water into and out of cells - cells can swell or shrink. Some plants have special structures called pulvini to control the movement of leaves. Pulvini are found in the bean family (Fabaceae), and plants like the sensitive plant (Mimosa pudica) and the Prayer plant (Maranta sp). Pulvini are usually located on the leaf stalk (petiole). A pulvinus is a small swelling on the stalk, it has a central core of vascular (water-conducting) tissue surrounded thin-walled cells (parenchyma tissue) with large fluid-filled vacuoles. The flow of water in and out of the vacuoles of these cells raises or lowers the leaf stalk / leaf. [caption id="attachment_36023" align="aligncenter" width="650"] Pulvinus on sensitive plant[/caption] [caption id="attachment_36032" align="aligncenter" width="650"] Young Mimosa pudica[/caption]
Oak trees, moths and resilience.
Ecology is concerned with understanding the relationships between organisms, and their relationship with their environment. This can involve how climate and soil influence the growth and development of organisms. Ecological studies may focus on a particular organism (autecology) or specific areas. One area that has been intensely studied is Wytham Wood, which lies just outside Oxford. The area includes ancient semi-natural woodland, secondary woodland, grassland and ponds. It is a designated SSSI, where some 500+ plant species and 800+ lepidopteran (butterfly and moth) species have been recorded. Records of bird populations go back some sixty or more years (with the work of David Lack and others); other ecological studies with long-term data include those on badgers, and also work on climate change. Wytham Wood belongs to Oxford University. Historically speaking, it is possibly the most intensely studied woodland in the world. Read more...
Woodland web updates 6.
Pesticides problems. The effect of pesticides on bees and bumble bees is now well documented. However, the combined effect of different pesticides is less well known. If pesticide A is known to kill 10% of the bees in an area that has been treated, and pesticide B kills another 10% then it might be reasonable to assume that 20% of the bees would be killed - IF the effects are additive. However, evidence is beginning to indicate that the effects of the pesticides is more than the sum of the parts - the pesticides work together / synergistically. Pesticide formulations that are sold to farmers are often ready mixed ‘cocktails’ so exposure to more than one pesticide is often the norm, so it is important that these co-operative effects are understood and known. Honey bees have been affected by not only pesticides but also varroa. Varroa is a mite, which lives and feeds on honeybees and their larvae. Fortunately, bees have complex hygienic behaviours, for example, removing dead larvae or pupae. Research indicates that honey bees are modifying this behaviour to deal with varroa mites. Helping pollinators Researchers at the University of Freiburg have recently published work establishing the importance of semi-natural habitat regions next to orchards and other agricultural landscapes for pollinators. Such areas (ditches, banks, overgrown fences etc) help ensure that flowers (and therefore nectar and pollen) are available over a significant period of time. This is important for pollinators such as hover flies, solitary bees, bumblebees etc. as nectar / pollen provided by crops is only available for a short and limited period. Such areas are also important for overwintering, nesting sites, providing food for larval stages etc). Their work focused on orchards near Lake Constance in Southern Germany. Soil remediation with lupins. There are many sites around the world where the soil is contaminated with metals (such as arsenic) as a result of past mining / industrial activities. Such arsenic contaminated soil might be ‘revived’ by using the natural mechanisms that some plants have evolved to deal with certain contaminants. The white lupin (Lupinus alba) is an arsenic-tolerant plant that might be a candidate for phytoremediation of soil. The tolerance of the white lupin to arsenic is thought to be due to the release of chemicals by the roots into the soil. Staff at the University de Montréal placed nylon pouches close to the roots to capture the molecule released. The chemicals were then analysed to see which could bind to the arsenic (phytochelatins). Phytochelatins are known to be used within plants to deal with metals but here they seem to be used externally. Quite how they work is yet to be determined.
Deer, damage and the pandemic.
Across the UK, there are several types of deer to be found in woodlands and rural areas namely : Red deer Sika Deer Roe Deer Reeves Muntjac Deer Fallow Deer Chinese Water Deer In recent times, the number of deer has increased and it is thought that there might be as many as two million wild deer in the UK - the highest number for many hundreds of years. Unfortunately, deer can cause substantial damage to trees and woodlands. Their feeding can cause a range of problems, which can include [caption id="attachment_34910" align="aligncenter" width="650"] Deer damage - bark removal[/caption] Stripping shoots, flower buds and foliage from plants Damage to woody stems, where a deer has bitten part way through the stem and then the shoot is tugged off - leaving a ragged end Eating the bark from younger trees. This mainly happens in winter when other food sources are scarce In addition to the damage associated with their browsing / eating activities, there is also the damage done by male deer who rub their heads / antlers against the trunks of younger trees. This rubbing may be for scent marking or to remove the outer skin (velvet) present on a new set of antlers. The antler rubbing results in cuts in the bark. [caption id="attachment_34415" align="aligncenter" width="700"] Remnants of birch woodland near Loch Muick are subject to browsing by red deer (especially in the winter), so temporary fences have been out in place to allow for regeneration and tree guards in place[/caption] Deer numbers are reduced by culling in order to supply restaurants, farm shops, and the hospitality sector with venison. However, with the onset of the pandemic and subsequent lockdowns / restrictions the demand for venison dropped significantly (as has price) so very few deer were culled. Consequently, the number of deer is increasing. Deer have probably gone through one or two breeding cycles since the first national lockdown, and numbers are set to increase. The increase in deer numbers not only affects the trees in a woodland but also plants of the herb and scrub layer. The loss of plant species and aspects of the structure of the woodland means that particular microhabitats are lost so that species such as nightingales and warblers are at risk. Without careful management of deer numbers, woodlands could become much more ‘uniform’ as deer have no natural predators (in the UK). It is important that deer numbers are monitored as they will do significant (most) damage to woodland in Spring as there’s not much food elsewhere for them. Young trees are particularly at risk, unless they are protected.
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...
August Fungi Focus: Oak Mazegill (Daedalea quercina) and Blushing Bracket (Daedaleopsis confragosa)
It is good to have points of orientation in the woods. No matter how familiar with a particular spot you might be, these environments can change so dramatically throughout the seasons – paths and clearings become overwhelmed with brambles, branches that weren’t an obstacle in the winter become suddenly more so when covered in leaves, and woodlands are ironically much gloomier in the summer months with a thick canopy overhead than when the trees are bare – that it’s surprisingly easy to lose ones bearings. One of the marker points in my favourite stomping ground, a chestnut coppice just outside of Canterbury, was a bracket fungus that I found growing from the top of a stump several years ago. It was a relatively easy identification for me from this sometimes daunting group – the labyrinthine arrangement of branching, elongated grooves quickly pointed me towards an Oak Mazegill, despite the fact it was growing on chestnut. Oak Mazegill For several years, this particular specimen by the side of the path also signalled the point where I knew I’d entered into a sector of more ancient woodland, and one of those hotspot areas where there were usually lots of exciting finds nearby. Then one day it was gone – the clean cut at the base where it grew from the wood indicating that is had been consciously removed with a knife. Even now, about a year later, I can still see traces of the patch where it had endured on the top of the stump for so many seasons. The Oak Mazegill, or Daedalea quercina – the first part of its latin binomial referring to the figure of Daedalus who in Greek mythology constructed the labyrinth at Knossos housing the legendary minotaur – is a particularly prevalent fungi in my local woodlands; much more so because, as a perennial, the fruiting bodies last for years rather than rot back or drop off at the end of the season. It shares this aspect with the tough woody brackets like the Artists Conk (Ganoderma applanatum), covered in passing in a previous post on brackets, which has been known to last for decades. Oak Mazegills aren’t quite as durable, although I’ve no real idea how long a fruit body might last. Their flesh is tough, but still possible to make a clean cut through it with a sharp knife with relative ease, as if it were a piece of rubber. Oak Mazegill This species highlights the importance however of always looking at the underside when trying to identify brackets. The top is rather nondescript, a sort of buff, pale yellowish brown colour ranging to orangish brown and reaches up to 20cm across. They often grow in semicircular tiers, with the full width of the body firmly attached to the wood making them very difficult to dislodge, and sometimes have an upside-down pyramidal shape, so that if viewed in profile, the maze-like underside is very easy to see. The growth isn’t always so uniform, however, drawing attention to the fact that there can often be a fine line between the brackets and certain poroid resupinate or crust fungi, with the form they assume heavily influenced by the orientation of their substrate. Oak Mazegills don’t always immediately form brackets when first emerging, with the specimen depicted here assuming a more resupinate form. For example, I found myself once very confused by a newly emerged Oak Bracket growing from the top of a stump that had yet to form a cap, so that all that could be seen was a think bulbous growth covered in brain-like grooves that could look like a number of other thick poroid resupinate fungi, such as the Common Mazegill (Datronia mollis) – and it should be mentioned that the Common Mazegill, while often found in its flat resupinate form, can form caps if growing on a vertical substrate, albeit with thinner caps of a far darker colour. The not dissimilar resupinate fungus the Common Mazegill has a less pronouncedly maze-like pattern of pores Mature Oak Mazegills, I do find pretty distinctive, but the reason I’m covering them for this month is that it is during the summer months that the new fruitbodies start emerging, so if you have any problems identifying them, I’d suggest going back and monitoring their progress over the coming months, for there are a couple of species that you could confuse them with before they are fully grown. The first of these is the Birch Mazegill (Trametes betulina), but these form much more delicate annual fruitbodies which are thinner fleshed and more easily broken, with grooves on the underside that are sharper edged and look more like conventional mushroom gills (although as I described in the post linked above, these aren’t true gills) and a felty upper surface. They also grow on birch, rather than oak or chestnut, so there shouldn’t so much room for confusion here. The Blushing Bracket is less ‘chunky’ than the Oak Mazegill, despite certain similarities when viewed from above. Rather more easily confused for the Oak Mazegill, however, especially in their early stages of growth, is Daedaleopsis confragosa, the Blushing Bracket. Again, these feel a lot slighter, thinner and flatter than the chunky, coarse gilled bodies of the Oak Mazegill, although the flesh is similarly tough. However the base is much narrower where it grows out of the wood, making it look more fan-shaped. Looking underneath, the pores are much less maze-like, and more like straight lines, which become more elongated as the cap grows radially outwards. The underside of the Blushing Bracket reveals very different patterns than that of the Oak Mazegill The cap surface starts out a pale beige, but as it grows, it darkens through pinks, browns, russets and vinaceous purples to near black, hence the name. They also are more pronouncedly ‘zonate’, with subtle differences in texture and colour appearing from the centre and outwards. The Blushing Bracket might be confused with a number of other long-pored brackets in their early stages, but if you follow their development across the months leading into winter, it soon becomes clear what they are. Again, they favour deciduous woods, but are less likely to be found on oak and chestnut than on birch, alder and willow. Some of the literature suggests that Blushing Brackets are perennials, like the Oak Mazegills, but my experience suggests that while the new fruit bodies from any given summer may be found well into the winter, very few make it past a year. Blushing Bracket : The upper side of the Blushing Bracket darkens and reddens across the winter months Blushing Bracket : Sometimes reddening to a dramatic deep red These are but a couple of the more common hardwearing brackets with elongated pores that are found in the UK that might seem a little drab when just glimpsed in passing, but actually are quite interesting when you know what you are looking at. Like so many fungi, the exact differences are difficult to describe precisely in words, but once you get a feel for them, they can be recognised at a glimpse. If you are a regular woodland wanderer, it’s worth paying at least passing attention to them because, as mentioned before, the new fruitbodies will have already begun appearing by now, and given that they’ll be with us for some months yet to come, it’s rather fascinating looking at how both species develop in form and colour. Additional images. Blushing Bracket Oak Mazegill Oak Mazegill Blushing Bracket
Birds from Woodcock Wood : Part 2 Our Nest and Nest Box Record
Checking nest boxes is deeply satisfying, and a fitting reward for all the time spent during “lockdown” making and installing a dozen or more new boxes. We now have 27 in the wood - some are specialised such as those designed for Treecreepers, some for large birds like our two Tawny Owl boxes, but most are standard boxes designed for the tit family. Checking the Boxes: There’s a strong feeling of anticipation when you lift the lid of the Blue and Great Tit boxes. Sometimes the adult is there and stays steadfastly put, or sometimes off she goes, revealing what? - a beautiful clutch of eggs, a huddle of chicks (featured image). Read more...