The diet of bees has changed over the years.   In the past, bees were able to forage and collect pollen and nectar from a variety of plants.  With the spread of highly mechanised agriculture, increasing urbanisation and road network - now their options are somewhat limited.  Large fields of monocultures, for example, of oil seed rape are now common. Whilst oil seed rape is a good source for foraging bees and bumblebees, they need to collect nectar and pollen from a variety of sources so that they get a range of nutrients, such as the essential amino acids.  Without these particular amino acids, the growth and development of bees is affected, as is their resistance to disease and their ability to raise the brood.  It is important that our pollinators are able to find a range of plants / pollen to provide all their nutrients. Whilst wild flowers [aka weeds], like dandelions, ragworts, and clovers are a lifeline for bees and bumblebees, recent research at the University of East Anglia has shown that woodlands can offer important habitats for bees, isuch as the leaf canopy.  The research team studied 15 woodland sites in agricultural areas across Norfolk (in Spring).  Within the woodlands, they looked at the bee activity in  the understorey  the woodland edge  and at different levels in the tree canopy.   They found that bees were active high up in the sunlit tree canopy, and their activity was particularly high near flowering sycamore trees.  Red tailed bumblebees (Bombus lapidarius) were busier in the canopies than elsewhere.  The understorey and woodland edges were also significant contributors to bee activity.  This study emphasises the importance of woodland habitats for the wild bee community.  

On the Red List! The capercaillie is threatened.  Its numbers in Scotland have roughly halved (between 2010 and 2020).  It was once widespread, but now it is found in the pine forests of the Highlands - notably the Cairngorms National Park.  It is a red listed species. The decline in numbers is associated with poor breeding success, poor weather in early summer when the chicks are developing, another problem is predation by species such as the pine marten, foxes and crows.  The Game and Wildlife Conservation Centre (GWCT) has identified another issue that these birds face - namely collisions with deer fences.     These fences are created to keep deer out of particular areas.  However, when the capercaillie (and black grouse) impact on these fences, they are injured or killed.  Marking these fences, reduces the number of collisions but does not stop them.  Unmarked fences are still killing adult birds.  Marking of these fences or their removal would help with the survival of the capercaillie, though removal would  mean trees and shrubs would be unprotected from deer. Mosquitoes! There are some 36 different species of mosquitoes to be found in the UK, which  are generally harmless (though they bite).  But that may change.  With longer and warmer summers, the UK may become a venue for other species such as the tiger mosquito.   This insect has been found in ‘traps’ (monitored by the UK Health Security Agency) at ports and rail terminals.  This insect is known to transmit various diseases, such as dengue fever.  The mosquito was found in Italy in 1990 and it is spreading on the continent. A species of Culex has also been found in some areas of the Thames estuary - which can spread the West Nile Virus. This virus can result in flu-like symptoms.  Outbreaks have been been mainly in the warmer areas of the Mediterranean, but with climate change and the potential for very hot summers here - vigilance will be needed. Floral defences. Many flowers release a distinctive scent.  The scent serves to attract pollinators like bees and butterflies, or  it may ward off pests that would feed upon the plant.. Many of the chemicals that contribute to scents are terpenes.  Recent research has investigated how these chemicals can affect the growth and development of butterflies - using painted lady butterflies.  These butterflies feed on a wide range of plants and hence are exposed to a variety of scents / terpenes. For these experiments, the researcher (at the University of Centra Florida) used four common floral terpenes  Limonene :  which has a fresh, citrus like smell Linalool. : has a floral scent, reminiscent of lavender Cineole : has a camphor-like smell, slightly medicinal contributes to eucalyptus oil. β caryophyllene : this has a spicy / woody fragrance. Different amounts of these terpenes were fed to caterpillars of the painted lady butterfly, and the subsequent development of the caterpillars was monitored and the size of the adults recorded.  The experiment was also conducted at different temperatures.  Temperature affects scent release by flowers. Higher levels of terpenes has significant affects on the survival of the caterpillars, especially when combined with the higher temperatures.  The caterpillars took longer to enter into pupation when given high levels of terpenes, though the size of the adults that emerged from pupation was unaffected.  If longer and warmer summers become more common, the combined effects of terpenes and heat could become important determinants of development. `

Tree survival and drought. Researchers at the University of California have been working on a method that helps predict whether forests / woodlands can survive periods of drought.  As climate change is altering patterns of snow and rainfall, so periods of drought are likely to become more common. Forests are important in terms of carbon sequestration, that is, they take up carbon dioxide from the air and convert it into sugars, starches etc that are stored in the leaves, branches, stems and roots.  However, in order to assimilate and convert carbon dioxide (in photosynthesis), trees (indeed all plants) need a supply of water.  When water is limited, trees need to make use of their reserve materials.  Just as we make use of body reserves of fat and glycogen when food / diet in inadequate. However, reserves can only sustain a tree for a finite period of time.  If drought persists, the tree reaches a ’tipping point’ and it will die.  The researchers studied a forest in the Sierra Nevada that experienced a period of drought between 2012 and 2015.   During this period, millions of trees died.  The team recorded rainfall, soil moisture and temperature in the forest AND the amount of carbon dioxide that the trees absorbed, and their reserve materials.  They found that the trees were able to maintain function / health after the onset of the drought but with the passing of time, the trees exhausted their reserves and were unable to use / convert carbon dioxide into food.  They had reached the tipping point and died.   The methodology of this study was called CARDAMON (carbon data assimilation with a model of carbon assimilation); it is hoped that it can be used to evolve strategies to enhance forest and woodland resilience in the face of climate change. Pollinators. [caption id="attachment_35902" align="aligncenter" width="675"] hoverfly[/caption] University researchers from the UK and Finland have been trying to determine the most effective pollinators of crop plants, like strawberries (and other fruits).  Plentiful and effective pollinators are needed to ensure a good harvest of the fruits. The researchers studied the pollinators at three strawberry farms through the (long) growing season for the fruit.  They adopted two approaches : They caught the insects that visited the strawberry flowers and analysed the pollen they carried in detail (pollen load and type). They also counted the number of flower visits by the different insects, (a quick way to identify key local pollinators). Many insects were identified, including :-  European drone fly :           Eristalis arbustorum Honeybee :                               Apis mellifera Levels drone fly :                   Eristalis abusivus Buff tailed bumblebee :     Bombus terrestris White tailed bumblebee :  Bombus lucorum Common drone fly :             Eristalis tenax Red tailed bumblebee :      Bombus lapidarius Early bumblebee :                Bombus pratorum Bent-shinned Morellia :   Morellia aenescens Hoverflies are true flies, that is, they belong to the order Diptera or true flies, as they have a pair of wings and a pair of halteres (balancing  / orienteering organs used when in flight). Several of the flies in the genus Eristalsis are known as Drone Flies (due to their resemblance to honey bee drones).  The larvae of Eristalis  species are commonly found in putrid / stagnant water and sometimes referred to as “rat-tailed maggots”. It was noted that pollinators also made use of the wild plants to supplement their diets, as strawberries alone cannot meet the nutritional needs of pollinators.  ‘Elsanta’ strawberries have a relatively low sucrose and protein content in both their nectar and pollen. The precise  order of importance of pollinators varied between farms.  Bee (Apis and Bombus) species  and hoverfly (Eristalis) emerged as key pollinators. The European drone fly was the most important pollinator at two of the three farms studied, evidence that hoverflies can be effective pollinators.  One farm had commercial hives of the honey bee but they were less significant than the activities of of the hoverflies and bumblebees. The abundance of a particular insect, coupled with its active period were /  are important determinants of pollinator importance.  Sawdust and plastics - a possible use?. Plastics represent a relatively new, but persistent and major form of pollution (on land, in the sea, indeed everywhere).  Whilst many plastic objects are instantly visible in the form of discarded bottles, fast food containers, many plastic pollutants are in the form of very small particles of plastics  - nano and microplastics.  The concern is that we and other organisms are taking these microscopic particles into our bodies from our food / drinking water. However, it is possible that plant materials may offer some ‘solutions’.  Water that contains micro and nano plastics can be filtered through sawdust that has been treated with tannic acid.   Tannic acid is large molecule, its molecular formula is C72H52O46 .  Tannic Acid is found in certain plant galls (swelling of trees caused by parasitic wasps) and in the twigs of certain trees, such as Chestnut and Oak.  The wood sawdust contains fibres of cellulose, combined with hemicelluloses and lignin.  Water can flow through this material by capillary action.  This plant-based filtration (known as bioCap) of plastic-laden water is capable of dealing with a wide range of nanoplastics (PVC, PET, polyethylene etc), and tests with mice suggest that the filtered water may be sufficiently free of plastic to pose little risk.  

Mason bees and agrochemicals The blog has reported many times on the threats to bees - money bees, bumblebees and ‘wild bees, such as mason bees / solitary bees.  The threat to bees from neonicotinoids has been well documented, now there is a report that suggests that certain other agrochemicals may be harmful to bees. Researchers at the Julius Maximilians University at Würburg have been investigation the effect of a fungicide (Fenbuconazole) on the reproductive behaviour of horned mason bees (Osmia cornuta).  A number of Osmia species are used to improve pollination in fruit and nut crops.    They are efficient pollinators having a special pollen collecting / carrying structure called a scopa.  Mason bees are solitary bees.  Each female is fertile and makes her own nest and no worker bees for these species exist. In the Spring, male and female bees emerge from a nest.  The males generally exit first and remain near the nest, ready to mate with the females.  A female bee selects a mate on their ‘smell’ / odour and the ‘quality’ of their thoracic vibrations (achieved through muscle contractions).  After mating the males soon die.  The females search for and select a nest site, visiting flowers to collect pollen and nectar for their nests.  Once a certain amount of food has been collected within the nest, the females lay their eggs on top of this material (in a series of cells) and then seal off the nest.  The eggs hatch to form larvae which feed upon the food and within weeks forms a cocoon, in which it continues to develop to an adult. Though the fungicide (Fenbuconazole) is considered to be of low toxicity and the bees were exposed to a sub-lethal dose, nevertheless the Fenbuconazole had significant effects on the bees.  Pesticide exposed males were more likely to rejected by the females, compared to ‘control’ bees that were not exposed to the fungicide.  The thoracic vibrations of the exposed males were less powerful / noticeable and the composition of their odour or smell was different. The smell of the bees is dependent on particular hydrocarbon compounds in their cuticle  - their exoskeleton.  It is possible, therefore, that the mating behaviour and reproductive success of these bees is being affected by agrochemicals. Carpenter bees. The microbiome refers to the collection of micro-organisms that lives on or in us, particularly within within the gut. Whilst these micro-organisms are small, they contribute to our health and ‘well being’. They offer protection against pathogens, help our immune system develop, and enable us to digest.  Just as we have a microbiome so do bees.  Scientists as York University (Canada) have been investigating the microbiome of three species of carpenter bees (from North America, Asia and Australia). The term "carpenter bee" comes from their nesting behaviour,  most species burrow into plant material such as dead wood or stems, though a few create tunnels in soil.   Social bees (like honeybees and bumblebees) acquire their microbiome by interacting with their hive or nest ‘mates’. Solitary bees, like the carpenter bees, get their microbiome from the environment as they forage for food.   The researchers found that: The bees’ microbiome contained Lactobacilli, which are important for good gut health, helping protect against fungal pathogens and facilitating nutrient uptake. They also discovered crop pathogens in the microbiomes of the carpenter bees which were previously only found in honeybees. Whilst these pathogens are not necessarily harmful, it is possible that the wild bees could be vectors for spreading disease.  With thanks to Pixabay  (Umsiedlungen and Sabinem34) for the above images of bees Finding flowers. Research at the University of Exeter has shown that bees can distinguish between various flowers through a combination of colour and pattern.  This selectivity is achieved despite the ‘acuity’ of a bee’s vision being quite low (about a 100 times lower than ours) - this means they can only see the pattern of a flower when they are quite close (a matter of centimetres).  The researchers analysed a significant amount of data on plants and visiting bee behaviour, and they used experiments involving artificial shapes and colours.  One particular finding was the importance of the contrast between the outside of the flower and the plant’s foliage.  This seemed to help beesfind their way to the flowers quickly .    

Plants have existed for hundreds of millions of year - as algae, mosses, liverworts, ferns but flowering plants only appeared about 140 million years ago. The exact timing of their appearance is a matter of some debate (see article) They have been a massive evolutionary success, there are perhaps 300,000 to 400,000 species world wide.  They reproduce using pollen.  This is used to fertilise the ovules and produce viable seeds.  Most plants rely on insects to transfer this pollen to the ovules, indeed over 80% of flowering plants have relied on insects for this service.  To this end, flowering plants (Angiosperms) have evolved a number of inducements to attract insects : colour, scent and nectar. When we think of pollinators, we generally tend to think of bees, bumblebees, hover flies.  But when flowering plants first evolved, fossil evidence suggests that many of these flowers were quite small so it is probably that the first pollinators were also quite small, and hence able to access these small flowers.  The first pollinators were probably small flies, midges or beetles (more than 77,000 beetle species are estimated to visit flowers).  Quite when bees (and their pollen collecting activities) evolved is not known.   A recent analysis of the "family tree" of the families of flowering plants indicates when different plant families evolved and when various forms of pollination emerged.  Insect pollination is / was clearly the most common method of pollination,  and was probably the first means of pollination.  This analysis also indicated that other means of pollination (involving small mammals, birds, bats) have evolved several times, as has wind pollination.  Wind pollination seems to have evolved more often in open habitats and at higher altitudes , whereas animal pollination is associated with closed canopy tropical forests. The pollen of insect pollinated flowers is significantly different to that of wind pollinated species.  Flowers that are insect pollinated tend to produce pollen that is heavy, 'sticky' and protein-rich.   Pollen is an important constituent of the diet of many insects.  Wind pollinated species by contrast produce large quantities of pollen, the grains being light and small.

I recently attended the National Allotment Society AGM, where the keynote speaker was Professor David Goulson.  His main academic studies focus on the threats to bees, bumblebees and other insects. He is based at Sussex University.  Back in 2006, he founded the Bumblebee Conservation Trust; a charity which has grown to some 12,000 members.  In his talk at the meeting, he made the following points : He loves allotments because they capture carbon and are rich in biodiversity.  They produce a lot of food.  Typically producing some 10 tonnes / hectare whereas farming productivity is about 3 tonnes per hectare.  The record on a 1m2 in an allotment is 10 kg, which is the equivalent of 100 tonnes / hectare.  Allotments not only produce good food for healthy eating, but people get good exercise through their gardening activities.  A study shows the ‘over-60s’ with allotments have longer life expectancies [controlling for other variables]. [caption id="attachment_40124" align="aligncenter" width="675"] A bee at risk of extinction.[/caption] There are over 300,000 allotment plots in the UK and some 90,000 people on waiting lists.  More allotments could help counter poor health and cut NHS costs. We should turn our cities, towns and villages into a network of nature reserves - essentially a form of urban rewilding. Gardens are a vital part of this, as there are some 400,000 hectares of them in Britain.   Prof Goulson is really keen on less mowing, more ponds and no pesticides. Interestingly, France banned pesticide use in public and urban areas, such as parks, back in 2014 - it is an example that we should follow. Even pet flea treatment is damaging to insect life.  The strength of the doses used means that the chemicals can pass into the environment - to grass, rivers, canals and pools.  Sadly, now 8% of gardens have some plastic lawns, and plastic hedges (and Wisteria !).  Plastic makes him despair.Plant diversity in pavements should be celebrated. Wild flowers / weeds are sources of pollen & nectar for pollinators.  Verges should be nature reserves.  A Scottish "On the Verge" group stopped councils mowing 8x a year and planted a seed mix to transform verges in their area.  Councils should mow less.  Some people may object, so people should strengthen their Council’s hands by writing to them and praising them for no-mow-May-type efforts.  The Buzz Club - has been set up, this is a citizen science project to see what works best for insects. There are lots of short films on his youtube channel . Bees and other pollinators need help.  He suggested lots of ways to help them, for example,  drilling holes in logs for bug hotels.  You can follow Prof Goulson on Twitter or Facebook. [caption id="attachment_40132" align="aligncenter" width="675"] Bumblebees 'enjoing' a small clump of poppies[/caption] [caption id="attachment_40129" align="aligncenter" width="428"] urban herbicide use[/caption]  

Trees for a longer life? Researchers from US Forest Service has completed a survey of tree planting in Portland, Oregon and concluded that the more tres are planted in an area, the longer people live. The Portland “Friends of Trees” have planted some 50,000 oaks, dogwoods and other trees around the city over the last thirty years.  After adjusting for factors such as race, income, age and education, the team found that where more trees had been been planted, fewer people died.    This was true for all areas - wealthy or less so. Furthermore, as the trees aged, the mortality rates of the people nearby went down.  Trees generally improve air quality and moderate extreme high temperatures.  A recent report in the medical journal The Lancet suggested that many of the premature deaths from the 2015 heat wave in Europe could have been avoided with 30 percent more tree cover. Birds in decline. UK bird populations are in decline.  Much of the decline occurred in the 1970’s and 80’s, and was particularly noticeable in populations of farmland and woodland birds.  However, the losses have continued in recent times, with a 5% decline between 2015 and 2020. Again, woodland birds have fared poorly with a 12% decline in this period.   The steepest decline in population numbers are seen in species such the Tree Sparrow, Willow Tit, Lesser Spotted Woodpecker and Nightingale.  These have all declined by 90% or more since the late 1960’s. The Turtle Dove shows the biggest decline of any species. Habitat loss is thought to be the main driver of population decline for many species, but oil and plastic pollution are also factors, as is disease - such as trichomonasis and avian flu  Certain species typically associated with urban areas / habitats (Swift, House Martin, Starling and House Sparrow) are also declining. Predation by cats might be a factor, the Mammal Society estimates that cats in the UK catch some 92 million prey items over Spring and Summer, of which around 27 million are birds. Disease such as avian malaria is another factor, one study found 74% of sparrows were infected with the parasite Plasmodium relictum; the changing nature of urban gardens may also be a consideration.  Bees and sunflower pollen grains Bees and bumblebees are struggling with various parasites /infections.  One parasite is the gut pathogen Crithidia bombi.  This is known to affect the ability of bumblebees to create a successful colony. Previous studies have indicated that the the gut microbiome of the bees can help protect against infection by this parasite.  Now a study at the University of Massachusetts Amherst has found that sunflower pollen can help bees resist infection.  It was not known why sunflower pollen was effective, it could be that the shape of the pollen grains was important or the chemical makeup within the grains, or a combination of the two. To test the ‘anti-parasitic nature of the pollen’, an experiment was set up so that some bees received the outer shell of the sunflower pollen (the sculptured exine), whilst another group received the materials from the centre of the pollen grains (but no outer coverings), and a third group received whole pollen.   Bees that received whole pollen grains or just the spiny shells had far less of the parasite in their gut compared to those eating the ‘soft centres’ .  The pollen grains and pollen shells reduced infection by 80 to 90+%.  So it is the spiny shape of the pollen grains that is important in reducing infection in the bees.  'Physical removal' of pathogens is known in other animals, for example, great apes infected with certain nematodes or tapeworms will consume bristly leaves.   These 'irritate' the gut and increase the expulsion of the parasites.

Earlier flowering times. A survey has shown that plants are flowering earlier in the year.  Cambridge University researchers compared the dates of flowering of some four hundred plus species before and after 1986. They found that plants are now flowering roughly one month earlier.  More recent decades have been associated with rising air temperatures. This change in flowering time may have profound consequences for the plants.  The vast majority of plants are dependent on pollinating insects (bees, bumblebees, hoverflies) to set seed and complete their life cycles.  By flowering early their cycle, plants may not match up  with the activities of their pollinators. They may flower but their pollinators bee ‘missing’. Their pollinators need to emerge from their overwintering stage earlier. Earlier flowering may not matter for those plants that are visited by several pollinators but for those that are dependent on one or two specific visitors - it may critical.  For example, Sainfoin.  Sainfoin is host to a particular (solitary) bee Melitta dimidiata (remote image here).   It is a monolectic bee; i.e., a bee that collects food (nectar and pollen) from only one species of flower - the sainfoin.  If the sainfoin flowers earlier in the year and the bee does not match the shift in flowering, then the bee has a problem. Work on the effects of climate change on pollinators has been somewhat limited to date, but studies in Japan suggest that bees / bumblebees are somewhat behind plants in their response to environmental changes. Bee and bumblebee news. Recent research data provide evidence that (buff tailed) bumblebees are not able to detect or avoid concentrations of pesticides [imidacloprid, thiamethoxam, clothianidin, or sulfoxaflor], as used ‘on the farm’ - from signals sent by their mouthparts. The mouthparts are covered with tiny hairs and these hairs have ‘pores’ in them. Chemicals pass through these ‘pores’ to sensory cells; this is how the bee tastes and smells. It seems likely that the bumblebees are at considerable risk of consuming pesticides in their search for nectar when visiting pesticide-treated crops. [caption id="attachment_19675" align="alignleft" width="300"] Bumbles foraging in artichoke[/caption] Another agrochemical,  Roundup,  has been found to affect the learning and memory of bumblebees. Roundup, which contains glyphosate, affects their ability to learn and memorise connections between colour and taste.  Impaired colour vision is likely to affect the foraging and nesting success of the bees.  The research was conducted in Finland by researchers at the University of Turku. In yet another concerning study, researchers at the University of Maryland have found that the life span of laboratory-raised honey bees has reduced considerably.    Five decades ago, the lifespan for a worker honeybee (Apis mellifera) under controlled laboratory conditions was about 34 days. Now it is some 17/ 18 days - according the report in Nature.  The study also reviewed the scientific literature [from the 1970s to now] and noted a trend in the life span of bees.   Shortened worker bee lifespan has implications for colony health and survivorship.  The work at the University of Maryland is ongoing. Methane release. Ghost forests are found in coastal areas.  As a consequence of climate change, sea water has ‘invaded’ low laying areas and trees have died. The dead trees are sometimes referred to as ‘snags.  A  number of woodland / forest communities along the eastern coast of the United States have been affected.  Recent work by North Carolina State University has shown that these ghost forests release methane.  The methane is generated by bacteria in the soil but then ‘escapes’ by means of the ‘snags’.  As it passes through the wood of the ‘snags’, microbes may consume and alter the methane.   As methane is a potent greenhouse gas, understanding the nature and extent of these methane emissions from ‘ghost forests’ is important. Tree rings The study of tree rings has been invaluable in dating many historic objects ./ archaeological sites.  Now, it seems that they could play a role in estimating the amount of carbon that trees are actually absorbing (carbon sequestration), if woodland / forest inventories are coupled with core samples of the trees. The measurement of the annual rings from such cores could create a record of ‘tree growth across space and time’, yielding a more accurate estimate of the amount of carbon being taken up by woodland and forests. Forests, soils and oceans are major ‘carbon sinks’.