Blog - Pests & Diseases

Problems for bees and bumblebees.

Problems for bees and bumblebees.

by The blog at woodlands.co.uk, 18 November, 2022, 3 comments

The decline in many insect populations across the globe is worrying, threatening economies and ecosystems.  A German study in 2017 indicated that the mass of flying insects (in various natural areas) had fallen by some 70%+.  The decline in insect populations has been associated with habitat fragmentation, the spread of agriculture and the use of pesticides, with the neonicotinoids being particularly associated with damage to bee and bumblebee populations. Recent work at the University of Konstanz suggests that when bumblebee colonies are exposed to limited resources of nectar and exposure to the herbicide - glyphosate,  then their colonies may fail.  Bumblebee colonies need a good supply of nectar as a ‘fuel’ in order to maintain a constant brood temperature (of approximately 32oC).  Only at this sort of temperature does the eggs & larvae develop quickly from egg to adult, and the colony grow from a single queen to several hundred bees.  If the temperature is not maintained, then the brood develops slowly or not at all.  The loss of wild flowers (and their nectar) plus the use of the herbicide (in agricultural areas) looks to be a problem for the bumblebees. Just as bumblebees are facing problems, so are honey bees.  The bees have faced infections with a variety of viruses, such as the deformed wing virus.  This virus affects wing development so that the wings are 'stubby' and useless, plus they may be deformities of the abdomen and leg paralysis;  the insect cannot function and dies.  The virus is transmitted by the Varroa mite - a parasite (that also feeds on the bees’ tissues).  The virus was originally identified in Japan in 1980’s and is referred to as DWV-A.  However, a new form of the virus (DWV-B) was identified in the Netherlands in 2001 and it is spreading across Europe, and to other continents.  Sadly, this variant of the virus kills bees faster and is more easily transmitted (according to research at the Martin Luther University).
great tit

Food for thought?

by The blog at woodlands.co.uk, 16 January, 2022, 0 comments

It is estimated that each year UK households spend some 250 million pounds on bird food.  This amounts to some 150,000 tonnes of suet pellets, fats balls, peanuts, sunflower seeds etc - on offer (in feeders of varying complexity*) in urban and sub-urban gardens.  These offerings are a marked contrast to the occasional kitchen scraps that were placed on home-made bird feeding tables some 50 years ago.  The question has recently been raised as to whether this is a good thing.  In 2019, research by the British Trust for Ornithology indicated that this provision of food can affect bird communities in the United Kingdom.   For example, species that rarely visited gardens in the past, have become common visitors. Now, researchers at Manchester Metropolitan University have suggested that these extensive offerings of food might be affecting the ecological balance between different species. Blue tits and great tits are regular feeders in gardens, and they appear to benefit from this provision.  Blue tits tend to be be quite dominant in terms of their interactions with other birds - whether quarrelling over food or nest sites.  Consequently, species like willow tits and marsh tits tend to ‘lose out’ in such altercations.  Certainly, willow tits miss out to blue tits in the competition for nesting sites.  Another species affected is the pied flycatcher.  This is a summer visitor, spending the winter in West Africa.  It, too, is in competition with great tits for nesting sites.  The provision of food for resident bird populations may tip the balance against summer migrants, like the flycatcher. The change in feeding patterns of some birds may of course be associated with the expansion of farming over the decades and the consequent loss of natural foods such as fruits, seeds, nuts and berries - from  hedgerow flowers and shrubs.  This may contribute to birds visiting gardens more often.  It may be that our desire to help garden wildlife needs more thought as to the type of ‘help’ that is offered.  This could involve allowing our roadside verges and gardens to be ‘wilder’, with less frequent moving of lawns / grassy areas, more ground cover, planting native trees (like crab apples, hawthorn), less weeding, allowing seeds and fruits  (eg. rose hips) to form, which would encourage insects / spiders Consequently more natural resources would be available to birds and only in harsh times would supplementary materials be needed.   NB : it is essential that feeders are regularly cleaned so that disease is kept to a minimum [e.g. Trichomonosis  caused by the protozoan parasite Trichomonas gallinae] . Remember later this month (28 - 30th January), there is the Big Garden Birdwatch, organised by the RSPB. For further information, click on the image below:-   A footnote : As a species, we have not always been kind to birds.  A recent paper from Tel Aviv University details how humans have been responsible for the extinction of hundreds of birds species (over the last 50,000 years).  They have listed some 469 species of birds that have been lost, though the true number is probably considerably higher.   Many of these extinctions occurred in a short time frame and  were due to either : The hunting of birds (and their eggs) for food or The killing of birds by animals (rats etc) that human expansion brought to islands / countries. Many of the extinct species shared a number of features : Most lived on islands Many were large or very large birds (e.g. the dodo on Mauritius - that provided humans with significant quantise of high quality protein. (A similar fate befell certain large lizards and turtles). Many of the birds were flightless and could not escape their hunters.  
Viruses, Varroa and honey bees.

Viruses, Varroa and honey bees.

by The blog at woodlands.co.uk, 2 October, 2021, 1 comments

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.
Protecting woodlands from pests and pathogens.

Protecting woodlands from pests and pathogens.

by The blog at woodlands.co.uk, 20 August, 2021, 0 comments

The fact that UK is an island has kept many potential pathogens and pests ‘at bay’.  However,  in recent times the growth volume of international trade has become a cause for concern.  Pests and pathogens can ‘hide’ in important plants and plant products (for example, timber that has not been debarked or suitably treated). The Great Spruce Bark Beetle is likely to have arrived here in wood that had not had its bark fully removed.  The beetle breeds under the bark of trees, creating tunnels resulting in the destruction of the cambium.  The cambium is a highly active tissue, producing new cells that will go on to form xylem and phloem tissue.  These tissues distribute nutrients and water around the tree.  With a damaged cambium, a tree is weakened and more susceptible to other pests or pathogens. In the case of the Great Spruce Bark Beetle, a bio-control measure was allowed; a natural predator of the bark beetle has been introduced (Rhizophagus grandis).  Consequently, the numbers of bark beetles have fallen.  Wherever the bark beetle goes, its predator sooner or later follows.  It is thought that its predator ‘finds’ the bark beetles due to the volatile chemicals released from the bark as a result of the beetles' burrowing activities. The U.K.’s control measures generally proceed by four steps : Try to prevents pests and pathogens arriving in the country eg. Inspection of plants etc at ports of entry If a foreign organism arrives then the authorities try to eradicate the pest / infected plants / trees, hopefully the organism does not become established If a pest or pathogen has become established then a containment policy is put in place If all of the above fail then the Forestry Commission and other bodies operate in a way that mitigates the effects of the pest or pathogen.   Phytophora ramorum is a disease of many plants that probably arrived here through the plant import trade.  It has persisted at a relatively low level for many years but from 2009 onwards it affected commercial stands of larch in South West England.  Felling of infected trees helps restrict the spread of this fungus-like pathogen; and a map is available to show where outbreaks of this disease have occurred. Clearly, these introduced species of pest / pathogen could significantly affect the make-up of our woodlands over the coming years, if diseases like acute oak decline / ash dieback are not controlled or contained.  Fortunately, the spread of disease-causing organisms and pests is monitored by both national and international organisations such as these : EU Plant Health Directive this requires nations to report new outbreaks or new pathogens, t the European Mediterranean Plant Protection Organisation is an intergovernmental organization responsible for cooperation in plant health within the Euro-Mediterranean region and  the International Plant Protection Convention, a plant health treaty signed by over 180 countries.  

Spittlebug Survey 2020

by The blog at woodlands.co.uk, 30 April, 2020, 8 comments

In 2019, the blog reported on the disease that has been destroying the olive groves of Italy, and that is spreading in Europe. The following is an appeal from the research scientists investigating the distribution of spittlebugs in the UK.  It was launched in 2020. NOTE : this survey / citizen science project has now ended. Spittlebug Survey 2020 Did you know that the ‘cuckoo-spit’ that you see in spring is produced by the immature stage (nymph) of a spittlebug or froghopper? It is thought that the spittle is produced to protect the nymphs from drying out and from their predators. Once the nymphs emerge as adults, usually in late June, they leave their spittle ‘nest’ behind and become free-flying. The name froghopper reflects the fact that their face is rather bulbous and therefore froglike, and that they are one of the most powerful jumpers in the animal kingdom. There are ten species of froghopper in Britain. The so-called Meadow Spittlebug, Philaenus spumarius, is one of our commonest insects and has possibly the broadest diet of any insect, being known to feed on more than 400 species of plant. [caption id="attachment_33177" align="aligncenter" width="600"] Spittlebugs on Rose[/caption] Interest in these insects has recently been heightened by the fact that they all feed on the liquid contents of the plant xylem tissue and are therefore capable of transmitting various plant diseases that reside there. One of these, the bacterium Xylella fastidiosa, has recently been responsible for the death of millions of olive trees in southern Italy.  We need to collect good data on two aspects of these insects to understand better how the Xylella bacterium would spread if it were ever introduced into Britain: the geographical distribution of the different species of spittlebug and the plant species that they feed on.  Last year, we started to collect some of this information through a national survey, funded by the Biotechnology & Biological Sciences Research Council (BBSRC) and coordinated through the RHS, focused on gardeners recording spittle on their garden plants. This year, the current restrictions on movement due to the coronavirus mean that extending the survey into the wider countryside will not be possible. But if you have a garden, you will be able to record the presence of cuckoo-spit on the plants in the garden.     https://youtu.be/anfH8DAC7p8 Can you help?  It will mean recording cuckoo-spit when you find it in your garden and especially the plant species on which you find it. Please consider contributing to this important survey.  Much more information and an online form for submitting your sightings can be found on the spittlebug website at: www.Spittlebugsurvey.co.uk If interested, there is is a page to help identify the different species of insects - here ; and the video (above) will also help with this.   To report a sighting, visit this page : https://www.spittlebugsurvey.co.uk/how-to-survey-for-xylem-feeding-ins Please let us know  where you saw it, when you saw it, and (if possible)  the species of plant on which it was found.  We also ask you to add at least one photograph of your find. NB : Please be sure to follow the government’s instructions to stay at home during the coronavirus emergency. We can only accept records from people’s gardens whilst the current restrictions are in place.   The above material supplied by the  BRIGIT research consortium PLEASE NOTE The original survey was in 2020, it is now complete. The web site has now been deleted. There is also some information available at the RHS site : https://www.rhs.org.uk/science/help-our-research/spittlebug-survey  

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