CABI Blogs: hand picked... and carefully sorted

Goliath and Titan – running out of leg room

A long, long time ago in a land far away, lived giant beasts stomping, scurrying and soaring over the earth. No, not a fairy tale but an image of life on earth around 290 million years ago before the climate continued to change, oxygen levels decreased and animals shrunk in size and long before humans came along.

In the late Carboniferous and early Permian, fossil evidence shows that most insects were much bigger than they are today. For example, Meganeura, a carboniferous dragonfly, had a wingspan of 75 cm and Ramsdelepedion schusteri, a carboniferous silverfish, was 6 cm long! Today, the largest insects include the Goliath beetles (Goliathus), which measure 5–11 cm in length as adults, and can reach weights of up to 80-100 g in the larval stage, Titan beetles (Titanus giganteus), which grow up to 16.7 cm in length (or 21 cm including antennae), the Titan stick insect (Acrophylla titan) with a body length of up to 50 cm and some butterflies and moths which have wingspans up to 28 cm. But why did the insects shrink?

There are a few evolutionary hypotheses for the decrease in size of the insects:

1. climate change – as oxygen levels decreased, it became more difficult to get enough oxygen to all the tissues via spiracles and diffusion alone.
2. the weight of an insect’s body at moulting might be greater than the soft cuticle could bear, and, being vulnerable to predators, they would probably have to hide.
3. the appearance and rise of vertebrate predators, e.g. reptiles made it an evolutionary advantage to get smaller to avoid predation and radiate into all the available empty niches.

A recent paper published in PNAS by Kaiser et al. lends extra support to the climate change hypothesis…

How we keep women workers in poverty

Next time you have a few minutes I would urge you to read ActionAid’s report Who Pays? How British supermarkets are keeping women workers in poverty, which describes how those low, low supermarket prices impact the workforce in the developing world.

The report highlights how women, in particular, are more likely to be negatively affected by the rock-bottom prices of food and clothing for sale in the UK. Women make up a large proportion of the clothing and fresh produce workers yet they are more likely to be employed on casual, piece-rate work with lower wages and longer hours.

Three case studies are presented:

• the clothing industry in Bangladesh– where the majority of workers are young women earning as little as 5p per hour
• banana production in Costa Rica– where price wars have resulted in increased job insecurity, longer hours and less pay
• and the cashew trade in India– the luxury nut that exposes workers to chemicals during shelling and roasting

So I know when we go shopping we have to strike a careful balance between what we buy and our bank account but what about taking a minute to think about supporting the economy of a country and the rights of its workers?

The next time I see a T-shirt for £2.99 in the supermarket I might just think again…

Don't waste your energy!

It’s the middle of Energy Saving Week and the Energy Saving Trust has come up with a range of themes to encourage people to reduce their energy consumption by 20%.  The Trust is government and private sector funded and the website features calculators, space for comment and plenty of contact details, yet Combat Climate Change think that the event has attracted little attention and relatively few people have pledged to reduce energy usage. The latter organisation offers a no-nonsense approach to climate change information, and thinks that whether climate change concerns are real or not, we can all do our bit to improve the world we live in.  They also suggest that if we switched to low-energy bulbs we could save £1.5 billion annually and reduce CO₂ emissions by more than 7.6 million tonnes.

Get set for a busy birdfeeder!

A recent article published in Bird Study gives some explanation of the varying numbers of birds you may see on your bird feeder from year to year. Dan Chamberlain, Andrew Gosler and David Glue from the British Trust for Ornithology and the Edward Gray Institute of Field Ornithology, Oxford investigated whether woodland species that feed on beechmast (nuts of Fagus spp.) will have significantly lower occurrence rates at garden feeders in mast years (a year in which there is abundant production of fruit/nuts of trees considered as food for livestock and certain kinds of wildlife*). They monitored garden feeders between 1970 and 2000 for 40 species to assess whether beechmast abundance explained further significant variation additional to underlying seasonal and annual trends.

As you may expect, they found that the 7 species listed below (see end for photos), which commonly feed on beechmast, showed significantly lower occurrence in gardens in years of highest beechmast abundance:

1. Great Spotted Woodpecker (Dendrocopos major)
2. Woodpigeon (Columba palumbus)
3. Great Tit (Parus major)
4. Coal Tit (Periparus ater)
5. Nuthatch (Sitta europaea)
6. Jay (Garrulus glandarius)
7. Chaffinch (Fringilla coelebs)

Blackbird (Turdus merula) and Siskin (Carduelis spinus) showed similar significant patterns and are likely to take beechmast as elements of their diet.

Needle cast diseases on Christmas trees

Christmas tree growers are advised to be on the lookout for needle infections by fungal pathogens causing discolouration and defoliation. Severe cases of needle drop not only decrease tree value, but result in poor tree health and vigour. Although most conifers are somewhat susceptible to needle cast diseases, certain varieties of Scots pine, Douglas-fir and Spruce growing in locations favourable for disease may be severely affected.

Blogging from BCPC/IPPC 2007 - Call for Agrochem Education

Day Three of the BCPC Congress here in Glasgow and everything is in full swing. There's a full programme of seminars, meetings and posters, alongside a buzzing exhibition hall. The quality of freebie giveaways is pretty low, but can whoever is giving out the squeezy brain stress toys please make themselves known? The CABI stand has seen fantastic traffic, drawn in by the chance to win a free copy of the 2008 UK Pesticide Guide, no doubt.

One of the highlights for me so far came in the Opening Address speeches - a thought provoking half hour from Hampshire, UK farmer Sam Browne. His talk "Farming at the sharp end with a blunt instrument" made an interesting point about pesticide usage in modern farming: pesticides are considered by some (and yes, there is widespread opposition) to be the only reliable way to grow crops with sufficient calorific content to meet rising worldwide demand; pesticide companies make a wide variety of effective crop protection products that farmers can use safely; using these products can so easily make a farmer's produce poisonous and dangerous in the eyes of the public. Chemical pesticides are all Evil Chemicals, the name carries an, automatic connotation of toxicity, danger and indiscriminate death-dealing, regardless of whether safety studies have been adequately carried out. Mr Browne called for a portion of the agrochemical sector's profits to be spent on education, explaining to the public if and how safe pesticide usage can be achieved, and informing people everywhere to counter scaremongering.

It remains to be seen whether his pleas will be heard, but considering the size of this meeting and the number of agrochemical companies represented here, he probably picked the right place to have his say. Now, if you'll excuse me, I may have spotted someone to ask about those brains...

(Not-so-)Happy World Food Day!

Today is World Food Day. Or World Food Week. Or World Food Month, depending on which country you're living in. This year the event, which has been taking place since 1980, centres on the theme of 'The Right To Food' and is held each year on the anniversary of the Food and Agriculture Organisation's foundation in 1945.

The United Nations' Food and Agriculture Organisation has recognised the right to food as a major target since 1996 when it incorporated the statement 'it is the right to feed oneself with dignity rather than the right to be fed' into its portfolio of rights. Importantly, World Food Day 2007 is not about aid.

Finding that needle: searching tips

I've spent the last few months constructing ready made searches for Nutrition and Food Sciences on CAB Direct. Here are some general handy tips for choosing the words for searches that I have gathered on the way. This isn't the CAB Direct helpfile, you'll find that on CAB Direct.

Gardening in Microgravity

Long-term space missions would need plants for recycling carbon dioxide and oxygen and producing food. However, growing plants in space is a tricky business – some of the basic signs of over- or under-watering (wilting and flopping) are simply not present in microgravity, and water does not spread through the soil as it would on Earth. Mary Musgrave of the University of Connecticut spells out some of the difficulties in a paper in CAB Reviews.

Microgravity also affects pollination, and the direction of airflow is critical for some species. Similarly, the debris from plants as they go through their normal life-cycle has the potential to block up ventilation systems. Harvesting seeds is also problematic.

The research area on space stations for growing plants have typically been very small (960 cm2), and none have yet been grown for consumption, and so there is much still to learn. Musgrave points out the flavour of plants will be affected by microgravity too. Small plants adapted to low light intensity and high carbon dioxide are being developed which would be appropriate for space travel.

The paper "Growing plants in space" by M.E. Musgrave appears in CAB Reviews: Perspectives in Agriculture, Veterinary Science, Nutrition and Natural Resources, 2007, 2, No. 065, 9 pp.

Carbon offsets - whats the deal?

At the UNWTO Conference on Climate Change and Tourism I attended in Davos, Switzerland last week, participants were requested to offset the carbon dioxide emissions of their travel and accommodation. Not an unreasonable request given the subject matter of the conference, and the fact that the conference itself was free to attend. But as reported in this article on Swissinfo, the whole question of offsetting, and the lack of consistency and clarity in the many alternative schemes on offer, led to debate in and out of the Congress hall.

When one delegate said on the stage the amount he had paid to offset the 6 t of carbon the conference offsetting scheme calculated for a return flight from New York, Philippe Rochat from the Air Transport Action Group responded that he didn't know how the 6 t figure had been worked out, as it should actually be around 3 t. Checking just two offsetting companies while writing this article, Climatecare (used by British Airways) calculated emissions of just 1.43 tonnes of carbon dioxide for a return flight between New York and Zurich, at a cost of £10.74, when accessed via British Airways, and 1.76 t of CO2 when I went directly to the Climatecare website. Atmosfair.de, however, charge 83 Euros (approx £56) for a calculated 4.1 t of carbon dioxide.

Not mush-room for fungi in school

The British Mycological Society runs an excellent website called Fungi4Schools. Not a school lunches initiative as you might expect, it's a resource for teachers who are looking for ways to introduce information about fungi in all their many forms to students of all ages.

A quick investigation of the UK National Curriculum, and I'll admit I only had a quick search, found no mentions of fungi/fungus and only one of 'microbes' (at Key Stage 4, with respect to environmental energy and nutrient cycles). I've seen for myself that even students starting undergraduate biology courses at university often don't have a clue about fungi. Given just how important fungi are to the environment, crop protection, human health, biotechnology and more, it's odd that more effort isn't made to tell students about them.

I don't know whether it's the same story in schools everywhere. Maybe you can have your say in the comments and let me know!

Pine beetles continue marching east

If this press release is anything to go by, hard times in Canadian forestry are about to get harder. The Mountain Pine Beetle (Dendroctonus ponderosae) has been chomping its way through the lodgepole pines of British Columbia since a shortage of cold winters has allowed it to spread unchecked. The beetles spread the deadly "blue-stain" fungus, Ophiostoma minus, through the wood of the tree as they bore (in much the same manner as is Dutch-Elm Disease; in that case caused by Ophiostoma ulmi).

Controlled burns of forests in Alberta were planned, to halt the expansion of the epidemic out of BC, but wet weather has put that on hold. It'll be spring before new attempts can be made. Another warm winter could see the spread of the beetles further afield.

The Canadian Forest Service runs an excellent "Mountain Pine Beetle Program" site here, the introduction to which predicts "At the current rate of spread, 50 per cent of the mature pine will be dead by 2008 and 80 per cent by 2013." Clearly, these are nervous times for the forestry industry.

There's loads on the CAB Abstracts database concerning the MPB, Canadian forestry and the techniques of prescribed burning. If you're not a database subscriber, then you're in luck, as a good selection of abstracts on these subjects are free for you to view via Google Scholar, here - MPB and lodgepole pines in Canada.

Sympathy for the devil

Scientists working on trying to control the facial tumour disease which threaten to wipe out the Tasmanian devil (Sarcophilus harrisii) have increased their understanding the disease. The Tasmanian devil is the largest carnivorous marsupial remaining and is now found only on the island of Tasmania, having been exterminated from the Australian mainland. The disease that is threatening this endangered species is a transmissible neoplasm that grows on the face leading to death from starvation. These creatures, immortalized by the Looney Tunes cartoon  character ‘Taz, are about the size of a small dog and have a predisposition to aggressive behaviour, as well as unearthly screeching and raucous communal feeding that has earned them their name. Their aggressive behaviour is probably the most likely way in which the disease is transmitted, through biting as they fight over food and mates.

Devil facial tumour disease was first seen in 1995 and has caused between 20-50% reduction in the devil population. More than half of the State of Tasmania is affected. Two 'insurance' populations of disease-free devils are being established at an urban facility in the Hobart suburb of Taroona and on Maria Island off the east coast of Tasmania. The decline in devil numbers is an ecological problem, since its presence in the Tasmanian forest ecosystem is believed to have prevented the establishment of the Red Fox, illegally introduced to Tasmania in 2001. Foxes are a problematic invasive species in all other Australian States, and the establishment of foxes in Tasmania may hinder the recovery of the Tasmanian Devil.

The scientists from the University of Sydney School of Veterinary Science working on the disease are saying that the tumour probably arose from a single individual and has spread on to other devils. The immune system of the original animal probably did not recognize the tumours as foreign, and because Tasmanian devil population is now so genetically similar, their bodies do not recognize that the tumours are foreign cells and so do not attack them. Tasmanian devils have lost genetic diversity in the most important gene region for the immune system, the Major Histocompatibility Complex (MHC). The devils all had a similar MHC type to the tumour. There appears to be some similarities with a transmissible cancer of dogs (canine transmissible venereal tumour).

There is a pilot program on the Tasman Peninsular where all the diseased devils captured are killed. There is currently no test for infected animals that do not yet show the neoplasm, so it is only those showing visible signs of the disease that are removed. There seems to be some evidence that this is working to protect the overall population, because, over time, the average age of the animals they capture has become older, suggesting that more animals are avoiding the cancer and surviving longer. But the program is expensive, and it is not clear how effective the programme will be in stopping the disease.

The problem seems, then, to be a result of the lack of genetic diversity in a small population. There are many other endangered species of wildlife that have populations as small or smaller and could suffer the same fate, falling to new or emerging diseases. Looking through the CAB Abstracts Database to see if there was any other information on biodiversity threatened by disease, I came across a paper by Maillard and Gonzalez entitled Biodiversity. The problems caused by lack of genetic diversity in making the population open to infectious organisms are described. The disease in the Tasmanian devil shows that certain neoplasms can also exploit the restricted gene pool.

Maillard, J. C.; Gonzalez, J. P. 2006. Biodiversity and emerging diseases. Annals of the New York Academy of Sciences, 2006, Vol. 1081, pp. 1-16 Record No: 20073114695

World tourism leaders tackle climate change

Earlier this week, some 600 representatives from over 100 countries, representing all sectors of the tourism industry (public and private sector, NGOs and governments) met in the idyllic Swiss resort of Davos to debate the  global challenge of climate change as it affects and is affected by tourism, at the 2nd International Conference on Climate Change and Tourism. This meeting was organised by the United Nations World Tourism Organisation (UNWTO) in collaboration with UNEP and the World Meteorological Organisation, and included many senior tourism figures. As CABI is a leading information provider in both environmental and tourism literature, I was lucky enough to be able to attend, both to learn more about the issues and consider what contribution CABI may be able to make in the area of information dissemination – one of the components of the Davos Declaration which was drafted at the end of the conference.

To give a full picture of the debate at the conference, and the issues involved, would take a book rather than a blog entry. But I’ll try and give a very broad-brush overview of the issues and conclusions, and will be presenting more detail of some of the ideas presented in CABI’s subscription website, Leisuretourism.com, over the next few days for those whose institutions are subscribers. There were some very impressive presentations at Davos from some leading figures in both the public and private sector, and it was heartening to see areas where governments and private companies are starting to take real action. It was clear that the tourism sector recognises the need for action, not least to avoid being used as a scapegoat for climate change and the target for kneejerk response, as is increasingly the case in some European countries (the UK’s Prime Minister Gordon Brown’s ears may have been burning, as speaker after speaker attacked his doubling of Air Passenger Duty, without designating the revenue raised for any positive action on transport, the environment or climate).

The Blandford Fly is not confined to Blandford (and other interesting facts about blackflies)

Although the weather has become quite autumnal in the last week or so, the mosquitoes which have been flying around my house in the evenings in unusually high numbers in recent weeks (fortunately without biting me much) have not yet disappeared, and have reminded me of an interesting article¹ that I came across earlier in the year about another biting insect. The blackflies (Simuliidae) are a significant nuisance in many parts of the world -- my aunt who lives outside Montreal in Canada has friends in the city who do not visit her during the blackfly season -- and in some places they are an even more serious problem. Adverse reactions to large numbers of bites have killed many livestock, for example around the Mississippi and Danube rivers prior to changes in river management that eliminated the flies' breeding sites². The most serious effect of blackflies on human health is the transmission of river blindness (onchocerciasis) caused by the nematode worm Onchocerca volvulus in parts of Africa and (to a lesser extent) South America.

In Britain, blackflies are not usually a major problem, and there is just one species that causes significant trouble to people, namely the Blandford Fly, Simulium posticatum. This is moderately well known for biting people in parts of Dorset, and takes its common name from the town of Blandford Forum, where the local brewery has even named a beer after it. The article that prompted me to write this piece indicated, to my surprise, that it has been recorded over much of southern and eastern England, including a second concentration just to the north of Oxford, not many miles from the CABI offices; apparently it is known locally as the 'Stonesfield Stinger' or the 'Woodstock Fly' after a village and a town in the area. I didn't visit this area during the blackfly season (late April to mid June) this year; if I do next year I will have to decide between covering myself with insect repellent to avoid the unpleasant consequences of a bite, which can include severe irritation, pain, swelling and blistering³, and leaving an easily visible area of skin uncovered in the hope of seeing this insect that I have, in writing this, read so much about.

My search of CAB Abstracts, the CAB Abstracts Archive and one or two other sources for information about S. posticatum, and other Simulium species in Britain, revealed a number of other interesting facts that I hadn't previously known. In 1989 there was a case of meningitis suspected (but not proven) to have been linked to a bite from this species⁴; the biological pesticide Bacillus thuringiensis var. israelensis is now used in Dorset to control the larvae of the fly^3,5,6 (one of a comparatively small number of instances where this widely used biopesticide has been used in the UK) and has reduced human biting rates by 99%³; the great majority of  S. posticatum females in fact bite species other than humans⁷ (just as well for us); onchocerciasis, transmitted by different species of blackfly, is found in cattle in Britain⁸, but does not appear to cause any significant symptoms⁹; and in the early twentieth century, before it was found to be a nutritional deficiency disease, pellagra was suspected to be transmitted by blackfly bites¹⁰.  Perhaps I or one of my colleagues might investigate one of these further for a future blog entry.

BSE: Twenty years old

Twenty years ago, a paper appeared in the Veterinary Record recording a new disease in dairy cattle. The syndrome had been seen in cattle in England for a couple of years but with the publication of the paper by Wells and others, the disease was described and named, and the new term bovine spongiform encephalopathy (BSE) entered the English language. This official name soon gave way, in the media, to the more catchy term mad cow disease.

Few people reading that original paper back in October 1987 could have imagined the full consequences of the outbreak as it grew to a peak of more than 30,000 cases in cattle in 1992. Public distrust of the government and scientists also grew, as original claims for the safety of beef were shaken by the arrival of a new form of Creutzfeldt-Jakob disease (v-CJD) in humans. The prospect of an epidemic of v-CDJ in humans on the scale of the BSE outbreak in cattle was truly terrifying to consider. The annual number of v-CJD cases in the UK rose to a peak of 28 in the year 2000, after which it has gradually decreased. Thankfully the epidemic of new-variant CJD did not reach the levels of BSE in cattle, although this was of little consolation to the families of the victims of that terrible disease. To restore public confidence in British beef and to recapture export markets, which had been closed, cattle over 30 months old were excluded from the food chain and stringent regulations on ruminant protein in cattle feed were enacted. The epidemic in the UK became the most expensive peace-time crisis for the Government.

The arrival of BSE and v-CJD prompted an upsurge of research on the causes and pathogenesis of these diseases, and their relationship to other similar diseases such as scrapie and chronic wasting disease of deer. The theory most widely accepted is that the disease is caused by an abnormal form of a protein, the prion protein, which is resistant to both heat and protease enzymes. The abnormal prion accumulates in the cells of the nervous system, causing nervous symptoms and finally death. The affected brain tissue takes on a spongy appearance. The abnormal prion protein appears to act like an organism, being able to replicate itself. The disease appears to be transmitted to cattle (and other species) from the practice of including ruminant protein in feed.

Although there is a substantial body of evidence to support this theory (not least the decline of the UK epidemic following the removal of ruminant protein from cattle feed) there have been several other possible causes suggested, including viruses, bacteria, and chemicals. For example, one suggested cause of the disease was organophosphates, as UK farmers were obliged to use these pesticides to combat warble fly. Although the organophosphate theory sounded plausible, attempts to create BSE experimentally using the pesticides failed in tests on cattle, so there has been no clear experimental evidence to support that theory. Another theory suggested that the infectious protein originated from human remains (rendered protein imported from India) included in cattle feed.

Other theories have included infectious agents as the cause. One such theory is that the disease is caused by bacteria and that prions are involved in the pathogenesis but are not the cause. A paper recently published in the Journal of Medical Microbiology (DOI 10.1099/jmm.0.47159-0) claims that Spiroplasma, small wall-less bacteria, can induce spongiform encephalopathy in ruminants.
The paper reports on experimental work carried out in Baton Rouge, Louisiana, where Spiroplasma mirum isolated from rabbit tick was inoculated into the brains of deer, sheep and goats. The deer developed nervous system symptoms and showed post-mortem signs of spongiform encephalopathy. Sheep and goats did not show nervous symptoms but post-mortem examination of their brains showed clear signs of progressive spongiform encephalopathy. Spongiform encephalopathy was also induced in deer and sheep inoculated with Spiroplasma isolated from brains of sheep and goats with the disease.

The idea that bacteria are behind transmissible spongiform encephalopathies (tSE) is also suggested in another recent paper, by another author. H. Peter Schmitt of Heidelberg University (Germany). He suggests that rather than the bacteria themselves, it is the bacterial toxic proteins (BTPs) that cause tSEs and diseases such as Alzheimer’s disease. His theory is that BTPs can meet the key-proteins of Alzheimer’s disease (AD) and tSEs in the lipid-rich domains of the plasma membrane called rafts. This then could enable them to start a large variety of unfavourable molecular events, eventually resulting in pathogenic cascades as in AD and the tSEs. The reasoning involves some pretty complicated biochemistry which would be out of place in a blog like this, but the reference is listed below for those who are not deterred by biochemical detail.

So are tSEs caused by prions, bacteria, bacterial proteins, organophosphates or some combination of these? Even looking through the published evidence (there are nearly 5000 references on BSE, scrapie and the other tSEs on the CAB Abstracts Database) one is always left with the feeling that there is some vital part of the story missing. The 20 years of research has certainly increased the understanding of these strange and terrifying diseases, but there is still much more to learn about them. I suspect that in 20 years time (unless the BTPs have got me) I will still be seeing new theories trying to explain BSE, CJD and the other tSEs.


Wells, G. A.; Scott, A. C.; Johnson, C. T.; Gunning, R. f.; Hancock, R. D.; Jeffrey, M; Dawson, M.; Bradley, R., 1987. A novel progressive spongiform encephalopathy in cattle. Veterinary Record, Oct 1987; 121(18), 419 - 420.

Schmitt, H. P. 2007. Profiling the culprit in Alzheimer’s disease (AD): Bacterial toxic proteins – Will they be significant for the aetio-pathogenesis of AD and the transmissible spongiform encephalopathies? Medical Hypotheses 69 (3), 596-609. DOI:10.1016/j.mehy.2007.01.022 

Bastian, F.O.Sanders, D. E.; Forbes, W. A.; Hagius, S.; Walker, J. V.; Henk, W. G.; Enright, F. M.; Elzer, P. H. Sproplasma spp. 2007. From transmissible spongiform encephalopathy brains or ticks induce spongiform encephalopathy in ruminants. Journal of Medical Microbiology, 56, 1235-1242. DOI 10.1099/jmm.0.47159-0