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Buzzkill: Arabica coffee plantations under increasing threat from the effects of climate change

Note that this content is from an article I wrote as part of my BSc degree in 2014. The latest reports indicate that coffee production and consumption have both increased since the slump of 2013 – 2016, while prices have shown a downward trend. Despite this, I think that the article remains relevant especially concerning coffee production and means of mitigating the inevitable effects of climate change.

Originating in the horn of Africa with cultivation possibly starting in Yemen around six
centuries ago, coffee is now one of the most popular hot drinks worldwide1. After oil, coffee is the world’s second-most traded commodity with 93.4 million bags, worth a staggering US $15.4 billion (£9.27 billion) exported from coffee-growing countries in 2009/2010. Now it seems that the world’s coffee-producing regions may be under threat from the effects of climate change, according to Aaron Davis and Justin Moat from Kew.

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By all accounts, we love our coffee, with nearly a third of the world’s population drinking it. The USA imported almost 27 million bags between November 2012 and October 2013 while the UK imported around 4 million bags over the same period, according to the International Coffee Organization (ICO). In total, worldwide imports for the 2012/2013 coffee season were an astonishing 133.9 million bags.

Reduction in productivity, increased and intensified management, and crop failure.

Of the 125 species of coffee plants found naturally, the two main types used in the production of coffee are arabica and robusta. Originally from the high-altitude, humid evergreen forests of Ethiopia and South Sudan, arabica is known to be climate sensitive with an ideal average temperature of between 18°C and 23°C and well-defined rainy and dry seasons. Arabica coffee is now grown in 52 countries worldwide. Robusta, as its name implies, is more comfortable with higher temperatures and produces a greater crop yield than arabica. With its higher caffeine content and more bitter flavour, robusta tends to be used in instant coffees while arabica is considered superior in quality and taste making up 70% of all commercially produced coffee. There are now thought to be around 26 million people working in the coffee sector worldwide. Our demand for coffee has never been greater and yet a series of climate-linked and interrelated problems such as increased temperature, unpredictable rainfall, the spread of insect pests and diseases, intensive farming, and urbanization could spell the end of coffee as we know it.

It’s getting hotter

Ethiopia (the fifth largest global exporter of coffee and Africa’s main coffee-producing nation) was used as an example by Davis and Moat when they looked at the possible future distribution of arabica coffee. They based their findings on the Intergovernmental Panel on Climate Change’s (IPCC’s) best estimates of anticipated temperature rises of 1.8°C to 4°C in global temperatures by the end of the twenty-first century and found that coffee production was likely to decrease significantly. Worryingly, they also found that there would be less land that is suitable for growing coffee, saying that it would lead “…to a reduction in productivity, increased and intensified management…and crop failure.”

Countries whose economies depend heavily on agriculture for their development may be hardest hit by a change in climate.

Responding to warming temperatures, some farmers are starting to grow their crops further up hillsides and mountain slopes. At higher elevations, where the temperature is slightly cooler, the arabica plants thrive once again. It is, however, harder to farm at higher altitudes and we cannot keep going up the mountains, we’ll simply run out of farmable land. There is also expected to be a climatic shift in latitudes so that the tropics and subtropics effectively move away from the equator, but this is incredibly difficult to predict because of air currents, ocean currents and local geography all affect this and act on one another. In a report by the International Trade Centre (ITC) entitled ‘Climate Change and the Coffee Industry’ the authors note that any shift in altitude or latitude may adversely affect the quality of the coffee and fewer parts of the world may end up being able to support arabica coffee production.

Unpredictable rainfall

As air and ocean temperatures rise, it is likely that wet areas will get wetter and dry areas will get drier according to both the ITC and IPCC. This is the rule-of-thumb measure for regions, but there is also expected to be far more variability; that is, more extreme droughts and more heavy rainfall. The increased warming will mean that for every 1°C increase in temperature the plants and animals that live in a certain area because the climate conditions are perfect for them there will have to shift by 160 km (about the distance between Birmingham and London as the crow flies) north or south, following those perfect conditions. In the case of some island nations a 160 km shift could be catastrophic. We should expect more humidity and higher rainfall to accompany the hotter tem- peratures. The seasonal and geographical rainfall and temperature patterns that we have all grown used to will change because of these shifts. This is of course incredibly bad news for arabica which needs quite particular weather conditions.

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Intensive farming methods

The way in which the coffee is grown can also contribute to some difficulties. Traditionally, coffee was grown under taller trees and shrubs of different heights with a large mix of plant species. This meant that the coffee plants grew in shade and that the soil was rich with the nutrients of all of the accumulated dead plant matter. On a number of farms this method of growing has been abandoned in favour of plantation-style planting which means that the farmer can squeeze more plants into an area and improve the size of the yield. This involves clearing the land by chopping down the trees, sometimes burning, and planting sun-resistant varieties of coffee that have been bred to tolerate growing in direct sunshine. This intense planting regime also requires the addition of many tonnes of expensive man-made fertilizers and chemical controls such as fungicides and pesticides every year. These changes in production practices have been found to exacerbate the problems associated with coffee-growing according to Juliana Jaramillo, from the Institute of Plant Diseases and Plant Protection, at the University of Hannover in Germany. Studying a coffee-producing area near Nairobi in Kenya, Jaramillo and her colleagues found that open plantations were 2°C higher than shaded ones. Obviously, the associated warmer temperatures are a problem for arabica growing, but it can also present coffee-growers with a whole new set of problems. The increased exposure to heavy rain can lead to nutrients being leached out of the soil, soil conditions quickly deteriorate leading to soil erosion, and in the worst cases, water run-off that turns into floods and landslides. This becomes a cyclical problem, as crops fail or yields decrease, more intensification occurs to make up the shortfall and worsens the conditions.

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The spread of insect pests & diseases

As with any crop plant, coffee can suffer from attacks by insect pests and diseases. With even small temperature rises and changes in rainfall patterns, these pests and diseases become more common and more difficult to control. The coffee berry borer beetle is the most destructive pest of commercially grown coffee, causing crop losses of more than US $500 million (£300 million) per year. These beetles actually benefit from increases in temperature. Based on a 1°C temperature rise over the next 50 years, Jaramillo expects to find the beetles reproducing faster and spreading further. Even now the insects are being found 300 metres higher up the slopes of Mt. Kilimanjaro in Tanzania than where they used to be ten years ago.

A devastating outbreak of coffee leaf rust in Central America was reported by Reuters News Agency in July 2013. The rust is very damaging to crop yields and was responsible for a 15% drop in production from the region last season with even worse effects expected for 2013/2014. Warm temperatures and high humidity are ideal conditions for the rust to spread, but it also needs the leaf that it is colonising to be wet to be able to first become established. Increased warming and heavier than usual rainfall in the region has created the perfect incubator for the rust. Ironically, another fungus, the white halo fungus, which attacks and partially controls the spread of the rust
has been wiped out by the systematic spraying of chemicals. “What we feel has been happening is that gradually the integrity of this once-complicated ecosystem has been slowly breaking down, which is what happens when you try to grow coffee like corn,” said US ecologist John Vandermeer.

The integrity of this once- complicated ecosystem has been slowly breaking down.

Rather than responding to temperature rises, the coffee white stem borer beetle, a major coffee pest in Zimbabwe, is becoming more common because of changes in rainfall. Adult beetles emerge from the infested coffee plants in the rainy season and with increased periods of rainfall up to 200% more beetles are expected there by the year 2080 says Dumisani Kutywayo and colleagues from the Coffee Research Institute (CRI). A quarter of Zimbabwe’s yield losses are due to infestation by coffee white stem borer and as rainfall patterns become more unpredictable and seasonality shifts, coffee farmers’ outlook can only be described as gloomy.

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What is to be done?

In the face of catastrophe, all is not lost. The planting of coffee plants under a mixed canopy of plants has shown time and again to be a very effective model for controlling temperature. This form of planting is known as agroforestry and apart from creating more favourable conditions for coffee growing also allows the farmer to grow an additional crop such as bananas. This model is already in use across the coffee-growing world and as Helton Nonato de Souza from the Department of Soil Quality, Wagenin- gen University in The Netherlands explains: agroforestry creates shade, maintains a cooler air temperature, improves the condition of the soil, retains soil moisture, and limits damage from high rainfall. In their study area in the Brazilian Atlantic Rainforest, de Souza and his team also identified not only a vast array of tree species average of 60% greater biodiversity than the surrounding forests.

This species richness is an invaluable part of a healthy ecosystem and contributes to the well being of the coffee plants through biological controls. Pests and diseases can be controlled by their natural predators instead of chemicals as long as we provide a space for them to live according to the US ecologist, Daniel Karp.

There is also ongoing research into developing new breeds of arabicas that are less heat-sensitive or show more resistance to pathogens and diseases. Returning to the birthplace of coffee; some coffee plants with resistance to extremes in temperature have recently been found in the Ethio- pian Great Rift Valley.

90% of all coffee production is located in the developing world.

Screenshot 2018-09-29 at 11.47.33.pngAll the signs regarding arabica coffee growing in an age of global climate change are troubling. We must expect that production will probably decrease, that quality may be affected, prices will rise, and that the livelihoods of millions of people are at risk. With many farmers finding conditions more difficult with less income, there is the real risk that intense production of higher-income cane sugar, palm oil, cocoa leaf or khat replace coffee. What is needed is a reevaluation of the pricing structure of coffee linked to new patterns of behaviour that value the wider natural system within which it is grown. With the fair financial support of consumers, coffee farmers will be able to take steps to protect their livelihoods from the devastations of unpredictable rainfall, increasing temperatures and the growing abundance of pests and diseases. There is now an opportunity for more farmers to embrace small-scale, shade-grown coffees that will benefit the wider environment, keep their businesses sustainable and keep producing good quality coffees.

As a Roaster from a coffee company in London said in an interview for this article: “The consumers have the knowledge, the power and the resources to do something proactive. If the consumer is willing to pay more from an ethical company … then the farmers have the resource to invest in strategies that will help to mitigate the issue [of climate change].

References:

Kew Royal Botanical Gardens http://www.kew.org/plants-fungi/Coffea-arabica.htm Last accessed 04/03/142

International Coffee Organization http://www.ico.org/prices/m1.htm Last accessed 01/03/14

Davis AP, Gole TW, Baena S, Moat J (2012) “The Impact of Climate Change on Indigenous Arabica Coffee (Coffea arabica): Predicting Future Trends and Identifying Priorities.” PLoS ONE 7(11): e47981. doi:10.1371/journal.pone.0047981

US Department of Agriculture (2013) “Coffee: World Markets and Trade”http://apps.fas.usda.gov/psdonline/circulars/coffee.pdf Last accessed 22/02/14

Kasterina A, Scholer M, and van Hilten HJ. (2010) “Climate Change and the Coffee Industry.” International Trade Centre http://www.intracen.org/uploadedFiles/intracenorg/Content/Exporters/Sectoral_Information/Agricultural_Products/Organic_Prod ucts/Climate-Coffee-Ch-13-MS-ID-3-2-2010ff_1.pdf

Wexler A. “Arabica-Coffee Prices Climb to 16-Month Highs.” Wall Street Journal 19/02/2014http://online.wsj.com/news/articles/SB10001424052702303775504579392853470572772 Last accessed 26/02/14

Jaramillo J, Setamou M, Muchugu E, Chabi-Olaye A, Jaramillo A, et al. (2013) “Climate Change or Urbanization? Impacts on a Traditional Coffee Production System in East Africa over the Last 80 Years.” PLoS ONE 8(1): e51815. doi:10.1371/journal.pone.0051815

Kutywayo D, Chemura A, Kusena W, Chidoko P, and Mahoya C. (2013) “The Impact of Climate Change on the Potential Distribution of Agricultural Pests: The Case of the Coffee White Stem Borer (Monochamus leuconotus P.) in Zimbabwe.” PLoS ONE 8(8): e73432. doi:10.1371/journal.pone.0073432

de Souza HN, de Goede RGM, Brussaard L, Cardoso IM, Duarte EMG, Fernandes RBA, Gomes LC, and Pulleman MM. (2012) “Protective shade, tree diversity and soil properties in coffee agroforestry systems in the Atlantic Rainforest biome.” Agriculture, Ecosystems and Environment. 146, 179-196

Jaramillo J, Muchugu E, Vega FE, Davis A, Borgemeister C, et al. (2011) “Some Like It Hot: The Influence and Implications of Climate Change on Coffee Berry Borer (Hypothenemus hampei) and Coffee Production in East Africa.” PLoS ONE 6(9): e24528. doi:10.1371/journal.pone.0024528

Nicholson M. “Central American coffee leaf rust sends roasters to new markets for beans.” Reuters News Agency 10/07/2013http://www.reuters.com/article/2013/07/10/coffee-fungus-supply-idUSL2N0EV20S20130710 Last accessed 01/03/14

Jackson D, Skillman J, and Vandermeer J. (2012) “Indirect biological control of the coffee leaf rust, Hemileia vastatrix, by the entomogenous fungus Lecanicillium lecanii in a complex coffee agroecosystem.” Biological Control. 61:1, 89-97

Erickson J. “Modern growing methods may be culprit of ‘coffee rust’ fungal outbreak.” Michigan News: University of Michigan. 12/02/2013http://www.ns.umich.edu/new/releases/21192-modern-growing-methods-may-be-culprit-of-coffee-rust-fungal-outbreak

Karp DS, Mendenhall CD, Sandi RF, Chaumont N, Ehrlich PR, Hadly EA, Daily GC. (2013) “Forest bolsters bird abundance, pest control and coffee yield.” Ecology Letters. 16:11, 1339-1347

Gonthier DJ, Ennis KK, Philpott SM, Vandermeer J, and Perfecto, I. (2013) “Ants defend coffee from berry borer colonization.” BioControl: Journal of the International Organization for Biological Control. 58:6, 815-820

The Walking (Un)Dead: Zombie ants and the strange effects of parasitic fungi on ant behaviour​.

In the understorey of a tropical forest, a carpenter ant, of the species Camponotus leonardi, has descended from the canopy away from her regular foraging trails and staggers drunkenly along a branch. Her movements are jerky and conspicuous. She twitchily moves forwards and suddenly starts convulsing with such ferocity that she falls from the branch onto the ground before again taking up an erratic fitful path that zigzags and circles back on itself. Around noon, after several hours of climbing and aimless lurching (now no more than about twenty-five centimetres above the ground) the ant finds herself on the underside of a sapling leaf where, without warning, she forcefully sinks her mandibles into one of the leaf’s veins, gripping it firmly between her tightly locked jaws. Within six hours the ant is dead.  After two days, white hairs bristle from between her joints and a few days later these have become a brown mat covering the whole insect and a pinkish-white stalk has started to erupt from the base of the ant’s head. The stalk continues to grow and within two weeks it has reached twice the length of the ant’s body reaching towards the ground below.

This is a description of a “zombie-ant”, part of the life-cycle of a parasitic fungus, Ophiocordyceps unilateralis. This bizarre behaviour was first recorded by Alfred Russell Wallace in Sulawesi in 1859, but was not researched in much detail until quite recently. It has since been discovered that the fungus disrupts the normal behaviour of the ant through chemical interference in the brain, causing the infected ant to behave in ways that will improve the fungus’ opportunities to spread its spores and so reproduce. The fungus grows throughout the body cavity of the ant, using internal organs as food while the ant’s strong chitonous exoskeleton serves as a kind of capsule, protecting the fungus from drying out, being eaten, or further infection.

The earliest known record of a fungus visibly parasitizing an insect dates from about 105 million years ago, it is a male scale insect, preserved in amber, with two fungal stalks projecting from its head. But this fossil cannot tell us if the infected insect’s regular behaviour was changed or disrupted in any way.  Evidence of “Zombie-ant” behaviour dates from around 48 million years ago from fossilised leaves that show the distinct markings on either side of leaf veins left by the lock-jawed mandibles of Eocene epoch ants. This association is evidently ancient and seemingly very common, with about 1,000 species of fungal parasites of insects known to exist today. These fungal pathogens have evolved to become either strictly species-specific or more generalist in their target insects, with some able to infect hundreds of different species. The variety of fungal pathogens and potential hosts has created some peculiar behaviours in insects which have most likely co-evolved with the fungi.

It is sometimes difficult to know which of these insect behaviours are entirely involuntary and driven by the fungus to improve its own reproductive success; and which the insects have evolved as a form of defence against infection. One of these unresolved odd behaviours is when the ant host climbs to an elevated position in what is known as “summit disease”. This increases the area over which spores can spread through wind dispersal, and removes the ant from close proximity with its colony or relatives. It is unclear if this behaviour is a zombie state caused by the fungus or if it is an altruistic act of self-sacrifice by the ant. By moving to an area away from its relatives it might be saving the rest of the colony from the immediate spread of infection by what is sometimes called “adaptive suicide”.

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In this age-old struggle for survival the ants have developed adaptations to protect themselves and their nests from fungal infections. Grooming themselves and socially cleaning each other, allogrooming, they remove potentially harmful spores before these can penetrate the cuticle and take hold. Some ants spray poison in their nests to act as fungicides and if that fails to stop an infestation, they partition their nests by sealing off contaminated chambers. In some cases infected individuals are carried out of the nest by healthy workers; and as a last resort the entire colony relocates, abandoning the nest.

Zombie-like behaviour in insects is also caused by other types of parasites including bacteria and even other invertebrates. Such parasites are extreme versions of the multitudes of microscopic organisms that exist in and on all living things. This raises fascinating questions about the nature of any organism’s true independence in what are undoubtedly highly complex interrelated living systems. Zombie-ants provide us with a glimpse into this intricately tangled-web of molecular influences and behavioural adaptations – often leading us to wonder: who, ultimately, controls whom?

 

References:

  1. Andersen, S.B., Gerritsma, S., Yusah, K.M., Mayntz, D., Hywel-Jones, N.L., Billen, J., Boomsma, J.J. and Hughes, D.P. (2009) The Life of a Dead Ant: The Expression of an Adaptive Extended Phenotype. The American Naturalist, 174(3): 424-433.
  1. Hughes, D.P, Andersen, S.B., Hywel-Jones N.L., Himaman W., Billen, J. and Boomsma J.J. (2011) Behavioral Mechanisms and Morphological Symptoms of Zombie Ants Dying from Fungal Infection. BioMed Central: Ecology, 11(13).
  1. Pontoppidan M.-B., Himaman W., Hywel-Jones N.L., Boomsma J.J. and Hughes D.P. (2009) Graveyards on the Move: The Spatio-Temporal Distribution of Dead Ophiocordyceps-Infected Ants. Public Library of Science: ONE, 4(3): e4835.
  1. Shang, Y., Feng, P. and Wang, C. (2015) Fungi That Infect Insects: Altering Host Behaviour and Beyond. Public Library of Sciences: Pathogens, 11(8): e1005037
  1. Hughes, D.P., Wappler, T. and Labandeira C.C. (2010) Ancient death-grip leaf scars reveal ant–fungal parasitism. Biology Letters, 7: 67-70.
  1. Roy, H.E., Steinkraus, D.C., Eilenberg, J., Hajek, A.E. and Pell, J.K. (2006) Bizarre Interactions and Endgames: Entomopathogenic Fungi and Their Arthropod Hosts. Annual Review of Entomology, 51: 331-57
  1. Bekker, C. de, Quevillon, L.E., Smith, P.B., Fleming, K.R., Ghosh, D., Patterson, A.D. and Hughes, D.P. (2014) Species-Specific Ant Brain Manipulation by a Specialized Fungal Parasite. BioMed Central: Evolutionary Biology, 14(166).

All images ©Alex Wild http://www.alexanderwild.com

Faking it as a survival strategy

224139Cheats and Deceits: How animals and plants exploit and mislead. By Martin Stevens. Published by Oxford University Press (2016).

Last year, on a trip to Devon, I saw my first ever oil beetle (Meloe proscarabaeus). She was beautiful. Her black carapace glistened violet and blue in the sunlight. She was gravid and crawling along the footpath in search of a place to dig a nest burrow to lay her eggs. But what I did not yet appreciate was the extraordinary life cycle of these captivating beetles. The young of a related species, Meloe franciscanus, emerge from the nest and swarm up a nearby plant where they congregate in a mass mimicking the shape of a female solitary bee (Habropoda pallida) and release a chemical compound similar to the bee’s sexual pheromones.  This proves all too irresistible to male bees who are drawn to this aggregation and attempt to mate with it, presenting the larvae with the perfect opportunity to grab hold of the bee and clamber onto his back.  He then carries these passengers with him until he finds a female to mate with at which point the larvae instantly decamp onto the female. From here they then transfer to her nest where they devour the stored nectar, pollen and the bee’s eggs. The evolution of this complex mimicry is absolutely fascinating and forms part of Martin Stevens‘ interrogation of deception in Cheats and Deceits: How animals and plants exploit and mislead.

This book is an immensely informative and enjoyable exploration of the multiple roles deception plays in nature. Stevens sets out a detailed examination of a wide variety of instances of natural deception from well documented examples such as the evolution  of camouflage through industrial melanism in the Peppered Moth (Biston betularia) to current research into the resemblance to falling leaves in the movement and colouration of Draco cornutus, a gliding lizard from Borneo. It is to Stevens’ credit that this book makes for entertaining and effortless reading while clearly citing all the relevant research within context and pointing to areas where knowledge is still lacking.

The language of deception is important. Stevens takes the time to explain some of the more commonly used terms associated with deception such as camouflage (blending in to the environment), mimicry (assuming the appearance – be that visual, chemical, behavioural or acoustic – of another organism) and masquerade (taking the form of an inedible object – as with stick insects). Mimicry and masquerade therefore lead to misidentification while camouflage reduces detectability or impairs recognition. Mimicry also comes in various guises some of which can be described as: aggressive, when predators mimic harmless species to enable prey capture; Batesian, when a palatable species mimics the characters of an unpalatable species, as seen in the chicks of an Amazonian bird Laniocera hypopyrra mimicking toxic caterpillars; and imperfect mimicry, as with hoverflies roughly resembling certain species of wasps and bees (for which there are a number of competing theories).

This, of course, only scratches the surface of a vast area of research that Stevens specialises in as head of the Sensory Ecology and Evolution group at the University of Exeter where he continues to research these themes. His enthusiasm for his topic is highly infectious; you find yourself transported from an explanation of background matching in cuttlefish, to an historical aside concerning the development of military camouflage, and on again to a description of his own field experiments in testing the efficacy of disruptive colouration.

“We must trust to nothing but facts: these are presented to us by nature and cannot deceive. We ought, in every instance, to submit our reasoning to the test of experiment, and never to search for truth but by the natural road of experiment and observation.” ~ 18th-century chemist Antoine Lavoisier

The book does rely heavily on zoological examples, and although Stevens doesn’t entirely neglect plants his observations do tend to mainly focus on carnivorous plants and orchids. But to be fair, Stevens does make the point that more research into botanical forms of deception is required and suggests that this should be undertaken with a view to specifically exploring the roles of chemical signalling and sensory exploitation. One of the examples cited in the book is the orchid Epipactis veratrifolia which attracts female hoverflies to lay eggs on the plant by releasing chemicals that mimic the alarm pheromones of aphids (the food source of hoverfly larvae). This may rather be a means by which the orchid exploits an inbuilt perceptual preference for chemicals associated with hoverfly larval food sources – either way the plant is deceiving the insect in order to  ensure protection from aphid infestation.

A form of deception more commonly associated with orchids is that of exploiting male insects to pollinate plants by mimicking the female form through the shape and colouration of the flower. However, Stevens points out that this mimicry is sometimes (as in Cryptostylis orchids) not particularly convincing to human eyes, but is overwhelmingly so to the male wasp which tries to mate with the flower and thus collects the pollinium which will be deposited at the next Cryptostylis flower that he visits. With this example (as with the oil beetle, among others) the author cautions researchers of deception in nature to be aware of anthropocentric biases that may arise through our observations and study, and to (wherever possible) approach our subjects in the manner and with the senses of the deceived species.

I am utterly delighted and inspired by this book and am certain that I will return to it again and again as a point of reference. I have no hesitations in highly recommending it to researchers, field naturalists and those with a passing interest in natural history.

Postscript

At the time of writing, Phil Torres and Aaron Pomerantz have discovered and documented kleptoparasitism of ants in a species of butterfly (Adelotypa annulifera) in the Peruvian Amazon which they believe might mimic ants through their wing patterns. This seems to me an ideal opportunity for further research looking at visual and chemical mimicry given both the wing patterns and larval associations.

Getting down and dirty with the Earthworm Society of Britain

I attended the Earthworm Society of Britain‘s annual general meeting at Cannock Chase Forest where I got to meet fantastic amateur enthusiasts, very knowledgable naturalists with a general interest in worms, and some hardcore earthworm specialists. It was an immensely enjoyable couple of days of field recording in various habitats found here including broadleaved woodland, grassland and heath as well as microhabitats such as dead wood.

“It may be doubted whether there are many other animals which have played so important a part in the history of the world, as have these lowly organised creatures”. Charles Darwin

Since Darwin’s observations and experiments with earthworms was first published in 1881 under the title The Formation of Vegetable Mould, Through the Action of Worms, With Observations on Their Habits a new area of little-known research relating to these fascinating creatures was born. Despite this, we still find a lamentable lack of data regarding the distribution of earthworms throughout the UK and are continuing to research the ecosystem-wide implications of their below-ground activity.

In attending the society’s field day and AGM I was curious to find whether earthworms would pique my interest as a naturalist and scientist or whether I had developed a nostalgic yearning for simpler times. I have vivid memories of when, as a child, I would gingerly lift the edge of the damp burlap sack to scoop out trowel-fulls of fusty earth from half an oil drum in which my grandfather bred earthworms to bait his fishing hooks. I think the answer is that they are probably both true. This area is rich for contributions to research and recording while also being a great opportunity to get my hands stuck in some dirt and forget about my everyday worries. And when Amy Stewart so eloquently points out in response to the relevance of Darwin’s research and the significance of earthworms, that they’re “…only carrying out the natural order of things, folding the ruins of a farm, a city, or a society into the lower strata of the earth. When our civilizations end, and when we as individuals die, we don’t ascend, not physically. We descend. And the earth rises up to meet us”, how could I resist?

Day 1

Looking for earthworms is a messy affair and you have got to be prepared to get dirty. Armed with spades, sorting trays and all-weather gear we set out to see what the various sites had to offer.

ESBWe started with the damp, waterlogged woodland near  the classroom we had booked for the day and were immediately set upon by midges and mosquitoes. Ankle-deep in mud, and stippled with insect bites we dug 5 soil pits here with a reasonable haul of worms before making a break for an area of bracken further up the slope and farther away from the biting flies. We didn’t find any earthworms in the bracken pits, but were entertained by a greater spotted woodpecker feeding her voracious and loudly calling young in a nearby nesting hole before we again set off to a new site. A stop on the way to explore the banks of a stream and some adjacent dead wood in varying states of decay provided a few more worms for our count as well as other obligatory detritivores – millipedes, centipedes and woodlice.

It was in the pits dug from the grass verge alongside a footpath with flowering speedwell and buttercups  where the highest number of earthworms were found, along with leatherjackets and other unidentified fly and beetle larvae. Our small party of slightly bedraggled and filthy earthworm explorers then headed back to the Forestry Commission classroom. Looking to all the world like a group of unsuccessful treasure hunters or end-of-shift gravediggers we traipsed back to the promise of piping hot tea and freshly made sandwiches while a retinue of dog walkers, mountain bikers and Segway riders passed us by.  After lunch we could be found sitting in drifts of leaf litter in an old disused drainage ditch beneath a small stand of beech trees opposite the car park where we turned up a few more worms.

Then on to the AGM. First we were treated to a fascinating presentation on the worldwide diversity of earthworms (look out for the fried egg worm when in the Philippines) and an update on the ongoing search for the world’s longest earthworm (currently hotly contested between researchers in the Amazon and another in South Africa) by the society’s chair. Thereafter, the recording officer presented an assessment of the state of earthworm recording in the UK compared to other ‘more charismatic’ species such as butterflies – I think it’s fair to say that we have some way to go yet, but that significant progress has been made since the establishment of the society.  New members were elected to the committee (I am delighted to have been accepted as the new treasurer) and all matters were concluded and followed by dinner and drinks in a local pub.

Day 2

The next morning started with a sighting of a pair of Little Ringed Plovers on a derelict brownfield site near the hotel where we were staying before we bundled into cars and headed back to Cannock Chase with the intention of doing some mustard sampling,  digging soil pits in the heath and surveying areas that were being grazed by cattle. We set off on foot from the car park along the road until we reached a small wooded area with birch trees and much dead wood where we started collecting worms accompanied by the call of a cuckoo.

And then on to the next site where the shallow, stony and root-filled heathland pits that we eventually managed to dig were predictably uninhabited by earthworms; but we did manage to extract some from beneath some carpet tiles that had been scattered on a grassy area nearby using the diluted mustard concoction below (which I’ve been told is as indispensable as a spade to earthworm recorders).

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A little further down the path a rather large felled tree was rolled away to reveal more worms and a host of other creatures including a palmate newt, a toad,  an unidentified moth larva, pill millipedes, centipedes and  carabid beetles. We were also treated to a view of a tree pipit calling from the top of an oak and the slightly stumbling flight of a scorpion fly. We then made our way on to the grazed area where we wanted to do our final sampling for the day. Or we would have, but as we walked past the cinnabar moths and the many humped yellow meadow ant nests we realised that we may have misjudged the distance somewhat, so picked up the pace but didn’t get there with enough time to do any sampling. As a consolation we did spy a green tiger beetle scuttle across the chalk path as we now hastened back to the car park for a final catch up before scrubbing our hands clean and going our separate ways.

More information

You may have noticed that for a blog post on earthworms, this has been fairly light on any detailed earthworm records. This is because we don’t yet have our full set of records from those who attended the field days, and for my part as I am still a complete novice I am still working my way through the ID process. For ID resources, there is an excellent key by Emma Sherlock and an online  multi-access key developed by Richard Burkmar, both of which I highly recommend.

For a bit more information about earthworms and some of the work of the Earthworm Society watch this short youtube video produced by Eco Sapien and the FSC explaining why earthworms are important.
To get involved you can either contact the Earthworm Society directly or if you first want to try your hand at surveying earthworms you can take part in the citizen science project Earthworm Watch.

 

What is the cause of the Zika outbreak in the Americas?

I recently read an article by Claire Bernishthat said that the release of GM mosquitoes was the cause of the Zika virus outbreak in Brazil – this immediately set alarm bells ringing. As it turns out, any real evidence to support these claims was lacking and Christie Wilcox, writing for Discover magazine,has done a fantastic job in demolishing this argument by showing the inaccuracy of the dates and the distances involved. The GMM release site was 300 km away from the epicentre of the Zika outbreak and the release was in 2011-12, not 2015 as was stated in a similar article by Oliver Tickell in The Ecologist.3

 “The Earth is round, not flat (and it’s definitely not hollow). Last year was the hottest year on record, and climate change is really happening … And FFS, genetically modified mosquitoes didn’t start the Zika outbreak.” – Christie Wilcox 

Although I have my own concerns regarding the control of mosquitoes by means of genetic modification, I think that the scare-mongering surrounding GMMs and the Zika virus does more harm than good – especially when the scientific data is at best deficient and at worst entirely fabricated. Amongst the inevitable conspiracy theories that have surfaced the “best” argument that has been put forward seems to be that “Nature will find a way”. On another note, I also find the seeming disdain of laboratory scientists towards ecologists to be somewhat worrying and rather baffling. These fields have so much potential crossover that I hope any enmity can be set aside so that robust scientific research and enquiry can be conducted in a collaborative way.

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Aedes aegypti. Emil August Goeldi (1859-1917). Source: Wikimedia Commons.

This brings me to Amy Vittor’s excellent and comprehensive assessment of the potential sources of Zika in the Americas and her highly plausible proposition for why we are seeing such high infection rates.4 The Zika virus was first recorded in a rhesus monkey in the Zika forest in Uganda in 1947, then in the Aedes africanus mosquito the following year. The virus is now also found to be transmitted by Ae. albopictus and Ae. aegypti mosquitoes. These species are now found throughout the tropics and subtropics and as their ranges have expanded, so too has the possible reach of Zika and other mosquito-borne diseases associated with them. It wasn’t until 2007 that a large-scale outbreak of Zika infecting humans first occurred, infecting 75% of the population of the island of Yap in Micronesia.4, 5 

The spread of the virus is in all likelihood the result of human-aided dispersal of both the virus and Aedes mosquitoes. As the virus may not be detected by infected humans (up to 80% of infected people do not show any symptoms)4,5 and there is currently no cure, it is possible for an infected person to travel to an area where the virus has not been recorded and to spread it to previously unexposed mosquito populations there, so creating new vectors.

But what has changed to bring about this rapid spread of the disease in the Americas? If we accept that international travel by humans and the worldwide transportation of goods have enabled the means to transport the disease and its vectors, why are we only seeing these effects in the Americas now? There are a combination of further factors that have, as Vittor points out, come together to create the perfect environment for Zika to take hold and spread, including: the creation of more suitable mosquito habitat as a result of deforestation and planting arable crops or urbanisation; climate-change linked increases in temperature and/or humidity in areas that were previously too cold or dry to support mosquito populations; the failure of previous Aedes aegypti population control programmes; and the large pool of susceptible human hosts living in close proximity to each other and to these mosquito-favourable habitats.4

Mark Lynas, writing in The Guardian newspaper, also very effectively takes on the various GM mosquito conspiracy theories and then goes on to conclude that innocent lives will be lost if we do not embrace this technology.7 Although there is no doubt that mosquitoes are responsible for spreading an array of terrible diseases; the fact that we have created the conditions and opportunities for the mosquitoes and these diseases to extend beyond their historical ranges and infect many more people must surely be accepted as our own responsibility. I think it is a sad indictment of our scientists and ecologists if they cannot (or will not) work together towards an overarching framework to protect people from the effects of our own actions. We need to promote and encourage the use of ‘good science’ to inform our decisions and ultimately our actions.

Further research into and analysis of mosquito ecology is urgently required so that we can more fully understand the implications of mosquito eradication (by genetic or conventional controls) on the various associated ecosystems and diseases. If we do not ask questions about the potential impacts of our proposed actions, we are destined to repeat the same mistakes that have led us to this point. Perhaps, we should also examine the implications of increased habitat loss, climate change and urbanisation, and consider whether we are prepared to live with the consequences or take action to limit the most deleterious effects.

References:

1. Bernish, C. (2016) Zika Outbreak Epicenter in Same Area Where GM Mosquitoes Were Released in 2015 http://theantimedia.org/zika-outbreak-epicenter-in-same-area-where-gm-mosquitoes-were-released-in-2015/

2. Wilcox, C. (2016) No, GM Mosquitoes Didn’t Start The Zika Outbreak. http://blogs.discovermagazine.com/science-sushi/2016/01/31/genetically-modified-mosquitoes-didnt-start-zika-ourbreak/#.VrXcU8eExo4

3. Tickell, O. (2016) Pandora’s box: how GM mosquitos could have caused Brazil’s microcephaly disaster http://www.theecologist.org/News/news_analysis/2987024/pandoras_box_how_gm_mosquitos_could_have_caused_brazils_microcephaly_diasaster.html

4. Vittor, A. (2016) Explainer: where did Zika virus come from and why is it a problem in Brazil? https://theconversation.com/explainer-where-did-zika-virus-come-from-and-why-is-it-a-problem-in-brazil-53425

5. Duffy, R. et al. (2009) Zika virus outbreak on Yap Island, Federated States of Micronesia. New England Journal of Medicine. 360(24):2536-43 http://www.nejm.org/doi/full/10.1056/NEJMoa0805715#t=articleTop

6. Giri, D. (2016) Zika Virus : Structure, Epidemiology, Pathogenesis, Symptoms, Laboratory Diagnosis and Prevention http://laboratoryinfo.com/zika-virus-structure-epidemiology-pathogenesis-symptoms-laboratory-diagnosis-and-prevention/#sthash.BYXGYuyI.dpuf

7. Lynas, M. (2016) Alert! There’s a dangerous new viral outbreak: Zika conspiracy theories http://www.theguardian.com/world/2016/feb/04/alert-theres-a-dangerous-new-viral-outbreak-zika-conspiracy-theories

Further reading:

World Health Organisation (WHO) Latest Zika situation report http://www.who.int/emergencies/zika-virus/situation-report/en/

Genetically modified insects and the precautionary principle

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Last week the Guardian newspaper reported on the findings from the UK House of Lords’ science and technology committee into the development and use of GM insects. According to the committee’s chairman, Lord Selborne:

“GM insect technologies have the potential not only to save countless lives worldwide, but also to generate significant economic benefits for UK plc, where we are an acknowledged world leader.”

No surprises there. The case for GM insects to be developed as a form of vector control has many proponents and seizing an economic opportunity is to be expected from the Lords. Apart from a cursory explanation of the means of developing GM insects, and a mention of the fact that the committee would like to see a reform of European Union regulation around GMOs (more on this later), the reporter fails to consider any environmental issues that may arise from the release of transgenic insects, in what seems to me to be a failure of research and the rehashing of the committee’s summary report.

Thankfully, in an attempt to provide a balanced argument the Guardian also published a piece that was more critical of the report, describing it as  “an unsophisticated form of moral blackmail” and laying out the possible extinction risks associated with gene drive systems. The scientific knowledge gap is highlighted by these authors, who write:

“We are not against GM insects. Our point is that we do not know enough. Nobody knows enough.”

Though I commend these authors for responding to the Lords’report in a more critical way, there are still a couple of findings in the report that hadn’t been directly addressed and which I think need exploring further.

The first is the issue of EU regulations of GMOs that the Lords describe as “failing lamentably” and would like to see amended. This critique is aimed at EU Directive 2001/18/EC which states that “due attention be given to controlling risks from the deliberate release into the environment of genetically modified organisms”. This is to be conducted through case-by-case environmental risk assessments, public consultation, a requirement to consult all relevant scientific and ethical committees, and development of “a mechanism allowing the release of the GMOs to be modified, suspended or terminated where new information becomes available on the risks of such release” before consent will be granted. It is a very robust piece of legislation which, when linked with Regulation (EC) No 1946/2003 that restricts the release and transboundary movement of any GMO within EU member states, makes this not “lamentable” as the Lords would have us think, but sound legislation based on the Cartagena Protocol which states that products from new technologies must be based on the precautionary principle and allow nations to balance public health against economic benefits. And which allows countries to ban imports of a genetically modified organisms if they feel there is not enough scientific evidence that the product is safe. It seems to me that an attack on the governing EU legislation is also an attack on the Cartagena Protocol which environmentalists need to be aware of.

The international consensus of the definition of the Precautionary Principle is:

“When human activities may lead to morally unacceptable harm that is scientifically plausible but uncertain, actions shall be taken to avoid or diminish that harm.”

And this brings me to my second concern about the House of Lords report, wherein Professor Rosemary Hails states that:

“the Precautionary Principle properly applied would also take into account the risks of not developing a particular technology and the benefits forgone. It is a misuse of the Precautionary Principle that has led us to this place.”

This reconstitution of the Precautionary Principle is a matter of great concern and has already been discussed at some length by the House of Commons Science and Technology Committee in their Fifth Report: Advanced Genetic Techniques for Crop Improvement: Regulation, Risk and Precaution wherein Sir Mark Walport framed the precautionary principle not as a response to scientific uncertainty, but as a guide to evidence-based decision-making. He said:

“Decisions must be informed by the best evidence and expert advice. The application of the ‘precautionary principle’ can help to guide this. This simple idea just means working out and balancing in advance all the risks and benefits of action or inaction, and to make a proportionate response. All too often, people citing this principle simply overreact: if there is any potential hazard associated with an activity, then it should not be done, or, if it is already being done, it should be stopped.”

By removing the imperative for evidence and advice that is provided to governments to be based on the principles and rigour of scientific enquiry, the report is effectively providing ministers with a means of bypassing environmental legislation. A recent example of this is when George Eustice MP recently cited food security as a reason to maintain the use of neonicotinoid pesticides under this bastardised definition of the Precautionary Principle.

If it were as simple as Sir Mark maintains to identify and stop hazardous activities we would not be facing some of the world’s current health and environmental catastrophes. That is why we must legislate against them and that is why scientific evidence needs to be the basis for that legislation. And when that evidence is lacking or inconclusive, aren’t we safer not taking the risk in the first instance?  If, as Prof. Hails maintains we need to consider the risks of not using certain technologies for their potential benefits we have to ask ourselves whose benefits are we talking about.

The Great Pottery Throw Down

The title of this blogpost is taken from the latest BBC television series that has just finished screening in the UK. The premise for this series is based on the model developed for the hugely successful The Great British Bake Off, in which contestants compete against each other day-after-day to produce a variety of baked goods that are then judged by experts. Replace baked goods for ceramics and you will have grasped the intricacies of The Great Pottery Throw Down in its entirety. But what, if anything, is the significance of this to the study of invertebrates?

Well, having recently read Animal Architecture by Ingo Arndt and marvelled at the complexity and ingenuity of animals to create structures such as the heaped nests of wood ants, the towering cathedrals of termites and the delicately partitioned nests of paper wasps; I was rather taken with the notion of insects as ‘makers’. Serendipitously, I stumbled across the website of naturalist and artist, John Walters – specifically across his marvellous illustrations and accounts of Heath Potter Wasps, Eumenes coarctatus.

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Eumenes coarctatus. Source: Wikipedia

Potter wasps, Eumeninae, are the most diverse group of Vespidae, with over 3,500 species in 210 genera found throughout the world. Of these, 23 species in 9 genera are found in the UK. They derive their common name of potter (or mason) wasps from the fact that the females tend to construct nests from mud and clay. These nests can take multiple forms, but one of the most elegant (in my view) is the vase-shaped nest of Eumenes coarctatus, the solitary Heath Potter Wasp.

Using heather, gorse or dead grass stems as nesting sites, the female will build her clay vessel over the course of two to three hours. During this time she will repeatedly fly from a water source to a quarry site, where she will form a ball of mud in her jaws, which is then transported to the construction site where she builds the nest. Once she has shaped the neck and lip of the nest she lays a single egg in the chamber suspended on a strand of silk. She will then search for, sting and collect a number of small caterpillars, especially pug and horse chestnut moth larvae, from the heathland vegetation and then fills the pot with them. A final trip to the water source and quarry then provides enough clay to seal the pot with between 9 and 38 paralysed caterpillars trapped inside. A female heath potter wasp may produce up to 25 pots in her lifetime (2 to 3 months) and occasionally she will cluster pots as shown in the series of photographs below. It is possible that these clusters prefigure the development of eusocial colonies as seen in some other vespids.

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Development of a cluster of clay nest cells built by a single Eumenes coarctatus. Bovey Heath, Devon. Photos by John Walters.

When the wasp larva hatches from its suspended egg it drops onto the paralysed prey on which it feeds for about a week before pupating. The emergence of the adult depends on the timing of the building of the pot. If the pot was built before the end of June, the adult wasp will emerge 2 to 3 weeks later; if the pot is built in early July, the adult will still emerge in the same year; however, if the pot is built after this date emergence will be delayed until the following April or May.

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Illustration of Heath Potter Wasps taken from the field notes of artist and naturalist John Walters.

Though the E. coarctatus larvae are predatory, the adults feed on the nectar of heathland plants such as gorse, heather, bramble, angelica and alder buckthorn.

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Distribution map of Eumenes coarctatus in the UK. Source: NBN

Found on lowland heaths in England (from South Devon to East Sussex, and north to Buckinghamshire) the Heath Potter Wasp is classified as nationally scarce, though not designated a BAP species.

I also love Jean-Henri Fabre’s description of Eumenes taken from The Wonders of Instinct:

“A wasp-like garb of motley black and yellow; a slender and graceful figure; wings not spread out flat, when resting, but folded lengthwise in two; the abdomen a sort of chemist’s retort, which swells into a gourd and is fastened to the thorax by a long neck, first distending into a pear, then shrinking to a thread; a leisurely and silent flight; lonely habits.” 

More:

John Walters has also made a video of a wasp building a nest.

Michael Archer’s Key to British Potter and Mason Wasps is a very useful resource for identifying the various UK species.