In the run up to both COP 26 and COP 15 many newspapers recently reported the shocking fact that Britain has lost almost half (47%) of its biodiversity since the industrial revolution. For naturalists and conservationists working in the UK this will,however, come as absolutely no surprise whatsoever.
Research by Prof Andy Purvis from the Natural History Museum in London showed that Britain is one of the most nature-depleted nations in the world, well below the global average of 75%. With the publication of the Biodiversity Intactness Index (BII) we can now clearly see in the data what naturalists have been warning about for decades from their field observations – Britain’s biodiversity is in peril.
What’s the deal with biodiversity anyway?
‘…Biodiveristy provides us with the food we eat, from the micro-organisms that enrich the soil where we grow our crops, to the pollinators who give us fruit and nuts… [and] many of our medicines originate from plants and fungi…’.
Sir Richard Attenborough
This beautiful animation (below) narrated by Sir David Attenborough and produced by The Royal Society explains the importance of biodiversity, both to us and the world at large.
When 67% of the UK is used for agriculture and a further 8% is built on that leaves a paltry and dwindling 25% for nature. According to official statistics from the Ministry of Housing, Communities and Local Government (2018), forest, open land and water constitute 21% of all land use in England.
‘As Presidents of COP26, the UK has put nature at the heart of the agenda, and we very much welcome this important study which highlights the crucial connections between climate and biodiversity and the urgent need to protect nature’.
Lord Zac Goldsmith, UK Government Minister for Pacific & the Environment
Damningly though, researchers from the RSPB have found that although 28% of UK land is reported by the UK government to be protected, only 11.4% of land area actually falls within protected areas designated primarily for nature conservation. And because of the poor condition of some of these areas, as little as 4.9% of UK land area may in reality be effectively protected for nature.
How do we effectively address this issue in Britain?
‘Governments possess the power – economic, political and legal – to address the planetary emergency, and there may still be time, but they must act now.’
Prof Andy Purvis, Natural History Museum
The British Ecological Society produced a report in May this year (2021) that called for a nature-based approach to tackling both climate change and biodiversity loss in conjunction with other climate and conservation actions. A brief summary of their specific policy recommendations provide examples of opportunities across a range of habitats through:
Restoring degraded peatlands and end burning on blanket bogs
Increasing native woodland and woodland connectivity in the right places
Establishing more saltmarshes
Protecting and re-establishing hedegrows in arable landscapes
Increasing agroforestry in arable landscapes
Increasing urban green spaces with a focus on native species
Unfortunately, any and all action to prevent further biodiversity loss is costly. A recent report from the Green Finance Institute claims that the UK governement faces as much as a £97 billion funding gap for its current commitments to nature-based actions over the next 10 years.
Regardless of the financial costs of mitigating and remedying biodiversity loss, we should never lose sight of the costs of inaction – not just economic, though these are significant. But also the legacy of a pillaged, spoiled and empty landscape; a depauperate and diminished native biota; and ultimately, an impoverished and increasingly precarious society.
I am a self-professed invertophile. I absolutely adore the myriad forms of insects and other spineless creatures. They are the most diverse and abundant group of organisms on earth, they can be found in every habitat imaginable, they have evolved some of the most complex forms, lifestyles and behaviours, and they are responsible for maintaining essential ecosystem functions and systems. How could one not be utterly awed by them?
I grew up in South Africa and lived on the outskirts of a small town in KwaZulu-Natal. I played on the edge of wilderness and ‘civilisation’ where the veldt and acacia scrub met our mowed lawn and meticulously weeded flower borders. The garden was surrounded by a low wall built from great chunks of blue-grey and rust-coloured igneous rocks (which were displaced by the flower beds) and poured concrete. I travelled in a circuit along these walls and around the garden marvelling at all the life that was to be found here: Citrus Swallowtail butterflies and their peculiarly pungent caterpillars that were resident in our lemon tree; ants that magically appeared around every dropped crumb; checkered yellow and black blister beetles which I knew not to touch; the iridescent snap of a dragonfly’s wings as it hawked overhead. I also kept my share of ‘pets’ that wandered too close to the house and ended up living in jam jars with holes punched through the lid. As I grew older the farther I wandered from the borders described by the walls, drawn further and further away by the towering curiosities that rose out of the earth and teemed with thousands of milky-white termites. I watched trapdoor spiders snatch up prey, ran with solifugids and scampered from scorpions. I carefully turned over logs and rocks and watched centipedes and beetles scurry from the light. I listened to the susurrus hiss of grasshoppers, and when those turned to the chirps of crickets I knew that it was time to head home for dinner. My childhood summers were glorious and almost every day was filled with LIFE.
Now, much later in life and living in London, I still find the presence of wild animals very rewarding. And still, none more so than the invertebrates. They are perhaps not as abundant or as large as those of my youth, but they are all around us even if we need to look a little harder. I now have a number of local patches where I go to observe invertebrates. All within a comfortable walking distance of my apartment and all quite different from one another: a local park, a cemetery and urban nature reserve, a city farm, a medicine garden and community space, and a brownfield site. So far this year I have recorded many species new to these sites, several new to the borough and new to me!
Although I understand that not everyone shares my passion for the myriad creatures that surround us and that some people can be downright hostile towards them; I can’t help but feel that they’re missing out on something quite incredible. And to that point I’ve been thinking a lot about observing and recording invertebrates recently – specifically about how people might get started with it.
How to get involved
There are many ways in which you can become involved with observing, identifying and recording invertebrates. Here, I will specifically discuss casual recording – by this I mean randomly walking through a space of your choosing and observing invertebrates in situ. There are no formalised procedures, no sampling methodologies, just you in nature. I think that this is a great way to become familiar with the variety of life out there. Having said that, you will find a few items incredibly useful for helping you along your new voyage of insect discovery:
Comfortable walking shoes,
A good introductory or general field guide,
A camera (a phone camera will most often work well enough),
A GPS or phone that can give you location coordinates,
A notebook and pen/pencil,
A 10x magnification hand lens.
I will follow this blog post up with another about different invertebrate sampling methods in the future.
A note on some of the field guides that are available: the Collins Complete Guide to British Insects by Michael Chinery, though by no means complete, is a decent place to start as it covers many of the more common species (>1,500) and was in fact my first field guide. I then moved on to Paul Brock’s A Comprehensive Guide to Insects of Britain and Ireland which, though not comprehensive, goes somewhat further than Chinery, covering more species (2,300) and also includes some of the rarer insects. Most recently (2021) Brock has published Britain’s Insects with WILDGuides which focuses on more popular groups and species. This is an interesting publication with some excellent entries and photography, but covers a reduced number of species (1,653). I own and regularly use all of these but also more specialist guides to various groups of insects. However, when starting out, I would recommend that you get one of these to use in the field and will point out some of the excellent online resources and forums that are also available. Please note that these books are available through other bookshops and online sellers, I have linked to NHBS as they actively support conservation.
How to find invertebrates
Stop. Pick a spot and stand still.
Get your eye in. Let your eyes slowly scan across the vegetation in front of you just below eye-level. Look for movement, see if there are any odd shapes or colours that stand out from the background. Remember many insects can be very well camouflaged so take your time.
Get down low. I tend to crouch a lot, but you could also kneel or sit on the ground. If you’re low down you will be more likely to see ground-dwelling invertebrates. This is why young children make fantastic “bug hunters”.
Listen. Some insects will make noise to attract mates like crickets and grasshoppers, but you can also hear the snap of dragonfly wings, the rustle of grass as something moves through it, and even the munching of leaves.
Move slowly and carefully. Don’t move far, but move a few steps at a time while keeping an eye on where you place your feet. As you move you want to try to avoid disturbing the vegetation as much as possible as invertebrates can be very sensitive to vibrations. Also, beware your shadow as this can frighten off the flightier individuals.
Look forsigns of invertebrate presence. Nibbled leaves, cut stems, silk threads, nest holes and the like. Sometimes even tracks in sand can be signs that invertebrates are about; and always keep an eye out for frass (essentially larval poop).
Don’t forget to look up. Remember that many insects can fly. Also, it is definitely worth examining vegetation at or just above head height.
Make notes and/or take photos. This is very useful for your own future reference, but also if you want to report your sightings to any of the recording schemes. I will talk about this in a bit more detail later on, but basic information that is useful is: a photo, the date, species name, number seen, and location.
Through recording wildlife we can determine a number of important data about what animals are found in which habitats. With long-term data we can see if these species change over time and this can help us to understand the drivers of those changes e.g. habitat loss, pollution events, land restoration etc. We can track the movement of species’ distributions in response to large-scale and seasonal effects such as climate change, and we can monitor the conservation status of species in order to identify those most at risk of extinction. Invertebrates are specifically important because it is in their changes that we tend to first detect issues of future conservation concern. I hope that I’ve managed to convince you that this is a worthwhile project to undertake for better understanding these incredible creatures that share the planet with us.
In Britain the recording community is largely voluntary, from people going out into the field to record what’s in their local patch to the experts who verify these records and the county or national recorders who collate it all. There are of course exceptions such as ecologists who might be employed to survey sites for invasive species or for endangered species that might affect construction projects. But for the most part people survey and submit records for their own personal reasons which can be as varied as the number of people involved; whether that’s about wanting to contribute to scientific enquiry, wanting to know more about the wildlife in a local area, or wanting to catch them all…
How to record invertebrates
Recording invertebrates is a two-step process. The first step is what information is kept in your field notebook. I tend to record a bit more information here than I will need for submitting to the recorders/recording societies.
On a new page in my field notebook I always start with this information:
Weather – the general outlook for the day.
Site notes – you may want to specify habitat type(s) or whether there has been any site management or disturbance since your last visit etc.
Casual recording – or specify which sampling method was used.
I then start searching for invertebrates and record them each like this:
Species name – if known, otherwise genus or family and update it later.
Male / Female / Mixed – if you can tell, it isn’t always possible.
Life stage – adult, larva, nymph, pupa, etc.
Identified by – this is if someone else has helped you with an ID.
Number – you need to decide on the scale you want to use here, I tend to include all individuals within 102 metres, but you can extend this to 1002 m or 12 km if you want to include a whole site.
Coordinates – I normally get latitude and longitude from my phone using either Google Maps or Apple Maps in decimal format.
Photo number – if using a camera that records this information.
Notes – any significant interactions or interesting behaviours.
And that’s it!
The second step is to submit your records and there are a few different ways in which you can do this. For the most part I use the online recording website iRecord which a large number of verifiers and recorders use. For more information about how iRecord works take a look at this blog post and video produced by Keiron Derek Brown.
Alternatively you can manage your own database in Excel and provide these records to the national recording scheme or relevant recorder directly via email if that’s what they would prefer.
The more you look…
I have lived in Tower Hamlets for 10 years and in the last few months I have been incredibly fortunate to find three endangered insect species in some of my local patches. This is because I have spent more time looking and got lucky. This is what makes casual recording so exciting for me, you just never know what might turn up.
I’ve spent the last couple of months in the Taita Hills in SE Kenya where I am studying the impacts of anthropogenic habitat degradation on bird functional diversity and composition. Specifically, I’m working in a sky island complex of massifs topped with remnant montane forests that form the northernmost extent of the Eastern Arc Mountains. The forest fragments on these hills are designated as Key Biodiversity Areas (KBA) and Important Bird Areas (IBA) because of high levels of endemism and biodiversity. This area is ideal for this research as it shows very high levels of historical habitat fragmentation and different degrees of degradation through various human land-uses.
I am starting with characterising the bird communities of the different forest fragments and the surrounding agricultural matrix by identifying bird species via point counts & AudioMoth sound recordings. This data will be combined with an existing traits database so that we can determine what functional roles are present (and to what extent) in each habitat.
Another approach that we’re using to try to understand how effective birds are at controlling pest insects is by using plasticine model “caterpillars”. The attack marks that are left behind help us to identify the levels of predation relative to habitat quality.
This lays the foundation for my next field season when we will be capturing birds to collect faecal samples which will be analysed using DNA metabarcoding. This will provide us with information on how birds’ diets are influenced by habitat quality and also allow us to quantify the ecosystem functions that birds perform – like controlling herbivorous insect pests and seed dispersal.
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.
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.
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.
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.
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.
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.
All 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].
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
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
Inspired by Gilbert White (naturalist, ornithologist and author of The Natural History and Antiquities of Selborne) the Selborne Society was formed in 1885 as Britain’s first national conservation organisation. Members of the Society went on to establish pre-eminiment organisations such as the National Trust and Royal Society for the Protection of Birds. Today, the Society manages Perivale Wood, an 11.6 hectare Local Nature Reserve in Ealing south-west London, where they organise an open day, and a wide range of indoor meetings and field excursions.
I was invited to talk to the Society and members of the public about the biology and ecology of ants. This blog post is a very abbreviated form of that talk with a tiny selection of the slides used to give a bit of an overview. To be honest, I was always a bit uncomfortable with the title of the talk. I knew it would be impossible to cover everything to do with ants, so I focused on some of the areas of ant biology that most interest me.
But what’s so special about ants anyway? Well, ants are everywhere. With over 16,000 extant species found in every terrestrial habitat (apart from the polar regions) they constitute a large proportion of all living biomass. Enormously successful as scavengers, herbivores, granivores, predators and mutualists, ants perform important ecological functions as ecosystem engineers and keystone species. Some species are also highly successful at invading new territories where they can become crop pests or outcompete native species for resources. Their eusocial lifestyles also make them ideal model systems for the study of social evolution.
Part of my fascination with ants comes from the tremendous morphological diversity within and between species. Not only can there be differences between castes within species, but species can range in size from the minuscule Carebara atomus (~1 mm) to the comparatively enormous Dinoponera gigantea (~4 cm). I also have a bit of a soft spot for the myrmecophiles (other invertebrates that live in association with ants) and especially the myrmecomorphs (invertebrates that mimic the appearance and/or behaviours of ants). To share some of the beautifully complex variety of forms in ants and the ant-wannabes I asked the audience to play a game that I call “Ant Bingo!”.
Everyone got into the spirit of it and after discussing some of the characteristic features of ants managed to identify all six ants displayed amongst the other fantastic creatures.
Belonging to the order Hymenoptera, the family Formicidae (what we commonly call ants) emerged in the late Cretaceous (~140 MYA) when they diverged from the Apoidea – spheciform wasps and bees. There are now more than 16,000 species of ants in over 470 genera that we know of – it is thought that there may actually be at least as many species still to be discovered. According to some estimates, there are more than 10 quadrillion individual ants alive at any time.
This variety in form is echoed in the highly complex and variable social structures and life histories that have evolved in different ant species. The numerous ways in which they gather food and create shelters to protect themselves from the elements and potential predators are both fascinating and ingenious. In order to feed the colony, there are ants that harvest honeydew from aphids, some that cultivate elaborate fungus gardens, and others that send out raiding swarms that capture anything too slow to get out of their way. For nest-building, there are ants that use larval silk to weave leaves together in the treetops, those that excavate elaborate underground tunnels, and those that have co-evolved with plants to live within specialized swellings and chambers called domatia which are produced by the plants for the exclusive use of their ant protectors. These examples only briefly touch on a few of the magnificent examples of diverse life strategies found within the ants.
There are many different social structures evident between (and sometimes even within) ant species. There are some with single queen colonies and some with multiple queens – in some cases hundreds of reproductive queens can live in the same nest. Queen number can also vary within a species so that there may be colonies with one or many queen(s). The colonies of some ant species can even persist without any queens; in these instances, worker ants can (rather peculiarly) become fully reproductive if the queen dies. These egg-laying workers are called gamergates. At the other extreme, there are the social parasites, where some species don’t produce a worker caste at all – their eggs will only produce the next generations of queens and males. These parasitic queens are known as inquilines, they take over the nests of closely related species who provide a ready workforce so there is no need to expend energy on creating more workers. And then there are what some people call the “slave-making” ants – these ants will raid other nests and carry the brood away to their own nest. The “slave” ants will then work in their new colony, defend it from attack and can even participate in future raids. This process of kidnapping and imprinting is more accurately referred to as dulosis.
I should also emphasise the fact that these social structures may vary over time depending on what life-stage the colony is at. For example, the number of reproductive queens within a colony may vary depending on whether the colony is experiencing a rapid growth phase such as the establishment of a new colony. At this early period, it can be highly beneficial to have many queens all laying eggs at the same time to quickly produce workers to protect the nest, forage for food and care for the brood. But after a time (once the colony is a bit more established) the need for multiple queens is diminished and what was a co-operative breeding chamber becomes an arena for a battle to the death until only one queen remains.
Ants are, in my view, remarkable animals. They have adapted to fill every conceivable terrestrial niche through evolving incredible morphological adaptations, variable social structures, and a dizzying array of life histories. There are also fantastic opportunities for research with many more species to be discovered and behaviours to describe.
This video clip from the BBC2 documentary Natural World: Attenborough and the Empire of the Ants shows wood ants (Formica sp.) defending their nest:
Last Summer I got to revisit an old haunt in South London where I used to volunteer with the London Wildlife Trust. I was very excited about returning to Hutchinson’s Bank Nature Reserve (it is in the suburb of New Addington and easily reached by tram from Croydon). I left the restoration project when I moved ‘North of the River’ some years ago and had not seen the final transformation from scrubland back to chalk grassland. I was not disappointed – this site is a bit of a treat even when the weather isn’t at its finest.
The reserve was taken on by LWT (on behalf of Croydon council) because of the potential to enhance the scrubbed over chalk grassland through habitat restoration & management work and by building on the planting and maintenance already undertaken by a group of dedicated locals who had successfully introduced small patches of Kidney vetch (Anthyllis vulneraria) and Greater yellow rattle (Rhinathus angustifolius). Because of these locals who were actively involved there was also already a very impressive list of butterfly and orchid records associated with the site.
Lowland calcareous grasslands form over shallow limestone-rich or chalky soils which have a typically high pH, low nutrient levels and tend to be free draining. Because they favour these particular conditions, chalk grassland plant species are called calcicoles (lime-loving plants). Much of Hutchinson’s Bank Nature Reserve is, as the name implies, on the slope of an embankment which aids with the drainage of rainfall, and the fact that the slope is south-facing ensures fairly warm conditions throughout the Summer months.
It is estimated that there is between 25,000 ha and 32,000 ha of chalk grassland in the UK1 where it is considered a nationally rare habitat. Calcareous grasslands have been described as being equivalent to coral reefs in terms of their species richness, and though this can be seen in small areas, the comparison doesn’t really hold once you increase the scale of the compared areas. As you increase the study area on a coral reef, you will continue to find new species at a higher rate than in chalk grasslands where you will fairly quickly find all the resident species, relatively speaking.
This notwithstanding, calcareous grasslands are highly species rich with a single square metre supporting between 50 and 60 species of vascular plant (including 37 Red Data Book species). As a result of this habitat heterogeneity, we find variation in vegetation structure and large numbers of different food plants which cater for one of the most diverse insect communities in Britain.2
What makes these habitats especially rare is the fact that they are remnants of Mesolithic agriculture; established about 9,500 to 5,000 years ago when forest cover was cleared for growing crops and rearing domestic animals which continued well into the Neolithic era. The highly porous soils meant that nutrients leached away and that these largely-unfertilized fields eventually lost productivity and were abandoned for new sites. But while they were productive, they were kept clear of encroachment by scrub and the succession to closed-canopy forest was inhibited.2, 3, 4 These cleared areas would then support grass swards and herbs associated with both steppe and Meditteranean vegetation types whose seeds had previously lain dormant in the soil seed bank. This anthropogenic land management system involves quite a specific regimen, and though supported by some historical pollen records and fossilised beetle fauna, it remains unresolved.4, 5
In 2000, Frans Vera proposed a new hypothesis to explain open patches of land (much like savannahs) based on the same evidence but concluded that these areas were maintained by large herbivores such as auroch, wild horses and deer. The Vera Hypothesis, as it has come to be known, remains controversial and has become the basis for a large-scale rewilding experiment at Oostvaardersplassen in the Netherlands. It is likely, in my view, that a mosaic of open areas was first created for agricultural use and then maintained by browsing and grazing of ungulates.
With this in mind, it is therefore interesting to view a map of Hutchinson’s Bank Nature Reserve from 2012 which shows the management plan for different areas including removing topsoil (the most recent land use was modern agriculture, rotational grazing and cutting back scrub. These accepted chalk grassland management practices6 are very similar to those used by Mesolithic farmers ~9,000 years ago.
The largest threat to chalk grassland ecosystems is therefore a lack of correct management which leads to encroachment of scrub and eventually reforestation. Add to this past (and perhaps recurring) socio-economic pressures to develop high-yield crops and provision of housing, and the threat becomes compounded. With only 29% of lowland calcareous grasslands assessed as SSSI being described as favourable by the Joint Nature Conservation Committee, there is real cause for concern. However, an additional 40% of sites are described as “unfavourable recovering”, but without any indication of what that means for each site in terms of actual improvement over time I am unsure of how much solace one can draw from that number.
It was on one of my volunteering days in August 2011 that we went to another chalk grassland managed by LWT nearby. We were here to survey the vegetation, plot the exact perimeter and identify areas for habitat management.
Saltbox Hill SSSI is located near Biggin Hill airport and is on a very steep hillside with ancient woodland on the ridge of the hill. With an impressive species list and located near the home of Charles Darwin, this area undoubtedly has natural history kudos, and it was here that I found one of the strangest looking insects that had me puzzled for quite some time.
Some small square sheets of corrugated iron had been set out to act as refugia for the resident slow worms and snakes. Sitting on the edge of one of these sheets was a segmented, rather hairy, caterpillar-like insect. I was completely stumped. I just about managed to get a photo with my phone and as soon as I got home I turned to the internet for help. iSpot is a very useful resource for these baffling discoveries – experts and amateurs alike will help with an ID of any species from a photo and some habitat information. Within a matter of hours I had an ID of Drilus flavescens. Turns out my insect was the female larva of a highly sexually dimorphic beetle found in chalk grasslands. It has a very limited range and is classified as scarce in the UK. Fascinatingly, the males look more like traditional beetles as adults, while the females remain looking much like their larval form. You can find more information at Mark Telfer’s excellent website here.
A visit to a chalk grassland in Summer is a complete sensory immersion. I implore you to go and walk through the grasses skirting the ant mounds; smell the heady herby scents of wild thyme and oregano as you brush past; be surrounded by the buzzing of bees and flies and the soft susuration of grasshoppers; and be dazzled by the sight of brightly-coloured flowers and dancing butterflies. These are spaces that celebrate the wonder of life. I am heartily looking forward to another visit this year.
Price, E.A.C. (2003) Lowland Grassland and Heathland Habitats (Habitat Guides Series), Routledge, London and New York.
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”.
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?
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.
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).
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.
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
Hughes, D.P., Wappler, T. and Labandeira C.C. (2010) Ancient death-grip leaf scars reveal ant–fungal parasitism. Biology Letters, 7: 67-70.
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
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).
I have been a card-carrying member of the Royal Society for the Protection of Birds for about 15 years. In that time I have seen some great successes and a variety of challenges faced by the society. The RSPB is the largest nature conservation charity in the UK (with over 1 million members) and also the oldest. Originally set up in 1889 by a group of women who were concerned about the hunting of birds for their feathers (which were a la vogue – especially the decorative use of grebe skins and egret plumes in the hats of Victorian ladies).
The ‘Birds’ component of the RSPB’s moniker is still very relevant today as they continue to work on species protection projects that focus on individual UK bird species which are in decline or under threat such as stone curlews, black-tailed godwits, corncrakes and lapwings. In fact this strategy proved highly successful in the past as with the red kite re-introduction project which saw numbers of a globally threatened species rise to 1,800 breeding pairs in Britain between 1980 and 2011. This methodology has, however, led to some criticism of the single-species approach for tending to select high-profile charismatic species, and employing management practices that may disadvantage non-target species. It also raises the question of why a particular species should receive conservation preference over any other. To this end the IUCN Red List of Threatened Species was established to help assess the conservation status of species by identifying threatened species and promoting conservation action. We aren’t even aware of the totality of extant species, nor do we have a full understanding of which of those are, or me be, under threat. Insects are a good example; with only 6,051 insect species listed in the IUCN Red List database (of somewhere between 1 million known species and up to 8.5 million expected to be found) there is still an enormous amount of work to be done.
The RSPB’s conservation work, does however involve more than the protection of individual species. Another component of this work is habitat management which is undertaken at more than 200 reserves maintained by the society. This presents the RSPB with opportunities to work towards conserving other (unfeathered) species either on their own or in collaboration with partner organisations. At a time when environmental protections in the UK are likely to be significantly eroded and underfunded, there is some small comfort to be drawn from the fact that there are many conservation organisations like the RSPB that will continue to work to maintain, manage and support wildlife and wild places. But conservationists will need to be focused and their priorities will need to be very clear.
In 2013 the RSPB added the tagline “Giving nature a home” to its logo exemplifying how it has become a conservation charity that now also focuses its attention on wild spaces and the plight of all the other featherless organisms. Though this could be seen as a large charity cannibalising and intervening in the work of smaller (and more focused) organisations in the sector, the sheer scale and associated land-area that the RSPB maintains does allow for a more holistic approach with regards ecosystem and habitat conservation – effectively creating opportunities for protecting and conserving a wide range of species through landscape-level management. What is significant here, though, is that we need to be able to maintain an interesting matrix of connected habitats of varying sizes in order to be able to support as much biodiversity as possible.
RSPB Rainham Marshes is one of the reserves in the society’s portfolio which was established in 2000 in an area of Essex along the river Thames that was formerly Ministry of Defence land and closed to the public for over 100 years. Part of the Inner Thames Marshes SSSI that stretches over an area of 479.3 hectares this area is a haven for wetland birds. On my recent visit I got to see some of these including swans, lapwing, oystercatcher, marsh harrier, shoveler, shelduck, mallard, canada geese, little grebe, grey heron, redshank, sedge warbler, reed bunting, as well as swifts, linnets, goldfinches, kestrel, sand martins and a displaying skylark. Hauled out on a sandbar on the far bank of the river was a group of 7 harbour seals. As fantastic as these were, why I really came to Rainham was for the invertebrates. The low-lying grazing marsh with wet grassland, ditches, scrub and reed beds on an urban and light-industrial fringe make for a complex habitat mix with a number of interesting ecotones.
It was for the most part a beautifully sunny afternoon, but quite windy at times making some of the photography quite challenging (as you’ll notice from a few rather blurry shots in the following slideshow). I’ve also made note of a few additional butterflies that I was just too slow to photograph – small heath, large white, peacock, red admiral and large skipper – as well as a broad-bodied chaser that zoomed past my head.
All of the invertebrates featured were found through observation and searching by hand because I wanted to photograph them as undisturbed and in as natural a setting as possible. This has meant that species that would have been found by using a pooter, sweep net or beating tray are lacking from my finds. Nonetheless, I was delighted with the dazzling green of the swollen-thighed beetle (Oedemera nobilis) perfectly placed at the heart of a dog rose its femurs bulging like metallic pantaloons, found quite soon after leaving the visitor centre. A leisurely walk along the bank of the river skirting the reserve presented many empid flies, jumping spiders, bumble bees and my first record of a knobbed shieldbug (Podops inuncta) scuttling for cover across a concrete embankment where I chose to stop for my ploughman’s lunch.
Please feel free to send me corrections if I have misidentified anything or if you can get closer to species with those I’ve only managed to identify to genus.
I then cut away from the river, crossing a channel of pebbles and loose rock aggregate where a mix of stonecrop, bramble and ragwort pushed up through the gaps. Here were more bees and another personal first of a couple of black-striped longhorn beetles (Stenurella melanura) on bramble flowers. This area also had a scattering of detritus washed up from the river: bits of plastic, wood, a child’s sky-blue bicycle lying on the mudflat. Beneath a plank I found a scuttling centipede and a cluster of earwigs all with abdomens raised and forceps flailing in defence. Then on along a grassy path and down an embankment, stopping to investigate the umbels of giant hogweed for ants, flies, wasps and other insects taking advantage of this high-energy nectar source. A bit of a detour through the grass saw a flurry of sightings: common blue (Polyommatus icarus), small tortoiseshell (Aglais urticae) and a summer chafer (Amphimallon solstitiale). Unfortunately a bit early in the year for the now fairly well-established and easily recognisable wasp spiders (Argiope bruennichi), but I think another visit in late Summer should do the trick.
I dropped in at the visitor centre for a fruit juice and then headed off into the reed beds along the boardwalks where I saw a female scorpion fly (Panorpa sp.) with her particularly oddly-shaped extended mouthparts and chequered wing patterns. Here too, on thistle, were 6 hairy shieldbugs (Dolycoris baccarum) sporting Art Deco-like purple and green thoraxes, and black-and-white banding along their antennae and laterotergites. Disappointingly, I only managed to get one photograph of a dragonfly, a blue-tailed damselfly (Ischnura elegans) before closing time. And as I made my way to the exit marvelling at all the wonderful creatures I had been fortunate enough to see I was surprised by a female mallard leading her ducklings along the boardwalk who, on sight of me, dropped over the edge and disappeared into the reeds.
Cheats 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 Evolutiongroup 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 whichattracts 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.
At the time of writing, Phil Torresand Aaron Pomerantzhavediscovered and documented kleptoparasitism of ants in a species of butterfly (Adelotypa annulifera) in the Peruvian Amazon which they believe mightmimic 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.