What have I learned during my PhD?

Instead of attending an in-person seminar this year, PhD students in our department at UCL were recently asked to produce a video in response to a question set by the Post-graduate Tutors.

This is my video responding to the question: “What have I learned (so far) during my PhD?”.

Observation, identification & recording of invertebrates

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?

Nemopoda nitidula an ant-mimicking fly from the ensign fly family Sepsidae.

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.

The Painted Lady (Vanessa cardui) is a long-distance migrant with each journey from tropical Africa to Europe taking up to six generations to complete.

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.

The mayfly, Ephemera vulgata, though common throughout Europe is in decline. It is thought that this may be due to the pollution of waterways.

How to find invertebrates

  1. Stop. Pick a spot and stand still.
  2. 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.
  3. 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”.
  4. 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.
  5. 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.
  6. Look for signs 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).
  7. 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.
  8. 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.

How to identify invertebrates

I am not going to spend too much time on this in this blog post (perhaps a future post though), apart from saying that if you are having trouble identifying invertebrates from your field guide you can try some of these generalist Facebook groups: Bug spotters UK, Insects and other Invertebrates of Britain and Europe, Insect Identification, and Insect, Spider and other Arthropod Identification. It is also worth having a look at groups which focus on certain taxa like hoverflies or beetles for more specialist advice.
You could also join a local natural history society or national organisations like the Amateur Entomologists’ Society, British Entomological and Natural History Society and Royal Entomological Society and head out into the field with groups of like-minded people with different levels of identification knowledge. There are also often opportunities to improve your ID skills by attending workshops provided by these organisations and I highly recommend the courses offered by the FSC BioLinks project and Tanyptera Trust.

Why record invertebrates?

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…

Lasius brunneus, the Brown Tree Ant has only been recorded from central and southern English counties despite suitable habitat being available across Britain. It is thought that its arboreal and timid nature mean that it is often overlooked and therefore under-recorded.

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:

  • Date
  • Weather – the general outlook for the day.
  • Site name
  • 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.

This is the first observation of the endangered picture-winged fly Tephritis praecox in Tower Hamlets and only the second record in Middlesex since 2016.

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.

Oberea oculata, the critically endangered and very scarce, Eyed Longhorn Beetle. I was able to add a new site to the previously known distribution of this species.

The Little Bombardier

Best stay out of the way.

There are more than 500 species of Bombardier beetle (a form of ground beetle – Carbidae) in the tribes Brachinini, Paussini, Ozaenini, or Metriini all displaying the highly effective defence mechanism of releasing a superheated pulsing jet of noxious chemicals sprayed directly at would-be predators.  I have always been fascinated by the ammunition of Bombardier beetles – their highly accurate and violent chemical attack brought on whenever you touch them – but it was only on reading Eisner’s essay that I started to fully grasp the incredible complexity of these beetles.

These diagrams are reproduced from Thomas Eisner’s fascinating book For Love of Insects which explores the variety of ways in which insects use chemicals for defence, signalling and prey capture. I cannot recommend this book highly enough for anyone interested in the pursuit of entomology or study of chemical ecology.

Screen Shot 2015-12-04 at 07.33.26
Diagram of a bombardier beetle with its 2 glands in place. R = reservoir; r.ch = reaction chamber; gl = glandular tissue; dt = duct

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The mechanism of operation of the bombardier glands. E = enzymes in the reaction chamber; R indicates that either a hydrogen (H) atom or a methyl group (CH3) can occur at that site on the hydroquinone or quinone molecule.

The chemical process involves hydrogen peroxide rapidly decomposing into oxygen and boiling water, while the hydroquinones oxidize into benzoquinone in the beetle’s reaction chambers. This mix explodes out of the beetle with an audible popping sound, in a volley of rapid-fire blasts – in a manner likened to the pulsing propulsion system of Germany’s V-1 “buzz bomb” in WWII. The consequent foul chemical burn (at 100°C) incapacitates smaller attackers like ants, and deters larger predators such as the unfortunate frogs in one of Eisner’s experiments.

By examining the propulsion mechanism using high-speed synchrotron X-ray imaging Eric Arndt from MIT confirmed Eisman and his colleagues’ qualitative passive ‘pulse jet’ model. This research shows that a flexible membrane and a valve passively control the spray pulsation – as pressure increases in the reaction chamber because of the chemical explosion, the membrane stretches and the valve closes. The membrane then relaxes and the valve reopens once the pressure has been reduced following the ejection of the liquid, and so the process repeats.

The only UK resident species of bombardiers are Brachinus sclopeta, the streaked bombardier beetle, and Brachinus crepitans, the common bombardier beetle, and both are rarely seen. B. sclopeta is so rare that it has only recently been accepted as a native species  (past records were  thought to be of rare migrants) and prior to 2005 had been presumed extinct since 1928. Because the beetles prefer habitats with thin soil, rubble and bare ground they tend to favour brownfield sites and have been found in east London; but with the continuous and unrelenting development of this area, these beetles’ futures are very precarious despite being listed as UK BAP priority species, and considered critically endangered by the IUCN. However, insect charity Buglife worked with developers to secure a site near London City Airport that is now the only known intact colony of the species in the UK. You can read Richard Jones highly informative blog about the relocation and conservation of this species.

Brachinus crepitans, though more common than B. sclopeta, is restricted to Southern England and Wales and especially the coastal areas of the South-East where it is considered nationally scarce. It is more commonly found in continental Europe, central Asia, the Middle East and North Africa, with central Sweden being the northernmost extreme of its range.

Brachinus crepitans. Image source: Wikipedia

Distribution of Brachinus crepitans. Source: NBN Gateway
Distribution of Brachinus crepitans. Source: NBN Gateway

Usually seen in May and June,  the beetle favours calcareous grasslands, arable field margins and chalk quarries. It is usually found in dry, sunny areas – typically under stones. Little is known about its life-cycle, but it is thought that the larvae are external parasites on the pupae of other species of beetle, particularly those of the ground beetle Amara convexiuscula and a staphylinid beetle, Ocypus ater. 

I think these gorgeous and enthralling beetles definitely warrant being surveyed for this coming Summer.


References:

  1. Eisner, T. (2003) For Love of Insects. Harvard University Press, Cambridge Ma.
  2. Lyneborg, L. (1976) Beetles in colour. Blandford Press, Dorset.
  3. Bombardier beetle found near Honeybourne. Worcestershire Biological Records Centre (December 2015): http://www.wbrc.org.uk/WorcRecd/Issue11/BombBtle.htm
  4. Isaak, M. 1997. Bombardier Beetles and the Argument of Design (December 2015):
    http://www.talkorigins.org/faqs/bombardier.html
  5. Streaked Bombardier Beetle. Buglife (December 2015) https://www.buglife.org.uk/campaigns-and-our-work/streaked-bombardier-beetle
  6. Brachinus sclopeta UK Priority Species Data Collation. Joint Nature Conservation Committee. http://jncc.defra.gov.uk/_speciespages/2093.pdf

Mosquito extinction. Is it really a good thing?

Anopheles_stephensi.jpeg

A few years ago I read an op-ed piece in the journal Nature that celebrated the potential demise of mosquitoes as scientists prepared to release genetically modified mosquitoes in Brazil in an attempt to eradicate populations carrying malaria. What most struck me about the piece was that the author concluded that mosquitoes performed no ecological function and that the world would be a better place without these pestiferous nuisances. This statement left me feeling a little uneasy. How certain could we actually be that mosquitoes performed absolutely no ecological function?

“Eradicating any organism would have serious consequences for ecosystems — wouldn’t it? Not when it comes to mosquitoes…”

In 2014 I listened to a podcast produced by Radiolab that reiterated the pointlessness of mosquitoes and again I wondered whether this could really hold entirely true. Apart from David Quammen’s valiant effort to convince us of the mosquito’s general innocence (it is after all only the females that bite, and even this is only in order to produce young). He also asks us to imagine just how quickly deforestation and exploitation of the tropics would have progressed without the relative protection afforded by the mosquito and all of it’s diseases.

 

According to the World Health Organisation (WHO) 17% of the global estimate of all infectious diseases are vector-borne. Of these, mosquito-borne diseases constitute the majority, with malaria causing an estimated 627,000 deaths in 2012 and infecting 1.5 to 2.7 million people a year. Some of the other mosquito-borne diseases that affect humans are Dengue fever, West Nile virus, Yellow fever, Lymphatic filariasis, Japanese encephalitis, Rift Valley fever, and Chikungunya; causing death, suffering and both social and economic hardship.
There are approximately 3,500 named mosquito species in the world. They are found in a variety of habitats in every biogeographic region apart from the Antarctic. Of these, only 40 Anopheles species are known to be effective transmitters of human malarial infection and only around 350 species are regarded as effective in all mosquito-borne human disease transmission.  The catholic nature of mosquitoes in relation to habitat selectivity is best illustrated in the breadth of the geographic area covered by dominant malarial Anopheles mosquitoes.  Mosquitoes are highly speciose, with the greatest species diversity being found in the Neotropical regions as shown in the map below.

 

tileshop.fcgi

This preponderance of mosquitoes to cause such human hardship has led to a variety of campaigns designed to control and eradicate them; from the use of DDT in the 1940s to attempts to sterilise males through exposure to radiation. Though there has been some success with these methods in the past, elimination of mosquitoes in the tropics has always proven difficult due to mosquito resistance, pathogen resistance to treatments, the lack of infrastructure and financial support. Conventional means of avoiding infection from mosquito-borne diseases have been to prevent being bitten through the use of mosquito nets and chemical repellents. I was therefore rather intrigued to hear about the work of Oxitec, the Alphey Lab and others in relation to developing genetic controls to exterminate this “winged scourge”.

The ecological niche filled by mosquitoes is little understood and has been poorly studied. In 2010, at the British Ecological Society’s annual meeting, the chair, Professor Charles Godfray said:
“We know very little about the [mosquito] community ecology… and this is significant because if you were to knock it out then you want to know what would take its place. […] And we don’t know enough, not for the want of trying, about the dispersal of the mosquitoes; how they move from one place to another.”
I simply couldn’t believe that such a large knowledge-gap existed with regards such an ubiquitous insect, so I decided to survey the scientific literature to figure out what is currently understood to be the ecological function performed by mosquitoes. I found that a very small number of papers actually concerned themselves with this topic directly and those that did were generally in relation to highly specific niches like larval processing of detritus chain interactions within pitcher-plants, the pollination of orchids, or focused on other species entirely, such as reindeer and caribou whose migration behaviour is influenced by the predation of mosquitoes and other biting flies. Understandably, most papers concentrated on the mosquito as disease vector – especially in relation to humans – but, apart from noting that mosquitoes constitute an enormous biomass, are found in both freshwater and terrestrial ecosystems at different life stages, and that they are highly speciose; there has been little scientific research into their ecological significance. We can extrapolate that they must be an important food source for a number of other insects, birds, reptiles, fish, amphibians and even mammals, but the data is lacking to support this – we need more research to be conducted to be certain. There is also a possibility that mosquitoes contribute to a disease dilution effect, but further study would be required to support any such claim.
So, is it a good idea to locally exterminate mosquitoes if we really don’t have any idea what will happen to their ecosystems? I would suggest that it probably isn’t the greatest idea. Possible scenarios are a reduction in available food for predators that will cause greater predation on other food sources thereby decreasing these at a faster rate and increasing competition. Increased competition can in turn lead to lower reproductive success and in the worst-case scenarios population collapse of apex predators. At least, I think it would be safe to assume that those ecosystems would no longer operate in the same way – their species composition would shift  to a greater or lesser degree and with that the functional ecology.

And what about the disease dilution effect? Well, if it holds true in the case of mosquitoes then we may witness an intensification of disease virulence and higher infection rates. An alternative hypothesis is that the pathogens might move into other host species and we would be left scrabbling for new control mechanisms.

As someone with a desire to understand the intricately interlinked nature of our world and all the living creatures in it, I couldn’t support the deliberate extinction of any species (despite the detrimental effects it can have on humanity) without first knowing what the knock-on effects of that extinction would be. In doing something that we hope would benefit humanity, we may in fact be creating new and more complex problems.

An American entomologist, Jeremy Lockwood, wrote of the need to establish an ethical basis of “philosophically sound, scientifically consistent” considerations with regards our relationship to insects. He proposed that we refrain from taking actions that would kill or cause nontrivial pain to insects, but not if by avoiding those actions there would be nontrivial costs to human welfare. Genetically modified mosquitoes, and by association other mosquito control mechanisms, would presumably be considered acceptable to most people within this  anthropocentric ethical framework. The irony of this position however is, as Lockwood points out, that a person considered a humanitarian is often referred to as, “one who wouldn’t hurt a fly”.
This blogpost is based on my final-year research paper. For those of you wanting a bit more in-depth information, you can read the full paper here.

References:

Alphey, L. (2014). Genetic Control of Mosquitoes. Annual Review of Entomology59(1), 205–224. doi:10.1146/annurev-ento-011613-162002

Fang, J. (2010) Ecology: A world without mosquitoesNature News, 466(7305), 432–434. doi:10.1038/466432a

Godfray, H. C. J. (2013). Mosquito ecology and control of malaria. Journal of Animal Ecology, 82(1), 15–25. doi:10.1111/1365-2656.12003

Lockwood, J. A. (1987). The Moral Standing of Insects and the Ethics of Extinction. Florida Entomologist70(1), 70 – 89.

Sinka et al. (2012). A global map of dominant malaria vectorsParasites & Vectors5(69). doi:10.1186/1756-3305-5-69

World Health Organisation http://www.who.int/whr/1996/media_centre/executive_summary1/en/index9.html.