Tag Archives: Edward Newman

Collect by all means, but….

Some of Wallace’s beetles

 

Leaving aside grant writing and committee meetings, which are, in theory, voluntary, the part of academic life I hate the most is marking assignments and exams.  At this time of year, however, I find myself actually enjoying marking student assignments. You may well ask why, what is it that makes these assignments different?  The reason is simple enough; many years ago, when thinking about ways in which to satisfy learning outcomes and to give our MSc students worthwhile skills in a different and enjoyable way, I had a flash of inspiration. I came up with two assignments that I felt our aspiring entomologists would appreciate and that I, and my colleagues would enjoy marking.  One is a written piece of work based on the Royal Entomological Society student essay competition. This not only gives the students the chance to write about something they like in a totally different format than their usual essays and lab reports, but as they are encouraged to submit their essays to the prize committee, they get the chance to gain a monetary reward, and many do so*.

The second assignment which I ‘borrowed’ from my own days as an entomology student, is to collect and curate a small insect collection, with the added twist of preparing a factsheet/booklet, suitable for use at outreach events, describing the collection with notes on the biology and ecology of the specimens, capped off with a fun fact for each insect. The students do a fantastic job with both the collections and the accompanying leaflets, booklets and posters (they are allowed a very free rein as to how they present the fact sheets).  They are so good in fact, that I borrow some of them to use at outreach activities**.

Some examples of the student collections.  Apologies for the lousy photographs 😊

Now on to the meat of my post. Although initially aimed at the use of live animals (by which they meant vertebrates, the three Rs of biomedical research, reduction, refinement replacement (Russell & Burch, 1959) now widely permeate society and have meant that many of the zoology practical classes that I did as an undergraduate, e.g. examining the effect of adrenaline on exposed frog hearts, or infecting scores of day-old chicks with Eimeria tenella, ready for killing (by the students) and subsequent dissection of the gut, are, and rightly so, no longer part of the student curriculum.  Although as entomologists we deplore the common perception that insects are not, for the most part, recognised as animals by funding bodies, or the general public, we are glad that this allows us to escape the dreaded ethics forms and licences to allow us to work on living material. As entomologists however, whether we work on pests or on insects of conservation interest, we are deeply in love with our study animals and although some of us (not me, I have always been an observer rather than a pinner) may own or manage large collections of insects, we do this from necessity not from a love of killing.  This is, and always has been, something of a conflict for us entomologists since the first one emerged from the undergrowth clutching a treasured specimen (Newman, 1841).

Newman (1841) on why entomologists are more humane than non-entomologists

 

Joseph Greene – another early ethical entomologist

Living insects are not always amenable to transport and display; the standard fare at outreach events are stick insects, leaf insects, flower beetles and Madagascan hissing cockroaches, fulfilling the hardiness, cuteness and “yuk” factors respectively and in all cases, being large enough to see easily.  I have taken living specimens of the “World’s biggest aphid” along on many occasions, only to be greeted with responses that can only be described as of complete underwhelming disdain 😊We want and need to show the fantastic diversity of insects and the easiest way to do this is with the standard display boxes.

Our basic outreach display box of common British insects

Boxes such as the above do not usually cause much controversy although some visitors do ask why we need to kill and pin the insects.  It is the boxes of what look like identical specimens lined out in serried rows that cause the most questioning.

Serried rows – the infinite variety withing species – thanks to Erica McAlister from the NHM for the photograph.

My response is to ask my interlocutor to imagine that they are a 10 metre tall explorer from a distant Galaxy that has landed on Earth and collected a couple of humans, which you carefully preserve and take back to your home planet and donate them to a museum as typical Earth specimens. Now, imagine another intrepid collector arrives on Earth with the description of your specimens which unbeknownst to either of you happen to be two males from an Amazonian tribe. Alien Explorer 2 has landed in Iceland at a ladies day at a hot spring.  What is han to make of the specimens han trapped? This is usually enough to make my point and of course I also explain about the huge importance of type specimens and the advantage of being able to look and compare whole specimens from every angle, which despite the huge advances in photography and 3-D imagery is not always possible with virtual images.

Unfortunately, not everyone has had the need for collecting and the importance of reference collections explained to them by an entomologist,  and some individuals can get very worked up about what they perceive as needless cruelty or desecration of Nature, sometimes with very unfortunate outcomes. The late Philip Corbet, one of the most eminent Odonatologist of modern times, then in his early 70s, was once badly beaten up by a member of the public at a Nature Reserve to which he (Philip) had been invited to collect a rare type specimen.  Adam Hart and Sierian Sumner received a deluge of personal abuse for asking people to kill and collect wasps as part of a citizen science project and at the risk of reopening a can of worms, annelid expert Emma Sherlock from the Natural History Museum London, was hounded on-line and in the main stream media for investigating the largest ever Lumbricus terrestris, to see if it was a species new to science or a genetic aberration.

The worm in question

In Emmas’s own words, “To identify earthworms generally there are less than half I can identify accurately alive, the rest you always have to preserve to identify. For the people saying you shouldn’t preserve animals how are you ever to conserve them? You need to add a name to the animal to be able to learn more about it and to conserve it if it needs help. Like the little polychaete worm that halted the big road development a few years back. If a specimen hadn’t been taken and given a name then it is just a worm, and there are lots of worms and therefore worms are not in need of protection”.

This is also the case for many insect species, which can for example, only be identified by close examination of their genitalia, in many cases, by dissection, so certainly not possible to do with living specimens.  Another point of concern that could be raised is the phenomenon of moth trapping.  Until I went on Twitter, I hadn’t thought deeply about moth trapping.  I was involved with running one of the Rothamsted Insect Survey moth traps when I was doing my PhD at the University of East Anglia, but hadn’t realised that it was a bit of a phenomenon with even hard-core ornithologists running traps in their gardens. Given the reports of insect declines over the last couple of decades (Leather, 2018) is this something we should deplore and restrict? Very sensibly, moth trappers (moth’ers) have not ignored the problem and the consensus seems to be that moth trapping per se, pales into insignificance when compared with the other pressures on insect populations.

I suspect that like most entomologists, I have what might seem to non-entomologists a contradictory relationship with insects.  My research spans the world of conservation and crop protection.  As an ecologist, my group and I are trying to come up with ways in which to enhance and protect insect diversity and abundance.  The other members of the group are looking at better ways to protect our crops so that we can feed the world, and this inevitably involves killing pest insects to reduce their populations.  In my own garden, insects are allowed to flourish and I cringe when I see or hear people telling me how they run their fingers and thumbs along rose buds to squash the aphids.  I feel guilty if I accidentally wash a spider down the drain when I am having a shower, but have no compunction at all in squashing a mosquito or swatting a stable fly when she attempts to suck my blood!

It is precisely this conflict of interests that has made entomologists think harder about the ethics of their profession than many ‘civilians’ do when swatting mosquitoes or spraying their vegetable gardens (e.g. Fischer & Larson, 2019; Didham et al., 2019).  In the end I turned to verse 🙂

Because we love them

We need to think carefully

When we collect them

 

References

Didham, R.K., Leather, S.R. & Basset, Y. (2019) Ethics in entomology. Antenna, 43, 124-125.

Fischer, B. & Larson, B.M.H. (2019) Collecting insects to conserve them: a call for ethical caution.  Insect Conservation & Diversity, 12, 173-182.

Greene, J. (1880) The Insect Hunter’s Companion 3rd Edition, W. Swan Sonnenhein & Allen, London.

Leather, S.R. (2018) “Ecological Armageddon” – more evidence for the drastic decline in insect numbers. Annals of Applied Biology, 172, 1-3.

Newman, E. (1841) A Familiar Introduction to the History of Insects. John van Voorst, London.

Russell, W.M.S & Burch, R.L. (1959) The Principles of Humane Experimental Technique. Methuen & Co, London.

 

*

If you scroll down the RES page link you will see that our students have done remarkably well over the years.

 

**

an example followed by some of our former students 😊

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Entomological classics – the sweep net

I am certain that everyone who has studied biology at university and/or been on a field course, will have used a sweep net and heard the phrase “It’s all in the wrist”.  Along with the pitfall trap it is the most commonly used entomological sampling technique used today.  Although the premise is simple enough, a sturdy net, attached to a handle that is swept along, through or above low-lying vegetation, when used as a scientific tool and not just as a collecting device, things become somewhat more complex.  The sweep net, as an insect collecting device, has been around for at least 180 years, the earliest reference that I have been able to find being Newman* (1835).  There are a number of slightly later references in both general entomology texts and group specific books (e.g. Newman, 1844; Clark, 1860; Douglas, 1860; Douglas & Scott, 1865). Instructions for their use at this time are minimal, as this extract from Newman (1841) illustrates.

Newman (1841) a very brief description indeed.

This slightly later description of how to make a sweep net is, however, much more detailed, albeit somewhat sexist.

From Stainton (1852), although he seems to be quoting Newman.  Apparently Victorian men were unable to sew.

More detailed, albeit fairly basic instructions on how to use a sweep net can be found in those two invaluable sources, Ecological Methods (Southwood & Henderson 2004) (two pages) and Practical Field Ecology (Wheatear et al., 2011) (one page).  I was amused to see that the text in Southwood & Henderson was identical to that of the first edition (Southwood, 1966).

Now we come to the wrist action. There are a surprising number of ways in which you can swing a sweep net, but they all depend on the wrist moving your hand, and hence the net, in a figure of eight. The two most commonly used are what I think of as the one row side step, and the double front step.  In the former you walk in a straight line swinging the net backwards and forwards at your side, ideal for sampling a row crop. The latter, the double front step, is similar, but instead of swinging the net at your side, you swing it side to side in front of you as you walk along.  In a crop, this is great for sampling multiple rows, in a non-crop a good way of covering a nice wide area of vegetation. There are a further two techniques specifically designed for sweeping the upper part of vegetation, both originally devised for sampling soybean insects, the lazy-8 and the pendulum (Kogan & Pitre, 1980).  Both these involve having the net raised, the lazy-8 with the net raised above the crop at the back and front swings, whereas in the pendulum, the net is kept within the crop on the fore and reverse swings.  The final bit of wrist action, and arguably the most important and difficult to learn, is the flick-lock, which neatly seals the net and stops your catch escaping.

Having completed your sample of however many sweeps (remember a complete sweep is the figure of eight), and sealed your net, the next step is to transfer your catch to your collecting tubes, bags or jars.  A good sweep net, as well as being made from tough material, should be a bit sock shaped.  By this I mean that there is a ‘tail’ at the base of the net which helps make your catch more manageable if you are transferring directly to a plastic bag, as you are able to grab the net above the ‘tail’ end and push it into the collecting bag, before everting the net.

Two examples of sweep nets, a large and a small one.  You can also get a medium one in this series supplied by the NHBS web site for about £34. http://www.nhbs.com/professional-sweep-net

When I was a student, the sweep nets we were supplied with, were large enough to stick not just your head inside, but also to get your arms in, so that you could Poot up anything interesting, your shoulders forming the seal to the net.  Admittedly you did sometimes have an angry bee or wasp to contend with, but that was a rare event 🙂  Nowadays, sweep nets seem to be constructed on a much more modest scale, which makes sticking your head, let alone your shoulders into one, somewhat difficult.

Even the biggest modern one is too small for me to get my arms in to do some Pooting.

I was pleasantly surprised on an ERASMUS exchange visit to the University of Angers a few years ago, to find that the French, or at least those in Angers, were using sweep nets that were big enough for me to actually delve inside just as I did when I was a student 🙂

The joys of a sweep net with a view 🙂

Despite their undoubted popularity, value for money and relative ease of operation, there are a number of problems associated with sweep netting as a sampling technique.  Although these problems are summarised elsewhere (Southwood & Henderson 2004; Wheater et al., 2011) I can’t resist putting my own personal slant on the subject.

  • The type of habitat can have a marked effect on what you catch. Not all habitats are equally amenable to sweeping; spiny and woody vegetation poses more problems than a nice meadow and you need a really tough net for moorlands 🙂
  • A sweep net doesn’t necessarily give you an accurate picture of the species composition of the habitat. Not all insects are equally catchable, you are for example, much more likely to catch Hemipterans than you are Coleopterans (e.g. Standen, 2000)
  • The vertical distribution of the insects also affects what you catch. Many insects have favourite positions on plants e.g. the cereal aphid, Sitobion avenae prefers the ears and leaves, whereas the bird cherry-oat aphid, Rhopalosiphum padi is usually found at the bottom of the plant (Dean, 1974).
  • The weather; anyone who has tried sweep netting during, or after, a rain storm knows that this is the ultimate act of folly 🙂 Wet nets and wet samples are not a marriage made in heaven.
  • Time of day can also affect what you are likely to catch, pea aphids for example, are found at different heights on their host plants at different times of day (Schotzko & O’Keeffe, 1989). To be fair, this is of course not just a problem confined to sweep net sampling.
  • Sweep nets have a fairly well-defined height range at which they work best, they are not good at sampling very short grass and once the vegetation gets over 30 cm you start to miss a lot of the insects associated with it as the net doesn’t reach that far down. Also the efficiency of the sweep netter is reduced.
  • Finally, how the hell do you standardise your sweeps, not only between sweepers, but as an individual? Additionally, can you reliably use them quantitatively? This has been recognised as a problem for a long time (DeLong, 1932).  No one disagrees that sweep netting, provided all the caveats listed above are taken into account, gives a very good qualitative and comparative idea of the arthropod community of the area you are sweeping and they have been so used in many important ecological studies (e.g. Menhinick, 1964; Elton, 1975; Janzen & Pond, 1975) and extensively in agricultural systems (e.g. Free & Williams, 1979; Kogan & Pitre, 1980).  Comparing any sampling technique with another is difficult, and any attempt to quantify a catch so that specific units can be assigned to the area or volume sampled is welcome.  This has been attempted for the sweep net (Tonkyn, 1980), although I confess that I have never seen anyone use the formula developed by him.  In fact, although, according to Google Scholar his paper has been cited thirteen times, only one of the citing authors actually uses the formula, the rest just use him to cite sweep netting as a sampling method. Poor practice indeed.

An illustration of how the various components of the sweep net volume formula is derived (from Tonkyn, 1980).

Sweep nets are, despite the inability to get inside them anymore, great fun to use, extremely good at collecting material for ecology and entomology practicals and of course, a great ecological survey tool when used properly.  Google Scholar tells me that there are over 38 000 papers that mention them.  That many people can’t possibly be wrong 🙂

References

Clark, H. (1860) Catalogue of the Collection of Halticidae in the British Museum. Physapodes and Oedipodes Part 1. Published by the Trustees, London.

Dean, G.J. (1974) The four dimensions of cereal aphids. Annals of Applied Biology, 77, 74-78.

DeLong, D.M. (1932) Some problems encountered in the estimation of insect populations by the sweeping method.  Annals of the Entomological Society of America, 25, 13–17.

Douglas, J.W.  (1856) The World of Insects: A Guide to its Wonders. John van Voorst, London.

Douglas, J.W. & Scott, J. (1865) The British Hemiptera Volume I Hemiptera – Heteroptera. Ray Society, Robert Hardwicke, London.

Elton, C.S. (1975) Conservation and the low population density of invertebrates inside neotropical rain forest.  Biological Conservation, 7, 3-15.

Free, J.B. & Williams, I.H. (1979) The distribution of insect pests on crops of oil-seed rape (Brassica napus L.) and the damage they cause. Journal of Agricultural Science, 92, 139-149.

Janzen, D.H. & Pond, C.M. (1975) A comparison, by sweep sampling, of the arthropod fauna of secondary vegetation in Michigan, England and Costa Rica. Transactions of the Royal Entomological Society of London, 127, 33-50.

Kogan, M. & Pitre, H.N. (1980) General sampling methods for above-ground populations of soybean arthropods. Pp 30-60 [In] Sampling Methods in Soybean Entomology. (Eds.) M. Kogan & D.C. Herzog, Springer, New York.

Menhinick, E.F. (1964) A comparison of some species-individuals diversity indices applied to samples of field insects. Ecology 45, 859-861.

Newman, E. (1844) The Zoologist. A Popular Miscellany of Natural History, Volume 2. John van Voorst, London.

Newman, E. (1841) A Familiar Introduction to the History of Insects. John van Voorst, London.

Newman, E. (1835) The Grammar of Entomology. Frederick Westley & A.H. Davis, London.

Schotzko, D.J. & O’Keeffe, L.E. (1989) Comparison of sweep net., D-Vac., and absolute aampling., and diel variation of sweep net sampling estimates in lentils for pea aphid (Homoptera: Aphididae)., Nabids (Hemiptera: Nabidae)., lady beetles (Coleoptera: Coccinellidae)., and lacewings (Neuroptera: Chrysopidae). Journal of Economic Entomology, 82, 491-506.

Southwood, T.R.E. (1966) Ecological Methods, Methuen & Co., London.

Stainton, H.T. (1852) The Entomologist’s Companion; Being a Guide to the Collection of Microlepidoptera and Comprising a Calendar of the British Tineidae. John van Voorst, London.

Standen, V. (2000) The adequacy of collecting techniques for estimating species richness of grassland invertebrates.  Journal of Applied Ecology, 37, 884-893.

Tonkyn, D.W. (1980) The formula for the volume sampled by a sweep net.  Annals of the Entomological Society of America, 73,452-454.

Wheater, P.C., Bell, J.R. & Cook, P.A. (2011) Practical Field Ecology: A Project Guide, Wiley-Blackwell, Oxford.

 

*Of interest to me, but perhaps not to my readers, Edward Newman was one of the founder members of the oldest and most exclusive, yet low-key, entomological society in the world, The Entomological Club, of which I have the honour of being a member 😊 https://en.wikipedia.org/wiki/Edward_Newman_(entomologist)  founder member of the Entomological Club

 

 

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