…at random

It’s coming up to Christmas so I thought I would be a bit of a Grinch 🙂  As someone who has refereed a lot of papers in my time, one of my particular bugbears is when I come across the phrases,  “taken at random”, “sampled randomly” or variations thereon. My edition of the OED defines at random as “haphazard without aim or purpose, or principle, heedlessly”; the statistical part of the definition qualifies this further as “equal chances for each item to be selected”.  Whenever I see the word random in the methods and materials section I annotate the paper with the phrase “truly random or haphazardly?”  Almost without exception*, when the author responds to my query, it is to admit that in reality they meant haphazardly.

There is a commonly held belief among field biologists that random sampling can be quickly and safely done by standing in a field and throwing a quadrat over their shoulder or closing their eyes and throwing the quadrat into the air. The late great Sir Richard Southwood  deals with this myth in his usual no nonsense style  “Biologists often use methods for random sampling that are less precise than the use of random numbers, such as throwing a stick or quadrat.  Such methods are not strictly random” (Southwood, 1966).  If you have ever tried this yourself, you will, I hope, be the first to admit, that you position yourself in all sorts of non-random ways, to make sure that the quadrat is not going to get lost, get hung-up in a tree, end up in a lake or river or miss the only green bit of vegetation in the field. Other so-called random approaches include the walking around the tree/into the meadow/along the path approach and examining the first leaf/branch/plant you come across after x number of steps and counting what you see on that. Again, this is equally subject to being confounded by the terrain and location of the site, and it is a rare person who isn’t subconsciously swayed for or against a leaf because of its appearance.  I was convinced that this mode of sampling, which is more accurately described as haphazard, was commonly called professorial random sampling.  A recent request by me on Twitter for people to tell me if they had heard of, or used the term themselves, resulted in a zero response rate, so perhaps it was just something we used in our lab. Of course, it wasn’t a random survey so I shouldn’t read too much into it 🙂

So, if you are going to claim that you sampled randomly or selected/arranged randomly, make sure you use a random number generator.  It is very simple to do, although somewhat time-consuming to implement in reality. When I was a student, most good statistics books included among all the other useful tables, a page of random numbers to help you meet a state of true randomness.

Pre-prepared random numbers from my copy of Sokal & Rohlf (1973)

 

Nowadays, you can, if you use Excel, generate random numbers using the function RAND. Those of you who are not fans of Excel can try this handy link https://www.random.org/sequences/

If you’re reading this, you now have no excuses left.  If you are going to claim that you did something randomly make sure you actually did so, or confess that you sampled haphazardly; it is nothing to be ashamed of 🙂 and is much faster than true random sampling, hence its popularity.  Alternatively, you can avoid the whole issue and sample along a stratified transect or arrange your experimental blocks using a Latin Square.

 

References

Sokal, R.R. & Rohlf, F.J. (1973) Introduction to Biostatistsics.  W.H. Freeman & Company, San Francisco.

Southwood, T.R.E. (1966) Ecological Methods.  Chapman & Hall, London.

*I have, on a few occasions, had an author respond that yes, they did indeed use random number tables and/or generators.

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Pick and Mix 25 – Natural History, Entomology & Ecology

 

Jeremy Fox asks “Did Darwin have a blind spot?”

Time to get more young people interested in taxonomy

On the same lines, an interview with Maya Leonard, author of the Beetle Boy trilogy and newly released Beetle Collector’s Handbook

Great to see someone starting a Natural History course at university level

Did you know that insects have had a huge influence on science fiction films?

Neither plant nor animal – a new branch on the tree of life?

Why museum collections are valuable and need preserving

More on the global decline in insect numbers and why we should be worried

A nice piece of research where the media headline is so wrong:  “Ants in Florida collect the skulls of other ants to decorate their nests” – see the actual paper here and make up your mind 🙂

How locust ecology inspired an opera

 

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Not all aphids are extant – fossil aphids

Mention the word fossil and most people immediately think of dinosaurs, ammonites, early hominids and perhaps plants from the carboniferous.  For those of you who have coal-burning fires, have a look in your coal-scuttle, you may be surprised at what you find.  What most people don’t realise is that there are fossil insects and these include those fabulous insects, aphids 🙂

A beautifully preserved aphid, Mindarus harringtoni, named after, and owned by my friend, and fellow aphid enthusiast, Richard Harrington.

The oldest fossil of a true insect dates back to the Pragian (early Devonian) era (396-407 million years ago (Mya)) implying that they can, almost certainly, be dated back to the earlier Silurian period (434 Mya) (Engel & Grimaldi, 2004). Aphids, being relatively soft-bodied animals, tend to be less commonly found as stone fossils, but there are some fine examples in existence.  The oldest aphid fossil found so far is Vasegus triassicus from the Vosges area of France and dating back to 174-163 Mya (Szwedo & Nel, 2011).  I have a great admiration for taxonomists in general, but paleoentomologists really are worthy of worship, working as they do, with material, especially that found in rock deposits, of an extremely taxing nature.

Wing of the aphid Vosegus triassicus  (Szwedo & Nel, 2011)

A more recognisable aphid wing from the Lower Cretaceous (140 Mya).  https://jurassiccoast.org/fossilfinder/1338-aphid-wing/

Another contender for the oldest aphid was found in the Daohugou beds in China on the boundaries of the provinces of Inner Mongolia, Hebei and Liaoning (Huang et al., 2015).  These deposits have been dated back to about 165 Mya.  Given the inevitable distortion caused by the squashing, the fossils do look like some modern aphids and I am pretty certain that I can see the cauda which is one of the distinguishing characteristics of aphids.

Daopaphis magnalata with a visible cauda? (Huang et al., 2015)

Somewhat younger, a mere 15 000 000 years old, Palaeogreenidea rittae, which displays the other dead giveaway that tells you that you are looking at an aphid, the siphunculi.

Palaeogreenidea rittae, note the distinctive siphunculi.  Middle Miocene from Nevada (approximately 15 Mya) (Heie, 2006).

Amber, fossilised tree resin, is, however, where you are most likely to find ancient aphids.  Tree resin is a carbohydrate-based extremely sticky secretion of trees, particularly conifers. It is part of their defence system and is used to seal wounds and to trap and encapsulate any insect intent on forcing an entry into the heart of the tree. The majority of the insects found in resin have arrived there by accident; they have landed on it and found themselves trapped.  They gradually become engulfed by the resin and die a slow and lingering death, unless a bird plucks them from their sticky surroundings as a tasty snack.  Go into a pine forest or look at the resin bleeds that you often find on fruit trees and you will very soon find some hapless insect victims. Over time the resin hardens and becomes a substance known as copal.  This can then find its way into the soil; the tree falls over or the copal becomes detached and falls to the round. Once in the soil, the copal has the chance, over several million years, to harden further still and eventually become resin.  Any insect trapped in resin is perfectly preserved, ready for the intrepid palaeoentomologist to discover and name or entrepreneur to sell to curio collectors.

A very fine specimen with a very long stylet; presumably this fed on the trunk of trees.  Germaraphis spp. (Pemphigidae)    http://www.fossilmuseum.net/Fossil-Amber/antaphid/amber-86.htm 

 

A very recognisable aphid indeed, the antennal tubercles, siphunculi and cauda are all very clear.  Photo from Ross (2009).

Not all aphids in amber are as easy to identify as the two specimens above.  The example below is why I have such a great admiration for palaeoaphidologists.

I am told that this is an aphid.  Photographed and found by Gracie Price a placement student at Oxford University Museum of Natural History, reproduced with thanks to Darren Mann.

I have written earlier about the close relationships that many aphids have with ants and it seems from the number of times ants and aphids have been found in close proximity in amber inclusions, that this association has been in existence for at least 73 million years especially with Germaraphis dryoides (Heie, 1967; Perkovsky, 2009).

Ant and aphid in amber. It will cost you €100 if you want to own this specimen.  http://www.amberinclusions.eu/ant-and-aphid-symbiosis-in-baltic-amber-4809#prettyPhoto

Another association, perhaps not so pleasant for the aphid, and also immortalised in amber, is that of a nematode parasite from 100 million years ago (Poinar, 2017).

Aphid in amber with nematode parasite (Poinar, 2017).

What can we learn from these amber inclusions?  First, by comparing them with modern aphids, we can make inferences about their life styles.  As Ole Heie (1967) pointed out, aphids with clawed tarsi (feet) and long mouth parts are almost certainly not only to be tree dwellers, but ones that fed through the bark on the stems or trunks.  Aphids that live on the underside of leaves need neither of these adaptations.  Are there any other inferences to be made? I have already pointed out that, the fossil evidence suggests the ant-aphid mutualism has been long-established.

Fossil aphids also allow us infer that as aphids are largely found in temperate zones, the climate in those sites where amber is easily found must also have been temperate when they were trapped by the then, fresh tree resin (Heie, 1967).  Palaeobiologists have attempted to reconstruct ancient ecosystems from fossils including insects.  A recent and innovative study comparing arthropods found in trapped in modern tree resins, sticky traps and Malaise traps with those in fossil amber suggests that amber inclusions reflect the insects closely associated with trees but not necessarily the overall community (Kraemer et al., 2018).  We can’t get DNA out of amber as suggested in Jurassic Park, but we can certainly get a lot of other biological information from this fantastic window into the past.

I’ll end on a cautionary note. Not all amber is real amber.  Fakes abound.  Plastic is often used as fake amber and is sold with insect inclusions or as jewellery.  An easy way to test if it is plastic or amber, is to see if it floats in a saturated salt solution, if it does it is probably amber. More difficult to detect, is fake amber that has been produced by melting down real amber or copal, and then had modern insects embedded in it while it is still liquid.  If your insect inclusion is very nicely and symmetrically arranged, then you can be sure it is a fake.  Not all such inclusions are sold as genuine, most openly advertise exactly what they are; I have several, gifts from families and students.

Modern insect embedded in plastic.

 

References

Engel, M.S. & Grimaldi, D. (2004) New light shed on the oldest insect. Nature, 427, 627-630.

Heie, O. (1967) Studies on Fossil Aphids (Homoptera: Aphidoidea) Especially in the Copenhagen Collection of Fossils in Baltic Amber. Spolia Zoologica Musei Hauniensis, Copenhagen.

Heie, O.E. (2006) Fossil aphids (Hemiptera: Sternorrhyncha) from Canadian Cretaceous amber and from the Miocene of Nevada. Insect Systematics & Evolution, 37, 91-104.

Huang, D., Wegierek, P., Żyła, D. & Nel, A. (2015) The oldest aphid of the family Oviparosiphidae (Hemiptera: Aphidoidea) from the Middle Jurassic of China. European Journal of Entomology, 112, 187-192.

Kraemer, M.M.S., Declos, X., Clapham, M.E., Arillo, A., Peris, D., Jäger, P., Sebner, F., Peñalver, E. (2018) Arthropods in modern resins reveal if amber accurately recorded forest arthropod communities. Proceedings of the National Academy of Sciences, USA, 115, 6739-6744

Perkovsky, E.E. (2009) On finding a single-clawed aphid, Germaraphis ungulata (Homoptera, Aphidinea), in a syniclusion with the ant Monomoroium mayrianum (Hymenoptera, Formicidae) in the Saxonian amber.  Paleontological Journal, 43, 1006-1007.

Poinar, G.O. (2017) A mermithid nematode, Cretacimermis aphidophilus sp. n. (Nematoda: Mermithidae) parasitizing an aphid (Hemiptera: Burmitaphididae) in Myanmar amber: a 100 million year association.  Nematology, 19, 509-513.

Ross, A. (2009) Amber – The Natural Time Capsule. NHM, London.

Szwedo, J. & Nel, A. (2011) The oldest aphid insect from the Middle Triassic of the Vosges, France. Acta Palaeontologica Polonica, 56, 757-766.

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Dear Dr Researcher – Epic Predatory Journal Fails!

As a follow-up to my earlier post on predatory journals I thought I would share some of the many invitations I have received since it appeared 🙂   What I do find annoying is that our email Firewall system sis extremely efficient at intercepting real emails and putting them on hold for us to approve, but that all the emails shown below got straight through the system without any trouble.

 Over the top glorification!

Beware of journals that use over the top language trying to appeal to your vanity.

 

Poor English is always a clue that things are not what they seem.

Precious indeed!

 

Totally wrong discipline

It is always a bit of a give-away when over the top language is coupled with a journal title where the field is somewhat removed from your own.  I am an entomologist and ecologist.

 

and then you have this journal – they desperately need a proof reader 🙂

These journals make the mistake of advertising a totally unrealistic publication schedule

 

It is possible that if they had put a more realistic publication schedule an engineer might have fallen for this one.

 

Cunning ploys

Here are a couple of examples where they are trying a bit harder and getting a bit more sophisticated.

 

The name of a real journal, Agriculture, Ecosystems and Environment highlighted to take advantage of the careless reader.

The suggestion that they are on the look-out for reviewers implies a certain degree of respectability.

 

I am sure that you have all had similar emails, but if you have had even more outrageous or more cunning invitations, please feel free to share.

 

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Four animals and insects that humans can’t live without

Worth a read

The CABI Blog

BeesGuest blog by Master Beekeeper ‘in the making’ Greg Long.

When people start to think about the ecosystem and nature as a whole, many don’t fully grasp the importance of relying on other species. Everything on earth is connected, whether we realize it or not. Human survival doesn’t rely on humans alone — the human species depends on tons of other life forms to stay in existence.

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Water butterflies and hairy wings – Caddisfly names around the world

“..great variety of cados worms.. “ Thomas Mouffet (1658)  Theatorum Insectorum

Adult Limnephilus caddisfly perched on top of its case-bearing larva.

Despite aphids being my favourite insect group, I have had rather a soft spot for caddisflies since I was about ten years old when I discovered that if I very carefully removed their larval cases and provided them with coloured sand, they would spin a technicoloured replacement 😊

A variety of caddis cases

I have, in the intervening years, moved on somewhat from those early experiments and largely left the wonderful world of freshwater entomology behind, except when I take students pond-dipping and give my once a year lecture on aquatic insects. I’m not going to say much about caddisflies because I am not an expert, but for those of you not overly familiar with these fascinating insects a little bit of background information may be useful.  Unless you are a caddisfly specialist most people don’t give them much thought and if they do know anything about them, it is probably limited to the fact that they are aquatic and live inside a case.

Most people probably wouldn’t recognise an adult caddisfly if they saw one and in my experience those people who do notice them, usually think they are some sort of moth.  This is actually a sensible guess as evolutionarily speaking Lepidoptera (moths and butterflies) and Trichoptera (caddisflies) are very closely related and are in the same Superorder, the Amphiesmenoptera.  Trichoptera literally translates as hairy wings, Lepidoptera as scaly wings and many adult caddisflies do look remarkably similar to micro-moths so it is an easy mistake to make.

Spot the difference – caddisflies on the left, Lepidoptera on the right

The majority of caddisflies have aquatic larvae, although a few have become completely terrestrial and spend their lives foraging in damp leaf litter and hiding in bark crevices.

Wingless female of the terrestrial caddisfly Enoicyla pusilla; doing her best to not look like a caddisfly. http://www.wbrc.org.uk/worcrecd/33/Green_Harry_7–Westwood_Brett–Sightings_of_adult_.html

Very generalised life cycle of a caddisfly.  The eggs are laid in water, on aquatic vegetation or nearby trees. On hatching, the larvae go through several (usual five) moults before pupating and the adults emerge in spring or early summer.

Caddisflies are probably the most successful of the aquatic insects. Data from stream surveys frequently list as many species of Trichoptera, or caddisflies, as species of Ephemeroptera (Mayflies), Odonata (dragon and Damselflies) and Plecoptera (Stonefleis) combined (Mackay & Wiggins, 1979).  Their success can be put down to their use of silk and ability to exploit a range of different aquatic habitats.  They can be described as lotic, those that live in running water, i.e. streams and rivers, or lentic, those that live in ponds and lakes.  Some of the ‘ponds’ can be very temporary, puddles for example, or contained in plants, e.g. Bromeliads. Those that live in running water are well supplied with fresh aerated water, but those living in ponds and pools have to make their own currents to pass ‘fresh’ water over their gills, to avoid suffocating.

Sedentary caddis larvae live in fixed shelters and use silk ‘fishing nets’ to catch their food.  If they live in fast flowing streams, their nets are coarse and tight.  Those living in slow flowing streams use baggy fine-grained nets.

Caddisfly fishing net https://www.flickr.com/photos/janhamrsky/5979065987/in/photostream/

Some caddisfly larvae are free-living foragers with portable cases. They also use silk, leaving a thread behind them, just as many other insects do, to attach themselves to the substrate so they are not floated downstream willy-nilly.  If they live in fast flowing streams their cases are streamlined making it easier for them to move against the current and less likely to be swept downstream.

I had originally started this article as a companion piece to my articles on the naming of thrips, aphids, cockroaches, and most recently, ladybirds, so I guess I had better get on with it. The origin of the word “caddis” is unclear, but according to Wikipedia it dates to at least as far as Izaak Walton’s The Compleat Angler (1653), in which “cod-worms or caddis” are mentioned as being used as bait. Thomas Muffet (Moufet) used the term cados worm in his book Insectorum sive Minimorum Animalium Theatrum which was written earlier (he died in 1604) but not published until 1658.  The term cadyss was being used in the fifteenth century for silk or cotton cloth, and “cadice-men” were itinerant vendors of such materials, but a direct connection between these words and the insects has not yet been established.  What about other languages, what attributes of the caddisfly have non-English speakers latched on to describe these fascinating insects?

Bulgarian – ручейник (rucheinik), which Google Translate will also tell you is rhinoceros 😊

Catalan – Frigànies which also translates as frigates, an indication of the association with water?

Czech – potočníky = stream legs

Dutch – kokerjuffer – the larval form, Schietmotten (pl) Singular: Schietmot – directly translates as shooting moths. Interestingly (or not), dragonfly is waterjuffer.

Finnish – Vesiperhonen – water butterflies, again reflecting the close resemblance to Lepidoptera; Finns call moths night butterflies, yöperhoset

French – Trichoptères – surprisingly not very flowery at all, but the larvae are more satisfyingly described as  à fourreau ou porte bois which roughly translates as with a sheath or wooden door

German – die Köcherfliege – also Frühlingsfliege, Fruhlings = spring, fliege = fly, Kocher = quiver as in arrows which given the shape of some of the cases is quite apt and the larvae are known as Köcherfliegenlarven

Icelandic – Vorflugur – Spring fly, reflecting the time of year when most of the adults emerge.

Polish – Chruścik – the wording on the stamp seems to translate as swamp yellow

Portuguese – o mosca d’água, The water fly

Spanish – el frígano similar to the Catalán and perhaps reflecting their association with wáter?

Swedish – Nattsländan –Natt = night and slandan = dragonfly?

 

Caddis case jewlery – if only I had been a bit more entrepreneurially  minded….

And finally, for those of you interested in exotic cuisine, and a non poultry alternative to red meat; in Japan caddisfly larvae are called Zazamushi and eaten as a delicacy.  They are so popular that they are commercially farmed (Cesard et al., 2015).

Many thanks to Daniela Atanasova, Gia Aradottir, Hannah Davis, Luisa Ferreira Nunes and Marlies vaz Nunes for help with the Bulgarian, Icelandic, German, Portuguese and Dutch respectively. They are much more reliable than Google Translate.

References

Cesard, N., Komatsu, S. & Iwata, A. (2015)  Processing insect abundance: trading and fishing of zazamushi in Central Japan (Nagano Prefecture, Honshū Island). Journal of Ethnobiology and Ethnomedicine, 11:78.

Mackay, R.J. & Wiggins, G.B.  (1979) Ecological diversity in Trichoptera.  Annual Review of Entomology, 24, 185-208

 

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Pick and mix 24 – pretty much all about insects this time!

 

Using Twitter for ecological research – lots of great examples

An excellent explanation by Stephen Heard of how to present statistics in scientific writing

Some great ant pictures

Fascinating – insects made from discarded circuit boards – the art of Julie Alice Chappell

How insects cope with winter

Half of the UK’s aquatic insects now contain microplastics!

A nice article about a weevil that pretends to be a fly!

Would you eat insects to prevent global warming?  An interesting paper on ways in which consumers might be persuaded to do so

More about the alarming decrease in insect numbers worldwide – link to the original article here

An excellent analysis of the same article by Manu Saunders and why it is so important

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Meat eating moths

This post is dedicated with thanks to Entomology Uncensored which gave me the idea for this post.

Unless you believe that the Very Hungry Caterpillar’s diet is truly representative of what a lepidopteran larva eats, you will, if asked, almost certainly answer that caterpillars eat plants and that the adults, if they do feed, do so on nectar. Although this is true for the majority of Lepidoptera, there are a couple of exceptions that have opted for a very different life style. Some of you may already now be saying to yourselves, “Aha what about the clothes moth? That doesn’t eat plants, it eats clothes doesn’t it?”, and you would be right. The larvae of Tinea pellionella, the Case Bearing Clothes Moth, are not plant eaters, they make a living eating wool, fur and feathers among other keratinous* delicacies (Cheema, 1956).

Tinea pellionella – clearly demonstrating why it is called the case-bearing clothes moth

There are some moth species that have gone a step further in adopting an animal-based diet, feeding directly on living animals and not on their cast-off skins and horns. In 1879 the American entomologist John Comstock (1849-1931) while studying a colony of the cottony maple scale Pulvinaria innumerabilis, was one day surprised to find a caterpillar busily eating his study organisms.  Rather than losing his temper and killing the caterpillar, he reared it through to adulthood and realised that this was a species new to science, which he named Dakruma coccidivora (Constock, 1979), now renamed Laetilia coccidivora and recognised as a useful biological control agent (e.g. Goeden et al., 1967; Mifsud, 1997; Cruz-Rodriguez et al., 2016).  Perhaps it had evaded being spotted by less keen-eyed entomologists from its habit of living underneath the scale insects it eats (Howard, 1895).

The hidden life style of Laetilia coccidivora as described by Howard (1895)

Laetilia coccidivora busy eating prickly pear scale insects

Less deadly to its host, but no less of a carnivore, is the moth Epipomponia nawai.  This, and all the other members of its family, thirty-two in total, are all ectoparasites of Hemiptera, especially cicadas and planthoppers (Jeon et al., 2002).  The larvae attach themselves to the abdomen of their host and feed on the juicy flesh underneath the cuticle.  Once ready to pupate they spin a silk thread, drop off their host and spin a cocoon on the bark of the tree their host has fed on (Liu et al., 2018).  The adults do not fed and only live long enough to mate and lay eggs.  For those of you who love a mystery, no-one knows how the moth larvae find their cicada hosts. One possibility is that they might use the cicada song as a cue but this has, so far, not been proven (Liu et al., 2018).

Larva of Epipomponia nawai parasitizing an adult cicada (Liu et al., 2018).

An even more striking example of predatory behaviour in moth larvae is that shown by members of an otherwise herbivorous Genus of Geometrid (looper) moths, Eupithecia.  The Eupithecia have a worldwide distribution, but in Hawaii, all but two of the species are ambush predators Montgomery, 1983).  The caterpillars show typical looper behaviour, remaining motionless pretending to be a twig or leaf, depending on their colour.  When a potential prey item bumps into the back of the caterpillar it rears backwards and catches the victim between its elongated and spiny thoracic legs and then chomps happily on its juicy meal.  It is thought that the absence of praying mantises on the Hawaiian Islands allowed the ancestors of the original Eupithecia that colonised the islands to fill their empty niche (Montgomery, 1983; Mironov, 2014).  The caterpillars are not fussy about what they eat, as long as they can grab and keep hold of it and it doesn’t fight back.  They have been recorded as eating flies, braconid wasps, leafhoppers, other Lepidopteran larvae, crickets and even spiders and ants (Montgomery, 1983, Sugiura, 2010).

Eupithecia orichloris attacking and eating an ant (Sugiura 2010)

Last in my list of carnivorous Lepidoptera and perhaps the most surprising are the Vampire Moths.  The phenomenon of “puddling” by butterflies to obtain sodium is well-known (e.g. Boggs & Jackson, 1991) and can be a very attractive sight.

A sight to enjoy – mud puddling https://www.earthtouchnews.com/in-the-field/backyard-wildlife/mud-puddling-the-butterflys-dirty-little-secret/

Somewhat less attractive behaviour is seen in a number of moth species from the Noctuid, Geometrid and Pyralid families which satisfy their desire for Sodium by feeding as adults from the tears and pus of mammals, including humans (Bänziger & Büttiker, 1969).

The Noctuid moth Lobocraspis griseifusa sucking lachrymal fluid (tears) from a human’s eye.  The author, whose eye this is, rather gruesomely asks us to “note the deep penetration of the proboscis between eye and eye lid” Bänziger & Büttiker (1969).

Some Noctuid moths have taken this a step further, perhaps a step too far. Moths of the Genus Calyptra, have very strong proboscises which allow them to feed through the skin of fruit, even oranges, hence their common name, fruit-piecing moths.  A few species however, have adopted a somewhat more interesting diet and have developed a taste for fresh mammalian blood, again, including that of humans, which they suck directly from their victims (Bänziger, 1968).  They are, of course, known as the Vampire Moths!

Calyptra thalictri Vampire Moth in action – note the barbed proboscis

Happy Halloween!

References

Bänziger, H. (1968) Prelimnary observations on a skin-piercing blood-sucking moth (Calyptra eustrigata) (Hmps.) (Lep., Noctuidae)) in Malaya.  Bulletin of Entomological Research, 58, 159-165.

Bänziger, H. & Büttiker, W. (1969) Records of eye-frequenting Lepidoptera from man. Journal of Medical Entomology, 6, 53-58.

Boggs, C.L. & Jackson, L.A. (1991) Mud puddling by butterflies is not a simple matter. Ecological Entomology, 16, 123-127.

Cheema, P.S. (1956) Studies on the Bionomics of the Case-bearing Clothes Moth, Tinea pellionella(L.). Bulletin of Entomological Research, 47, 167-182.

Comstock, J.H. (1879) On a new predaceous Lepidopterous insects.  The North American Entomologist, 1, 25-30.

Cruz-Rodriguez, J.A., Gonzalez-Machoro, E., Gonzales, A.A.V., Ramirez, M.L.R. & Lara, F.M. 92016) Autonomous biological control of Dactylopius opuntia (Hemiptera: Dactlyliiopidae) in a prickly pear plantation with ecological management.  Environmental Entomology, 45, 642-648.

Goeden, R.D., Fleschner, C.A. & Ricker, D.W. (1967) Biological control of prickly pear cacti on Santa Cruz Island, California. Hilgardia, 38, 579-606.

Howard, L.O. (1895) An injurious parasite.  Insect Life, 7, 402-404.

Jeon, J.B., Kim, B.T., Tripotin, P. & Kim, J.I. (2002) Notes on a cicada parasitic moth in Korea (Lepidoptera: Epipyropidae). Korean Journal of Entomology, 32, 239-241.

Liu, Y., Yang, Z., Zhang, G., Yi, Q. & Wei, C. (2018) Cicada parasitic moths from China (Lepidoptera: Epipyropidae): morphology, identity, biology, and biogeography.  Systematics & Biodiversity, 16, 417-427.

Mifsud, D. (1997) Biological control in the Maltese Island – past initaitives and future programmes.  Bulletin OEPP/EPPO Bulletin, 27, 77-84.

Mironov, V.G. (2014) Geometrid moths of the Genus Eupithecia Curtis, 1825 (Lepidoptera, geometridae): prerequisites and characteristic features of high species diversity. Entomological Review, 94, 105-127.

Montgomery, S.L. (1983) Carnivorous caterpillars: the behaviour, biogeography and conservation of Eupithecia (Lepidoptera: Geometridae) in the Hawaiian Islands. GeoJournal, 7, 549-556.

Sugiura, S. (2010) Can Hawaiian carnivorous caterpillars attack invasive ants or vice versa? Nature Precedings

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Aphids don’t suck sap! (usually)

Aphids are sap feeding, most of the time they feed from the phloem, or sieve elements, that part of the plant responsible for transporting the food made in the leaves by photosynthesis, around the plant.  Aphids face three problems arising from their phloem feeding habit. First, the phloem sap is largely composed of sugars, with a few trace elements and nitrogen in the form of soluble amino acids.  The aphids are mainly interested in the nitrogen and that poses the second problem, the amino acids are mainly non-essential ones.  Thirdly, the phloem is under pressure, figures range from 2 to 40 Bars* (about twice to forty times atmospheric pressure) (e.g. Mittler, 1957; Rogers & Peel, 1975; Barlow & Randall, 1978; Wright & Fisher, 1980).  Imagine that you are trapped in an air-tight room and your only source of air is an inflated tractor tyre.   You have a sharp metal straw which you can stick into the tyre to release the air into your mouth.  If you put one end of the straw in your mouth and then pierced the tyre wall, your head would explode.

Sadly I couldn’t find a picture of an exploding aphid and my cartoon version was a failure, so this is it 🙂

Aphids face the same sort of pressure. Fortunately evolution has provided them with a very strong pharyngeal pump and incorporated a series of valves in their mouth-parts (stylets = straw) with which they are able to control the flow of the phloem into their bodies.  The last thing they want to do when plugged into the phloem is suck, it would be the last thing they did 🙂 and that’s why aphidologists get upset when people describe aphids as sap-suckers!

 

Aphid feeding apparatus – adapted from McLean & Kinsey (1984)

To be fair, we are being somewhat pedantic, the fluid transported in the xylem tubes, largely water, is also colloquially known as plant sap. The xylem, unlike the phloem is not under pressure (Sperry et al., 1996), so on those rare occasions when the aphid does need to drink water, they do have to suck sap (Spiller et al., 1990).  The other occasion on which aphids need to suck rather than regulate the flow of sap is when they are feeding in very artificial laboratory situations, on leaf discs or on artificial diets where the nutrient solution is between two pieces of Parafilm™.  In both these cases there is negative pressure and the cibarial pump does then come into operation. Interestingly, it is sometimes quite difficult to get aphids to feed on artificial diets unless a phagostimulant is included to overcome their reluctance to feed on sap that is not under pressure (Mittler & Dadd, 1963), but that’s a story for a future post.

Aphids feeding on leaf discs, in this case for insecticide assays at Rothamsted Research

 

Aphids feeding on artificial diet through Parafilm™. Photo Meena Haribal https://www.sciencedaily.com/releases/2015/12/151216151742.htm

 

References

Barlow, C.A. & Randolph, P. A.  (1978) Quality and quantity of plant sap available to the pea aphid.  Annals of the Entomological Society of America, 71, 46-48.

McLean, D.L. & Kinsey, M.G. (1984) The precibarial valve and its role in the feeding behavior of the pea aphid, Acyrthosiphon pisum. Bulletin of the Entomological Society of America, 30, 26-31.

Mittler, T.E. (1957) Studies on the feeding and nutrition of Tuberolachnus salignus (Gmelin) (Homoptera, Aphididae) I. The uptake of phloem sap. Journal of Experimental Biology, 34, 334-341.

Mittler, T.E. & Dadd, R.H. (1963) Studies on the artificial feeding of the aphid Myzus perslcae (Sulzer) – I. Relative uptake of water and sucrose solutions. Journal of Insect Physiology, 9, 623-645.

Sperry, J.S., Saliendra, N.Z., Pockman, W.T.,  Cochard, H., Cruiziat, P., Davis, S.D., Ewers, F.W. & Tyree, M.T. (1996) New evidence for large negative xylem pressures and their measurement by the pressure chamber method. Plant, Cell & Environment, 19, 427-436.

Rogers, S. & Peel, A.J. (1975) Some evidence for the existence of turgor pressure gradients in the sieve tubes of willow Planta (Berl.) 126, 259-267.   

Spiller, N.J., Koenders, L. & Tjallingii, W.F. (1990) Xylem ingestion by aphid – a strategy for maintaining water balance.  Entomologia experimentalis et applicata, 55, 101-104.

Wright, J.P. & Fisher, D.P. (1980) Direct measurement of sieve tube turgor pressure using severed aphid stylets. Plant Physiology, 65, 1133-1135.

 

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Pick and mix 23 – links from far and wide

For entomologists, a gender gap remains in academic, government employment

Food is not waste until it is wasted – find out where and when by reading this

Warning signs to look out for at academic interviews – great post from Terry McGlynn

Social media is not a waste of time – it can be used to monitor phenological events in Nature

Interesting paper – Connections with Nature and Environmental Behaviors – the plastic bag experiment is both novel and revealing

Terry McGlynn again – this time on the use of mobile phones in class

 Excellent Open Access paper from Seirian Sumner on why we love bees and hate wasps

Climate change may not all be gloom and doom for UK butterflies – interesting article from Richard Fox of Butterfly Conservation

What are the main causes of tropical deforestation?  Results of a new study show that commodity crops and forestry account for just over half of forest loss

A really interesting article about crop domestication and how the rush for yield and palatability has increased susceptibility to pests and diseases and reduced genetic diversity

 

 

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