Tag Archives: Hemiptera

What use are bedbugs?

As an entomologist, I have, over the years, become used to being asked by non-entomologists “What use are wasps?” My wife and mother-in-law being frequent interrogators. What they actually mean is “What use are Vespids?”, in particular what the Americans call yellow jackets, and their ilk.

Wasp

Not a bed bug – The European wasp Vespula germanica https://en.wikipedia.org/wiki/Yellow_jacket#/media/File:European_wasp_white_bg.jpg

I now have a well-polished response where I explain that wasps are beneficial insects keeping the caterpillars that eat their garden plants under control and that the occasional hole they make in my interlocutor’s soft fruit is just payment for the job they are doing. I am not saying that this answer always satisfies them, especially if their plums have been devastated, but at least they agree that there is some justification for their existence.

Unfortunately I now have a new question to answer. Last summer (2015) my wife and I took our usual holiday to France. We put our car on the Brittany Ferry, m/V Mont St Michel, and after a drink in the bar retired to our cabin, 9108 in case you want to avoid it, me in Bunk A my wife in Bunk B.

Bedbug2

Sailing in comfort?

The next morning my wife was not a happy lady and the question I now have to answer is “What use are bedbugs?”!

Bedbug3

The bed bug culprit, Cimex lectularius and victim

I have in the past made a convincing case (well I think so) for the usefulness of mosquitoes compared with pandas, but I suspected that making a case for the usefulness of bed bugs that would satisfy my wife, might be more difficult.

Even the Encyclopaedia of Life has nothing good to say about bed bugs. For evolutionary biologists, ecologists and entomologists, bed bugs are very useful in allowing us to relate horror stories about non-conventional sex. Male bed bugs favour a very robust approach to reproduction, as they indulge in what is somewhat coyly termed ‘traumatic insemination (Reinhardt & Siva-Jothy, 2007). Basically they don’t bother with the female genital opening, they mount the female and search for a pouch (Organ of Ribaga or ectospermalage) on the underside of the female (they have been known to mount other males) which they pierce with their intromittent organ (penis) and into which they release their sperm. The spermatozoa then migrate through the body of the female to the oviduct, taking from 2-10 hours to do so (Cragg, 1920). Apparently males never use the genital tract for insemination (Reinhardt & Siva-Jothy, (2007). This somewhat unconventional approach to mating has, as you might expect, harmful effects on the female, with life spans being reduced by about 30% or even causing death (Morrow & Anrnqvist, 2003), multiple matings can be particularly damaging (Mellanby, 1939).

For their human hosts, bed bugs can have a number of unpleasant effects (Reinhardt & Siva-Jothy, 2007), ranging from psychological distress, allergic reactions as in the case of my wife, secondary infections and economic costs, especially if you are an hotelier. All in all, not a very promising candidate for being useful to us humans 🙂 I was beginning to feel that bed bugs had no redeeming features and that if there was a coordinated campaign calling for the destruction of the entire species, I would be unable to defend them. Then a former student came to their rescue. In desperation, I had emailed Mike Siva-Jothy at Sheffield University who has worked on bed bugs since the late 1990s. He passed my email on to Sophie Evison (a former MSc student of mine) and she came to their rescue as follows

I’ve had a think about this, and I think there are two approaches: 1. dazzle them with the traumatic insemination story or 2. Forensics. I’ve not looked into it, but I’m pretty sure a situation could arise where the contents of a bedbug could drop someone in it, or even perhaps prove an alibi! Do you think your wife would accept that as reasonable?”

I was pretty certain that my wife would not be happy with option 1, but felt that option 2 was definitely worth following up. I very quickly found a paper (Szalanski et al, 2006) in which the possibility of testing the DNA of the blood found in bed bugs was suggested as having a possible forensic application. According to Wikipedia (well if it is good enough for my students) there has already been some success in real life using this very approach. I was now pretty confident that I had found an answer to the question posed by my wife. To be fair, I tested both of them out on her. As predicted, she did not buy the evolutionary biology aspect of the traumatic insemination story as being of any use, but as a great fan of the CSI and NCIS TV shows, she has grudgingly accepted that there is indeed a use for bed bugs! I just hope that all the bed bugs out there appreciate all the effort I have gone to on their behalf 🙂 If anyone else has further suggestions please let me know.

References

Cragg, F.W. (1920) Further observations on the reproductive system of Cimex, with special reference to the behaviour of the spermatozoa. Indian Journal of Medical Research, 8, 32-79

Mellanby, K. (1939) Fertilization and egg production in the bed-bug Cimex lectularius L. Parasitology, 31, 193-199

Morrow, E.H. & Arnqvist, G. (2003) Costly traumatic insemination and female counter-adaptation in bed bugs. Proceedings of the Royal Society of London Series B, 270, 2377-2381

Reinhardt, K. & Siva-Jothy, M. (2007) Biology of the bed bugs (Cimicidae). Annual Review of Entomology, 52, 351-374

Szalanski, A.L., J.W. Austin, J.A. McKern, C.D. Steelman, D.M. Miller, and R.E. Gold. 2006. Isolation and characterization of human DNA from bed bug, Cimex lectularius L., (Hemiptera: Cimicidae) blood meals. Journal of Agricultural and Urban Entomology, 23, 189-194.

 

 

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Living inside your grandmother – the wonderful world of aphids

How many of you realise that when you look at an aphid you are simultaneously looking at first, a clonal organism and secondly a mother, her daughter and her granddaughters, all housed in the same body?  This is the wondrous phenomenon known as telescoping of generations.  Aphids, except just before overwintering, give birth to live young (viviparity), and without the need of a male (asexual reproduction/parthenogenesis).  Thus for most of the time when you look at an aphid, you are looking at one member of a clone i.e her sister-self-daughter.  Not only that, but you are looking at not only the aphid in front of your eyes, but at her daughters and her daughter’s daughters, all of which are neatly lined up in tidy rows within the ovarioles of their respective mothers.  With aphids, it is not just maternal effects you have to consider, but also grand-maternal effects, so any experiments should take into account the host-plant and environmental conditions that the ‘grand-mother’ experienced, not just those of the ‘mother’.

aphid telescoping generations

Reproduced from Dixon (1973)

In addition, as the eggs are hatched within the aphids before they are born, their total development time, compared with those insects that lay eggs which hatch externally to their mothers, is significantly reduced, thus giving them a head-start in the population development race.  This is suggested as one of the reasons why aphids are so successful as pest insects.

Generally speaking, this wonderful world of internal generations is hidden from us, unless we cruelly dissect the clone mother and extract her ovarioles.  In some aphids however, such as the small willow aphid, Aphis farinosa, where the offspring are a completely different colour from their mother, the next generation of aphids becomes clearly visible without the need to cut open the mother.

Aphis farinosa

And before you ask, as far as I know, there is no evidence that the generations within a generation go on ad infinitum, like a hall of mirrors, although it would be really cool if they did.

No wonder I love aphids so much.

Dixon A.F.G. (1973)  The Biology of Aphids, Edward Arnold, London

P.S. Tony Dixon’s little Biology of Aphids book is a great introduction to the subject, unfortunately out of print, but the good news is that it is still possible to buy second-hand copies for less than £5. Another great and very readable book, is Aphid Ecology, also by Tony and again out of print, except as an e-book.  The really bad news is that the cheapest copy I have been able to find is priced at £43.31 prior to shipping, so if you want to read it the best option is to borrow it from the library.

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Magic roundabouts – not just traffic calming devices

Roundabouts or traffic circles as they are known in some parts of the world, are a common feature of modern life.  They can range greatly in size; some are big enough to house small communities such as the Shepherd & Flock roundabout on the outskirts of Farnham, Surrey, which has it’s own pub,

Shepherd & Flock Farnham

whilst others are simple grass covered circles, such as the one shown below on the outskirts of Bracknell, Berkshire.  Others, even if lacking pubs, may have a mixture of different plants present, some even with mature trees on them, such as the Sports Centre roundabout also in Bracknell.

Simple roundabout   Diverse roundabout

Traditionally, roundabouts have been thought of as simple devices to regulate the flow of traffic and were usually circular raised areas of tarmac, stone, concrete or brick.  More recently however, town and city councils began to add plants and/or artwork.   Some of my favourites in this latter category are found in southern France as shown below or in the title picture of my blog site.

DSCF1038DSCF1036

Ecologically speaking however, roundabouts are even more interesting.  For almost fifteen years, I and a number of my students, from undergraduate to post-graduate, have been investigating the ecology of roundabouts and other green spaces in the town of Bracknell, Berkshire.  What started as a purely pedagogic exercise (Leather & Helden, 2005a), turned into a voyage of discovery and a realisation that roundabouts are, and can be, great sources of biodiversity (Helden & Leather, 2004), and in addition, could perhaps act as nature reserves (Leather & Helden, 2005b).  With close attention to mowing regimes (Helden & Leather, 2004) and increasing the proportion of native trees and other plants on them, it is not only insect diversity that is enhanced, but birds also (Helden et al., 2012).

We have found that roundabouts behave very similarly to biogeographical islands, i.e. the bigger they are and the more diverse the habitats present, the more diverse and interesting the fauna that can be found on them.  For example, we found the rare and endangered bug (Hemiptera) Gonocerus acuteangulatus, alive and well on one of the roundabouts and amusingly, another species, Athysanus argentarius, usually found in coastal locations.  Perhaps the salt from winter gritting operations fooled it.

Gonocerus acuteangulatus

Athysanus

Roundabouts may not be the equivalent of tropical forests but, they and other urban features such as suburban gardens, as demonstrated by Kevin Gaston and colleagues in a series of ground-breaking papers arising from the BUGS project http://www.bugs.group.shef.ac.uk/ in Sheffield and Jennifer Owen in her 30-year study of her Leicester garden (Owen, 2010), are immensely valuable tools for enhancing and conserving biodiversity in our increasingly impoverished world. We have much more to report, from bees, to butterflies and even woodlice.   Watch this space for future instalments.

Helden, A. J. & Leather, S. R. (2004). Biodiversity on urban roundabouts – Hemiptera, management and the species-area relationship. Basic and Applied Ecology 5: 367-377. https://www.harper-adams.ac.uk/staff/profile/files/uploaded/Helden & Leather2004.pdf

Helden, A. J., Stamp, G. C. & Leather, S. R. (2012). Urban biodiversity: comparison of insect assemblages on native and non-native trees.  Urban Ecosystems 15: 611-624. https://www.harper-adams.ac.uk/staff/profile/files/uploaded/Helden_et_al_2012.pdf

Leather, S. R. & Helden, A. J. (2005a). Magic roundabouts?  Teaching conservation in schools and universities. Journal of Biological Education 39: 102-107. http://www.harper-adams.ac.uk/staff/profile/files/uploaded/Leather_&_Helden_JBE_2005.pdf

Leather, S. R. & Helden, A. J. (2005). Roundabouts: our neglected nature reserves? Biologist 52: 102-106. http://www.harper-adams.ac.uk/staff/profile/files/uploaded/Leather_&_Helden_Biologist_2005.pdf

Owen, J. (2010 ) Wildlife of a Garden: A Thirty Year Study,  Royal Horticultural Society, London

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