Rhinoceros Beetles in Britain? Well, yes and no...

Last night, over a vodka or two, a Russian friend of mine asked me whether we had Rhinoceros Beetles in Britain - we got there after chatting about how his small daughter was interested in bugs. My answer was along the lines of 'no, but...' and shows how the use of non-scientific (vernacular) names can be problematic i.e. it all depends what you mean by 'rhinoceros beetle'.

Generally, rhinoceros beetles are considered to be those in the Dynastinae, a subfamily of the scarabs, Scarabaeidae. Most live in Africa and Asia, although one, the European Rhinoceros Beetle (Oryctes nasicornis), occurs as far north as Scandinavia, though not in Britain. One of Europe's largest insects at around 6cm long, O. nasicornis lives associated with wood of various types (e.g. stumps, sawdust) and is quite scarce, being protected by legislation in some countries. The images below show what a splendid beast it is, and if you visit here, you can see a 3-D image from a CT scan of an Oryctes specimen being rotated.

O. nasicornis adult.

O. nasicornis pupa.

However, although splendid, it still isn't found in Britain, so why my non-committal answer? Well, we do have one species commonly known as the 'Rhinoceros Beetle' - Sinodendron cylindricum which is Britain's sole member of the Syndesinae, a subfamily of the stag beetles, Lucanidae. At 1.5-1.8 cm in length, it may not challenge Oryctes in size, but it is still striking, especially in close-up with its sculptural punctures. They are found in woodlands during May to October, and feed on tree sap; the larvae feed on rotting wood and are particularly fond of beech.

S. cylindricum adult.

So, via a slightly circuitous route, my answer to the original question about the presence of rhinoceros beetles in Britain has to be 'yes, but...' although I'm sure even the relatively small S. cylindricum will be much appreciated by my friend's bug-loving daughter.

Image credits

Oryctes adult: Thanks to 'Epp' via the Wikimedia Commons (public domain).
Oryctes pupa: Thanks to 'Banco de imágenes del CNICE - MEC' via the Creative Commons Attribution-Share Alike 2.5 Spain license.
Sinodendron adult: Thanks to 'Siga' via the Wikimedia Commons Attribution-ShareAlike 3.0 Unported license.

Leek Moth in Britain: spread and chemical-free control

The Leek Moth (Acrolepiopsis assectella) is a native of continental Europe and Siberia and can be a significant pest of various Allium crops, especially leeks. First recorded in Britain in 2003, it has spread around southern and eastern England, and although it is largely found near the coast, it does also occur further inland but is generally rather scarce and localised. The NBN map below shows the approximate current distribution although they are highly likely to have been found on other sites – the dot marked with an arrow is the location I mention below and was added by me (it’ll end up on NBN eventually!); it’s also spreading north and west and has been found in North Wales. I don’t know of any research on this, but it does seem to be a candidate for a species that’s benefiting from the warmer average temperatures associated with climate change – it would be interesting to see if this has been analysed, although a longer dataset would probably be needed than available in Britain – there may be a recorded spread through continental Europe as well... In any case, in Britain at present, although it does have localised impacts, its numbers are too low to really be considered a major pest, at least yet.

NBN map of leek moth distribution in Britain, though it has now moved further north...

However, research in Canada (Mason et al. 2010) has looked at the species biology and development in the Ottawa Valley where it has also recently become established. This found that at a threshold of 7°C, populations required 444.6 day-degrees for development from egg to adult, and noted that there were spring, early-summer and late-summer flight periods with adults overwintering. Depending on the temperature pattern, the life cycle took 3–6 weeks in the field, with up to three generations being produced. Comparing this to the case here in Britain, as temperatures rise in spring, the moths become active with egg-laying in April and May. Larvae hatch after about a week, feeding for about a month before moving back up the leaves and pupating in silken cocoons.

Leek moth larvae in situ showing feeding damage.

Damage from younger larvae higher up the leaves; note the frass to the left.

A fairly mature larva approaching 1cm in length.

A second generation of larvae feed from August to October; as far as I am aware, there is currently no third generation as seen in Canada, but I wonder if climate change may shorten the life cycle and/or extend the egg-laying/feeding season and thus permit a third generation to be produced. I will be checking leeks this summer and will note the occurrence of leek moth larvae to see if I can collect useful data on their life cycle.

The adult is harmless and fairly nondescript in appearance, but the young larvae burrow inside leaves, and as they grow they move down into the stem or bulb – this phase causes more serious damage and also facilitates secondary bacterial or fungal infection. This is when the leaves tend to turn yellow and slimy. On the whole, they are not a major problem for commercial growers as they are controlled by other pest-control activities; however for gardeners, allotment holders, and other small-scale producers, as well as organic farmers, they can cause a great deal of damage. You’ll see from my pages on the right that there is one about Highbridge Farm – this is the location of our local community farm project and as a chemical-free (though not organic-certified) concern, we were not pleased to find leek moth larvae happily burrowing through our leeks; it’s also where the photos of larvae were taken.

An adult leek moth; very similar to other species in the family Yponomeutidae.

However, as a community farm we do have many pairs of hands, so mechanical (but not mechanised) control is available in the form of us picking off the affected parts at an early stage, and pulling up badly affected plants if they were not identified quickly enough. These can then be composted. This does work (leeks are tough and recover well from the damage), although I have heard anecdotal reports of leeks being effectively ungrowable on a small scale in some places. In general, if keeping away from pesticides, any or all of the following measures are ones that I personally like:

• Check plants for damage in the spring; remove and destroy any caterpillars, pupae and damaged parts, and destroy severely infested plants.
• Protect the crop, from seedlings onwards, with covers such as horticultural fleece to prevent adult moths from laying eggs.
• Later planting (after May) may avoid the first generation of larvae.
• Encourage predators - birds, bats, hedgehogs, frogs and beetles will eat adults, pupae and larvae.

Other options include clearing away plant debris at harvest (as adults and pupae can overwinter in this) and dig over the soil to disturb overwintering adults and pupae; however they both involve unwanted toil and I feel are likely to impact on non-pest, even beneficial, invertebrates as well.

So, from a veg-growing point of view I hope they don’t appear this year (if they didn't trash the leeks, my bug-nerd side would consider them an interesting and scarce species), but if they do, it will at least be an opportunity to try to collect useful data – if I do, you’ll be able to read about it here...

Reference


Mason, P.G., Appleby, M., Juneja, S., Allen, J., & Landry, J.-F. (2010). Biology and Development of Acrolepiopsis assectella (Lepidoptera: Acrolepiidae) in Eastern Ontario The Canadian Entomologist 142(4):393-404. 2010 , 142 (4), 393-404 : 10.4039/n10-026

Hey! Who ate my glue-pot?

OK, a slight departure from the usual types of organism today. Recently, while doing a bit of DIY, I needed some glue. ‘Ah-ha’, I thought to myself, ‘there’s a big tub of PVA in the shed’ and went to fetch it. However, on opening it, all was not well. It had gone a variety of colours in blobs from creamy yellow to dark, almost-blackish green and grey, with bits of orange, red and brown in between – it had also lost its texture and consistency, going watery; definitely not usable. ‘So what?’, you may ask, ‘this is a nature/ecology blog’. Well, I got to thinking about what had done this – there’s nothing for the PVA to react with except for air, so where did all the colours come from? With the colours looking like moulds of various types, I got to thinking about fungal action – could Fungi degrade PVA? Short for polyvinyl acetate, it’s essentially a string of esters, but not being a biochemist I decided to head for the Web...

My tub of PVA - not looking good...

The nastiness in close-up.

A few minutes later I found an article by Garcia (1988) detailing just how genera of soil Fungi such as Aspergillus and Penicillium could grow in, and thus degrade, PVA when it is the only source of carbon - basically if it's in monoculture as in this case (presumably when the Fungi have no other choice). The research saw the depletion of carbohydrates, protein, and DNA, which was interpreted as an active turnover of those metabolites during degradation. This means these Fungi can metabolise PVA, and not only that, an increase in esterase activity (the enzyme breaking down esters) was seen along with a reduction in viscosity – yes, just like my tub of glue, it got more watery. So, I had suspects - all the circumstantial evidence was there, but was that what happened here?

Above and below - images of Penicillium under different lighting conditions, showing asexual reproductive structures; this one courtesy of CMI...

...and thanks to 'Schimmel' for this one.

Aspergillus threads (stained); courtesy of the Australian Society of Cytology Inc.

Aspergillus asexual reproductive structure under an electron microscope (Thanks to the Fungal Cell Biology Group)

A quick trip out to the glue-pot, a sample, my microscope on x400 and what do we get? Well, it’s looking good – many cells/spores and a few elongate/fibrous structures; pretty much exactly as in the rather better pictures above, and many others found on the Web.

At x400 and unstained, my specimen - threads, cells and maybe squashed reproductive structures.

I couldn’t find any nice clear examples of those splendid ‘floral’ reproductive structures show in the electron microscope image, but some of the structures seen in my sample do look like rather more battered and squashed versions. So, I’m pretty sure that it’s Fungi such as these that ate my PVA, and I don’t even leave it open when it's not being used; ah well...

Reference

Garcia, T.A. (1988). Fungal degradation of polyvinyl acetate. Ecotoxicology and Environmental Safety 16(1): 25-35.

Bushbuck: two species where there was one

Back in the day, the bushbuck was considered a single species, Tragelaphus scriptus, found in various habitats across much of sub-Saharan Africa. Recently however, genetic studies have indicated that T. scriptus is actually a complex of two distinct species, the Kéwel (T. scriptus) and the Imbabala (T. sylvaticus). This evidence shows that these two bushbuck species are more closely related to other tragelaphines than to each other; the Imbabala being closest to the Bongo (T. eurycerus) and Sitatunga (T. spekeii), and the Kéwel to the Nyala (T. angasii) (Moodley et al. 2009).

The Kéwel is found from West Africa, across the Sahel into East Africa, and as far south as Angola and the Democratic Republic of Congo (DRC). Meanwhile, the Imbabala is found from the Cape northwards to Angola, Zambia and East Africa, meaning that the two species’ ranges overlap in parts of Angola, DRC and East Africa.

The Kéwel is the smaller of the two, and shows clear stripes and patterning on a reddish to yellowish background; there is little or no sexual dimorphism in this ground colour. In contrast, the Imbabala shows considerable colour variation with geography and habitat, especially in males (yellow to red-brown, through brown and olive to almost black), and only the most genetically ancient of populations (from Angola, Zambia, southern DRC, Botswana and northern Zimbabwe) have any significant striping. Even in these cases the horizontal stripe, where it exists, is formed of a series of spots rather than the solid striping of the Kéwel. never occurs. Mountain-dwelling forms of the Imbabala (Gregory Rift Highlands, Mt. Elgon, Imatong Mountains and Ethiopian Highlands) appear larger and are dark with little or no pattern. Until recently, most bushbuck studies focused on the Imbabala, hence little was known about the biology of the Kéwel beyond what could be obtained from museum specimens and hunting trophies.

Imbalala bushbuck from Zimbabwe (courtesy of Graeme Guy). For a kewel image from The Gambia see here.

Both species are primarily browsers, but will eat other plant matter too. They can be active at any time of day, although are more likely to be nocturnal near humans; their most active times are however early morning and parts of the night, so may appear nocturnal in any case. Most are solitary, with some living in pairs; all have a ‘home range’ of around 5 hectares in the savannah (larger in forests), although these ranges do overlap.

Although the split into two species is fairly well understood (even if most non-scientific sources still refer to a single ‘bushbuck’), the more detailed taxonomy remains disputed with numerous potential subspecies and ecotypes having been described. For example, analysis of mt-DNA sequences (cytochrome b and control region) by Moodley & Bruford (2007) identified 23 phylogenetically distinct groups (‘ecotypes’) whose distribution correlated well with the pan-African eco-regions described by Olsen et al. (2001). 19 of these ecotypes corresponded with previously suggested subspecies, while six other haplotypes were newly recognized forms in the Volta region, Niger, Angola. and Luangwa and Zambesi Valleys. However, further research is onging to clarify the taxonomic status of bushbuck species, subspecies and ecotypes, so the situation is likely to remain somewhat fluid for a while – however, this does provide an opportunity to link the use of genetics in taxonomy to large-scale conservation in Africa, given the widespread distribution of bushbuck (in the broad sense) and apparent more local/region distribution of subspecies and ecotypes (Wronski 2009).

References

Moodley, Y. & Bruford, M.W. (2007). Molecular Biogeography: Towards an Integrated Framework for Conserving Pan-African Biodiversity. PLoS ONE 2(5): e454. doi:10.1371/journal.pone.0000454

Moodley, Y., Bruford, M., Bleidorn, C., Wronski, T., Apio, A., & Plath, M. (2009). Analysis of mitochondrial DNA data reveals non-monophyly in the bushbuck (Tragelaphus scriptus) complex Mammalian Biology - Zeitschrift fur Saugetierkunde, 74 (5), 418-422 DOI: 10.1016/j.mambio.2008.05.003

Olson, D.M., Dinerstein, E., Wikramanayake, E.D., Burgess, N.D. & Powell, G.V.N. (2001). Terrestrial ecoregions of the world: a new map of life on earth. BioScience 51: 933-937.

Wronski, T. (2009). Bushbuck, harnessed antelope or both? Gnusletter 28(1): 17-19.

Pattern variation in Rutpela maculata in a local woodland

Rutpela maculata (previously Strangalia maculata) is a widespread and fairly common species of longhorn beetle (Cerambycidae) in England and Wales, sometimes known as the black-and-yellow longhorn. The pattern is well known to be variable, but typically consists of four more-or-less broken black bands on the otherwise yellow elytra. The 'usual' pattern (i.e. the one that tends to be illustrated in books) is shown below.

'Typical' R. maculata, courtesy of Galerie du Monde des insectes

However, last summer, while walking in local woodland (Stoke Park Woods, Hampshire, UK), on sweet chestnut foliage I saw a specimen that definitely did not conform to this pattern. The photo below (apologies for the poor focus) shows the much greater amount of black with fusing of bands.

The 'Stoke Park' R. maculata showing a greater than usual amount of black.

Although still clearly recognisable as R. maculata (the shape, leg colour and spines etc. are unchanged), it is worth noting the superficial similarity to other banded longhorn species such as Judolia sexmaculata, the three-banded longhorn.

J. sexmaculata, courtesy of 'Cerambyx'

Despite the superficial similarity, it is clear that the patterns are different with J. sexmaculata having differently shaped spots/bands, generally with more angular edges. It also has more rounded elytral tips and tapers less towards the rear as well as having darker legs than R. maculata. So, a good example (I think) of pattern variability in a common species, although not one that should cause too much confusion. For more about British Cerambycidae, including identification by pictures, a good place to start is the following two-parter in British Wildlife: enjoy!

Duff, A. (2007). Longhorn beetles: Part 1. British Wildlife 18(6): 406 - 414.

Duff, A. (2007). Longhorn beetles: Part 2. British Wildlife 19(1): 35 - 43.

What's in the box? no.2

The second offering from my occasional diary of a beetle recording scheme - generated when a mystery beetle arrives in the post...

This time, I was expecting a new arrival as the collector had emailed me and given the background i.e. the habitat details and why the specimen was difficult to ID. It had been collected back in March 2010 on vegetation on a Lasius flavus anthill on a Derbyshire grassland. Initially it looked to be the common and widespread Chrysolina staphylaea, but a couple of features such as small size and heavy puncturation had induced the collector to look more closely and dissect it.

The mystery Chrysolina...

So, what did he find? Well, the tip of the aedeagus of this species is pointed in lateral view and rounded in dorsal or ventral view. However, in this specimen the dorsal view showed the tip to be angled or 'shouldered'. Now, the aedeagus is usually a good diagnostic feature when variations in colour, size, pattern etc cause confusion - but maybe not in this case.

Aedeagus (lateral)

Aedeagus (dorso-ventral)

So, onto the diagnosis...

The lateral view above looks about right - there's a bit of clag on the tip, but the aedeagus is pointed right at the tip, then expanding so that there is a shallow dent near the tip on the inside of the curve. It's a bit obscured in the pic but it is there (honest). So, this is good for C. staphylaea. However, the dorso-ventral view is unusual and not the rounded shape expected. Leaving this aside for the moment, what about the other features?

Well, the size (a little over 6mm long) is fine for this species, although cited as 'smaller than others in my collection' by the collector but that's fine as there can be site/habitat/regional variations and so on. The punctures are a little coarse but again are within the normal range of variation, and the microsculpturing looks OK too. Also, though not diagnostic, the overall colour, habitat and so on are also fine for C. staphylaea. Now, the only other option (it certainly isn't any other known British species) would be a species new to Britain. Two were found so it isn't a single individual blown in from elsewhere, but could it be a newly-discovered British colonist? Well, it's possible, but looking through superficially similar species from continental Europe and the Mediterranean, nothing seems to have this combination of colour, size, habitat and aedeagus so it appears unlikely.

Therefore, after much musing, book/web-trawling and peering down microscopes, my conclusion is that it is an aberrant form of C. staphylaea - time (and the potential collection of more specimens) will tell whether the unusual aedegus is a constant feature and so whether it is something more important like a new subspecies... however, with any single apparently-aberrent specimen like this, it could be something else so I'll be looking again - and as ever, comments & suggestions are most welcome...

Britain's jawless wonders: brook lamprey ecology and taxonomic status.

Lampreys (family Petromyzonidae, ‘stone-suckers’) belong to the Agnatha, (‘jawless’), the most primitive of all living vertebrates. They have no lower jaws and the mouth is surrounded by a round sucker bearing circles of rasping teeth. They are eel-like in shape but have neither paired fins nor scales and their skeletons are entirely cartilaginous. There are three species of lamprey in Britain: brook (Lampetra planeri), river (Lampetra fluviatilis) and sea (Petromyzon marinus), but having seen L. planeri nest-building in a nearby river (the R. Itchen in Hampshire), it is this species that I want to focus on here.

Brook lamprey (Lampetra planeri) nest-building in the River Itchen, Hampshire, UK.

L. planeri  is the smallest of the three British species at 13–15 cm long. The teeth are blunt and less developed than in the other more predacious species, and it does not feed as an adult. Larvae (‘ammocoetes’), are semi-translucent and dull grey-brown in colour, though a 'golden' form does exist with reduced pigmentation. Larvae occur in suitable silt beds, mainly in running water but sometimes in large numbers in silt banks in lakes. Although not common, it is the most abundant and widespread British lamprey and its distribution can be seen in the maps below for the National Biodiversity Network (NBN); the larger-scale map shows Hampshire and surrounding areas. However, due to a decline in several parts of Europe, it has some legal protection including being long-listed in the UK Biodiversity Action Plan.

British distribution of L. planeri (from NBN as of 6th Jan 2011)

Distribution of L. planeri in and around Hampshire (from NBN as of 6th Jan 2011)

Usually cryptic and nocturnal, L. planeri (like most lampreys) are rarely seen except at spawning time (April & May) when they move into shallow, clear water during daylight to start their complex, communal nest-building activities - the photo above was taken in April 2009. As spawning approaches, adults move from silts and migrate upstream at night, often in large numbers, until they reach suitable spawning grounds. These are areas of small stones and gravel in flowing water where the current is present but not too strong. When the water reaches 10–11ºC they tend to spawn at the lower ends of pools, just where the water is starting to break into a riffle. The nest may be constructed by a dozen or more adults moving stones with their suckers and is normally an oval depression 20–40 cm across and 2–10 cm deep. Females produce about 1,500 eggs each and hatched larvae (3–5 mm long and blind) drift downstream to burrow in suitable areas of silty sand. The adults die soon after spawning. Larvae live for around 6½ years in Britain, filtering fine organic particles from the silt. Metamorphosis occurs during July to September, after which they are more silvery, though the back remains dark. They also develop teeth and full vision, though adults do not feed.

Upstream migration can only occur in the absence of barriers, either natural (e.g. waterfalls) or man-made (e.g. dams, weirs or polluted areas). Little is known about their requirements in terms of water quality and quantity, though some limited pollution appears to be tolerated if it does not lead to substrates being smothered. They need suitable conditions (e.g. substrate type) in spawning areas and nursery habitat, and rivers should not be changed to produce excessive cover or fast flow. Channelisation and some aspects of management for angling (e.g. dredging of pools and construction of weirs) has been damaging to lampreys, mainly through habitat destruction, with potential impacts from use as bait. The removal of riffles and associated spawning gravels, and the dredging of silt beds can entirely eliminate lampreys from a river. Similarly, water abstraction and land drainage can produce unstable habitats with variable water levels which flood and disturb spawning gravels and nursery silts at some times and dry out at others. Climate change is likely to produce similar problems, with heavy rain in the autumn and winter, and drought in the summer.

Also, although L. planeri and L. fluviatilis are generally treated as separate species, there is some genetic evidence that this might not be the case. Schreiber and Engelhorn (1998) found very little difference in the DNA content between both species suggesting L. fluviatilis may just be an anadromous form of the relatively 'stationary' L. planeri, with gene flow inferred between them. Their taxonomic relationship and status is still a matter for debate although further research continues to suggest that they may not be truly separate species. For example, Lesne et al. (2010) show a high incidence of communal spawning of the two species in a French river, suggesting that they are less reproductively isolated than previously believed.

From a practical conservation perspective, L. planeri (whether or not it is a species separate from L. fluviatilis) does have some key requirements, but nothing that a little more considerate and thoughtful river/habitat management shouldn't be able to provide in abundance, and which would in turn help mitigate the likely effects of climate change.

References

Lasne, E., Sabatié, M., & Evanno, G. (2010). Communal spawning of brook and river lampreys (Lampetra planeri and L. fluviatilis) is common in the Oir River (France) Ecology of Freshwater Fish, 19 (3), 323-325 DOI: 10.1111/j.1600-0633.2010.00428.x

Schreiber, A., & Engelhorn, R. (1998). Population genetics of a cyclostome species pair, river lamprey (Lampetra fluviatilis L.) and brook lamprey (Lampetra planeri Bloch) Journal of Zoological Systematics and Evolutionary Research, 36 (1-2), 85-99 : 10.1111/j.1439-0469.1998.tb00781.x

Further reading

• More on lamprey ecology can be found here.
• An identification guide to British lampreys can be found here.
• A guide to monitoring lamprey can be found here.