Bug-hunting, leaf-twitching, data-analysing and me

Written for CISFBR (Cornwall & Isles of Scilly Federation of Biological Recorders) Newsletter

So, what’s your PhD on then?  Those immortal words which, after several years of being a PhD researcher, still manage to provoke in me a feeling of dread the moment they’re uttered.   Depending on my audience (and after a deep intake of breath), my response will vary, from ‘invertebrates, of the non-native variety’ to ‘how non-native species interact with native species’ or ‘how non-native invertebrates do their stuff in native foodwebs’.  The more scientific version/ working title of my thesis is ‘The integration of non-native phytophagous invertebrates in native interaction networks’, so now that I’ve got that out of the way, I’ll attempt to shed  some light on what that actually means, and perhaps more pertinently, what I actually do.

It all began with a Cornwall-based project proposal to investigate the indirect effects of the introduction of a non-native insect, the release of which was (is) hoped to help combat the massive ecological disaster that is the ever-increasing presence of Japanese Knotweed Fallopia japonica in Britain.  In March 2010, Defra granted approval for the host-specific psyllid Aphalara itadori to be used as a biological control agent, and its release/monitoring programme is currently underway.  Despite rigorous testing and scientific research, the deliberate introduction of a non-native species has met, not surprisingly given the popular history of past exploits, with varying degrees of (dis)approval.  I won’t go into the arguments for and against the psyllid’s use here, other than to say that, given my knowledge of psyllid ‘mechanics’ and host-specificity combined with the devastating impact of Japanese  Knotweed on native ecosystems, I know in which camp I firmly sit.

Indirect effects can probably best be described as the impact of the presence of a species on another species via an intermediary species, and as such, can be negative or positive – potentially harmful or potentially beneficial.  Despite the thorough testing carried out prior to the release of the psyllid, the indirect effects of its presence in native foodwebs/interaction networks is not known, and from an applied point of view, there is every possibility that some of these effects could prove useful in helping to effectively control other species considered ‘pests’ in certain circles.  And this is where I was to come in.

Due to a combination of funding issues and thus far negligible impact of the psyllid’s release, the above proposal soon developed into a less species-specific but still Cornwall-focused project along similar lines.   Rather ironically, considering the oft-prevailing doubts surrounding the notion of a non-native species being invited to reside amongst our very own flora and fauna, it soon became clear that Aphalara itadori is a tiny, tiny drop in the ocean of what is the presence of non-native species in Britain.  The GB Non-native Species Secretariat currently provides information for over 3000 non-native plant/animal species, describing a non-native species as ‘a species that has been introduced into the country by human intervention (either deliberately or accidentally) since the end of the last ice age’.[1]  But to put things into perspective, of these 3000+ species, only c. 10% are considered to impact negatively and/or socio-economically[2], although invasive non-native species are still designated as one of the main drivers of biodiversity loss[3]. 

Introduction routes for non-native species are numerous, with agriculture, aquaculture and ornamental horticulture all playing significant roles – historically, most have come from other parts of Europe but more recently, species have originated from temperate Asia and North America.  Keeping with the theme of plant-munching (phytophagous) invertebrates, as per Aphalara itadori, many examples of such exhibit host-specificity (specialist feeders), whereas others have evolved to feed less restrictively (generalist feeders).  Non-native specialist feeders require particular host-plants, and being non-native, more often than not, the latter will be a non-native species also, which leads on nicely to the role of the host-plant.

What’s so significant about Cornwall?  Well, with its southerly latitude and (in places, sub-tropical) maritime climate, Cornwall is home to many flourishing gardens, featuring a large variety of exotic plants from many different parts of the world. Add to this an increasing number of specialist horticultural nurseries and an established agricultural trade, and there exists a veritable Smörgåsbord of potential introduction means, habitats and host-plants for non-native species.  With this in mind, one of my tasks is to sample a percentage of the invertebrate population of Cornwall’s historic/municipal gardens in order to determine the presence of non-native invertebrate fauna (and performing some possibly complicated-sounding data analysis along the way).  As a compulsive recorder of all things biological, the prospect of purposefully poking my nose around Cornwall’s gardens for days on end makes me very happy; of course, this is something I already do on a routine basis, albeit rather more haphazardly.  Yes, I‘m a self-confessed leaf-twitcher – get me within 6 or so metres of a plant, and I have no choice but to turn over its leaves, check its stems and peer into its flowers to seek out resident or visiting invertebrates.  Systematic surveying aside, my leaf-twitching has already proved very rewarding, revealing all manner of previously-overlooked species, as well as enabling an insight into the microcosmic worlds that exist right under our noses.  

Now, I have another confession – before the commencement of my research, I knew very little about psyllids, and definitely don’t recall actually having seen one.  They’re interesting little critters, most closely related to aphids, whiteflies and scale-insects, and I personally think that they resemble mini cicadas, although they are far less noisy than their larger cousins.  The number of extant species in the world currently stands at 3338, just fewer than 100 of which can be found in Britain^[4]. According to my records, I have now managed to see 22 of these, 6 being non-native and including one species new to Europe: Cacopsylla fatsiae or tetrapanaxae (Fig. 1) (the jury’s still out on which one it is, or even if the two species are actually one and the same), an Asian species currently thriving on Fatsia japonica and Tetrapanax papyrifer plants in West Cornwall, one species new to Britain: Agonoscena targionii (Fig. 2), a European species very much at home on Pistacia lentiscus at the Eden Project, and another species found at various locations throughout southern Britain but new to Cornwall: Acizzia uncatoides (Fig. 3), an Australian species found on Paraserianthes lophantha  (formerly Albizia lophantha) in Penzance.

 

Figure 1: Cacopsylla fatsiae/tetrapanaxae - adult (length 3.5-4.5 mm)

Figure 2: Agonscena targionii - adult (photo: C. Malumphy/Fera) (length 3-4 mm)

Figure 3: Acizzia uncatoides – adult (length 1.5-2 mm)

Psyllids aren’t the only phytophagous invertebrates with which I’ve become uncommonly closely acquainted.  I’ve also befriended a particularly attractive little-known aphid species Crypturaphis  grassii (Fig.4), believed to be monophagous, feeding only on Italian Alder Alnus cordata, and native to Corsica and Southern Italy.  First recorded in the UK in 1998[5], it is found in relatively low numbers throughout Britain, and was first recorded in Cornwall in 2011[6].  Another of my aims is to investigate the potential for Crypturaphis grassii to switch hosts to one or more related (congeneric) species, by means of a series of host-preference tests, and also to find out more the species’ overall biology.  

Figure 4: Crypturaphis grassii – aptera (length 2-3 mm)

Arguably one of weirdest groups of phytophagous invertebrates about which I have had the pleasure of finding out more has to be scale insects.  Highly specialised plant parasites, appearance-wise, scale insects are massively diverse (see Figure 5), with sexually mature females exhibiting neoteny, the retention of immature external morphology.  These mature females are usually immobile, feeding in situ, whereas most of the early instar nymphal stages (‘crawlers’) have functional legs and are highly mobile, seeking out a suitable feeding spot for the subsequent stages of their development.   Short-lived winged adult males occur in some species, when sexual reproduction will occur; however, as in aphids, parthenogenesis is commonplace.

Figure 5: Scale insects l-r by row:

Row 1 - Bambusaspis bambusae (non-native); Lichtensia viburni (probably native); Pinnaspis strachani (non-native)

Row 2 - Aspidiotus nerii (non-native); Carulaspis cf. minima (non-native); Dynaspidiotus britanicus (probably native)

Row 3 - Pseudococcus viburni (unknown); Saissetia oleae (non-native); Nipaecoccus nipae (non-native)

Row 4 - Coccus hespiridum (non-native); Pulvinaria floccifera (non-native); Chrysomphalus aonidum (non-native)

Linking all of the above phytophagous invertebrates are parasitoids – parasitic organisms that have often co-evolved to spend a significant portion of their life (usually egg and/or larval stages) in or on its host, ultimately resulting in the latter’s demise.  The dynamics of host-parasitoid relationships is a truly fascinating subject, and also a very useful example of indirect effects, with numerous studies demonstrating how behaviours such as predator-avoidance in one species can alter population densities, feeding behaviours, reproduction strategies and similar in another.  However, attempting to explain it further in a straightforward, let alone succinct manner is proving too much for my addled brain!

Other examples of phytophagous invertebrates subject to my scrutiny include those which live and feed inside plant tissue, such as leaf/stem-mining insects and various gall-makers.   The Horse Chestnut Leafminer Cameraria ohridella (Fig. 6) is a prime example of a non-native leaf-mining moth, first recorded in Britain in 2001/2 (Wimbledon), its distribution is increasing rapidly.[7]  It causes significant, unsightly damage to the foliage of Horse Chestnut Aesculus hippocastanum (also non-native) and related trees; however, as yet, there is no evidence of the moth’s presence having any serious impact on the tree’s survival.  Accordingly, I am about to embark on a literature search to establish what is currently known about C. ohridealla and its parasitoid complex, paying particular attention to known associations of parasitoids with native hosts, clinal variation, novel interactions with native species, etc. 

Figure 6: Cameraria ohridealla on Horse Chestnut Aesculus hippocastanum Image © Opuntia via Wikipedia Commons, 20 Jan 2013, Creative Commons Attribution.  

So, for now, that’s what I’m up to.  Needless to say, there are more projects on the horizon but then, aren’t there always?

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[1] GB Non-native Species Secretariat [online] at: http://www.nonnativespecies.org/home/index.cfm (accessed 17 January 2014)

[2] Roy, H.E., Bacon, J., Beckmann, B., Harrower, C.A., Hill, M.O., Isaac, N.J.B., Preston, C.D., Rathod, B., Rorke, S.L., Marchant, J.H., Musgrove, A., Noble, D., Sewell, J., Seeley, R., Sweet, N., Adams, L., Bishop, J., Jukes, A.R., Walker, K.J. & Pearman, D. 2012. Non-Native Species in Great Britain: establishment, detection and reporting to inform effective decision making NERC Centre for Ecology & Hydrology, 110pp. https://secure.fera.defra.gov.uk/nonnativespecies/downloadDocument.cfm?id=753

[3] Millennium Ecosystem Assessment http://www.unep.org/maweb/en/index.aspx

[4] Ouvrard, D. 2014. Psyl'list - The World Psylloidea Database. [online] at: http://www.hemiptera-databases.com/psyllist  (accessed 17 January 2014)

[5] Harrington, R. 1998. An aphid new to Britain Entomologist’s Record & Journal of Variation 110: 288.

[6] Luker, S. 2011. Crypturaphis grassii (Sternorryncha: Aphidae): first records for Cornwall Br. J. Ent. Nat. Hist 24: 205-209.

 [7] Pocock, M., Evans, D. Straw, N. & Polaszek, A. 2011. The horse-chestnut leaf-miner and its parasitoids. British Wildlife Vol. 22 Number 5 June 2011 p. 305-313.

A BioBlitzing we will go...

12 August 2012

Originally posted in BioList 2013: http://biolist2012.blogspot.co.uk/2012/08/a-bioblitzing-we-will-go.html

“The time has come”, the Blogger mused,

“To write of many things:

Of bugs – and bees – and butterflies –

Of harvestmen – and – fleas

And why the weather’s up the spout –

And what to have for tea.”

(With apologies to Lewis Carroll)

Hello my little blog-friend, it’s been a while, hasn’t it?  I do hope you and the family are keeping well.  Eek, what to write – or perhaps that should be ‘how to write’, given the number of mistakes I’m making as I type.  But…  less of my personal failings and hang-ups - on with the job-in-hand.

In the land of BioListing, recording and the generally wonderful-but-perhaps-a-little-bit-nerdy world in which I’ve chosen to live, the past few months have been dominated by BioBlitzes – 24-hour events during which a given space is surveyed in order to find, identify and record as many wild species as possible*.

The first such event was the inaugural Tremough Bioblitz, which took place at the Combined Universities in Cornwall Tremough Campus in Penryn, and was admirably organised by University of Exeter Centre for Ecology & Conservation undergraduates.   A highly organised event, which was open to the public for only some of the 24 hours, as a so-called ‘expert’, I’d been enlisted to lead a number of walks.  Despite the best-laid plans, these turned into just the one walk, with the remainder of the time spent going about the usual business of wandering around, rummaging here, there and everywhere, with senses on full alert.   Disappointingly, the weather left a little to be desired, so it was definitely a case of nipping outside between downpours.  It was all a rather hectic yet fun experience, with some new species to add to the list: aphids, millipedes and plants, and some lovely new people met.  And, needless to say, one of the additional highlights of the event was the presence of a certain Nick Baker…

The Small Person with Nick Baker at Tremough BioBlitz

Next up was the third Rosewarne BioBlitz – a thoroughly enjoyable low-key event at Duchy College, Rosewarne near Camborne, where the usual suspects (plus a handful of extras) were on hand to get stuck into the job of seeking out all things wild and wonderful that reside on the extensive college site.  For once, the sun was shining, and we really couldn’t have asked for a nicer day, encompassing some inspirational botanising, dragonfly- and butterfly-pursuing antics in the wildlife garden, a relaxed sojourn by the wildlife pond, a group venture to the site’s outer limits, and some frantic moth-recording by means of a light and white sheet.  Highlights are too numerous to list in full but include the first ever Common Lizards Zootoca vivipara for the site, some lovely bugs, and some rather comical Screech Beetles Hygrobia hermanni.

Common Lizard Zootoca vivipara at Rosewarne BioBlitz

Then, the weekend of July 21-22 saw another inaugural event – the Garden BioBlitz:http://www.naturewatched.org/gbb.html  A combination of very little notice and having prior commitments meant that I was unable to give this the level of attention that I would have liked to.  However, on the Saturday, I did manage to spend a couple of (very hot) hours in my tiny, tiny jungle before being whisked away to experience the joys of Lafrowda Day in St. Just in the far, far west (as opposed to simply the far west), whilst on the Sunday, a far more concerted effort was made in fellow BioLister Brenda’s larger outdoor space.

What it lacks in area, our little garden certainly makes up for in species diversity, so despite only managing a couple of hours of investigating, all manner of goodies were uncovered.  Having a certain inclination towards the smaller, multi-legged creatures of this world, I took great delight in observing multiple colonies of five different aphid species, one of which was new to me: Cavariella pastinacae – found busy at work on the Parsnip plants leftover from last year’s vegetable-growing efforts.  Other new species included a single Lacehopper Cixius nervosus, a vast quantity of mines on Aquilegia produced by the dipteran larvae Phytomyza minuscula, and a previously-unnoticed rust Puccinia pulverulenta on the omnipresent Broad-leaved Willowherb Epilobium montanum.

Macrosiphum rosae on Teasel Dipsacus fullonum Garden BioBlitz

Blitzing Brenda’s garden proved to be equally (if not more) rewarding, perhaps notably due to the excitement of finding a thriving population of the Pittosporum psyllid Trioza vitreoradiata, hanging out, rather appropriately on Pittosporum bushes.  Admittedly, psyllids aren’t or wouldn’t be everybody’s cup of tea but each to their own, I guess!  In addition to my rather lovely psyllid, I was able to add another new bug to my list, this time a late instar Field Damsel Bug Nabis ferus, which was merrily wandering around Brenda’s mini-meadow, as were Common Green Capsids Lygocoris pabulinus and a good number of bouncy Common Froghoppers Philaenus spumarius.

A few unidentified odds and ends (mainly spiders and flies) notwithstanding, nearly 80 species were recorded for my little garden and about 150 for Brenda’s – not a bad weekend’s work, especially considering we had no moth trap to hand and lacked the time to have a really hardcore rummage in the undergrowth, let alone a decent delve into the soily depths.  Who knows how many more species we might have unearthed!

Common Frog(let) Rana temporaria Garden BioBlitz

Then, a mere week later, it was time for the long-awaited Windmill Farm BioBliz, when BioList members and other interested parties got together to do their stuff at Windmill Farm Nature Reserve (CWT/CBWPS) on the Lizard, here in Cornwall.  As others have already produced event retrospectives (see: http://wfarmnaturereserve.blogspot.co.uk/2012/07/bioblitzed.html and http://consideringbirds.wordpress.com/2012/07/31/big-bioblitz-weekend-part-1/ et al.), I’ll try not to whitter on at length (I know, don’t hold your breath!).

So, the sun was shining, the tent was packed, some strange cakes had been made, and off we headed to Lizard Land, with Brenda in tow.  Itching to get started, we unloaded our stuff and took up residence in what was to be our home for the weekend.  It wasn’t long before other participants turned up, although the Up Country component didn’t make it for about another hour, and at 2pm, it was time to get started.  But where to begin?  I’d been eyeing up the nearby large patch of nettles and thistles, so for me it was easy, even if it did mean losing my starting companions, who headed off across a field towards one of the ponds/scrapes.  However, my nettle-poking efforts were soon interrupted by Warden-Andy and the invitation to accompany him in checking the known Adder Vipera berus sites.  How could I resist such an offer?!  After being rewarded with the find of several Adders (all female) enjoying the warmth provided by sheets of corrugated material, I was drawn to the allure of the dragonfly pond around the corner, whereupon I was greeted by the sight of Dragonfly-Steve thigh-deep in the water, busy collecting dragonfly and damselfly exuviae, which must have numbered in their hundreds.  Rather reluctantly, I managed to tear myself away from the dragonfly pond and all its glistening winged jewels, and headed off to the remarkably dry wet woodland, via a meadow alive with grasshoppers, butterflies and all manner of buzzing insects.

A Froghopper Neophilaenus lineatus Windmill Farm BioBlitz

Now, BioBlitzing certainly takes its toll, and after totting up a good number of species, reuniting with lost companions and greeting friends from afar, it was time to head back for a breather and to sort out notes, sort out unidentified finds, and generally recompose oneself. 

After a continuation of much of the same, mainly involving sweeping through vegetation, turning over leaves and beating trees, it wasn’t soon before the sun began to set (rather beautifully) and talk turned rather animatedly, to moth-traps.  I’m not entirely sure how many moth-traps were put in place around the site that evening but they numbered at least five.  Some rather intrepid BioBlitzers spent most of the night in the vicinity of one particular trap, interspersed with the odd 40 winks every now and again, in an attempt to record moths that decided to drop in for a passing visit only.  Despite protestations of low night-time temperatures and moth numbers being low generally, come the morning, there was a good variety of furry, winged beasties on which to feast our eyes.

Drinker Euthrix potatoria Windmill Farm BioBlitz

Drinker Euthrix potatoria Windmill Farm BioBlitz

Then it was back out there in an effort to up numbers before our 24 hours were up.  All-in-all, an excellent time seemed to be had by all (even if I did spend the next couple of days prostrate on the settee, hurting from head to toe), with 400+ species being recorded.  The big question is, when and where will the next one be?  Bring it on, I say!

*For some general info on BioBlitzes, take a look here: http://www.bnhc.org.uk/home/bioblitz/

A Snowy Day January 21, 2013 Originally posted in BioList 2013:

A Snowy Day

January 21, 2013

Originally posted in BioList 2013: 

http://biolist2012.blogspot.co.uk/2013/02/january-21-2013-land-at-back-of-village.html

The 'land at the back of the village hall'

Having twenty minutes or so spare before we needed to depart for the day’s activities, I decided to pop outside to take some photos of what experience had taught me would be a short-lived covering of snow.  Whilst most of the country had been snowed under for some time, our little bit of Cornwall had been basking glorious sunshine.  OK, so I might be exaggerating somewhat but sunshine had definitely been a feature!  Anyhow, I digress.  So, wellies donned and woolly hat pulled over my ears, with camera in hand, I trundled off for a quick crunch around the village - down the hill, around the corner, past the church and the pub, and through the wrought iron gates into the area of land behind the village hall. 

I’m never really sure what to call the ‘land behind the village hall’ – part is an open green space, part is given over to planted, spiral flower beds, a grass-covered mound aka the ‘sleeping dragon’, some rustic benches, a willow erection and a rather lovely carved wooden seal, the latter in memory of a local Mousehole resident, and some serves as an extension to the church graveyard.  The area is lined with a rather interesting collection of tress, including sallows, myrtles and sycamores.  These trees are proving to be a fabulous haven for a massive array of lichens, mosses and liverworts, many of which I am thus far sadly only to admire without being able to confidently give them a name.

With the exception of community events, such as the annual church summer fête, more often than not the ‘land behind the village hall’ is free of people, allowing one to wander at will, leaf-turning to one’s heart’s content, and generally pottering about without the ever-present awareness that at any given moment, one will turn around to find somebody watching one with that characteristic look – the look that says, ‘I’m not really sure of what you’re doing, I’m not really sure that it’s a very normal thing for one to be doing but I think I’ll stand here and watch anyway, and with any luck, I’ll be able to catch your eye, then I’ll be able to make some witty remark about whatever it is I think you might be doing, before moving on and leaving you to get on with whatever it is you’re actually doing’. 

Well, fortunately, this morning was no exception, and it was little ol’ me, my camera and the birds.  Taking care not to slip on the gravestones which form the paved path leading from the entrances to the newer graves area at the end, I carefully made my way along the path, stopping every now and again to photograph the snow-covered features and nearby buildings as I went.  In the trees furthest from me were chattering Rooks and Jackdaws, up above soared Herring Gulls, and hopping about only ever a few feet from me, was a glossy male Blackbird, no doubt on the look-out from tasty worms and other titbits.  Then, as I neared the end of the path, something caught my eye – a brilliant flash of red, as something flew swiftly from the ground up into the corvids’ tree.  That scarlet flash and the characteristic flight that followed could mean only one thing – a Great Spotted Woodpecker.  Given their relatively new-found fondness for garden birdfeeders, you might think that my excitement at seeing a Great Spotted Woodpecker is somewhat over-the-top; however, it was the first time I’d seen one in the village, and anyway, why shouldn’t I get excited about seeing a Great Spotted Woodpecker?!  Too soon it was time to wander back home in order to depart for the day…

·   ·   ·

With the snow now pretty much all gone and the sun shining away merrily, we decided to interrupt our journey home with a stopover at Helston Boating Lake.  Here we hoped to see the Whooper Swan which had popped in for a visit but rather disappointingly we were out of luck, as despite having been seen here earlier the same day, it was now nowhere to be found.  Still, the friendly Mute Swans managed to win us over with their affections – the comedy of their ever-probing beaks coupled with their searching, dark eyes that eyed us longingly, wordlessly saying, ‘Feed me, feed me’.  We were also treated to an unexpected performance by a pair of ‘dancing’ Shovelers – a first for me in Cornwall.

Dunnock, Helston Boating Lake

Boating lake fully-circled, apple trees duly inspected for woolly aphids and psyllids (still too early), just as we were about to get into the car, I happened to spot the unmistakeable sight of the town’s sewage treatment works.  Golly gosh, how exciting!  Now, I have to emphasise that sewage works wouldn’t be my usual first choice of places in which to hang out but I’d been hearing interesting things about Helston Sewage Works – something to do with Siberian Chiffchaffs?  Of course, there was fat chance of my being able to identify a Siberian Chiffchaff but I still couldn’t resist further investigation.  After nipping off for a quick recce, I soon returned to gather the troops, filling their ears with the promise of ‘Goldcrests, funny finches and lots of little brown jobs’.  Who knew there was so much fun to be had at a sewage works?  Mind you, the lingering aroma wasn’t particularly pleasant but the thirty or so Goldcrests, funny finches (some turned out to be of the Gold variety but we were unable to properly make out the others), Chiffchaffs galore (some possibly of the Siberian variety…), Long-tailed Tits and other feathered delights more than made up for it.

And after that, it was time to go home…  but not before waving a quick ‘hello’ to a Snipe and a Little Grebe at Marazion Marsh and a fleeting visit to Penzance’s Battery Rocks to smile at the antics of the rather lovely semi-resident Purple Sandpipers.  All in all, a proper job of a birdy day!

Purple Sandpiper, Penzance