Some childhood experiences can be strangely formative –
learning to ride a bike, losing a tooth, or perhaps facing the occasionally
despicable nature of your fellow man full in the face for the first time. This
happened for me on my first trip to Hungary aged 11, when our accommodation was
broken into and my Ipod nano, and more importantly our flapjack was stolen. This
cosmic episode stuck with me in the ensuing years, but so did the extraordinary
wealth of wildlife (at the time, avian was the main interest) is such seemingly commonplace settings – in
gardens, little woods and all the farmland – here was a place that hadn’t been
totally put under the plough in a post-war race to the bottom and still
retained a large proportion of its seething, heaving mass of ancestral
biodiversity – these thoughts lay dormant in my young mind, and as I became
more interested in butterflies and moths, germinated into a cold and perhaps
unrealistic certainty – I had to return.
And so it was that 8 years later I took up Butterfly
Conservation’s European Interest Group Annual Research Bursary (http://www.bc-eig.org.uk/downloads/EIG_Annual_Research_Bursary.pdf)
and did just that. The grant is offered
every year and put simply is both extraordinarily generous and extraordinarily
helpful – up to £500 to hit the continent and study butterflies – any
butterflies, anywhere in Europe, the opportunity of a lifetime. As one of this
year’s lucky recipients, I used mine to head to the Ferto-Hansag National Park
in the North-West of Hungary for 6 weeks this summer.
The park is around the Hungarian part of the Neusidlersee,
the lake that straddles the border with Austria and whose Hungarian part is
known as the ‘Ferto-lake’, and is of great importance for wetland birds (think
droves of herons, White-Tailed Eagles, waders, terns, Moustached Warblers etc.),
also taking in areas of classic Hungarian steppe habitat with species like
Saker Falcon and Eastern Imperial Eagle (both satellite-tagged as part of EU
LIFE projects and yielding fascinating results), and extensive areas of wet
woodland and meadows in the Hansag region. For invertebrates the Ferto-Hansag
perhaps lacks the reputation of some other areas of Hungary – the Zemplen
Mountains and the Buuk Hills with their beasts from the east, and the chalk of
the Balaton uplands with their Lesser Fiery Coppers and Clouded Yellows, but
does have internationally important populations of a very special group of
butterflies – the Maculineas.
Coming from Somerset, I’m already an acolyte of arion – the
Large Blue – the winged victory of British butterfly lovers (returning after a
re-introduction project, the most successful of its kind anywhere in the
world). Those that know this butterfly well will be familiar with its extraordinarily
convoluted life-cycle. Eggs are laid on the flower heads of Wild Thyme (or
Marjoram at a couple of sites) and the resultant larvae hatch out and tear
through all 4 of their instars in a couple of weeks, dropping off the
flower-head in the evening to be adopted by red ants (specifically Myrmica
sabuleti) which carry the larva as one of their own into the nest after
‘milking’ its honey gland. Here the larva goes rogue and will attack and eat
the ant grubs, puncturing their skin and feeding on their bodily fluids,
steadily growing to become a giant, implacable, pale imposter in the nest,
before hatching out the following year to dance over the herb-rich slopes on
midsummer days.
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| A Somerset arion |
There are several more species of ‘Large Blue’ in Europe,
3,4 or even 5 depending on how you work your taxonomy, Dusky Large Blue
(nausithous), Scarce Large Blue (teleius) and Alcon Blue (alcon) are dead
certs, while some people produce Mountain Alcon Blue (rebeli) from Alcon and
‘Maculinea ligurica’ from Large Blue. Despite being some of the best studied
European butterflies (as a result of their extraordinary life cycles and
precipitous declines), a great deal of uncertainty still seems to remain about
the classification of Maculineas. Rebeli for example, like alcon, is a cuckoo
(feeding on regurgitations from ants rather than larvae, like arion does), but
with a different host ant (Myrmica shencki as opposed to ruginodis), and on the
whole tends to be slightly darker (something frequently seen in butterflies
that fly at higher altitudes, arion does this too, with f. obscura described
from the Swiss Alps), but some studies (like Als et al. 2004) suggest very
little divergence from alcon. Ligurica too tends to be larger, paler and slower
flying than arion, also flying later in the year, but again it’s difficult to
be sure how distinct it is from its parent – Berecski et al. (2014) suggest
that it’s a species in the making – showing differences in the structure of the
wings and the male genitals, but only small ones in the genetics.
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| Scarce Large Blue |
This is all rather complicated, but at least illustrates an
important point about maculineas and indeed butterflies in general – like many
insects, with their short generation times, they’re able to constantly adapt
and evolve to a changing world – to paraphrase Matthew Oates – never underestimate
a butterfly, you only have to look at the Quino Checkerspot’s extraordinary
re-invention (https://www.theguardian.com/environment/2014/apr/07/endangered-butterfly-species-defies-climate-change-quino-checkerspot)
to see the truth of these words. What this means is that the boundaries between
forms/species can be even more blurred than they usually are, with fascinating
evolutionary experiments happening right before our eyes.
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| The Ferto-Hansag's Maculineas - alcon, nausithous and teleius. |
Anyway, in Hungary, I was helping with
mark-release-recapture work on three species: Scarce, Dusky and Alcon (Large
and ‘ligurica’ are found in other parts of Hungary too) around the Ferto Hansag
from the 10th July to the 20th August. These three species all favour damp
grasslands (in contrast to arion’s herb rich slopes), where teleius and
nausithous lay on the heads of Great Burnet (Sanguisorba officinalis), using
young unopened and old, flowering heads respectively, while alcon scatter their
eggs in what seems to be a fairly haphazard way over Marsh Gentians. Why the
Maculineas lay in the ways they do seems to still be the subject of on-going
debate, alcon appear to fire their eggs over the gentians with all the
precision of a small machine gun bound to a couple of jackhammers, often 60 or
70 white pin-pricks on one rather small plant, but Van Dyck et al. (2000)
reckoned they were cleverly laying them within the range of host ant (M.
ruginodis) nests, gradually shifting to favour ones further away later in the
season to reduce competition and cannibalism (the latter is rife amongst young
Maculineas). This makes a lot of sense – a young larva only has one shot at
adoption and has to be taken in by the correct host, otherwise its chances of
survival are pretty low. Still, in order to get to the stage where it dupes
innocent ants, a Maculinea larva has to find enough foodplant to get it through
the early weeks. This means that the conclusions of Thomas and Elmes (2001)
also make a lot of sense, deciding that egg-laying in all the European Maculinea
species is governed by host plant phenology – the plants have to be the right
age to provide food for the larvae.
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| Alcon ova scattered with gay abandon over a Marsh Gentian. |
Clearly then, an
impasse has been reached, come forth then Patricellia et al. (2015) to change
the game completely, deciding that neither conclusion is correct for M. arion, instead
proposing an explanation that is in fact far more complex (and interesting!).
When under stress, plants will often produce certain VOCs (volatile organic
compounds) to try and turn the tables on their stressor. Marjoram and Thyme
(the foodplants of arion), for example, produce Thymol and Carvacrol (both
isomers of each other), when their roots are damaged by growing ant colonies.
These are biocides that will kill the ants, thus saving the plant. Myrmica
species (such as our, and arion’s friend, M. sabuleti) are able to upregulate
genes to detoxify these compounds, causing the plant to produce them in ever
higher concentrations in order to win the battle for survival. Thus, high
concentrations of Carvacrol/Thymol around Marjoram/Thyme indicate the presence
of Myrmica nests, and as you’ve probably guessed, are highly attractive to
female Large Blues, they don’t detect the ants themselves, but a trophic
interaction caused by them – intricate, and quite extraordinary!
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| Scarce and Dusky Large Blues |
Back to Hungary then, where the three Maculineas are
increasingly threatened by changing farming practices – mowing of meadows tends
to happen in July, taking down the gentians and burnet, and with it Maculinea
eggs, abandonment of Maculinea country (often already quite dense, tussocky
grassland) quickly leads to scrub and no more Maculineas, and introduced Canadian
Goldenrod (the cursed Soldago) has swept across Hungary and frequently takes
over the damp meadows if not managed correctly. In other words, Maculineas are
threatened by just about any change in either direction to their habitat, and
their continued survival requires careful management and constant monitoring.
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| Scarce Large Blues (with a bonus Dusky)! |
As it happens, both of these things are happening in the
Ferto Hansag, and Maculineas are doing rather well. When I visited, they were
having a boom year (there’s some evidence that their abundance is cyclical,
following a similar pattern to Holly Blues and Marsh Fritillaries in the UK,
though for different reasons) and numbers were very high at all four of the
sites we worked at. In fact, we marked record numbers at several of them, with
2500 at one, and my personal tally coming to a respectable 2410 butterflies
processed overall. The peak of lazy high summer days for any British butterfly
enthusiast is an evening on the chalk, surrounding by little pale flags winking
in the grass heads – a communal roost of butterflies is a hard sight to beat,
and one indelibly associated with Chalkhill Blues in our butterflying psyche.
They’re not infrequent with Common Blues too, and sometimes even Adonis if they’re
feeling really enterprising – but Large Blues? No, surely not! To see communal
roosts of 20, 30, 40 Maculineas in Hungary was quite mind-blowing, a sight so
wrong, but so right, unquestionably ‘how it ought to be’, and a sight that will
be one of the abiding memories of the trip.
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| Marking a Dusky Large Blue |
This biblical abundance was no co-incidence, these are some
of the strongest Maculinea colonies in Hungary (perhaps Europe as a whole),
with much of it due to the hard work of the staff in the Ferto Hansag,
constantly seeking to compromise, to balance the needs of the butterflies with
the needs of a rapidly intensifying agricultural industry; allowing some areas
to be mown for hay with refuges for the butterflies, allowing hunters to clear
scrub and burn some areas in return for leaving others. Meeting the needs of
these most capricious of butterflies in a fast-changing world is never easy,
but it seems it can be done, with just the right amount of sensitivity,
patience, and most importantly, hopeless devotion to the cause.
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| Scarce Large Blue |
Andras Ambrus, the park’s resident lepidopterist, one of the
most energetic people I’ve ever met (living proof of the adage that butterflies
keep you young) with whom I was lucky enough to work, fits that bill perfectly,
having carried out the MRR work on some of the sites for over 17 years. While I
was struggling with my first words (sadly not ‘butterfly’), he was marking Maculineas,
and has continued to do so ever since. This ongoing project provides vital data
about population sizes (how are the butterflies responding to management, and
wider changes in the countryside and climate?), dispersal (what’s their ability
to deal with obstruction and colonise new areas like? It turns out nausithous
is much more able to deal with tree-lines than teleius), and phenology (are the
Maculineas, like other species, emerging earlier in response to a warming
climate?), that in turn feeds into their conservation. Without people like
Andras, and their work, young buttefliers like me wouldn’t be able to enjoy
such rare butterflies in such extraordinary abundance, we owe them a great
deal.
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| Dusky Large Blue |
Not only do I owe a great deal to Andras, but also to EIG –
I’ve already said that the Annual Research Bursary is the opportunity of a
lifetime, but this cannot be overstated. Being able to spend every day for 6
weeks not only surrounded by Maculineas, but mythic, scarcely-imagined beings
like Large Coppers, Lesser Purple Emperors and Common Gliders, seeing Eastern
Imperial Eagles passing low over your garden, and Sakers diving on hapless
kestrels just down the road – these are memories that will last forever, and
are all because someone saw fit to reward my enthusiasm and an A4 page setting
out my plans with a whole £500.
If you are a young person with an interest in nature reading
this, the message is quite simple – apply!
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| Maculinea country |
References
Als, T., Vila, R., Kandul, N., Nash, D., Yen. S-H., Hsu,
Y-F., Mignault, A., Boomsma, J., Pierce, N. (2004). The evolution of
alternative parasitic life histories in large blue butterflies. Nature. 432 (7015),
p.386.
Bereczki, J., Tóth, J., Sramkó, G., Varga, Z. (2014). Multilevel
studies on the two phenological forms of Large Blue ( Maculinea arion )
(Lepidoptera: Lycaenidae). Journal of Zoological Systematics and Evolutionary
Research. 52 (1), pp.32-43.
Hayes, M. (2015). The biology and ecology of the large blue
butterfly Phengaris (Maculinea) arion : a review. Journal of Insect
Conservation. 19 (6), pp.1037-1051.
Patricelli, D., Barbero, F., Occhipinti, A., Bertea, C.,
Bonelli, S., Casacci, L., Zebelo, S., Crocoll, C., Gershenzon, J., Maffei, M.,
Thomas, J., Balletto, E. (2015). Plant defences against ants provide a pathway
to social parasitism in butterflies. Proceedings. Biological sciences. 282 (1811).
Thomas J. and Elmes G. (2001). Foodplant niche selection
rather than the presence of ant nests explains oviposition patterns in the
myrmecophilous butterfly genus Maculinea. Proceedings of the Royal Society B:
Biological Sciences. 268 (1466), pp.471-477.
Van Dyck, H., Oostermeijer, J. G., Talloen, W., Feenstra,
V., Hidde, A. V. D., Wynhoff, I. (2000). Does the presence of ant nests matter
for oviposition to a specialized myrmecophilous Maculinea butterfly? Proceedings
of the Royal Society B: Biological Sciences. 267 (1446), pp.861-866.
