Wednesday, December 14, 2011

Not Quite an Insect

Campodea spp.
Even though there are only four species present in Ireland (all from the genus Campodea (1)), diplurans are often observed in soils, where they are perfectly adapted to life there feeding on live prey and decaying organic matter amongst the leaf litter. With their lack of eyes, lack of pigment, long tapered bodies and long antennae they resemble miniature centipedes, but their six legs on their three segmented thorax tell another story. Diplurans are hexapods, and while often placed in the class Insecta, they should really be seen as insects' closests relative (2). While sharing many features with insects (body divided into head, thorax and abdomen, three pairs of walking legs, and a segmented abdomen devoid of legs), they are distinguished from insects by having antennae devoid of a chordotonal sensory organ in the pedicel and by the lack of an appendicular ovipositor and of a median unpaired caudal filament (2). Often referred to as 'two pronged bristletails', this name is derived from presence of only one pair of caudal appendages, the cerci. There are about 1000 species of diplurans described present throughout the planet in all but the harshest areas (deserts, polar regions and areas above 3500 metres). Three major lineages exist: Campodeoidea, Projapygoidea, and Japygoidea (3).

  1. Ferriss et al., 2009. Irish Biodiversity: a taxonomic inventory of fauna
  2. Kock, 2009. Encyclopedia of Insects (Second Edition) pp. 281-283
  3. Luan et al., 2004. Pedobiologia 48 pp. 453-459

Saturday, December 3, 2011

What's In A Song?

Technically speaking, birds make two sounds: a call and a song. The call is relatively short and somewhat muted and is used for basic contact or in times of alarm, whereas the song  is a much elaborate and intricate affair and is associated with courtship and mating. Birdsong consists of sequences of smaller discrete units called elements. Groups of elements are combined into intermediate units called syllables, which in turn combine to make songs. If these units, elements and syllables, exist throughout an entire species they are called universal categories (1). 
Male (top) and female Chaffinch (Fringilla coelebs)
The song of the Chaffinch (Fringilla coelebs) is a wonderfully bubbly affair, especially when compared with the simple “pink” that is its call (2). Its song consists of an initial trill of several repeated syllable phrases, followed by a “flourish,” which typically consists of a short phrase of high-pitch elements and one long buzzy element (3). It has been shown that male Chaffinches assess songs differently from females based on the relative length of the trill and the flourish, showing that the differences in the two parts represents a communicative relevance (4). Analysis of Chaffinch song with a dynamic time-warping algorithm showed that the syllables were linked to certain positions within the song and were not randomly distributed (2). This lends further credence to the theory that birdsong has parallels with human language.

  1. Lachlan et al., 2010. Journal of Comparative Psychology  124 pp. 92-108
  2. Sterry, 2004. Collins Guide to Irish Wildlife
  3. Thorpe, 1954. Nature 173 p 465
  4. Leitão et al., 2006.  Animal Behaviour 71 pp. 1289-1296.

Friday, December 2, 2011

Sniffing Out a Meal

Figwort Weevil, Cionus scrophulariae
The wonderfully patterned Figwort Weevil (Cionus scrophulariae) is a fairly common but shy animal in Ireland that can be found on plants of the family Scrophulariaceae. The larvae may also be seen here, covered with a shiny, sticky substance. This is a diffuse peritrophic membrane that acts as a deterent to any potential predators (1). Production of this membrane in the posterior mid-gut stops once the larva has stopped feeding and a new, ribbon-type structures begin to be made which are used to construct cocoons.
Figwort, Scrophularia nodosa
The weevil's main food source is the Figwort (Scrophularia nodosa) from where it gets its name. Figwort is an excellent coloniser, but mainly of waste ground and populations are therefore often scattered across an area. C. scrophulariae can find these populations using odors from Figwort. The larger the patch size of Figwort plants, the stronger the odor and the higher the density of  C. scrophulariae individuals associated with them (2).

  1. Tristram, 1978. Journal of Insect Physiology 24 pp. 391-398
  2. Anderson and Hambäck, 2011. Athropod-Plant Interactions 5 pp. 269-277

Thursday, December 1, 2011

Local Evolution in the Large White Butterfly

Large White Butterfly Larva, Pieris brassicae, feeding
The bane of any gardener attempting to grow a few tasty brassicas, the larvae of the Large White Butterfly (Pieris brassicae) is a rapacious feeder. Reports in the past of 100% crop loss (1) may have been reduced but globally the loss to its main 18 food plants runs to 1% of total yield (2). Such heavy damage by this widespread, Palaerartic species is due to the practice of females laying batches of eggs, as opposed to its close relatives who tend to lay eggs singly (3). The results can be devastating to behold, with plant leaves reduced to skeletal forms.
Large White Butterfly Adult, Pieris brassicae
Like many other insect species, P. brassicae undergoes diapause in response to short photoperiods which serves to outlast periods with unsuitable conditions such as low temperature and low food supplies (4). However, one population of P. brassicae in Andalusia in southern Spain has evolved an additional response to long photoperiods (3). This summer diapause (or aestivation), which is only found in this Spanish population, last three months and represents something of  a major evolutionary novelty, because it cannot have evolved via a gradual transformation of the ancestral photoperiodic response in which only short day-lengths induced diapause. Its role is unclear as the butterfly loses three generations by undergoing aestivation. It has been shown that the attack rate of its main parasitoid, Cotesia glomerata is reduced as a result of aestivation, thus increasing survival rate of the larvae (5).
Large White Butterfly Larvae, Pieris brassicae
  1. Cansdale, 1876. Entomologist 8-9 p. 257
  2. Feltwell, 1978. Journal of Research on the Lepidoptera 17 pp. 218-225
  3. Held and Speith, 1999. Journal of Insect Physiology 45 pp. 587-598
  4. Beck, 1980. Insect Photoperiodism
  5. Pörschmann and Spieth, 2011. Entomological Science 14 pp. 31–36

Monday, November 28, 2011

Invasion of the Egret!

Little Egret, Egretta garzetta
Its easy to see the attraction to the Little Egret (Egretta garzetta). Its snowy-white plumage contrasts beautifully with its black, dagger-like bill. Unfortunately the attraction proved to be the undoing of E. garzetta populations in Britain and Ireland. In the breeding season the adult grows two long nape feathers (1). E. garzetta was hunted to extinction in much of norther Europe for these feathers which were used in the production of hats (2). This example of fashion gone crazy resulted in the death of millions of Little Egrets up to the start of the 20th century when a combination of changing fashion tastes and a growing awareness in conservation reduced the hunting of the bird (3).
E. garzetta became an occasional winter visitor in Ireland after this time and up until late 1980's and early 1990s. Large numbers of autumn migrants in 1995-6 lead to a wintering population of about 60 birds. Finally in 1997 a breeding site of 12 birds was established on the River Blackwater on the border between counties Cork and Waterford (4). Breeding sites have increase since then and now Cork has four further established (at Ballannan Wood, Fota Island, Rostellan and the Atlantic Pond) and one possibly established (Carrigaline) sites (5). In these sites, the birds nest in close porximity to the Grey Heron (Ardea cinerea). While the reestablishment of E. garzetta is a welcome development, the speed which with this has occurred is very interesing: from no birds to six breeding sites in just twenty years.

  1. Sterry, 2004. Collins Guide to Irish Wildlife p. 36
  2. Stubbs, 1910. Zoologist 14 pp. 310-311
  3. Bourne, 2003. British Birds 96 pp. 332-339
  4. Smiddy and Duffy, 1997. Irish Birds 6 pp. 55-56
  5. O'Donoghue and Smiddy, 2008. In Practice p. 14

Come Fly With Me

Migrant Hawker, Aeshna mixta
The Migrant Hawker dragonfly (Aeshna mixta) is a relatively new addition to the odonate fauna of Ireland, with the first sighting being reported in 2000 (1). However, this was during the DragonflyIreland survey of dragonflies and damselflies and it may have been present before this. It has the latest emergence of all dragonflies in Ireland, appearing in in the south and south-east of the country in late July and present till late October. Its flight is quite impressive to behold:- hovering around low-lying vegetation, it can quickly shoot high into nearby treetops with ease. Studies of the flight in Aeshna spp. using both tethered animals and model wings have revealed it to be a very complex process (2). It was seen that Aeshna spp. fly by using unsteady aerodynamic mechanisms to generate leading edge vortices or high lift when needed and that the dragonfly controls the flow mainly by changing the angle of attack of the wings. Unsteady aerodynamics refers to the effects on flight that changes in the air flow or in the position or orientation of a body (in this case a wing).
Migrant Hawker, Aeshna mixta
  1. Nelson and Thompson 2004. The Natural History of Ireland's Dragonflies pp. 193-199
  2. Wang and Sun, 2005. The Journal of Experimental Biology 208 pp. 3785-3804

Thursday, November 10, 2011

Sticking with it: Footprints of the Starfish

The most common starfish found in Irish waters, and in the north-east Atlantic as a whole, Asterias rubens can be found in quite deep waters, but is usually found in the intertidal region where it feeds on a variety of molluscs (1). The quantity of prey to be found is quite high here, but so are the challenges posed to A. rubens. These chiefly come from the disruptive action of waves, which can easily wash individuals onto the shore line, which is just what happen to the starfish pictured.
Common Starfish, Asterias rubens
A. rubens overcomes this by the ingenious use of adhesives. The numerous tube feet located on the underside of the animal that are used for locomotion, secrete globular nanostructures forming a meshwork deposited on a thin homogeneous film (2). Two cell types have been identified in the production of this adhesive material:- type 1 cells, which produce the material forming the meshwork, and type 2 cells which are responsible for the release of the material constituting the homogeneous film. These will leave behind a footprint with a reticulate pattern on the substrate. This pattern is due to the arrangement of the adhesive cell secretory pores on the disc surface of the tube feet.

  1. Allen, 1983. Journal of Experimental Marine Biology and Ecology 70 pp. 79-90
  2. Hennebert et al., Journal of Structural Biology 164 (2008) 108–118

Wednesday, October 26, 2011

Established: The Harlequin Ladybird

Harlequin Ladybird (Harmonia axyridis var. succinea) adult at site of establishment near Cork city
Our recent record of the Harlequin Ladybird (Harmonia axyridis) prompted me to reexamine some older pictures of Coccinellidae beetles, to see if any other of the morphs had inadvertently been seen. Lo and behold, buried among the pictures of moths, flowers and wading birds, there was an example of H. axyridis var. succinea. However, this was just one picture among about 25 taken. The rest showed no more adults, but, worryingly, did show many, many pupae as well as larvae. These pictures taken on the 19th of October, 2010 show the first evidence of establishment of H. axyridis in Ireland. 
Harlequin Ladybird (Harmonia axyridis) pupa at site of establishment near Cork city
The site of establishment is a collection of Griselinia littoralis bushes that border a footpath and that is backed by a small stream on a previously heavily industrialised area about 2 km from Cork city centre. The area is quite near the river Lee, Cork city's main river, and also near Tivoli Dock, a major container port that may be the site of entrance for H. axtridis. Examination of the site last week, just over a year after the first sighting, showed H. axyridis pupae still present on the same G. littoralis bushes, showing that it survived the unprecedently harsh weather last winter, something that has been observed in other countries such as Belgium (1). This is not the only site, with another being reported from Co. Carlow in July of this year. Establishment of H. axridis in Ireland is worrying, as they have had adverse effects on other Coccinellidae species where introduced in North America, reducing numbers by up to 20 times in some cases (2). They have also been seen to cause damage through feeding to soft fruits (grapes) and pears.
Harlequin Ladybird (Harmonia axyridis) larva at site of establishment near Cork city
  1. Berkvens et al., 2010. Journal of Insect Physiology 56 pp. 438-444
  2. Kock, 2003. Journal of Insect Science, 3 pp. 1-16

Wednesday, October 19, 2011

King Harvest Has Surely Come

Leiobunum rotundum, feeding. Note the missing second leg on the animals left side. This is an example of autopasy, a defensive strategy involving losing an appendage along a preformed brake plane in response to stress such as a predator.

Everybody knows them, but few know much about them: Daddy Long Legs. Because of this lack of knowledge, much of what is known is superstition and folklore. Even the very name we give them, 'Daddy Long Legs', suggests a monstrous, lurking menace rather than the fascinating and ancient creatures that they are.
Daddy-Long-Legs (or Harvestmen) are arachnids of the order Opiliones and with over 5000 species described they are the third largest group of arachnids after the Acari (mites and ticks) and Aranae (spiders) (1). Their body has two basic regions; a prosoma (or cephalothorax) which carries all the appendages and eyes, and a limbless opisthosoma (or abdomen) which has the spiracels and genital opening. Although they resemble spiders, the two body regions are not clearly defined and they thus lack the constriction or waist that can be seen in spiders. Opiliones also lack spinning organs and so do not spin webs. They are in fact much more closely related to scorpions and pseudoscorpions (2) and are among the oldest of arachnids, with fossil records showing little morphological change in the group in 400 million years (1). They possess many characteristics that are unique to their group. These include the presence of paired trachae, the presence of a penis or spermatopositor organ in males and an ovipoistor in females and scent glands that are present on the prosoma (3). These glands release chemicals during defensive behaviour that can repel other arthropods (4). Other than these chemicals, opiliones do not produce venom and the commonly held belief that they are poisonous is untrue.
They are found on every continent, bar Antarctica, in moist to wet habitats and are excellent indicators of undisturbed environments where they feed on arthropods, snails and worms. These they ingest in particles, unlike many arachnids which need to liquify their food, and also may eat vegetable matter (2). Most species in the Northern Hemisphere overwinter as eggs, hatching in the spring. Maternal care is common in opiliones, as it is in many other arachnid groups, but uniquely so is paternal care. Adults reach maturity in the Autumn, which has lent them one of their common names, Harvestmen. Many species are very tolerant of other individuals, again unlike other arachnid groups, and often large aggregations of adults and subadults can be seen near water sources.
One of the most conspicuous of the 18 species of opiliones present in Ireland (15 native, 3 introduced and naturalised) (5) is the longlegged Leiobunum rotundum. Preferring open spaces, L. rotundum feeds on a variety of invertebrate prey as well as soft fruits (6). The individual pictured is mising one of its legs and thus shows an example of autopasy (also called autotomy). This is a situation where an outside agent is responsible for the severance of an appendage at a preformed breakage plane (e.g., the loss of limb to a predator who has seized it) (7). The limb will not grow back.

  1. Pinto-da-Rocha et al., 2007. Harvestmen: the biology of Opiliones
  2. Giribet et al., 2002. Cladistics 18 pp. 5-70
  3. Giribet, 2009. Encyclopedia of Insects pp. 247-248
  4. Hara et al., 2005. Biochemical Systematics and Ecology 33 1210-1225
  5. Ferriss et al., Irish Biodiversity: a taxonomic inventory of fauna pp. 83-84
  6. Höfer et al., 2002. Arthropod Structure and Development 29 pp. 13-21
  7. Maginnis, 2006. Behavioral Ecology 17 pp. 857-872

Monday, October 17, 2011

Irish Spurge Is English Too

Irish Spurge, Euphorbia hyberna
Ireland scored a little bit of a coup when Irish Spurge was given the scientific name Euphorbia hyberna. A spurge from Ireland, is the (very) rough translation, even though it is also found extensively in the south-western Mediterranean region and northern Portugal (1). Indeed its distribution in Ireland is limited to the south-west of the country, in Co. Kerry and west Co. Cork. It is to be found in damp, shaded areas, particularly wooded slopes where its upright stems bear striking yellow flowers that lack sepals or petals (2) and that were unfortunately gone from the plant pictured here. Due to its distribution in Iberia and the west of Ireland, it is frequently quoted as one of the 'Lusitana Flora' common to both areas, but lacking in the flora of Ireland's nearest neighbour, Britain. However this assertion is not true: E. hybernia is present in the flora of West Cornwall, North Devon and South Somerset, being extremely local in all three areas (3).
Irish Spurge, Euphorbia hyberna
  1. Appendino et al., 2002. Fitoterapia 73 pp. 576-582
  2. Sterry, 2004. Collins Guide to Irish Wildlife p. 218
  3. Stace, 1997. New flora of the British Isles p. 459

The Size of the Emerald Damselfly

Female Emerald Damselfly, Lestes sponsa
In the race to be the top of the heap in biological terms, organisms can follow two paths. They can take their time about it all, growing nice and big and strong, but missing out every time a potential mate comes by and they are not developed enough to take advantage of the situation. Or they can rush into things, becoming sexually mature quickly but growing to be small in size, and possibly unattractive to potential mates. What makes this choice all the more difficult is the prevalent environmental conditions that can, and often do, hinder the organsisms development. Availability of resources, threats from predators and the vagaries of the seasons mean that the chosen path is soon skewed. This has been elegantly demonstrated in a series of studies on the Emerald Damselfly, Lestes sponsa (1). This attractive, bottle-green odonate overwinters in the egg stage, has a brief larval period in spring, then emerges and reproduces in late June, the latest Irish damselfly to do so. It is common and widespread through out Ireland, commonly found near small lakes and acid ponds. L. sponsa individuals were measured for foraging activity, development rate and mass at emergence when exposed to the presence/absence of predators and the perceived onset of winter, and the abundance/scarcity of food and, again, the perceived onset of winter. In the presence of predators, all three perameters measured were reduced, while individuals under time constraints showed increased foraging and development, but decreased mass at emergence. Larvae that had an abundance of food showed high levels of all three parameters, while those that had time constraints in high levels of food showed lower mass at emergence, as was to be expected. What was not expected, however, was larvae at low food levels under time constraints showed very slow development and that largest mass at emergence. This is thought to be a result of this last group delaying emergence until the following season. Such life history plasticity is a feature of the life of L. sponsa.
Female Emerald Damselfly, Lestes sponsa
  1. Johansson et al., 2001. Ecology 82 pp. 1857-1869

A Record of the Harlequin Ladybird in Cork City

Harlequin Ladybird, Harmonia axyridis f. spectabilis
One of the most imminent threats to native Irish species by invasives is the one the Harlequin Ladybird (Harmonia axyridis) poses to Irish native ladybirds. H. axyridis is larger and more aggressive than native Irish ladybird species and is thus able to out-compete them in hunting their preferred food of aphids. They also can have up to four generations per year, compared to the just one for native ladybird species and display less susceptibility to common diseases and parasites (1). Allied to this, H. axyridis also targets many non-aphid insect species, such as lepidopteran larvae and, most worryingly, ladybird larvae (2).
Harlequin Ladybird, Harmonia axyridis f. spectabilis
H. axyridis is native to Asia, specifically China, Japan, Korea, Mongolia and Siberia (1). Its voracious appetite for aphids marked it out as a seemingly effective biolocontrol agent and was introduced as such into the US in 1916. Establishment took some time but H. axyridis was recorded as such in 1988 and is now considered a pest there. Other than its effect on native ladybird populations, its tendency to overwinter in nooks and crannies in houses in quite large numbers make it a nuisance and may cause allergic reactions in inhabitants. Despite such problems, H. axyridis was inexplicably marketed as a biocontrol agent in mainland Europe in the 1990s. Commercial field releases first occurred in 1995 in France and was subsequently introduced as such in Belgium, Germany, Greece, Italy, the Netherlands, Spain, Portugal and Switzerland. H. axyridis has since spread to Austria, Luxembourg, Demark, Norway, Sweden and Great Britain, where it was first recorded in 2004 (3). The first Irish record for H. axyridis was in 2007 in Co. Down, with the first record for the Republic being in 2010 in Co. Wicklow (4). Another individual was recorded in 2010 in Cork City in November entering a house where individuals are wont to overwinter.
The individual pictured here was sighted entering a dwelling in the suburbs of Cork City on the 12th of October. Specifically, it was H. axyridis f. spectabilis that was sighted. This is the same variety that was seen in both records in 2010. Two other varieties are present throughout Europe, f. succinea and f. conspicua. H. axyridis is distinguished from other ladybird species by being noticibly larger, having red legs, being more domed than other species and may have a distinctive 'M' or 'W' mark on its pronotum (4).

  1. Brown et al., 2008. Biocontrol 53 pp. 5-21
  2. Rhule et al., 2010. Biological Control 53 pp. 243-247
  3. Roy et al., 2005. British Wildlife 16 pp. 403–407

Monday, October 10, 2011

Common or Soprano: Which Bat Is It?

Pipistrelle in Flight
I recently saw a Pipistrelle bat fly past my window, its erratic flying pattern indicating it was feeding. Now I don't claim to have excellent eyesight, butI knew it a Pipistrelle as I know there is a roost nearby. Beyond this however, I could not say what species it was. Ireland has three species of Pipistrelle: Nathusius’ Pipistrelle (Pipistrellus nathusii), the Common Pipistrelle (P. pipistrellus) and the Soprano Pipistrelle (P. pygmaeus). The only confirmed breeding colony for P. nathusii in Ireland was recorded in 1997 near Lough Neagh and while there has been recordings in other counties, no records exist for the bat as far south as where I live (1). Its therefore extremely unlikely that is was P. nathusii that I saw. So that leaves P. pipistrellus or P. pygmaeus. However if I had spotted this bat pre-1999, I would have been sure that it was P. pipistrellus. Prior to this, P. pygmaeus was not recognised as a species in its own right. The two species are morphologically identical, measuring about 4 cm long with a 20 cm wingspan. Their difference lies in the frequency used by both bats during echo location (2). P. pipistrellus uses a call of 45 kHz, with P. pygmaeus using one of 55kHz. While differences were noted within the P. pipistrellus species as early as 1865 (2), it wasn't until the 1980s that the use of bat detectors revealed differences in the echo locating frequency of the two species. Further investigation showed that the two species occurred in close association however they did not share roosts. Conclusive support for the two-species theory was provided in differences in the cytochrome b genes.

  1. Russ et al., 1998. Journal of Zoology, London 245 pp. 345-349
  2. Hulva et al., 2004. Molecular Phylogenetics and Evolution 32 pp. 1023-1035
  3. Barrat et al., 1997. Nature 387pp. 138-139

Friday, October 7, 2011

Giant Rhubarb

Gunnera are big. Very big. Well, not all of them: Gunnera herteri stands only 6 cm tall (1). But the big ones are very big. They're old too, with the fossil record showing they have been in existence for at least 95 million years. It is their size, however, that is most obviously impressive. G. mantica has a leaf diameter of 3 m (1). Its not alone in this, with many other of the c. 50 species of this monogeneric family towering, in some cases 6 meters, over any other vegetation.
Gunnera tinctoria
This height has posed a problem in Ireland where the species G. tinctoria was was introduced from its native Chile some time in the past 100 years, probably as a ornamental. While not as big as enormous as some of the Gunnera giants, it still clocks in at an impressive 2 meters tall with leaves 2 meters in diameter. It tends to grow in dense colonies that out-compete and displace native vegetation. It was first recorded wild here by the renowned Irish botanist Robert Lloyd Praeger in 1939 on Achill Island, Co. Mayo and it is here today that the plant colloquially called 'Giant Rhubarb' shows the extent of its dominance (2). Large tracts of the island are now almost entirely covered with G. tinctoria. As such, it is considered an invasive in the west of Ireland where it has colonised many habitats such as grassland, waterways, roadside verges, bogs, heaths and coastal cliffs (3). While its sparse distribution throughout the rest of the country may be reflective of the different climatic conditions there, it may also may just be evidence of the beginning of its invasion. 
Gunnera tinctoria leaf
While the size of G. tinctoria accounts for its adverse effect on other plants, it is its methods of reproduction that account for its invasive nature. As a perennial rhizomatous plant, it can spread easily from year to year once established. It also produced many seeds which may be carried to new sites by birds feeding on them (3). Ireland's wet climate also assists these damp loving plants, which accounts for their status as an invasive in similarly inclement New Zealand. The rhizomes mean mechanical removal may not always be effective, so herbicides such as Round-Up are a valuable tool in controlling the plant. 
Gunnera tinctoria flowering parts
Other than their height, Gunner species also possess a distinct adaptation that singles them out from all other flowering plants. They form symbiotic relationships with Nostoc cyanobacteria (4). The cyanobacteria are uniquely harboured internally by the plants which surround the Nostoc filaments with membranes where they fix nitrogen for the plant. Entry is made via specialised glands on the Gunnera stems. Interestingly it has been shown that G. manicata grown on substrate with sufficient nitrogen did not develop these glands (4).

  1. Wilkinson, 2000. Botanical Journal of the Linnean Society 134 pp. 233-266
  2. Praeger, 1939. Proceedings of the Royal Irish Academy 45B pp. 231-254
  3. Armstrong et al., 2009. Giant Rhubarb (Gunnera tinctoria) Invasive Species Action Plan
  4. Chiu et al., 2005. Plant Physiology 139 pp. 224-230

Wednesday, September 28, 2011

A Soldier Fly, Sargus bipunctatus

Two Spotted Centurion, Sargus bipunctatus
Soldier flies, family Stratiomyidae, are so name because of the bright, almost militaristic colours of their body parts. Over 2800 species are described worldwide, varying widely in appearance, ranging in size from 3 to 30mm, possessing spines on the scutellum numbering from zero to eight, and bearing colors of metallic green, red, yellow, and black (1). Thirty two species are recorded in Ireland (2). Of these, one of the largest and certainly most attractive is the Two Spotted Centurion (Sargus bipunctatus). Ranging in size from 11 to 14 mm, there is pronounced sexual dimorphism between sexes. Males are are bright green, while the femals have an intense brown-red abdomen (3). Males and females have two white spots on their heads. Both adult forms can be seen on the wing from early July to late October (4), but rarely after mid October: larvae are to be found in dung compost and other rotting material, where they feed on detritus (5).
Two Spotted Centurion, Sargus bipunctatus
  1. Brammer and Dohlen, 2007. Molecular Phylogenetics and Evolution 43 pp. 660-673
  2. Ferriss et al., 2009. Irish Biodiversity: a taxonomic inventory of fauna p. 101
  3. Reichholf, 2007. Entomofauna 28 pp. 141-148
  4. Drake, 1991. Provisional atlas of the Larger Brachycera (Diptera) of Britain and Ireland p. 21
  5. Roberts, 1969. Journal of Zoology 159 pp. 381-398

The Royal Fern

Fertile Frond of the Royal Fern, Osmunda regalis
Some ferns are quite similar. The small filmy ferns Wilson's Filmy Fern (Hymedophyllum wilsonii) and Tunbridge Filmy Fern (H. tunbrigense) are virtually identical at first glance, with subtle features like the presence or absence of toothed edges on the scales protecting the sori having to be examined to differentiate them. One fern that doesn't have that problem though is the Royal Fern, Osmunda regalis. A strikingly distinctive fern, found in wet bogs and fens throughout Ireland (with a global distribution spanning Europe, Asia and Africa) its fronds can reach heights of 160 cm (1). Most of these are sterile, with the fertile fronds rising above the others in the centre of the plant. Their shuttlecock-like appearance and the fern's overall imposing height are unmistakable.
The Royal Fern, Osmunda regalis
Or are they? Homosporous ferns have two free-living generations, the sporophyte generation which is what most people would call the fern, and the relatively short lived gametophyte generation. The gametophyte generation is much smaller and shows far less morphological complexity. This means that identification is often next to impossible. Identification of fern gametophytes is important as they play an important part in fern dispersal and ecology. This problem has been overcome by the use of DNA-based identification. A sample of a gametophye in cultivation that was unknown for 30 years was identified as O. regalis using plastid sequencing (2). The gameteophyte never produced antheridia, and so never produced the sporophyte stage, and morphological analysis was inconclusive. Its identification as O. regalis shows the power of DNA-based techniques in revealing more about the ecology of fern gametophytes.

  1. Phillips, 1980. Grasses, Ferns, Mosses and Lichens of Great Britain and Ireland p. 105
  2. Schneider and Schuettpelz, 2006. Molecular Ecology Notes 6 pp. 989-991

The Pill Millipede Misleads with Convergent Evolution

The Pill Millipede (Glomeris marginata)
One of the most striking examples of convergent evolution I have come across is that of the Pill Millipede (Glomeris marginata) and the Pill Woodlouse (Armadillidum vulagre). Convergent evolution describes the acquisition of the same biological trait in unrelated lineages (1), and in both these animals the architecture of their exoskeleton allows them to curl into a ball (or “pill”) when alarmed. Closer examination of both species shows they are obviously not related, the most distinguishing feature being that G. marginata has two pairs of legs per segment, and many more to boot than the seven pairs possessed by A. vulgare. G. marginata also has shorter antennae and its dorsal plates are edged with cream rims. It can be found in leaf litter in mature woodlands (2), whereas A. vulgare is far more common - individuals can often be happened upon in urban gardens.
Convergent Evolution: Pill Millipede (Glomeris marginata) on left and Pill Woodlouse (Armadillidum vulgare) on right.
However, G. marginata may have further features, that show its apparent relatedness to insects, that are a result of convergence. Traditionally, morphological features such as loss of second antennae, formation of Malpighian tubules, postantennal organs and trachea have indicated that the myriapods are close relative to the insects (3). Yet these features have been shown to be prone to convergence (4), and molecular evidence also points to a far more distant relationship than previously thought. Of the four extant arthropod subphyla, the hexapoda and crustaceans are now seen as sister groups and mitochondrial genome analysis has revealed the same to be true for the myriapods and the chelicerates (5). This is backed up further by 18S/28S rRNA sequences and Hox gene analysis of the myriapods (3)
Overturned Pill Millipede (Glomeris marginata)
Analysis of neurogenesis in G. marginata has provided morphological evidence to support these claims (3). In the development of neuroblasts in G. marginata, groups of cells invaginate to form the the ventral neuroectoderm. This is similar to neurogenesis in spiders, but quite different than that in insects where single cells give rise to the neuroectoderm.

  1. Miller et al., 2010. Convergent Evolution
  2. Sterry, p. 172
  3. Dove and Stollewerk, 2003. Development 130 pp. 2161-2171
  4. Dohle, 2001. Annales de la Societe Entomologique de France 37 pp. 85-103
  5. Hwang et al., 2001. Nature 413 pp. 154-157

Friday, September 23, 2011


The Blackberry Skeletoniser, Schreckensteinia festaliella
Schreckensteinia festaliella is the only member of the bristle leg moths, family Schreckensteiniidae, to occur in Europe, and only one of five species in whole the family. Although it is a small (c. 10 mm) moth, it has a fearsome common name: the Blackberry Skeletoniser. Putting one in mind of a character from the 1980's cartoon serial 'He-Man', it gets this name from the larvae's feeding habits on blackberry and other Roseacea species (1). Attacks can lead to extreme damage, leaving nothing but skeletons of leaves on plants, hence the name. However, only one case of severe damage to cultivated crops has been noted, that of Raspberries in Scotland (2).
The Blackberry Skeletoniser, Schreckensteinia festaliella, in distinctive repose with hind leg raised. Note the spines on the hind leg.
The bristle leg moths get their name from the quite large spines that occur on the hindmost legs. The slender winged adults are may be seen in repose with, quite distinctively with their hind legs raised and projected over the abdomen. Although native to Europe, S. festaliella was introduced to North America between 1963 and 1969 to control invasive wild blackberry (Rubus argutus) (3).

  1. Capinera, 2008. Encyclopedia of Entomology p. 564
  2. Alford, 2007. Pests of Fruit Crops: a Colour Handbook p. 238
  3. Nagata and Markin, 1986. Proceedings of the Sixth Conference of Natural Science, Hawaii Volcanoes National Park pp. 541-547

Tree Lungwort and the Doctrine of the Signatures

Tree Lungwort, Lobaria pulmonaria
Spleenwort, Liverwort, Toothwort: seemingly picaresque names for common plants, their origin is actually based in an ancient concept of medicine, the Doctrine of Signatures. The early botanist – and all-round occultist – Paracelsus von Hohenheim (1493-1541) was the first to expand on ideas from antiquity and early European Christianity as the Doctrine of Signatures (1). The central tenet of the doctrine was that the shape, colour and other attributes of a plant indicated its use in healing. So the liver-shaped thallii of the Liverwort genus Marchantia spp. are, according to the doctrine, useful for treating liver ailments*. The Doctrine of Signatures was based on the belief that God marked all his creations with a sign, or signature. The sign showed its purpose. Its rise in popularity during the 15th and 16th centuries is rooted in the role 'resemblance' played in Western culture at that time.
Tree Lungwort, Lobaria pulmonaria
While the Doctrine of Signatures has long been rejected by botanists and chemists on the basis of scientifically controlled data, it has left us with a plethora of colourful names. However, one of these is, in a way, well deserved. Tree Lungwort (Lobaria pulmonaria) is an impressively large lichen that has the green alga Dictyochloropsis reticulata as its photosynthetic partner (2). It is found attached to the bark of trees in old to ancient woodlands with high levels of rainfall (3). While the pitted appearance of the thallii resemble lung tissue, the name 'Lungwort' is appropriate in another sense. Found in moderate regions of the tropics and throughout boreal regions of the norther hemisphere, it thrives in places of low pollution and has dissappeared entirely in parts of Central Europe in the 20th century due to falling air quality (4). Pollutants in the atmosphere condensing to form acid rain fall on the forests. L. pulmonaria colonise drainage channels below old and large wounds on deciduous trees. These channels are richer in minerals and had a higher pH than normal bark (5), but concentrate pollutants in rain. Populations of the lichen are thus wiped out
Tree Lungwort, Lobaria pulmonaria showing fruiting bodies
While the effect of L. pulmonaria on the lungs has yet to be proven, it has been shown to have some  pharmacological properties (6). Liquid extracts from the lichen tested on rats showed moderate anti-inflamatory and strong antiulcerogenic affects.

*Note: The suffix 'wort' is derived from the old English word for plant.

  1. Pearce, 2008. European Neurology 60 pp. 51-52
  2. Widmer et al., 2010. Fungal Biology 114 pp. 583-544
  3. Sterry, 2004. Collins Complete Guide to Irish Wildlife p. 282
  4. Walser et al., 2003. Fungal Genetics and Biology 40 pp. 72–82
  5. Gauslaa, 1995. The Lichenologist 27 pp. 59-76
  6. Süleyman et al., 2003. Phytomedicine 10 pp. 552-557

Wednesday, September 21, 2011

Notes on Irish Orthoptera with a Provisional Checklist

The Orthoptera are the grasshoppers, groundhoppers and crickets. Twelve species are found in Ireland and regarded as native (1). Throughout the 19th and 20th centuries, a lack of attention was paid to Irish Orthoptera, with a few exceptions (2). Therefore the true extent of distribution of species may not reflected in the literature.
Irish Orthoptera Species
Family Species Common Name Note
Tettigoniidae (Crickets) Conocephalus dorsalis Short Winged Cone Head First recorded in 1989
Leptophyes punctatissima Speckled Bush Cricket Found in south
Meconema thallsainium Oak-Bush Cricket Found in south-west
Metrioptera roeselii Roesel's Bush Cricket First recorded in 1977
Pholidoptera griseoaptera Dark Bush Cricket First recorded in 1983
Tetrigidae (Groundhoppers) Tetrix undulata Common Ground Hopper Widespread
Tetrix subulata Slender Ground Hopper Restricted to Galway
Acrididae (Grasshoppers) Myrmeleotettix maculatus Mottled Grasshopper Widespread but local
Chorthippus brunneus Common Field Grasshopper Widespread
Chorthippus albomarginatus Lesser Marsh Grasshopper First recorded in 1960
Omocestus viridulus Common Green Grasshopper Widespread
Stethophyma grossum Large Marsh Grasshopper Found in west

Five species of grasshopper are present in Ireland (see table). Chorthippus brunneus and Omocestus viridulus are the most common, both being found in a variety of grassy places (3). Myrmeleotettix maculatus prefers drier areas such as dunes and heaths and therefore tends to be more local. Ireland's largest grasshopper, Stethophyma grossum, is locally restricted to floating acid bogs in the West of Ireland. C. albomarginatus is the most recent addition to the Irish grasshoppers, with a first record in 1960 (2). It is restricted to a few site in the south-west, favouring grassland and dunes.
Common Green Grasshopper, Omocestus viridulus
The grounhoppers are a family of orthopterans that resemble grasshoppers, but are much smaller in size. Unlike other Orthoptera, most groundhoppers overwinter as adults. Two species are present in Ireland. Tetrix undulata is of widespread but local occurence. T. subulata is similar in appearance, but has a longer protonum and wings and is restricted to Galway.
Crickets in Ireland are less common than grass- or groundhoppers. Five species of crickets are present in Ireland, with three of these being first recorded only in the last 34 years. Leptophyes punctatissima can be found in hedgerows but is restricted to the local areas in the south of Ireland and quite scarce. Meconema thallsainium is again restrcited to the south west of the country, favouring woodlands, but may also be seen sometimes in gardens. Found in damp meadows, Metrioptera roeselii was first recorded in 1977 (2). Pholidoptera griseoaptera was first recorded in Ireland in 1983 in the south east (4). it is found in in hedgerows and amongst scrub near sea cliffs and dunes. The most recent addition to the list of Irish orthopera is Conocephalus dorsalis. This was recorded in 1989 in the south west prefers two distintct habitats: coastally on saltmarshes and sand dunes and inland on lowland bogs and fens.
Common Field Grasshopper, Chorthippus brunneus
As well as frequent records of one-off species arriving on imported produce, three other orthoptera species of note have been recorded in Ireland. The European Mole Cricket, Gryllotalpa gryllotalpa, was recorded in from one site in Northern Ireland pre 1970, but is not considered native. The non-native House Cricket Acheta domesticus was present in Ireland until about 1960, but although recent sightings have been reported (5), it is now considered rare or absent. The Greenhouse Camel Cricket, Tachycines asynamorus can be found as an introduced species in Ireland, but as it tends to become established in artificial situations such as greenhouses, it is not included in the Irish list of Orthoptera.

  1. Ferriss et al., 2009. Irish Biodiversity: A Taxonomic Inventory of Fauna p. 108
  2. Haes and Harding, 1997. Atlas of grasshoppers, crickets and allied insects in Britain and Ireland
  3. Sterry, 2004. Collins Complete Guide to Irish Wildlife p. 124
  4. O'Connor and O'Connor, 1985. Entomologists' Gazette 36 pp. 229-232
  5. O'Connor, 1993. Irish Naturalists' Journal 24 p. 337

Tuesday, September 20, 2011

Fighting Tooth and Claw

Velvet Swimming Crab, Necora puber
The Velvet Swimming Crab (Necora puber) is unique in a couple of senses. Firstly, it is the only member of the genus Necora, having been classified as such following reexamination of type material in 1987 (1). Secondly it, unusually for a swimming (or portunid) crab, occurs predominantly on hard substrates (2). It is also the largest swimming crab to be found in the waters surrounding Ireland and Britain, its final pair of pereiopods being flattened, fin-like to aid swimming. However its most striking features are its red eyes (lending it the alternative common name, “Devil Crab) and its velvety appearance. This is due to tiny hairs covering the carapace and appendages which allow a layer of algae to cover the crab. An important commercial crab (3), N. puber is usually found in shallow water to a depth of 20 m where it feeds on a variety of organisms including other crustaceans, molluscs and brown algae.
Velvet Swimming Crab, Necora puber, with swimming pereiopod on right
Interaction between individual crabs are more often than not antagonistic, with fights occurring between all sizes of crabs. They seem to prefer a solitary lifestyle and it is assumed that this is because large numbers of crabs increase the presence of predators and competition for food (4). In laboratory conditions (4), N. puber individuals were seen surprisingly not to engage in an escalation of violence, but rather in sporadic bursts. Fights between individuals were won in the majority of cases by the larger crab, yet smaller crabs never backed down from confrontation. This might seem a bit foolhardy on their parts, having little chance of winning, but under the laboratory conditions all crabs were in intermoult stage and had a hard outer shell. In vivo, fights may be one by smaller crabs against larger but softer ones.
Velvet Swimming Crab, Necora puber
  1. Holthuis, 1987. Zoologische Mededelingen 61 pp. 1-14
  2. Norman and Jones, 1992. Estuarine, Coastal and Shelf Science 34 pp. 71-83
  3. Robson et al., 2007. Food Microbiology 24 pp. 419-424
  4. Thorpe et al., 1994. Behavioural Processes 32 pp. 235-246

The Threat to a Seemingly Widespread Species: Small Copper Butterfly

When it comes to species under threat, its the specialists that seem to be in the most trouble. Relying on, say, a single rare plant species for food or existing only in a specific microhabitat spells trouble in the extinction stakes. Yet the news is seemingly equally as grim for some widespread species.
Small Copper Butterfly, Lycaena phlaeas
The Small Copper (Lycaena phlaeas) is a common butterfly of hedgerows and woodland verges in Ireland, although it is also frequently spotted in fields and even gardens. It is considered common throughout Europe, Asia, North America and even north Africa, feeding on Common Sorrel (Rumex acetosa) and other Rumex spp. (1). However a detailed study of numbers in north Wales showed a population level decline of 89%, a level comparable to that of species considered rare and threatened (2). Habitat loss and fragmentation are the causes of the reduction in numbers. This illustrates the difficulty in foreseeing what consequences our further misuse of natural resources will have on a range of species.

  1. Endo et al., 1985. Journal of Insect Physiology 31 pp. 525-532
  2. León-Cortés et al., 2000. Ecological Entomology 25 pp. 285–294

Lavender in the Salt

Sea Lavender, Limonium humile
With its sprigs of purple flowers on stalked shoots, Sea Lavender (Limonium humile) does indeed resemble its namesake Lavender (Lavandula spp.). Its there though that the similarity ends, as the resemblance is superficial with no relationship existing. L. humile can be found growing, sometimes with local abundance, in salt marshes where its flower bearing stems can rise to 20 cm above a basal rosette of rounded leaves. Salt marshes pose the dual problem of high salinity and low oxygen levels. Both of these pose there own particular problems for L. humile, but the lack of oxygen to the root systems is possibly the greater of the two evils. It, along with other Limonium spp., overcome this problem by switching root respiration to a very high level of lactate fermentation, a protracted level much greater than the transient lactate glycolysis seen in most plants at the transition from normoxic to anoxic conditions (1). The lactate subsequently produced in the Limonium spp. root cells is of a degree that would lethally acidify them and is transported out of the cells into the environment, thus maintaining cell homeostasis.
Sea Lavender, Limonium humile
  1. Rivoal and Hanson, 1993. Plant Physiology 101 pp. 553–560

Monday, September 19, 2011

Two Sun Planet

As recently mentioned on this blog, its been a miserable summer sun-wise. Not so for a planet recently discovered by the Kepler spacecraft. Launched in March 2009, Kepler's aim is to find and analyse terrestrial and larger planets in or near the habitable zone of a wide variety of stars (1). And its come up with quite the find: a planet in orbit around two suns (2). Known as Kepler-16b, the Saturn sized planet describes a 229-day orbit around its two stars, which in turn eclipse each other. The stars are 20% and 69% the size of our own star, the sun, and have a 41 day orbit.

Kepler-16b (in blue) orbiting its two stars (orange and yellow).
Note that distances are not to scale
  2. Doyle et al., 2011. Science 333 pp. 1602-1606

Wednesday, September 14, 2011

Sun Bathing Butterfly

Silver-washed Fritillary, Argynnis paphia
The sun has been in short supply in Ireland this year, and with September in full swing it looks (and feels) like we've had our, some may say inadequate, share for the year. These some would not include the Silver-washed Fritillary, Argynnis paphia. A large and attractive species native to Ireland that is common in woodlands, it has a yellow-orange upperwing marked with black that are similar to other Fritillary species, but is distinguished by the silvery sheen of the underwings (1). The adults are often found on their favourite food of brambles, basking in the sun. Here, they use their wings to absorb solar radiation and maintain their temperature above the ambient. By adjusting the angle of its wings at rest, it can absorb as much or as little sun as possible. Under artificial conditions, A. paphia was seen to adjust its wing position to maintain a thoracic temperature of 34±1.5 °C (3).

  1. Sterry, 2004. Collins Complete Guide to Irish Wildlife p. 106
  2. Kammer and Brachi, 1973. Comparative Biochemistry and Physiology 45 pp. 1057-1063
  3. Vielmetter, 1958. Journal of Insect Physiology 2 pp. 13-16

Cormorant Washing Line

Cormorant, Phalacrocorax carbo
The Cormorant (Phalacrocorax carbo) is one of the largest seabirds in Ireland, and also one of the most familiar. It can often be seen feeding in estuaries and perched in trees, where they sometimes breed (1). With its dark body and long, hooked bill it could be mistaken for its relative the Shag (P. aristotelis). However, the Shag is a smaller bird by about 20 cm and is rarely seen inland. Adult Cormorants have an attractive blue-green sheen to their plumage, a yellow and white bare patch of skin on its face and a white thigh patch that disappears after the breeding season (1).
Cormorant, Phalacrocorax carbo
Recently, I observed a Cormorant perched on an old mooring post in a river estuary. It held its wings out from its body in a drooping fashion that is known as a spread-wing posture. Many birds engage in this type of behaviour. Cormorant feathers retain moisture when diving for food, which decreases buoyancy and aids underwater pursuit of prey. Only the outer layer of feathers are wettable however, and a a layer of insulating air is maintained next the skin when diving (2). Yet the outer feathers remain wet upon emergence and therefore need to be dried. Hence the spread-wing posture (as seen in the photographs) of the Cormorant, a living washing line.

  1. Sterry, 2004. Collins Complete Guide to Irish Wildlife p. 34.
  2. Elowson, 1984. The Auk 101 pp. 371-383

Spooky Dragonflies

Male Common Darter, Sympetrum striolatum
The Common Darter (Sympetrum striolatum) is, as its name suggests, a common and widespread dragonfly in Ireland, indeed in Europe as a whole. Flying between June and October, it can often seen resting on paths or stones in sunny, open areas. S. striolatum is a very aggressive, territorial species and will “dart” at other, often larger dragonfly species. Males and females differ in their colouring, with mature males having orange-red, unwaisted abdomens in contrast to the the dull, yellow-brown females.
Female Common Darter, Sympetrum striolatum
Individuals are most often seen near favoured breeding sites of shallow ponds and small lakes, so it was therefore a surprise when in Hungry S. striolatum (along with five other species of Sympetrum)  individuals were observed in large numbers in a cemetery that was nowhere near any water source (1). Were they just being spooky or was there a more rational answer?
Common Darter, Sympetrum striolatum
The dragonflies were seemingly attracted to polished black gravestones, where their behaviour was the same as if by water. This involved perching near the gravestones and defending their perch, flying individuals repeatedly touching the gravestone surfaces with their ventral sides and pairs in tandem position frequently circling over the gravestones. It was found that the gravestones reflect highly and horizontally polarised light in a manner almost identical to smooth water. S. striolatum, along with many other dragonfly species, find their aquatic habitats by means of polarotaxis, the use of reflected polarised light to discriminate between surfaces (2). This explains the attraction to the gravestones, an attraction that is so strong that females are sometimes lead to oviposit on the gravestones.

  1. Horváth et al., 2007. Freshwater Biology 52 pp. 1700–1709
  2. Bernáth et al., 2002. Freshwater Biology 47 pp. 1707–1719