A Personable Little Bug

Firebug, Pyrrhocoris apterus

As I progress through life, my opinions and outlook has changed, in a way that I would like to think is more mature. One thing that has not changed about me though is how I tend to be led by my stomach. When I'm hungry I need to eat. Otherwise I get irritable and withdrawn. People often mistake it for some deep troubles within me, but its just a primal need to fill my belly. However I have learned to deal with it though in the simple possible way: regular eating. And sometimes the joys are not only culinary. Recently hunger grabbed me in Cork city and I made my way into the nearest cafe, a wonderful vegan eaterie (I'm an omnivarian, I'll eat anything at all, and don't mind if there is no meat with my meal as many carnivores often do). While tucking into my felafel and salad (which was smashing, if you were wondering), my eye was caught by something small and red on the Crassula plant that was in front of me. I was a Firebug (Pyrrhocoris apterus), a species that if not native to Ireland and a species that, as far as I can ascertain, has not been reported here before. The mature adult had been there at least one week, according to the staff, and may have arrived in one of the many deliveries of vegetables that they receive every week from continental Europe where P. apterus has its base. A flightless bug, it feeds on Lime trees and tree-mallows, and is most associated with its swarming behaviour whereby numerous individuals clamour together. Its common name, Firebug comes from its wonderful crimson colour that contrast wonderfully with the black markings on its abdomen creating an almost face-like effect.

As with all insects, P. apterus goes through a series of ecdyses through out its life, five in all from hatching to adulthood. Interestingly it has been shown that at different stages of moult, individuals show distinctly different personalities. Larvae differed from adults in general in that they were bolder, explored their environment more thoroughly and seemed to be more active before final ecdysis (1). This raises the intriguing concept of personality differences between individual organisms as inherited traits. In an environment, it is argued, if fitness payoffs are dependent on an organisms behavioural history and the frequencies of competing strategies then personality differences can be selected for (2). It certainly is an interesting idea and is supported by evidence from diverse sources as lab rats, where heavier newborns are braver and more explorative (3), field crickets, where personality changes at maturity (4), and squid, where size determines personality. How exactly the behavioural changes take place in P. apterus is not know, but it may be due to hormonal reorganisation.
 

So perhaps my apparent grouchiness due to lack of food is just my inheritance...

References:

1. Gyuris et al., 2012. Animal Behaviour 84 pp. 103-109
2. Dall et al., 2004. Ecology letters 7 pp. 734-739
3. Rödel and Meyer 2011. Developmental Psychobiology 53 pp. 601-613
4. Niemelä at al., 2011. Functional Ecology 26 pp. 450-456
5. Sinn and Moltschaniwskyj, 2005. Journal of Comparative Psychology 119 pp. 99-110

A Mayfly in December

Mayfly

It has been a a mild winter here in Ireland, especially considering the arctic conditions of two and three years ago. It is therefore not unusual to see a few strange phenological events occurring, such as plants in full flower and moths on the wing. One of the oddest, yet most delightful that I have seen recently is most certainly an adult mayfly, on the wing, not eleven days ago some 17 km from Cork city. It was odd because, as the name suggests, mayflies tend to emerge around May. Yet the emergence period for some species can from March to October. Still, seeing one a little over a week from Christmas was a little peculiar.

This sighting is also of interest as it brings to mind the recently published Red List of Irish Ephemoptera (1), detailing a check-list of the Irish species and their conservation status. Ireland is home to 33 species of mayfly, quite a low number in comparison to that of mainland Europe (350 species, (2)). However, even this relatively low number of species contributes greatly to their associated aquatic habitats. Mayflies spend the majority of their life in nymphal form (in some cases up to three years), and the feeding of these nymphs contributes greatly to the cycling and availability of nutrients in aquatic habitats (3). Such feeding can also greatly contribute to the cleansing of water systems and help maintain their integrity. On emergence from the nymphal stage the mayfly, uniquely in the insect world, passes through two terrestrail adult stages: the winged subimago and the winged and sexually mature imago. The life of these two stages is quite short in comparison to the nymphs (little more than a couple of hours in some stages), but large scale, synchronous emergence of adults results in significant movement of nitrogen and phosphorus from aquatic to terrestrial environments (3).

Check-list of Irish Mayflies. Key: CR = Critically Endangered, EN = Endangered, VU = Vulnerable, NT = Near Threatened, lc = least concern dd = deficient data.

Species	Conservation Status
Siphlonurus armatus	CR
Baetis atrebatinus	EN
Ephemerella notata	EN
Rhithrogena germanica	VU
Procloeon bifidum	VU
Leptophlebia marginata	VU
Kageronia fuscogrisea	NT
Ameletus inopinatus	NT
Baetis fuscatus	dd
Alainites (Baetis) muticus	lc
Baetis rhodani	lc
Baetis scambus	lc
Baetis vernus	lc
Caenis horaria	lc
Caenis luctuosa	lc
Caenis macrura	lc
Caenis rivulorum	lc
Centroptilum luteolum	lc
Cloeon dipterum	lc
Cloeon simile	lc
Ecdyonurus dispar	lc
Ecdyonurus insignis	lc
Ecdyonurus torrentis	lc
Ecdyonurus venosus	lc
Electrogena lateralis	lc
Ephemera danica	lc
Heptagenia sulphurea	lc
Leptophlebia vespertina	lc
Paraleptophlebia cincta	lc
Rhithrogena semicolorata	lc
Serratella ignita	lc
Siphlonurus alternatus	lc
Siphlonurus lacustris	lc

In Ireland, six species of mayfly are listed as critically endangered, with two more near threatened (1). All of these species have restricted distributions and it is unfortunately unsurprising that they are classed as such. The are species found in streams and rivers, which points to the increased pressures of pollution that these habitats have had, and unfortunately continue to have (1).

References:

1. Kelly-Quinn and Regan, 2012. Ireland Red List No. 7: Mayflies (Ephemeroptera). National Parks and Wildlife Service, Department of Arts, Heritage and the Gaeltacht, Dublin, Ireland
2. Brittain, Michel Sartori, 2009. Encyclopedia of Insects pp. 328-334
3. Burian, 2009. Encyclopedia of Inland Waters pp. 299-314

A Winter-time Orange

Yellow Brain Fungus, Tremella mesenterica

Trees denuned of their leaves can make for many a forlorn vista at this time of the year, but they do provide the opportunity to spot some strange fruit indeed. Arboreal fungi that would otherwise remain obscured are quite visible among the bare branches. One of the most obvious is the shocking-orange coloured Yellow Brain Fungus (Tremella mesenterica). For all the world looking like somebodies discarded worryingly luminous bubblegum, T. mesenterica is (like all members of the Tremella genus) an obligate parasite of other fungi. In Ireland it is most commonly encountered on Gorse (Ulex spp.), where its host is most commonly found growing, fungi of the genus Peniophora. Indeed, T. mesenterica is often found growing on the upper part of a Gorse branch with the Peniophora species producing fruiting bodies on the underneath of the branch (1).

Yellow Brain Fungus, Tremella mesenterica

T. mensenterica's almost cartoonish colour belies an organism that has shown itself to have a number of surprising and useful applications. For example, fruiting bodies of the fungus fed to rats with diabetes have been shown to have a significant effect on the disorder (2). It also posses extracellular polysaccharides that have been shown to have immunomodulatory properties and thus may have potential in anti-tumor and anti-inflammatory treatments (3). Specifically, it has been shown to surpress the production of hormones (human chorionic gonadotropin) associated with tumor cells and therefore may have a role in the chemotherapeutic treatment of certain forms of cancer in the future (4).

References:

1. Roberts, 1995. Mycologist 9 pp. 110-114
2. Hui-Chen et al., 2006. Life Sciences 78 pp. 1957-1966
3. Nan-Yin et al., 2006. Food Chemistry 99 pp. 92-97
4. Yen-Wen et al., 2006. Life Sciences 79 pp. 584-590

The Holly and the Ivy... and the Ivy

The two leaf forms of ivy (Hedera helix), cordate (left) and palmate (right)

Its Christmas time, and all around the house... people have placed a variety of plants to add to create a festive spirit about. Poinsettias have become quite popular in this part of the world (and make a convenient, low risk present for neighbours), but the traditional Christmas trees and garlands of holly and ivy are still the most popular. All three of these now Christian traditions arose from older traditions (1): ivy (Hedera helix) in particular was considered a sybol of female fertility because of its late flowering period (September to November) and production of berries (around this time of the year) (2). Although it can be quite an invasive pest in some parts of the world, these two facts make it an important source of nectar and pollen for insects in late autumn/early winter and an equally important source of food for birds later in the year in its native range.

However, one of the most striking features of holly is that two distinct, different leaf shapes will be seen on the one plant - a five lobed, palmate form and a cordate form that shows little to no lobing. The lobed leaf is found on the climbing, juvenile stems of the plant, with the cordate form on the flowering stems. This is known as heteroblasty, a phenomenon that is found in many plant species, but that is most famously illustrated in ivy. It was first described by Karl Goebel in 1898, who noted that as plants grow they add new modules (stem with attached leaf) which show gradual changes of form in most cases (3). However in some species, such as ivy, the changes are more dramatic. The reasons for this are still unclear but defence against herbivory and nutrient and water supply differences have been suggested as causes (3). Indeed, Ivy has been shown to produce palmate leaves in low light conditions and cordate leaves in high light (4).
 

References:

1. Miles, 2008. Christmas in Ritual and Tradition, Christian and Pagan p. 275
2. Phillips, 1977. Wild Flowers of Britain p. 172
3. Zotz et al., 2011. Botannical Reviews 77 pp. 109–151
4. Rogler and Hackett, 1975. Physiologia Plantarum 34 pp. 141–147

Hiding Out With The Cuttlefish

Common Cuttlefish (Sepia officinalis)

The ability of cephalopods to vary their colour has been known since antiquity and while most species can achieve impressive colour changes, few can match the common cuttlefish (Sepia officinalis) for sheer dramatic quality. This is in part due to the size (1.5 mm in diameter) and density (50 per square mm) of the chromatophores (1), the neurally controlled colour bearing organs that can change the pigmentation and hence appearance of the animal with incredible detail. However in part it is, as the chromatophores are just one movement in the symphony that makes each animals body pattern.

Body pattern change is used in feeding feeding, avoiding predators and communication, and is therefore an integral part of S. officinalis life history. Its most striking aspect are the chromatophores, organs that are unique in the animal kingdom to cephalopods. Body pattern is controlled in a hierarchical fashion in S. officinalis: behaviour will dictate body pattern and hence organ response. Body pattern is constructed using four components, such as coloration of which chromatophores play a part. However, they are aided by organs such as leucophores which scatter light of all waveslengths and iridiphores, which produce interference colours when viewed from certain angles, often giving pink and iridescent greens and blues (1). The other three components are textural (the smoothness or papillation of the skin), postural (the orientation of the body parts) and locomotor (the action of the animal, e.g. resting, burying, scuttling, etc.). These components are themselves divided into units which are in turn divided into elements, such as the previously mentioned chromatophores. This complex hierarchy of organisation allows for the wide variety of body shapes observed in S. officinalis.
 

Such an intricate response mechanism is under tight control of the central nervous system and is driven by visual stimuli. Environmental cues taken in by the eye and transferred to the optic lobe where information is processed and transferred to the lateral basal lobe which will control motor response (1). Amazingly, these neural areas are already well developed upon hatching in S. officinalis and newly emerged cuttlefish are immediately able to conceal themselves from predators (2). They use strategies such as colour resemblence, disruptive coloration, obliterative shading, shadow elimination, disguise and adaptive behaviour to avoid becoming a meal from fish such as the Comber (Serranus cabrilla).
 

Human ability to distinguish symmetrical objects easily and quickly lead to the assumption that the use of these behaviours would be greatly enhanced by the use of asymmetrical patterns. However, it has been demonstrated that in cryptic behaviour, S. officinalis will exhibit a high degree of bilateral symmetry (3). This seems counter-intuitive: symmetrical objects would stick out much more obviously in a random, asymmetrical environment. Yet S. officinalis is notoriously difficult to spot in its native environment. This may be due to a number of factors (3). Predators of S. officinalis may not use symmetry as a visual clue. Also the orientation of the axis of symmetry is important, as unless the axis is horizontal or vertical, symmetry becomes less apparent to the viewer. Alternatively, symmetry may play a vital role in concealment. By highlighting a symmetrical pattern on its body, S. officinalis may be taking the emphasis off its own body shape, making it seem just an interesting but inedible artifact to its predators.

References:

1. Hanlon and Messenger, 1998. Cephalod Behaviour pp. 31-46
2. Langridge, 2006. Proceedings of the Royal Society Series B 273 pp. 959-967
3. Hanlon and J. B. Messenger, 1988. Philosophical Transactions of the Royal Society of London, Series B, Biological Sciences 320 pp. 437-487

Cuttlefish picture taken at Galway Atlantiquaria, Salthill, Co. Galway.

First Irish Record for the Southern Oak Bush Cricket

Ireland is home to 12 species of breeding orthopterans (grasshoppers and crickets), with five of these being classed as crickets or bush crickets (1). It is only in the last thirty five years that three of these have been recorded, with Pholidoptera griseoaptera, the Dark Bush Cricket, being first recorded as 1983 (2). This trend may be due to the lack of attention that Irish orthopterans have been paid in the past, or may be a phenomenon that has been seen in European dragonflies, that of the spread of certain species from the center of mainland Europe to its peripheries.

Female Southern Oak Bush Cricket, Meconema meridionale

This is most evident in the case of the Southern Oak Bush Cricket, Meconema meridionale. This species was thought to be an exclusively Southern European species, but has extended its range and during the 1990's was to be found in France, Holland and Belgium (3). In 2001 it had reached Britain (4), being discovered in three localities in England from where it has steadily spread. This introduction was though to have been via imported horticultural material and given the strong trade links between Britain and Ireland it is assumed it can only be a short time before M. meridionale reaches Irish shores. And so it has proved to be. On the 9th of November last, I spotted a female adult M. meridionale on a limestone pillar at the entrance to a building on the Western Road in Cork city. The weather at that point had been unseasonably warm and when I first saw it I assumed it was the closely related (and Irish native) the Oak Bush Cricket (Meconema thallasinium), a species often seen close to houses and other buildings. However this individual was lacking in the distinctive long, green wings associated with M. thallasinium and was in fact brachypterous (having abnormally small wings). This is the distinguishing feature of the otherwise almost identical M. meridionale. This may be an errant traveling individual, but the species recent range expansion points to the discovery of a breeding population in Ireland being a very distinct possibility in the not too distant future.

References:

1. Haes and Harding, 1997. Atlas of grasshoppers, crickets and allied insects in Britain and Ireland
2. O'Connor and O'Connor, 1985. Entomologists' Gazette 36 pp. 229-232
   Maclean, 2010. Silent Summer: The State of Wildlife in Britain and Ireland p. 533
   Hawkins, 2001. British Journal of Entomology and Natural History 14 pp. 207-213

Hold On

Common Limpet, Patella vulgata

Probably the most familiar intertidal organism on western European coastlines is the Common Limpet, Patella vulgata. Its conical shell can often be seen in enormous numbers on rocky shore of all degrees of wave action, and numbers are maintained by the relatively long life of certain individuals. Where conditions promote slow growth, some individuals can live up to 17 years of age (1). For a sedate looking animal, often encountered encrusted with algae and barnacles, they are voracious feeders. Although they have been reported to consume a wide variety of micororganisms (2), algae of the intertidal zone is the food of choice. And what a choice; P. vulagata feeds a plethora of different species, including Fucus spp., Ulva spp. and red encrusting algae (1). This is all facilitated by the iron and silica hardened teeth on the radula, which rasp the algae with incredible efficiency. In situations where P. vulagata have been artificially removed form shorelines, Ulva spp. have quickly covered the rocks.

Common Limpet Home Scar

A rocky shore is not for the faint of heart, with waves action dislodging anything not firmly attaced to its surface. Organisms need to be firmly attached to the rock, and P. vulgata is truly a master at this. Depending on where the animal is to be found on the rock face, the shell height will vary. Those at high shore levels have tall shells with a small shell length, while individuals at a low shore levels have shorter but longer shells, which keeps them closer to the rock (1). P. vulgata attaches to their substrate by using a combination of suction and glue like adhesion (3). The specific mode of attachment is dependant on their location at the time. At high tide, when P. vulgata is at its most active feeding, suction is employed. This involves decreasing the pressure under the foot of the animal which forms a tight seal with the substrate. At low tide, when foraging does not occur due to the increase risk of predation, P. vulgata employs a glue-like secretion from its foot which creates a seal that is stronger than that created by suction, however it is more permanent and does not allow movement for foraging. At rest, P. vulgata also employs a home scar, a depression created in the substrate by chemical action and abrasion by the shell of the animal. This is returned to after each foraging excursion as it increases the adhesion power significantly (4).

References:

1. Fish and Fish, 2011. A Student's Guide to the Seashore pp. 205-206
2. Jenkins and Hartnol, 2001. Journal of Experimental Marine Biology and Ecology 30 pp. 123-139
3. Smith, 1992. Journal of Experimental Marine Biology and Ecology 1600 pp. 205-220
4. Smith, 1991. Journal of Experimental Biology 161 pp. 151-169