Possible Legacy of Winter

With many trees showing full green coats, its becoming more difficult to remember the intense cold of last winter. Yet the scars can still be seen, be it gaping potholes in the tarmac of roads or the desolation of the Cordyline trees in many gardens (1). Worries of a lack of salt for the roads seem a little quaint now, as the warm days bring forth multitudes of insects. However as flowers seem to pop up overnight, the prospect of future cold winters may indirectly influence their future populations. Over 100,000 tonnes of salt were used on Irish roads during the 2010-'11 winter (2), making verges more suitable for plants usually associated with coastal habitats, plants better able to cope with high saline conditions. This is common throughout America and Europe and was first noted in 1982 in England (3), with the coastal plant common scurvy grass (Cochlearia offininalis) being added to a list of roadside plants for the first time.

Common Scurvy Grass, Cochlearia officinalis

C. officinalis should actually be seen as a species complex rather than a distinct, single species, with a number of different cytotypes present, each with a number of ecological distributions (4, 5). Interestingly, C. officinalis originated as a derivative of C. pyrenaica, and the origins of many Cochlearia spp. are as a result of changes in ploidy levels (6), demonstrating the role that polyploidisation plays in the evolution of new species.

References:

1. http://www.irishtimes.com/newspaper/magazine/2011/0409/1224293914850.html
2. http://www.irishtimes.com/newspaper/ireland/2010/1216/1224285654909.html
3. Scott and Davison, 1982. Watsonia 14 pp. 41-52
4. Erikson and Nordal, 1989. Ecography 12 pp. 31-38
5. Pegtel, 1999. Plant Species Biology 14 pp. 201-215
6. Koch et al., 1998. Botanica Acta 111 pp. 411-425

The Importance of Being Smelly

Scents plays very important roles in the life of a moth. Recognising food is one. Some moths can distinguish individual scents that indicate food rewards from cocktails of more than sixty floral scents (1), and the hawkmoth Manduca sexta will not feed on a flower when the appropriate scent has been removed, even if the visual floral signal is still present and correct (2).

Angle Shades Moth, Phlogophora meticulosa

Of possibly more pressing concern however is the role scents play in mating of moths. Take the Angle Shades moth (Phlogophora meticulosa) for example. This noctuid moth is commonly seen in Ireland from May to October and is easily recognisible by the ragged margin of its forewing, with a leading edge rolled in at rest (3). The olive green to brown wings show pinkish triangular marks. Mating for the Angle Shades takes place at dawn, when the males remain at rest until the females expose their scent organs to release pheremones (4). The male then flies around the female, dousing her with burst of his own pheremones which seem to act jointly as an arrestant, preventing her from flying away, and an aphrodesiac, to persuade her to accept him as a mate (5). The pheremones in males are released from structures that are known as hair pencils. Scent plays such a vital role in P. meticulosa mating that removal of these results in an inability of males to mate (6).

Angle Shades Moth, Phlogophora meticulosa

References:

1. Riffell et al. 2009, Proceedings of the National Academy of Sciences of the USA 106 pp. 19219-19226
2. Raguso and Willis 2002, Animal Behaviour 64 pp. 685-695
3. Sterry 2004, Collins Complete Guide to Irish Wildlife p. 116
4. Burton and Burton, 2002 The International Wildlife Encyclopedia p. 1822
5. Preton-Mafham and Preston-Mafham 1993 The Encyclopedia of INvertebrate Behaviousr p. 105
6. Birch et al. Annual Review of Entomology 1990 35 pp. 25-58

Update on the Red Lily Beetle: Infestation

An update on the Red Lily Beetle (Liloceris lilii) previously reported on in this blog. I sighted the beetle again in the same garden as before. However this time there was a veritable infestation. I removed 12 individuals alone from one lily plant. Many were engaged in mating, which is to be expected from them at this time of year. Below are examples of the beetles on the lily in question, and the damage done to the plant.

In Memory of Slugs

Yellow Garden Slug, Limax flavus

Why do slugs attack seedlings? For food, certainly, but why every year do gardeners and farmers have to spend millions on controlling their attacks on emerging crops? Take the Yellow Garden Slug, Limax flavus. This large yellowish slug with a mottled olive-brown body is found throughout Europe, as well as an introduction in America and Australia (1). Interestingly, it produces a lectin (LFA) that has been shown to disrupt neurotoxins produced by Clostridium botulinum and C. tetani (2). It feeds voraciously on seedlings and vegetables, often causing significant damage to root crops such as carrots and potatoes (3). Does L. flavus remember the specific food stuff that it likes, or does it use a trial and error feeding habit?

Yellow Garden Slug, Limax flavus

Well it seems that it has a very good memory indeed. L. flavus is attracted to smells and the range of it memory was demonstrated when the slug was conditioned to avoid carrots, a favoured food (4). This was achieved by presentation of carrot juice along with the bitter tasting quinidine sulfate. Retrograde amnesia of this event was achievable by cooling the slug, after which it continued to feed as normal. However a few days after conditioning, retrograde amnesia could not be induced by cooling. This showed that L. flavus has three memory states: short term, which is followed by long term-cooling sensitive, which is in turn followed by long term-cooling insensitive. Further investigation showed that reactivation of memory in L. flavus altered the memory state from cooling insensitive to cooling sensitive (5). These discoveries compare well with those found in other animals, showing that L. flavus remembers very much as we do.

References:

1. Sterry 2004, Collins Complete Guide to Irish Wildlife p. 156
2. Bakry et al. 1991, Journal of Pharmacology and Experimental Therapeutics 258 pp. 830-836
3. Davidson 1976, Oecologia 26 pp. 267-273
4. Yamada et al. 1992, The Journal of Neuroscience 12 pp. 729-735
5. Sekiguchi et al. 1997, Learning and Memory 4 pp. 356-364

Sooty Leaves

Sooty Mould on an Ivy (Hedra helix) Leaf

Staying clean for a plant is important. Dirt, be it biological or the plain old dust variety, covering leaves can lead to a reduction in the levels of photosynthesis in a plant (1). The slippery, waxy cuticle of plant leaves should stop any particles from sticking and accumulating, however often a sooty deposit can be observed on certain plants. This is a sooty mould (any of a variety of Ascomycete fungi) that has begun to colonise the plant leaf. Often this is just a cosmetic problem, however in extreme cases inhibition of photosynthetic activity can lead to a reduction in the size of new fruits, shoots and leaves. Respiration may also be affected by the physical closure of stomata by the fungus' vegetative growth. Inspection of the leaves soon reveals that the mould easily flakes away with just the slightest abrasion. So how does it stick in the first place?
 

A Variety of Scale Insects on the underside of an Ivy Leaf

The answer lies with a superfamily of bugs, the Coccoidea, commonly known as scale insects. Coccoids are highly specialised insects, with a high number of morphological adaptations to allow them to feed which makes them an economically important pest of many crops (e.g. the cotton cusion scale, Icerya purchasi (2)). Sexual dimorphism is very pronounced, with ephemeral, winged adult males lacking developed mouth parts and large, sedentary females (3). It is the female form that is most commonly seen, and encounters with them, often seen underneath leaves, immediately explain the origin of their common name, scale insects. They are covered with a scale or waxy material that protects them as they feed on plant sap. Appendages are very mush reduced in the females, especially legs which combined with the coverings reduces mobility (3). One of the problems with the reduction of mobility is the build up of honey-dew waste. Coccoids have evolved a number of anal adaptations to counteract this, such as the ability to create droplets or expel the honey-dew by squirting it off, often a considerable distance for what are generally small insects. While ants will collect the honey-dew from some species, it often ends up covering surrounding plants parts. It is this sticky covering that allows sooty mould to establish and proliferate.

A Variety of Scale Insects on the underside of an Ivy Leaf

As stated previously, this is often just a cosmetic problem. However in a garden situation it is cosmetic problems that are often the most vexing – problems that I have seen most recently in Camelia bushes. Control of Coccoids in such situations is tricky. Pesticides may often be ineffective against established females, but will control juveniles. The females may be suffocated using oils. Once the insects are controlled however, the sooty moulds are easily removed using water sprayed on the leaves (1).

References:

1. Nameth et al., Ohio State University Extension Factsheet "Sooty molds on trees and shrubs" HYG-3046-96
2. Miller et al., 2005. Proceedings of the Entomological Society of Washington 107 pp. 123-158
3. Gullan and Krosztarab, 1997. Annual Review of Entomology 42 pp. 23-50

Cherry Blossoms Are About To Fall

Cherry Tree (Prunus serralatum) on Pearse Road

I have made up my mind to post this blog entry today because I feel it necessary for anyone reading this, not having to wait until the following year if the cherry blossoms falling on Pearse Road in Ballyphehane, Cork are missed. This road connects the Kinsale Road directly with the Lough, is lined with cherry trees (Prunus serrulata) and Corkonians are very proud of these sakura indeed. So permit me now to treat of this subject in depth.

Look to the sky and watch the blossom fall

Not for as long as I can remember but for as long as I care to recall, the cherry trees on Pearse road were shown to me from the car window. We would pass this way when going to the Lough to look at the swans or when travelling the back roads to UCC. As I grew older I realised that the blossoms did not last that long at all and the trees themselves bore fruit that resembled nothing like the glazed cherries I was already familiar with whilst baking my queen cakes. (I do not bake them anymore). These cherries are from a different species Prunus avium - the wild cherry. Still, it is not the lack of recognizable fruit of which I write but of the shortness of the life of the blossom.

From the 5th century AD, the flowering cherry blossom (Sakura) has been held in high esteem by the Japanese Emperor and his court. The Japanese associate the transient beauty of the blossom with that of a human life itself. (1)

Yo no naka wa

Mikka minu ma ni

Sakura kana

[Life is short, like the three day

glory of the cherry blossom](2)



CGRMV (Cherry green ring mottle virus) is a known infection found in Prunus serrulata and other Prunus species including P. cerasus (sour cherry), P. persica (peach), P. armeniaca (apricot) and P. avium (sweet cherry) and occurs in fruit growing regions of North America, Europe, New Zealand, Japan and Africa. Up to recently, the only method of detection of this virus was through a grafting assay which would express the viral symptoms in 'Kwanzan' cherry, a woody indicator. Li and Mock show that their plate trapping RT-PCR (Reverse Transcriptase Polymerase Chain Reaction) technique is a reliable, quick and cheap method of detection of the virus over the grafting assay. (3)

Returning to today let me urge you all to turn your velleity to resolve, cast aside all solicitudes and take a trip down to Pearse Road and watch the cherry blossoms fall. The whole affair is short-lived but beautiful.

Later,

Ken.

1. Jefferson and Fusonie, 1977, The Japanese flowering cherry trees of Washington, D.C.: a living symbol of friendship pp.1-2 [http://naldr.nal.usda.gov/NALWeb/Agricola_Link.asp?Accession=CAT78696066] Retrieved 2011-4-20
2. Masso Yoshikawa, Romance of Japanese Cherry Blossoms Closely Related to Philosophy of Life, Washington Sunday Star, April 18, 1926, ed.
3. Li and Mock, 2005, Journal of Virological Methods 129 pp. 162-169

Mr. T (Moth)

Emmelina monodactyla

Plume Moths, the Pterophoridae, have always seemed to me terribly exotic animals, their T-shaped wings putting me in mind of some stick insects from the deepest jungle. Their shape comes from the narrow forewings which are held perpendicular to the body with the hindwings tucked under or folded within the forewings. The wings are often divided into lobes (or plumes, hence the common name) with long fringe scales accentuating the feather-like appearance (1). Ireland is home to 22 species of Pterophoridae (2), of which easily the most common is Emmelina monodactyla. This mottled brown species is found in many regions through out the globe and has proved itself to be a useful biological control agent against the Field Bindweed, Convolvulus arvensis (3). The larvae of E. monodactyla feed on the plant leaves, causing extensive defoliation of this troublesome agricultural pest.

References:

1. Capinera, 2008. Encyclopedia of Entymology p. 2953
2. Ferriss et al. 2009, Irish Biodiversity: A Taxonomic Inventory of Fauna p. 106
3. Toth and Cagan, 2005. Biocontrol News and Information 26 pp. 17N – 40N

Smells Like Pollination

Arum maculatum

 April, and as the days get warmer, plants and animals are shaking off the last of the lethargy of winter. As insects become more populous, plants vie for their attention to be pollinated. Timing for this is often essential, as can be seen in the case of the Lords and Ladies (or Cuckoo's Pint, Arum maculatum).This perennial plant emerges from underground tubers in late winter/early spring in shaded woodlands and hedgerows, with striking pale green flowers arriving in April to May (1). In a study of four populations of the plant over five years in Northampton found that plants flowering during late and early periods were more likely to have less fruit than those flowering during peak time (2). Indeed, the seeds for peak flowering plants were significantly heavier than those from other times. Pollination of A. maculatum is achieved principally by the psychodid midge or moth fly Psychoda phalaenoides which is attracted to the flowering plant by a cocktail of volatiles emitted from the spadix appendix and the spathe chamber (3). The attracted P. phalaenoides becomes trapped by the the flower and is released a short time later. During this time pollination is achieved.

Psychodid midge

Interestingly the volatiles emitted by the flower to attract its pollinator, specifically p-cresol, ingenuously mimic those of cow dung, the microhabitat for P. phalaenoides. This duping of the insect is of obvious advantage to the plant but is not mutualistic. The insect receives no food for its interaction and indeed has wasted a considerable part of its short life (4).

References:

1. Phillips, 1978. Wildflowers of Britain and Ireland
2. Ollerton and Diaz, 1999. Oecologia 119 pp. 340-348
3. Kite, 1995. Biochemical Systematics and Ecology 23 pp. 343-354
4. Urru, 2011. Phytochemistry, Article in Press