Water Transport in Cicidella viridis

Female Cicidella viridis

While many leafhoppers are rather drab in appearance, there are some that aim to dazzle. One of the most colouful found in Ireland is Cicidella viridis. Its yellow head and yellow and green protonum give way to strking wings, a wonderful turquoise in females, but a lot darker (often a blue-purple) in males. They feed on a variety of grasses, sedges and rushes by by inserting two pairs of feeding stylets (modified mandibles and maxillae) into the host plant tissue, injecting saliva, and ingesting fluid (1). This feeding method, common to all Auchenorrhyncha (Cicadas, Spittlebugs, Leafhoppers, Treehoppers, and Planthoppers) presents a particular problem. When sap is ingested, a large volume of excess water is also taken in, which presents a raft of osmotic issues. C. viridis posses an organ called a filter chamber to combat this problem. This rapidly transfers excess water from the initial midgut to the terminal midgut down a transepithelial osmotic gradient (2). The membrane of the filter chamber is composed of a protein known as P25, a member of a family of protieins (MIP) that are permeated by water but not any associated solutes.

References:

1. Dietrich, 2009 in Encyclopedia of Insects (Second Edition) pp. 56-64
2. Beuron et al., 1995. The Journal of Biological Chemistry 270 pp. 17414-17422

Spot the Moth

Six Spotted Burnet, Zygaena filipendulae

One of the most attractive moths to be seen in Ireland, the Six Spotted Burnet (Zygaena filipendulae) is currently on the wing. Flying during the day, this moth has a lazy, almost awkward pattern of flying. The adult wings are a dark, metallic green and spotted with the most delightful deep-red spots, six on each forewing. These six spots distinguish it from its close relative the Narrow Bordered Five Spotted Burnet (Z. lonicerae). The adults feed on flowers of knapweed and scabious plants, with the larvae feeding on birdsfoot trefoil (Lotus corniculatus). The larvae derive a level of protection from their host plant, sequestering the cyanogenic glucosides linamarin and lotaustralin (1). These act as defence compounds against preadtors. These cyanogenic glucosides are integral to Z. filipendulae's life cycle and larvae fed wildtype L. corniculatus  showed faster development times than those fed transgenic, acyanogenic plants. Larvae are also capable of de novo synthesis of the cyanogenic glucosides and adult male Z. filipendulae transfer a nuptial gift of the compunds to females during mating, with females showing a preference for males with higher cyanogenic glucosides levels (2).

Six Spotted Burnet, Zygaena filipendulae feeding on Knapweed

References:

1. Zagrobelny et al., 2007. Insect Biochemistry and Molecular Biology 37 pp. 10–18
2. Zagrobelny et al., 2007. Insect Biochemistry and Molecular Biology 37 pp. 1189–1197

Urban Gem

Greater Quaking-grass, Briza maxima

Plant species that are considered scarce are generally found in places with little disturbance and, by association, little human interference. This is not always the case though. Take for example Greater Quaking-grass (Briza maxima). This attractive plant, with its large, pendulous spikelets, is present in few Irish sites (1). Yet one of these is smack bang in the centre of a major Irish city. As the river Lee makes its way through the city of Cork, some of its quaysides are lined with old wharf timers, used in former times for unloading produce from merchant ships. Surprisingly, on some of these timbers at Union Quay and Morrison Quay, B. maxima proliferates from April to May. The specimen pictured was just observed in all its quaking glory just steps from Trinity foot bridge.

Greater Quaking-grass, Briza maxima

References:

1. O'Mahony, 2009. Wildflowers of Cork City and County p. 29

Larvae Fit for a Fight

Arge gracilicornis

While many sawflies display bold, showy colours on their abdomens, there are also quite a few that are more demure. Take Arge gracilicornis, a rose sawfly. In colour and appearance it resembles a fly, with its dark body and dusky wings. In common with other Arge spp. it also has quite reduced antennae which add to its fly like appearance. In its larval form, however, it is a different story. It has a translucent green body, dotted with vibrant yellow and black spots. A. gracilicornis larvae feed on the edges of rose and related plant leaves, leaving them quite exposed to predation by birds and a range of invertebrates. The spots along the body may act as a warning to predators: it has been shown that starlings (Sturnus vulgaris) avoid feeding on the larvae (1). The body of the larvae are also lined with bristles making them unpalatable. More impressively though, A. gracilicornis larvae, along with other Arge spp. larvae, produce antifeedent chemicals. Ants that bit Arge spp. larvae showed a pronounced lack of co-ordination (2). Extracts from the gut of larvae also exhibited a paralysing effect.

References:

1. Boevé and Müller, 2005. Chemoecology 15 pp. 51–58.
2. Petre et al., 2007. Journal of Insect Physiology 53 pp. 668–675

"We Seek Him Here..."

Scarlet Pimpernel, Anagallis arvensis

The Scarlet Pimpernel (Anagallis arvensis) is a common annual of roadsides, cultivated land and dunes, and is most famous for its delicate scarlet flowers (1). These are at the end of straggling stems that are often up to 25 cm in length. The flowers open in the morning and close at mid afternoon, lending it the alternate common name of “Shepherd's Weatherglass”. The plant is a source of a diverse number of natural compounds, with 14 flavanoids, 3 anthocyanins (2), oleanane triterpenes, saponins, flavones and cucurbitacins (3) to name but a few, isolated to date. One of the triterpene saponins isolated from A. arvensis has even been shown to have antiviral activity against the herpes simplex virus and poliovirus (4), proving it to be a useful plant indeed.

Scarlet Pimpernel, Anagallis arvensis with flower closed

References:

1. Phillips, 1977. Wildflowers of Britain p. 46
2. Kawashty et al., 1998. Biochemical Systematics and Ecology 26 663-668
3. Yamada et al., 1978. Phytochemistry 17 p. 1798
4. Amoros et al., 1987. Antiviral Research, 8 pp. 13-25

To Live Among Nettles

There's no two ways about it, stinging nettles (Urtica dioica) hurt. Their leaves and stems (which is pretty mush all of them) are lined with time hairs that act as hypodermic needles, injecting a cocktail of chemicals into whatever brushes off them. This induces the stinging sensation associated with them. This would seem to make them unsocial organisms in our eyes, repelling all comers. Yet this is not the case, with many animals readily living with, and even on, U. doica. Take the mirid bug pictured, Grypocoris stysi.

Grypocoris stysi

It can regularly be observed amking its way through the leaves of nettle plants feeding on aphids and the flower heads, impervious to the hairs which, due to the bug's size (c. 6 mm), are easily avoided.

A Darkling Beetle, Lagria hirta

Lagria hirta

A conspicuous little beetle, with an abdomen that looks all the world like a miniature kiwi fruit, Lagria hirta is most commonly found in sandy places in Ireland, but can be found throughout the country. While the larvae eat detritus, the adults can be found feeding on a variety of flowers such as umbellifers and Compositae (1). L. hirta has a univoltine life cycle, that is it produces just one brood per year. Adults are present for only a short time in summer, whereas the larval stage extends from autumn to spring (2). This adherence to univoltism has been shown to be due in part to larval diapause (or dormancy) (3). It was shown under laboratory conditions that larvae did not pupate if kept at constant temperature. Pupation was only achieved if larvae were reared at 15-20°C, followed by a three moth chilling period of 5°C.

Lagria hirta

References:

1. Joy, 1932,  A practical handbook of British beetles
2. Zhou, 2001. Environmental Entomology 30 pp. 686-691(6)
3. Zzhou and Topp, 2000. Entomologia Experimentalis et Applicata 94 pp. 201–210