Fever pitch

By Jane Canaway

Published in OUTthere Magazine, the official inflight publication for REX (inc.Air-Link), SkywestAirNorth, and Pel-Air

A Broome biplane, by Sarah Narkiewicz

As the wet season progresses and the thunderheads disappear, the sky over Broome is instead filled with growing clouds of gossamer wings, some gold, some black, or glittering in metallic shades of red, blue and bronze.

With the approaching dry season, dragonfly numbers explode across the Kimberley as the water-borne larvae climb out of their swamps and burst from their skins as adults. Suddenly the town seems invaded by battalions of miniature biplanes fighting their own private battles in the humid tropical air as they defend their territory, search for a mate, and hunt down airborne prey.

The dragonflies are harmless to humans but, unless you share their flying skills and appetite, watch out for the mosquitoes that make up the bulk of the dragonfly’s meals, in case you become mossie fodder yourself.

While the cool south-easterly winds are always associated with increased mosquitoes – and the ripening of the Grey Mangrove fruit was a signal for Aboriginal tribes to shift camp to the beaches to escape their bites – this year the mossie invasion brings with it an extra sting: The WA Department of Health’s surveillance program has detected widespread activity of Murray Valley encephalitis (MVE) virus and Kunjin virus, as well as less-severe Ross River Virus and Barmah Forest Virus disease.

Department of Health Medical Entomologist Sue Harrington said recent rainfall and flooding in the northern half of the state had resulted in large numbers of mosquitoes that could be carrying these viruses.

While the risk of infection is low, the symptoms are severe.

“Initial symptoms of MVE include fever, drowsiness, headache, stiff neck, nausea and dizziness, and people experiencing these symptoms should seek medical advice quickly. In severe cases, people may experience fits, lapse into a coma, and may be left with permanent brain damage or die,” she said.

Kunjin virus fever is usually less severe but with similar symptoms.

“In young children, fever might be the only early sign, so parents should see their doctor if concerned, particularly if their child experiences drowsiness, floppiness, irritability, poor feeding, or general distress.”

Many cases of Ross River Virus disease have been notified in people from the Kimberley and Pilbara regions, and cases of Barmah Forest Virus disease are also being notified from the Midwest region. The illnesses caused by these viruses are similar, with symptoms including painful joints, aching muscles, lethargy, fever, headache and skin rashes, and symptoms may last from days to months.

“There are no specific cures or vaccines for any of these mosquito-borne diseases so it is very important that people take care to prevent being bitten by mosquitoes,” said Ms Harrington.

For humans, the best defence is to avoid being bitten, by staying the safe side of a fly screen at dusk and dawn, wearing long, loose-fitting clothes and using protective lotions and gels.

Diplacodes haematodes by Jan Taylor

Luckily for us, the delicate-looking dragonfly, which appears so fragile and decorative, is actually a fierce killing machine doing its best to reduce the mosquito population.

Dragonflies lay their eggs on or around water, and these hatch into larva or nymphs that live in the water.

“They’re quite active with six legs,” describes Kimberly-based AQIS entomologist Luke Halling. “They actually have really impressive mouth parts – they’ll eat mosquito larvae and larger things; they’ll eat tadpoles and even small fish if they can.”

Some larvae moult up to 15 times before emerging as an adult and, unlike most other insects, there is no pupal stage; they simply climb out of the water, attach themselves to a plant, and burst out of their skins as fully formed adults. This transition from larva to adult is known as incomplete metamorphosis.

At least two months is needed for eggs to reach adulthood, but some larva may spend more than a year underwater before emerging. The adult stage is usually the shortest in the life-cycle and rarely lasts for more than a few weeks.

However in that short time they are awesome hunting machines, catching insect prey in the ‘net’ of their forward-facing front legs and displaying incredible flying skills, made possible by their four unconnected wings that move independently, allowing them to change direction in a split second.

The bad news is that even a sky-full of Kimberley dragonflies cannot wipe out the huge numbers of mosquitoes – especially after this year’s long wet season – but imagine how much worse the mossies would be without them.

Hemianax papuensis by Russell Best

Dragonfly facts

  • Dragonflies have existed on earth for about 250 million years – that means they were around long before dinosaurs left footprints at Gantheaume Point.
  • Prehistoric dragonflies were huge, the largest flying insects ever, with wingspans of 70-75cm.
  • One reason dragonflies have survived for so long is their excellent hunting skills; they can hover, move in zigzags and even fly backwards.
  • Some dragonflies can reach speeds of 70km per hour.
  • Of the 6,000 species of dragonflies, 324 are found in Australia.
  • The biggest living dragonfly is found in Central American (about 19cm) but Australia boasts the bulkiest dragonfly, the Giant Petaltail from Queensland (Petalura ingentissima), with a wingspan (in females) of about 16 cm.
  • Perhaps the smallest Dragonfly is the Scarlet Dwarf (Nannophya pygmaea) from Malaysia and Japan. It is 15mm long with a wingspan of about 20mm.
  • Dragonflies may challenge the Wanderer butterfly for the longest migratory pattern of any insect, with one species thought to travel 18,000km between India and Africa on monsoonal winds.

How to avoid mosquito bites

  • Avoid outdoor exposure from dusk and at night.
  • Wear protective (long, loose-fitting) clothing outdoors.
  • Use a personal repellent containing diethyl toluamide (DEET) or picaridin. Lotions or gels are best. Most natural or organic repellents are not as effective.
  • Ensure insect screens are installed and completely mosquito-proof.
  • Use mosquito nets and mosquito-proof tents.
  • Ensure infants and children are adequately protected against mosquito bites, with suitable clothing, bed nets or other forms of insect screening.

Dragonflies and Damselflies

Both belong to the order of insects known as Odonata. As a rule, dragonflies are larger than damselflies, but there are five main points of difference:

  • Dragonflies are in the sub-order Anisoptera (meaning “unequal-winged”) and the hind wings are usually shorter and broader than the forewings. Damselflies are insects in the sub-order Zygoptera (meaning “paired-wings”) and all four wings are roughly equal in size and shape.
  • Dragonflies are usually large, strongly flying insects often found well away from water; damselflies are usually small, weakly flying insects that stay close to the water.
  • When at rest, dragonflies hold their wings out from the body, often at right angles to it. Most damselflies hold their wings along their bodies.
  • Dragonflies eyes are large and usually touch. Damselfly eyes never touch.
  • Damselfly larvae have external plates at the end of the abdomen that act as accessory gills; dragonflies do not.

Source: www.british-dragonflies.org.uk

 

Wine, wildflowers and wallabies

By Jane Canaway

First published in Your Garden, Autumn 2012

Sue and Sean Delaney tasting wine at Sinclair's Gully

It was a year or two after bringing in professionals to manage their vineyard that Sean and Sue Delaney noticed all the insect and aquatic life around their dam had disappeared.

“We realized all the herbicides, pesticides and fungicides the contractors were using was running off to the holding dam and killing everything off,” Sean explains.

“We thought ‘this is ridiculous’ – we’re living at the bottom of hill with this run-off heading to our house with young children and we could see the damage water-soluble sprays were doing; biodynamics was a way to find alternative method to break our reliance on chemicals.”

At this stage you may be thinking: ‘biodynamics – yes, heard of that – Rudolf Steiner’s take on organic farming, isn’t it?’ and, yes, that’s part of the story.

But biodynamics also requires planting, cultivating and harvesting according to the lunar calendar, as well as more spiritual aspects that critics have compared to alchemy and magic – such as creating compost improver from ‘Oak bark fermented in the skull of a domestic animal’, fermenting dandelions in a cow’s stomach for another preparation, stirring spray solutions in alternative directions for an hour to energise the mix, and burying a cow’s horn to improve the soil’s condition.

Such unorthodox methods might raise eyebrows in a Nimbin commune, so what was the appeal for city professionals with accounting and engineering backgrounds?

From skeptic to accept-nik

“As an engineer I was very skeptical,” agrees Sean. “But I thought ‘if it works I’ll try it and if it doesn’t I won’t’. And, you know, a lot of it works.”

Sean quotes pruning as an example.

“When you’re pruning, you’re cutting 70-80% of the plant away, creating large wounds and increasing the chance of disease; in biodynamic culture you wait until the sap is moving up into the plant so when you cut the plant the wound will be wet – if you cut at a different part of the cycle when the sap is going down, you could pull disease into plant.

“So I tried it and cut the plant when the lunar calendar says it’s good to prune and [the wound] was dripping like a tap. I tried again four or five days later and it was dry. I did it a few times with different plants and it was always the same.

“As engineer I needed to know how things work but as I’ve got older I’ve had to accept that I don’t have to understand it if it works. I don’t believe in all that life force stuff but I think there’s a lot of stuff we don’t know about soil and growth so it will probably be explained one day.”

Because biodynamic methods aim to improve the soil health, and soil plays such a key role in determining a wine’s taste, biodynamic principals are being adopted by a growing number of wine makers who believe it improves their end product.

“I can’t put my heart on my hand and say it’s a better, healthier product but the methodology of making them is healthier,” Sean says. “Others who have gone down this path do it because they say it expresses the terroir and sense of place better in their wine; I can’t guarantee that – it may well but we do it because we live at the bottom of hill below a vineyard.”

Filling a gap in the forest

The Delaneys’ winery is the Adelaide Hills’ only cellar door in the area to be “climate action innovator and advanced eco-certified” and their business model has won a slew of tourism and environmental awards.

Sean and Sue are also happy with the Sauvignon Blanc and Chardonnay their vines are producing and their sparkling wine has been ranked an impressive 93 in the prestigious James Halliday rankings. However farming was not even on the radar when they bought their 10.5-hectare patch of bush in 1997.

“We had no horticultural or agriculture background at all, but we had been looking for a project we could work on together and we fell in love with the property,” Sean says.

Wildflower walks through the Candlebark Woodlands are nearly as popular as the Sinclair's Gully wines

The land is home to a miraculously well-preserved stand of Candlebark woodland – an endangered ecosystem that has the highest conservation rating in the Mt Lofty Ranges.

“But the trees had been cleared from the top 5 acres – it was too big to revegetate and in ’96-’97 there were good tax incentives for primary production. Soil samples suggested it would be a good site for cool-climate grapes or olives – well, olives were a weed species that we were pulling out on the other side of hill, so we looked at grapes.

“If the land hadn’t been cleared we wouldn’t have had a vineyard, so it is just through serendipity that the property has been able to provide us with an income.”

Seedbank is biggest asset – and biggest threat

Aware of their land’s value in terms of habitat and biodiversity, the Delaneys have put huge amounts of time, money and passion into restoring its natural balance.

“Only 2% of remnant vegetation remains intact in South Australia,” Sean explains. “A lot of Candlebark woodland has been grazed, so you get the beautiful white trees and no understorey; our property has about 150 plant species and supports 66 birds,” he says.

However the Delaneys’ block was still under threat from weeds.

“Our biggest asset is the native seed still in the soil – it can stay viable for many decades – but our biggest liability is the weed seed that is also in the soil,” Sean says.

Their solution was to use “strip burning” techniques; burning off to sterilize the soil and create light and space to encourage seeds to germinate.

“The main weed species like broom and gorse emerge first but we can use a selective herbicide to knock that out and then the second flush is native seed.”

Some 600,000 plants have also been planted on the property and, through local Landcare group, Sue has recently won a grant to establish a biolink between Morialta to Coralinga parks, covering 260 hectares on 19 adjoining properties – an essential feature in a landscape where fragmentation is one of the greatest risks to remnant vegetation.

To complete the sustainable picture, the business has a policy of zero waste policy (“you buy differently and do a hell of a lot of washing up,” says Sean), all water is harvested and reused on the property and, to attract beneficial insects and increase biodiversity, native grasses are being replanted between the vines.

Good karma

As if repaying them, nature is rewarding their efforts.

Guided wildflower walks, live music events and the kids’ discovery trail through the bush are nearly as popular as wine tastings and South Australia’s Natural Resources Management Board uses the property as a showcase.

Interestingly, since adopting biodynamic principles, the vines’ yield has actually dropped by a third, but the quality has improved, and they save money on sprays. Plus the frogs have returned to the dam.

To help protect the local population of Yellow-tailed Black Cockatoos, community baiting has removed at least 2,300 foxes over 13 years.

“We also have a family of Yellow Footed Antechinus living under the floor,” Sean adds.

The couple is constantly amazed by the power of the Australian bush to heal itself.

“Near here there’s a place that burnt down in 1980 and sat vacant for many years,” Sean tells. “A few years ago developers finally removed the concrete and a huge amount of native orchids and lilies came up; they had been buried for 37 years and yet the seed was still viable,” he marvels.

“Living here, you can’t help but be affected by the beauty of the place.

“We have mob of Tamar Wallabies that always give birth on same night – summer solstice – and two major insect hatchings on full moon twice a year; when you are living in the city, focused on TV, you don’t notice things like that.”

http://www.sinclairsgully.com/