Finding Nematode
From the March 2009 edition of Agriculture Today.
They're everywhere, and the nematode’s reputation, soiled by the parasitic antics of the relatively few, is being vigorously exhumed by a Queanbeyan company.
Microscopic ENs - or entomopathogenic ("insect-killing") nematodes - are a natural alternative to chemical pesticides for controlling plant pests and are important for maintaining crop and pasture health.
Less than one millimetre long, a line of 25 individual ENs would stretch across a bottle top.
Argentine scarab beetles, argentine stem weevils, red and black headed cockchafers, African black beetles and fungus gnats, and your ilk, beware.
ENs don’t need to know where you live. They’re everywhere. Inevitably, you will come to them.
Free-living (that is, non-parasitic) nematodes wriggle their way through the soil in the thin films of water surrounding soil particles, feeding at every level of the soil food web - on bacteria, fungi, protozoa and other nematodes.
"They are also very important for supplying plant available nutrients in the root zone, in addition to their value as predators and controllers of some agricultural pests," NSW Department of Primary Industries’ Queanbeyan soil project officer, Susan Orgill, said.
"My favourite is Heterorhabditis zealandica, which preys on large soil animals 10 times their size, such as borer grubs and cockchafers.
"They pierce the grubs with their stylet and inject symbiotic bacteria from their gut.
"Then they just sit back and wait for the bacteria to multiply and kill the grub and go in for dinner."
ENs then breed in large numbers within the pest.
The cadaver ruptures and releases millions of infective juveniles back into the soil to seek out further targets.
The fascination of their existence also makes nematodes a great teaching aid.
Ms Orgill highlights to farmers in the frequent workshops she organises, that nematodes are a readily available biological agent in soils, which they can encourage in Integrated Pest Management programs.
"Education is the key to a successful migration from chemical dependence to biological control," Ms Orgill said.
"However, it is important to recognise that like all farm inputs they have their limits and sometimes may not be applicable or feasible.
"It is important to accurately identify which pest needs attention, understand its life cycle and recognise the challenge of working with a living soil environment before deciding which treatment to use."
Contact Susan Orgill, Queanbeyan, (02) 6298 0806, susan.orgill@dpi.nsw.gov.au
Bagged in their millions
Beneficial free-living ENs (entomopathogenic nematodes) that make up about 65of the 80,000 types so far described around the world do not parasitise plants.
That still leaves farmers about 15,000 types of parasitic nematodes (or roundworms) to wrestle with, out of a possible total of up to half a million nematode types that may exist, habits unknown.
Queanbeyan based company Ecogrow grows and sells many varieties of ENs in their mega-millions for sale.
CSIRO Entomology developed the technology over 30years, led by Dr Robin Bedding, before Ecogrow became the original licensee, then commercialised it a decade ago to become a stand alone company.
The most common multi cellular creatures in the soil, nematodes would be unfortunate to hate each other’s company - 30 million or more of them can share the same address in just one square metre of soil.
Ecogrow’s facility manager, Craig Wilson, showed Agriculture Today how ENs breed with the same density at the company’s production factory, initially in flasks full of "nematode food" (symbiotic bacteria or fungus), and are then released into bags filled with similar nourishment, to multiply in special heat controlled rooms.
"They are then washed into solution in large tanks, which are then drained, sieved and vacuumed so all that is left is a nematode paste," Mr Wilson said.
"This paste is added to a water absorbent cellulose pulp then divided into plastic containers ready for distribution."
Ecogrow delivers successful treatments of various scales to amenity turf, horticulture and occasionally agricultural clients.
Related to applications in agriculture, Mr Wilson said it was important to be able to pre and post irrigate to maintain moisture for the nematodes.
"Also the environmental benefits need to be considered when costing on a per hectare basis," he said.
"We have seen good benefits from the nematode’s ability to overcome chemical resistance in pests."
The website for Australasian Biological Control offers specific information about producers of beneficial organisms in Australia/New Zealand at www.goodbugs.org.au
Contact Craig Wilson, Ecogrow, eechogro@bigpond.net.au or visit www.ecogrow.com.au
