Down to Earth
In this series of articles staff, students and graduates of Burnley College
share their views with Global Garden readers on a range of topical horticultural
issues. Burnley College is
part of the University of Melbourne’s Institute of Land and Food Resources and
enjoys an esteemed reputation as one of Australia’s premier horticultural
institutions. Click
here for a list of other articles in the series.
Using Biological Control Agents to Control Pest & Diseases
Many home gardeners are interested in avoiding chemical use in their gardens and most appreciate the value of bird and animal populations in reducing populations of pest insects. This month we talked to John Brereton about making use of insect control agents to control pests and diseases.
1. Which biological agents are readily available and how well do they work?
Beneficial insects and mites available in
Australia are listed in the ABC Australasian biological control The GOOD BUG
Book.
The listing includes predatory mites, for the control of Two Spotted Mite; Encarsia
wasps for the control greenhouse white fly; Aphytis melinus, a parasite
of red scale and citrus scale and a nematode that is applied to soil and
controls fungus gnats. These types of biological control agents are sold by
Biological Services in Loxton, South Australia (Ph. (08) 8584-6977). Their
clientele are primarily nurseries and commercial producers. Other commercial
suppliers include Bugs for Bugs (Ph. (07) 4165-4663) in Mundubbera in Queensland
and Beneficial Bug Company in Sydney (Ph. (02) 4570-1337.)
The examples listed above are well-known, tried and proven agents that are used
to manage pest populations down to acceptable levels, but people should be aware
that they are not eradicant treatments.
Some beneficial insects are available for home gardeners, but not as many as are available overseas. Bugs for Bugs (Ph. (07) 4165-4663) sell a range of biological control agents including Trichogramma wasps for the control of butterflies and moths commercially, but also sell a selection of "good bugs" to home gardeners. These include Green Lace Wing larvae. These insects are good general predators and will eat aphids, two-spotted mites, whitefly, scale, caterpillars and moth eggs. Cryptolaemus is a native beetle that specifically eats mealy bugs and they are sold as both larvae and as adults. Bugs for Bugs also sell larvae of a native ladybird which is a scale predator. Spotted ladybirds and preying mantids are not available.
Bugs for Bugs also sell fruit fly traps and sticky traps
for catching flying insects. Sticky traps come in yellow (for trapping aphids
and whitefly) and blue (for thrips and leaf miners.) However these traps catch
all flying insects and will also reduce the populations of "good
bugs".
3. How
can gardeners go about increasing natural populations of useful insects in their
gardens?
Home gardeners mainly encourage populations of biological control agents by maintaining plant diversity and by careful and judicious use of chemicals, selecting low hazard non-persistent chemicals wherever possible. Other treatments include the use of bio-insecticides such as Bacillus thuringiensis (sold as Dipel), a bacterium which destroys caterpillars, for example on Brassicas - cabbages, broccoli, stocks, etc. Also gardeners should avoid blanket spraying of gardens. Careful selection of plant species suited to the growing environment is important, as is the maintenance of plant vigour and good sanitation and hygiene practices, ie physical removal of infested plant debris.
_________________________________________________________
About John Brereton: John is a Senior Lecturer in Plant Protection at Burnley College, University of Melbourne. His special interest is the promotion of sustainable pest management practices.
Copyright
protected - refer all copyright enquiries to Global
Garden
Global Garden http://www.global-garden.com.au
More
"Down to Earth" articles
Click here to RETURN TO GLOBAL GARDEN HOME PAGE