Departments > Parks, Recreation and Culture > Parks Division > Integrated Pest Management > Victoria's Beneficial Release Progam 2004

The warm spring and summer in Victoria saw a bumper crop of aphids on street trees, roses, Abutelon, Brugmansia and other aphid susceptible plants. Early spring monitoring indicated increasing levels of aphids with few natural predators available to manage their populations. A predator release programme using 143,000 ladybird beetles, Hippodamia convergens from March to July knocked back the aphid population to a level that it could be managed by other natural controls upon emergence such as syrphid flies and predatory midges.

A number of insect pests were favoured by the Victorian weather in 2004. The greenhouse whitefly is a subtropical species that can live on outdoor as well as indoor plants and continue through mild winters. Whitefly are not true flies but are closely related to aphids, mealybugs and scale insects. Adult females can lay 200 to 400 eggs deposited in circular clusters on the undersides of leaves. The optimum range for population increase is 18 to 24°C whereby whitefly numbers can build up rapidly. The City of Victoria released 27,000 miniwasps called Encarsia formosa to control whitefly on nursery plants prior to planting out and also on susceptible outdoor plants.

The adult and larval stages of the mealybug destroyer, Cryptolaemus montrouzieri feed on all stages of mealybugs. Victoria released 100 adults in 2004 for the control of mealybugs.

As with aphids, whitefly and mealybug; scale insects also proliferate during the warm springs and summers and mild winters. As these scale parasitoids are host specific it is important to correctly identify the scale insect problem. Victoria released 200 scale parasitoids, Metaphycus helvolus to control soft brown scale on indoor plantings. In addition to Metaphycus, Victoria is testing the scale eating ladybird beetle, Rhyzobius, under interior conditions to evaluate it as a scale predator.

Additional release of the pests own enemies in 2004 included nematodes for the control of fungus gnat larvae and vine weevil; different predatory mites for thrip, spider mite and fungus gnat control.

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