Australia's horticultural crops are attacked by a number of insect pests, including codling moth, oriental fruit moth, budworms and other leaf rollers. Relying on pesticides to control insects such as these is expensive and hazardous to the environment. The dependence by moths on pheromones during their lifecycle provides the opportunity to develop an alternative, environmentally safe means of pest control.

Pheromones are chemical signals that insects use for communication. Moths commonly use pheromones to attract others of their kind, including mates. For example, female moths broadcast minute amounts of a sex pheromone from the tips of their abdomens. Male moths detect this airborne signal and, responding to the pheromone plume, find a female and mate. Females then lay their eggs on a food source and caterpillars hatch from the eggs, feed and grow. After pupating they emerge as adult moths and the cycle continues.

Studies of the physiology and behaviour of moths have identified the pheromones of many species. Many of these have been chemically identified and duplicated in the laboratory. These synthetic pheromones can be produced in large quantities commercially and used for pest control. Synthetic pheromones are now widely used for monitoring pests and for direct control by means of mating disruption.

The Division of Entomology has pioneered the use of synthetic pheromone dispensers for the control of pests by the mating-disruption technique. In this technique, the air in orchards is 'flooded' with a synthetic copy of the pheromone of the target moth. The normal female-searching behaviour of male moths is disturbed and they fail to find and mate with females. As a consequence, the unmated female moths lay eggs that do not produce caterpillars. Through this technique, the amount of damage done by the pest to fruit in orchards can be drastically reduced.

"Isomate M" is a pheromone dispenser system developed from this CSIRO research. This system is commercially produced by Biocontrol Ltd and is registered for use against oriental fruit moth in peach orchards in Australia, USA, and France. Orchardists simply attach the dispensers to fruit trees and the pheromone does the rest, avoiding the need to use pesticides.

Another common use for synthetic pheromones is in pheromone-baited traps. Growers can use these traps to determine if pests are actually present in an area and so restrict pesticide spraying to times when it has the most effect. Scientists in the Division of Entomology have done much research into the use of pheromone traps to monitor pests, such as with codling moth in apple orchards and cotton bollworm in cotton crops.

Another aspect of this research is the study of the pheromone detection systems of moths. By understanding these complex physiological/behavioural systems, clearer predictions can be made about the response of target pests to the pheromone control method.

Current research is investigating the use of the mating-disruption technique for control of codling moth in apple orchards. Other potential targets for pheromone control include important pests such as pink spotted bollworm, cotton bollworm and macadamia nut borer. All these projects have the potential for commercial production and involve a number of collaborators, including State Departments of Agriculture and commercial private companies.

Russell Moran,
CSIRO Division of Entomology

DATE: January 1993

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