A new era in insect pest monitoring in forestry arrives

Most species of moth use chemical signals to facilitate mate location and thereby ensure fertilisation of the female. Such chemicals have long been used in the northern hemisphere as tools to assist with population monitoring and even for the management of some forest Lepidoptera. In 1999 a collaborative project supported by the CRC-SPF and involving Austrian, Swedish and Australian experts began to determine the existence, identity and efficacy of the female sex pheromone of the Autumn gum moth (Mnesampela privata). This project's ultimate objective was to develop a sex pheromone lure for monitoring populations of Autumn gum moth in plantations. Such a lure would be more cost effective than light trapping for moths because the lures would work for longer, attract only the Autumn gum moth and need less labour to maintain.

The glands of female moths were extracted and the chemical components contained within surveyed using gas chromatography (GC, using a flame ionisation detector, FID). Gas chromatography in combination with simultaneous electroantennographic detection (EAD) was then used to determine which of these compounds the antennae of male moths responded to. When an 'active peak' was identified, gas chromatography in combination with mass spectroscopy (MS) was used to determine the chemical composition of the active compounds.

When the chemical identity of an active compound had been established, a synthetic analogue from overseas collaborators was obtained for further EAD studies. This synthetic analogue elicited a reaction in male antennae comparable to a compound extracted from female organs.

Field trapping with synthetic lures, prepared using the synthetic sex pheromone analogue and virgin female moths, began at experimental sites around Canberra in 2002 to determine their relative efficacies in attracting male moths. Male moths were caught in the synthetic sex pheromone lures in similar numbers to the numbers of males caught in traps baited with virgin females. Hence the existence and identity of the sex pheromone of Autumn gum moth has been confirmed under both laboratory and field conditions. Further work with a Swedish collaborator is planned for 2002/3003 to refine the use of the lures. When these studies are complete the potential to commercialise the lure will be investigated.