Extensive surveys during the winter months in inland areas of Australia have greatly extended both the range and known hosts of Australia's two pest Helicoverpa species. H. punctigera was the more common species, being collected from c. half of the sites sampled. Here a further 47 plant species in 8 families are recorded as possible host plants; the majority (all except two) are new records of native hosts, and greatly extend the existing lists. H. armigera was less common, being recorded from c. 10% of the 554 sites sampled. This species was reared from 28 species in 10 plant families. Both moth species are recorded for the first time from various native plant species, predominantly in the Asteraceae and Fabaceae. The Goodeniaceae is also added to the host list of both species. Determination of the status of host plants is discussed.

Genetic (electrophoretic) variation was examined in the two pest species of Heliothis found in Australia,//, armigera (Hiibner) and//, punctigera Wallengren. They could be differentiated by seven loci which enabled identification of individual eggs and small larvae not normally distinguishable by their morphology. The traditional criteria for distinguishing the larger larvae of the two species were shown to be unreliable. The genetic distance between the two species was 0-34 ± 0-02. The percentage of loci polymorphic in both species, 32%, and the mean heterozygosities, 11-3% for//, armigera and 10-8% for H. punctigera, are lower than those reported in the American species, H. virescens (F.) and H. zea (Boddie). Populations throughout Australia were differentiated from each other, but there did not appear to be a marked geographic pattern to the variation. Genetic distances between populations of H. armigera were low (<0-01). It was concluded that the effective population size of Heliothis is large and that significant gene flow probably occurs between widely separated regions.

Attract-and-kill has considerable potential as a tactic in integrated management of pests of agricultural crops, but the use of sex pheromones as attractants is limited by male multiple mating and immigration of mated females into treated areas. Attractants for both sexes, and particularly females, would minimize these difficulties. Volatile compounds derived from plants or fermentation of plant products can attract females and have been used in traps for monitoring and control, and in sprayable attract-and-kill formulations or bait stations. Recent advances in fundamental understanding of insect responses to plant volatiles should contribute to the development of products that can help manage a wide range of pests with few impacts on nontarget organisms, but theory must be tempered with pragmatism in the selection of volatiles and toxicants and in defining their roles in formulations. Market requirements and regulatory factors must be considered in parallel with scientific constraints if successful products are to be developed.

This paper reports olfactometer studies to determine the attractiveness of synthetic equivalents of plant volatiles to Helicoverpa armigera (Hübner) moths. Synthetic volatiles identified from host plants and other volatiles reported in literature as attractants to various noctuid species were tested in a two-choice olfactometer. Of 34 single chemicals tested, only seven were significantly attractive, and six were significantly repellent. However, when presented as blends of two or more volatiles, 21 of 31 blends tested were significantly attractive, and only one was significantly repellent. The most attractive blends were those containing four to six components, including aromatic volatiles primarily found in flowers, especially 2-phenylethanol and phenylacetaldehyde and volatiles found primarily in leaves, including green leaf volatiles and terpenoids. Some general principles in blending volatiles for developing attracticides for H. armigera are presented, including the need for blend complexity, the combination of volatiles from leaves and flowers, and early consideration of pragmatic factors such as price and toxicological profile.

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