The Australian Field Crops Resistance Management Strategy has been in place now for 7 seasons. The impact of the Strategy on resistance levels is monitored in three areas; the Namoi and Gwydir river valleys of nonhem NSW (a temperate cotton monoculture), the Emerald Irrigation Area of central Queensland (a sub tropical mixed cropping area) and a sample of the unsprayed Refugia centred on Inverell in northern NSW. Resistance to both pyrethroids and endosulfan is assessed, as these two groups account for over 80% of the insecticides used against Heliothis spp. in Australian cotton. Studies with the oxidase inhibiting synergist piperonyl butoxide (Pbo) have indicated that the dominant mechanism of pyrethroid resistance in the field is via oxidative detoxification. This has led to the investigation of two possible chemical countermeasures for managing pyrethroid resistance: synergists and structurally modified pyrethroids (also called resistance breaking pyrethroids). A brief summary of each of these findings will be given followed by an outline of the future for managing pyrethroid resistance.

Small parasitic wasps, scientifically known as Trichogramma, are used as biological control agents of moth pests in overseas countries, thereby reducing the need to use insecticides. These wasps attack the egg stages of moths, killing them before they hatch and cause damage. Large numbers of Trichogramma need to be produced and released per hectare of crop (hundreds of thousands) to have an affect on a pest population.

The Bureau of Rural Resources has estimated the area in central Queensland potentially suitable for raingrown cotton production at 60-80,000 ha. With cotton prices above 1989$ 400 per bale, raingrown production can be highly profitable with even mediocre management. While the needs, risks, and management options for raingrown cotton have been dissected by other speakers at this conference, what happens to an insect management strategy which is totally dependent on the remedial use of insecticides should this potential suddenly be realized? Clearly it is important that we develop, now, a management strategy that reduces our reliance on conventional chemical control of insects and which is stabilised by the integration of some alternative pest control methods.

The purpose of our four-year study on the Darling Downs was 1) to investigate the population dynamics of heliothis and to quantify the significance of the major controlling influences (parasites, predators, pathogens, weather and host plant effects) on population change; and 2) to assess the potential for an management approach to the suppression of populations through the practical manipulation controlling

Heliothis spp. are very successful as pests for a number of reasons (Fitt 1989): adult moths are highly mobile and have a high reproductive rate, larvae can utilize a wide range of host plants including most crops, and successive generations can develop resistance to pesticides. Management of such pests in commercial crops relies on regular scouting to provide information on egg and larval densities within each crop, and their likely resistance levels. We believe that the local management of Heliothis could be improved if predictions of the densities and the origin of Heliothis eggs on each crop could be made several days in advance. Regional management strategies (see Murray. these proceedings) and insecticide resistance management (see Forrester, these proceedings) would also benefit if overall seasonal predictions of likely densities for each species of Heliothis could be made with confidence. Such information would be available if we understood the population dynamics of Heliothis on a regional scale. To this end we are developing. a series of simulation models under the name "HEAPS" (HEliothis Annigera and Punctigera Simulation) (Hamilton and Fitt 1988).

An important question is the area of origin of these spring immigrants. Over the last 3 years, we have been investigating the ecology of Heliothis spp. in inland Australia (Gregg et al. 1987, 1989). The most recent findings of this work are summarised by G. Fitt et al.in these Proceedings. Large populations of H. punctigera, and smaller but still significant populations of H. armigera, have been found over vast areas. They breed on native annual plants in winter. These plants dry off rapidly in spring, and the Heliothis disappear. This paper presents evidence which indicates that in 1989 they emigrated from the inland, and that significant nunbers arrived in the cotton areas of northern N.S.W. and southern Queensland.

Heliothis spp. are clearly the major pests of Australian cotton and consequently there has been considerable research on their biology, ecology and control (Zalucki et al 1986). Most of this research has focused on Heliothis populations on particular crops within cropping areas. However, these species are not restricted to crops and exploit a wide range of non-cultivated host plants within and outside the cropping areas, in addition to their many cultivated hosts.

The pattern of flight activity within or between habitats or crops is dependent upon the distribution of those habitats/crops in both space and time. Similarly the pattern of movement of moths over large areas may be determined largely by shifting seasonal patterns of habitat availability. In both these instances, the inherent flight capacity of an individual is critical in determining its ability to exploit the ephemeral nature of both cropping and non-cropping systems.

Information about the frequency and intensity of immigration and emigration movements is essential for forecasting Heliothis infestation levels in crops, and thus for developing more efficient strategies for managing this pest. In particular, there is a specific need for this information for incorporation into computer models of Heliothis population processes that are being developed as aids to pest managers (Dillon & Pitt 1990). To meet this need, a comprehensive study of Heliothis movement is being undertaken at Narrabri Agricultural Research Station by researchers from CSIRO's Division of Entomology. In this paper, we outline the research methods being used and present some preliminary results for the first full season of observations, 1989/90

The potential for extensive adult movements is one of the key factors contributing to the success of Heliothis spp. as pests (Farrow & Daly 1987, Fitt 1989). Adult movements may occur on several spatial scales; from one field to another, between areas within a valley or between regions (see Gregg et al 1990). Quantitative information about adult behaviour, and movement in particular, is required for the Heliothis population models currently being developed to provide forecasts of infestations on cotton crops (Dillon & Fitt 1990). There are a number of questions to be answered and these are being tackled using a range of techniques (Drake & Fitt 1990) to provide a comprehensive picture of Heliothis movement In particular we are interested in the behaviour of newly emerged moths produced from crops within the cotton areas. How far do these moths fly before colonising a crop in which to lay eggs? When do they leave? How do they move in relation to the wind? What characteristics of crops cause moths to leave or stay within them to mate and lay eggs? To answer some of these questions we are conducting a series of mark recapture studies at Myall Vale.