The 1997-98 cropping season in southern Queensland was characterised by a severe, sustained and damaging outbreak of H. armigera. This situation arose as a result of a combination of factors. Helicoverpa attacks most of the crops grown in the Darling Downs agroecosystem, and successive generations can occur where seasonal

conditions are favourable, and control poor, or ineffective. There is a high dependence on insecticides for the management of heliothis in all crops. This over-reliance on insecticides has led to declining efficacy of registered insecticides because of resistance in H. armigera, resulting in more frequent field control failures,increasing pest densities, and increasing costs of control.

The impact of the 1997-98 season on the economic viability of most crops resulted in a widespread realisation within the fanning Ccommunity that a change in the current approach to heliothis management was needed to ensure a farming future in this region. Under greatest threat was the grains industry because it is highly

dependent on 'old' compounds for heliothis management(eg. carbamates). There were also increasing concerns about environmental and human health hazards associated with increasing insecticide use.

In 1998-99 this project was initiated to develop a regional management approach for heliothis on the Downs.

Reflecting the mixed cropping system of the region, the project was jointly funded by the GRDC and CRDC. After consultation with growers, consultants, researchers and funding bodies, two pilot study areas were defined, and a draft strategy developed. The two study areas were on the limbourfloodplain and the other

between Brookstead and CGcilPlains. The Jimbour floodplain area is predonxinantly a dryland grain production region with smaller areas of dryland and irrigated cotton. The Brookstead-CecilPlains area produces predominantly irrigated cotton and grains with smaller areas of dryland grain crops and cotton. Strong local support for the project was expressed at initial grower meetings in each of the areas.

The regional management strategy for H. armigera is based on the theory that it is a local and recycling population of the pest that drives the spring-sumrner build up in pressure. A strategy that targets bottlenecks in the population development will result in a reduction of the overall H armigera population, reducing pest

densities and the frequency with which chemical control are required. Flowing on from the lowered pest pressure and reduced insecticide use would be a reduction in the level of insecticide resistance in the population, and consequently greater opportunity for the use of biological insecticides (eg. Bt and NPV), and other IPM options.