This project has delivered outcomes that address major agronomic and crop protection issues closely linked to the profitability and sustainability of cotton production enterprises in CQ. From an agronomic perspective, the CQ environment was always though to support economically viable cotton production in a wide sowing window from the middle of September to early January prior to this research. The ideal positioning of Bollgard II varieties in the CQ planting window was, therefore, critical to the future of the local cotton industry because growers needed baseline information to determine how best to take advantage of the higher yield potential offered by the Bt cotton technology, optimise irrigation water use and fibre characteristics.

The project’s outputs include a number of key agronomic findings. Over three growing seasons, Bollgard II crop planted in the traditional sowing window from the middle of September to the end of October consistently produced the highest yields. The project delivers a clear and quantitative assessment of the impacts of planting outside the traditional cropping window - a yield penalty of between 1-4 bales/ha for November and December planted cotton. Whilst yield penalties associated with December-planted crops are clearly linked to declining heat units in the second half of the crop and a cool finish, those associated with November-planted cotton are not consistent with the theoretical yield potential for this sowing date. Further research to understand and minimize the physiological constraints on November-planted cotton would give CQ cotton growers far greater flexibility to develop mixed/double/rotation cropping farming systems that are relevant to the rapidly evolving nature of Agricultural production in Australia. The equivalence of cultivar types with clearly distinguishable, genetically based growth habits, demonstrated in this project, gives growers important information for making varietal choices.

The entomological outcomes of this project represent strategic and tactical tools that are highly relevant to the viability and profitability of the cotton industry in Australia. The future of the cotton industry is inextricably linked to the survival and efficacy of GM cotton. Research done in the Callide irrigation area demonstrates the unquestionable potential for development of alternative and highly effective resistance management strategies for Bollgard II using novel technologies and strategies based on products such as Magnet®. Magnet® and similar technologies will be increasingly important in strategies to preserve the shelf life and efficacy of current and future generations of GM technology. However, more research will be required to address logistical and operational issues related to these new technologies before they can be fully exploited in commercial production systems.

From an economic perspective, SLW is the sleeping giant in terms of insect nemeses of cotton, particularly from the standpoint of climate change and an increasingly warmer production environment. An effective sampling and management strategy for SLW which has been delivered by this project will go a long way towards minimising production costs in an environment characterised by rapidly rising input costs. SLW has the potential to permanently debilitate the national cotton industry by influencing market sentiment and quality perceptions. Field validation of the SLW population sampling models and management options in the Dawson irrigation area cotton and southern Queensland during 2006-07 documents the robustness of the entomological research outcomes achieved through this project.

In the mid-1990's the Australian cotton industry adopted Ingard®, a transgenic variety that contains a Bt toxin (CrylAc) which is specific to the group of insects including the target Helicoverpa armigera, but excluding natural predators and parasitoids of this pest. . In the 2004/05 season, Bollgard II® replaced Ingard as the transgenic variety of cotton available to Australian growers. It improves on Ingard® by incorporating an additional insecticide protein (Cry2Ab) to combat H armigera. In its first available season Bollgard II® was well adopted, with an average of 70% of the planted area throughout the industry.

·We know from artificial selection experiments in the laboratory that H armigera can develop Bt resistance. In addition, CSIRO Entomology has worked on resistance by natural populations of H armigera to transgenic cotton for many years, and presently maintains strains that are resistant to CrylAc or Cry2Ab. In both cases, the forms of genes (alleles) that confer resistance were isolated from field populations (CSE102C and CSE104C).

. To help prevent the development of Bt resistance in field populations of H armigera and thus prolong the utility of Bollgard II®, growers that use this tool must follow a resistance management plan (RMP). The RMP involves, in part, the growing of dedicated refuge crops aimed at producing sufficient Et-susceptible H armigera moths such that there is a high probability of them mating with resistant moths that may arise from the transgenic crop. The RMP is largely based on information from studies of the ecology and population genetics of H armigera, and the outputs of computer simulation models that use biological information to predict the likelihood of resistance developing under different scenarios. These models assume that any individuals which are resistant to the toxins in Bollgard II® survive to successfully reproduce in cotton landscapes.

However, natural enemies that frequent Bollgard II® crops may kill Bt resistant individuals. Such mortality is not represented in current models which predict the temporal aspects of development of resistance,. and is currently unquantified in the field. It would also be useful to know if such mortality differs between Bollgard II® crops and the common refuge crops (unsprayed conventional cotton, pigeon pea).

Some studies have characterized the arthropod fauna in fields of Bollgard II® versus sprayed conventional cotton. Bollgard II® crops are believed to contain a higher abundance and diversity of arthropods because broad-spectrum synthetic insecticides are not usually applied to this crop to control Helicoverpa. These arthropods include species that are natural enemies (predators or parasitoids) of a range of species including Helicoverpa. However they can also include secondary pests of cotton, such as mirids, which are controlled with synthetic

chemistries (e.g., Regent®) that also kill other sucking pests, thrips, and hymenoptera. Some of these arthropods include natural enemies of Helicoverpa (e.g., mirids attack eggs of Helicoverpa). Therefore, improved abundance and diversity of natural enemies in Bollgard II® fields may prevent Bt resistant larvae from reaching adulthood, but the frequency of use of synthetic insecticides to control secondary pests such as mirids might also affect this situation.

In the 2004/05 season Bollgard II® replaced Ingard® as the transgenic variety of cotton available to Australian growers. It improves on Ingard® by incorporating an additional insecticide protein (Cry2Ab) to combat H. armigera. Sequence information indicates that these genes are distantly related and the toxins they encode do not share a common binding site. Consequently it is thought unlikely that a single mechanism could confer resistance to both toxins. Due to the perceived difficulty for H. armigera to evolve resistance to both proteins within Bollgard II®, the RMP for transgenic cotton was relaxed to allow growers to plant up to around 95% of the total area to this product. Bollgard II® was well adopted, with >70% planted area throughout the industry.

The cotton industry has sought to acquire early warnings of changes in sensitivity of insect populations to toxins that may signal the presence of resistance to transgenic varieties of cotton. The sensitivity of field-collected populations of H. armigera and H. punctigera to Bt products was assayed before and subsequent to the widespread deployment of Ingard® cotton expressing Cry1Ac in the mid-1990’s. During CSE102C, baseline levels of susceptibility to Cry2Ab were established in preparation for replacement in the 2004/05 season of Ingard® with Bollgard II®.

Preserving the efficacy of Cry1Ac and Cry2Ab is critical for the future of the industry, not only for the efficacy of the Bollgard II® varieties of cotton, but also for the long-term future of cotton varieties expressing Cry1Ac or Cry2Ab in combination with other effective toxins.

In this project we achieved our main aim of rigorously assessing the sensitivity of field

populations of Helicoverpa to both Cry1Ac and Cry2Ab to detect early signs of the development of resistance to genetically modified cotton. Through the introduction of a new screening technique (F1 tests) we found that for H. armigera the assumed frequency of Cry2Ab resistance alleles in populations may be substantially (up to 6 times) higher than previously thought. In 2007/08 there was a significant increase in the frequency of Cry2Ab resistance alleles obtained using F1 screens compared to previous seasons for H. armigera. Since the introduction of Bollgard II the frequency of Cry2Ab resistance alleles obtained using F2 screens has also increased in H. punctigera. Despite these findings, Bollgard II should continue to provide excellent protection against Helicoverpa provided that the industry manages its stewardship responsibilities.

We recommend that the industry improve its compliance with the RMP particularly in

terms of producing high quality refuges. Also, because late in the season Helicoverpa may be exposed to cotton that only expresses Cry2Ab, it is important to implement an effective pupae busting procedure to kill that last generation which may be enriched with Cry2Ab resistance genes.

There have been no reported field failures of Bollgard II and the occasional occurrence of threshold levels of Helicoverpa in some Bollgard II fields is not due to Bt resistance. Although survivors on Bollgard II are not currently resistant, it would be useful to control them so that they are not exposed to low doses of toxin which can select for resistance in the future. We need to verify the extent and distribution of fields with Helicoverpa survivors, and determine whether it’s possible to predict if a particular field will have a problem. Gavin Whitburn is currently working with CCA members to collect this data.

Despite a poor history in developing resistance to conventional insecticide, the industry

needs to regard H. punctigera as a potential risk of developing resistance to Bt.

For more information contact: Sharon Downes (Sharon.Downes@csiro.au) or Rod Mahon

(Rod.Mahon@csiro.au), CSIRO Entomology

Aims 1. Promote awareness of the importance of soil management 2. Collate existing research results and practical knowledge of the management of irrigated cracking clays. 3. Provide, in consultation with users, a decision-support system for soil management suitable for use at the workface. 4. Provide a framework for identifying research needs and for co-ordinating future research efforts.

This project was initiated under the name "CS66L - SIRATAC Plus configuration and testing". However, the Siratac Plus project proved a failure and all development was abandoned in 1990. These developments were reported in progress reports for Project CS66L in 1990/91. At that time it was decided that the future for computer based pest management for the cotton industry was in standalone microcomputer packages. Consequently staff empolyed in design of the water balance model (A.T. Wells) and testing of SIRATAC Plus (S. Griffin) were re-deployed to the construction and testing of hydroLOGIC; a 3rd generation decision support system (DSS) for irrigation management, further development of the cotton model and to the development of entomoLOGIC, an expert system for pest management. This report covers these developments in detail.

The objective of this project was to look at economic optimisation within the SIRATAC framework.

Aims: *Use data which relates mite numbers to yield loss in order to derive and test action thresholds. * Finalise the development of a sampling technique in association with action thresholds and include both into SIRATAC. * Initiate developmental studies to determine the effects of temperature, humidity and host plant quality and variety on the rate of development of mite populations. * Continue studies of the abundance of mites on weeds and sources of infestation into cotton.

To quantify movement of Heliothis adults Into cotton crops from local and distant source regions. To estimate the migratory capacity of Heliothis in a form which can be Incorporated into regional population models and other decision-support systems for managing Heliothiss populations and their resistance to insecticides

Aims: (i) to quantify the contribution of alternative host crops to the dynamics of Heliothis on cotton using an elemental analysis technique developed in a previous project. (ii) to study the colonisation of cotton crops by adults and subsequent development of populations using night vision devices, pheromone and light traps and direct sampling techniques. (iii) to quantify the catch efficiency of pheromone traps and factors affecting efficiency in cotton at different times of the season. (iv) to study patterns of local movement from discrete source crops, using mark-recapture, elemental analysis, night vision devices and trapping systems

To provide adequate access to computing facilities for SIRATAC, Trichogramma and Heliothis Ecology/Modelling projects at the Toowoomba Laboratory