Cotton pest management

The challenge

Tackling emerging pests and delaying Bt resistance

CSIRO's pest management research efforts and delivery of cotton varieties containing genetically modified (GM) traits for insect resistance to control caterpillars of Helicoverpa, have helped reduce insecticide use by 85 per cent in the Australian cotton industry. Bollgard 3™, also known as Bt, is the genetically modified trait package from Bayer used in our cotton for built-in insect protection.

Reduced insecticide use against Helicoverpa (the main pest of cotton) has allowed other pests to survive and emerge as important pests. CSIRO is also looking at these emerging pests, including aphids, mirids, whitefly, thrips and jassids to improve our management strategies.

We are also looking at ways to significantly slow resistance developing in Helicoverpa caterpillars to the Bt insect-resistance trait used in our cotton. This requires an integrated approach to pest management as well as close working relationships between key stakeholders in the cotton industry and our breeding and pest management research teams. With the recent invasion of Helicoverpa armigera into the Americas, a global perspective is required that considers the possibility that populations of this species that carry new resistances could enter Australia.

Our response

Integrated pest management: a holistic approach to dealing with pests

Our scientists have partnered with industry for over 30 years to study and advocate a holistic approach to pest management known as IPM (Integrated Pest Management). IPM seeks to manage pests using a wide range of methods:

• using plants with resistance to the pests, such as Bt-cotton
• destroying over-winter food sources of pests, particularly weeds
• managing over-winter stages, for example the pupae of Helicoverpa
• using trap crops that are more attractive to pests than cotton
• conserving 'beneficials' (predators or parasitoids that destroy pests)
• effective sampling to understand the abundance of pests versus beneficials
• using pest thresholds to decide when control is needed
• preferentially using selective insecticides that preserve beneficials
• tolerating non-economic damage
• adopting strategies that limit exposure of pests to selection from insecticides
• using strategies to dilute resistance, such as creating nurseries of susceptible insects
• using broad spectrum insecticides as a last resort.

Our IPM research has contributed to the development of the Integrated pest management guidelines for cotton production in Australia1; the Guide to pests and beneficials in Australian cotton landscapes2; and the Cotton Pest Management Guide3 which combined provide the Australian cotton industry with core information to support improved pest management. Cotton insect management tools are also delivered through our decision support systems.

CSIRO is engaged in international consortiums that compare the governance of Bt resistance management across countries using Australia as a 'best case' scenario. We also work on improving surveillance for not only new insect species but also pests that currently exist in Australia but may enter the country carrying new resistances.

We have extended our work beyond cotton, for example to engage urban stakeholders in the sustainable management of arthropod pests. We have conducted a number of studies in grains and horticulture on pest and beneficial insects, including studies on pest suppressive landscapes and new knowledge to improve the timing of pest management decisions. This includes the use of spatial simulation modelling, for example to predict pest population response to various management strategies, including Bt resistance management.

The results

Conserving beneficial insects and delaying Bt resistance

Our research findings and pest management publications are widely used by the Australian cotton industry to make decisions about when, how much and what insecticides to spray in order to conserve beneficial insects while minimising crop damage from pests. These publications also inform best practice in pest management internationally, and the principals have been extended to urban contexts.

Thanks to our research and evidence-based strategies for delaying insect pest resistance to Bt cotton – such as planting non-GM refuges where non-resistant insects can pass on their susceptibility to the rest of the population – Australian cotton growers are keeping one step ahead of insect pests such as Helicoverpa.