Conserving a good population of beneficial insects in the crop starts with making well informed and rational pest management decisions using the following considerations;
- Pesticides applied to crops can reduce beneficial abundance
- Bollgard II ® reduces the need to spray pesticides, but is susceptible to some pests.
- If pesticides drift onto areas of native vegetation this may deplete beneficial numbers there as well.
- Use of effective pest and plant damage sampling and use of pest thresholds will ensure pesticides are only applied when needed.
- Pesticides vary in their effect on beneficials.
> Regularly sample and correctly identify pest and beneficial populations. Observe beneficial activity (e.g. thrips in mite colonies, parasitised aphid mummies). The correct sample size will produce more accurate results.
> Regularly sample plant damage and observe plant health.
> Use industry pest and damage thresholds to assess if pests require control.
> If control is required use the most selective effective pesticide. This will leave beneficials to help control any survivors or other pests. Often a more expensive selective spray will save money in the longer term by reducing the risk of inducing pest outbreaks.
> Seed treatments are generally more selective than foliar sprays for control of seedling pests.
> Avoid spray drift into neighbouring crops and areas of native vegetation.
> Consider collating data on gross margins and yields and benchmarking against other farms and farming systems to determine what economic benefits beneficial management is having on the farm.
Sampling techniques, industry pest and plant damage thresholds and insecticide impact tables are updated annually in the Cotton Pest Management Guide.
||Monitoring crop health and pest damage. Pest numbers alone do not give an accurate indication of the need for pest control. Photo: M. Dillon
| A virus effected Helicoverpa larvae. Use the most selective insecticide available. Photo: M. Dillon.
||Aerial spraying. Consider the effects on beneficial populations in areas of native vegetation used as spray drift buffer zones. Image: J. Wark.