Executive Summary
What the report is about
This project examined the comparative effectiveness of pesticides that are available for use by organic producers and their effects on beneficial species, and whether natural populations of beneficial species can be augmented with commercially produced beneficial species.

Who is the report targeted at?
This report is targeted at farmers who are growing crops organically and are deciding the best method for dealing with pest problems.

Background
The three main methods of dealing with pest problems in agriculture are the use of pesticides, biological control agents and cultural (management) techniques. Farmers growing crops organically can use these three methods, but have imposed their own restrictions on the type of pesticides that can be used. This means that many organic producers are willing to put more effort or reliance on biological and cultural control techniques than other producers. It is important for organic producers that the pesticides that they do use are effective against the pests and do not interfere with any biological control. Organic producers will benefit by having a greater selection of more appropriate control methods, and this will lead to higher quality produce and more sustainable production.

Aims/Objectives
The aim of the project was to improve ecological sustainability and to minimise the effects of pesticides on non-target organisms. The project provided data on the impact of pesticides both currently used and that may be available in the near future.

Methods used
Laboratory trials were conducted to evaluate specific products against different species of insects, and field trials looked at the effects of augmentative releases of insects and mites. Suitable pesticides were tested in the laboratory for lethal and sub-lethal effects on pest and beneficial insects. Field trials were conducted to measure the impact of augmentative releases of beneficial insects.

Results/Key findings
Some of the products tested were highly effective against certain pests and safe to most beneficials (Bacillus thuringiensis sprays and Spinosad). However, most products tested did not have both efficacy in killing pests and safety to beneficial species. Although such a result may have been hoped for or believed by growers, most products that killed pests also killed beneficial species. The difference between these sprays and most conventional pesticides was in the time that residues would kill beneficial species. Almost all insecticides available for organic use had very short residual action and relied on direct contact with insects or mites.

Augmentation with beneficial species showed that addition of certain predators could make a significant difference to pest numbers and pest damage. However, in all cases releases needed to be made early in the life of either the crop or the season to have an impact. When releases of beneficial insects were made instead of spraying insecticides, then of course there was a greater abundance of many beneficial species, not only those being released. For example, in table grape vineyards where we released the main predators of mealybugs (Cryptolaemus and green lacewings), the control achieved was due to the combined effects of these predators plus other naturally occurring predators and parasites. Numbers of green lacewings in particular decreased markedly when district wide use of broad-spectrum synthetic insecticides began in December. This in turn resulted in a flare of mealybugs as newly emerged mealybugs were no longer eaten. We predicted a further increase in the problems with two-spotted mites as another consequence of predators being eliminated from the ecosystem.

Recent reports confirm that this has eventuated.

Implications for relevant stakeholders
The role of beneficial species on pests is of relatively greater importance in organic agriculture than in conventional agriculture, because organic growers do not have recourse to the highly potent insecticides (such as synthetic pyrethroids) with which to tackle major pest problems. However, even major (multi-national) producers of synthetic insecticides recognise the importance of bio-control agents and are now producing a range of products which offer selectivity of action.

Recommendations
It is recommended that:

1. Growers need to know the results of pesticide testing.
2. Growers need to understand that several different tests are used to assess effects of pesticides.
3. Growers need to be able to identify beneficial species as well as pests.