Rearing Orius armatus for controlling western flower thrips in the vegetable industry (VG08186)

This is a final research report from Hort Innovation’s historical archives. Please note that as these reports may date back as far as the 1990s, the content and recommendations within them may be superseded by more recent research.

What was it all about?

Integrated Pest Management (IPM) was a strategy used to control pests. It was usually adopted when the conventional approach of applying pesticides had failed. This project was initiated because of the commercial failure of a pesticide –based strategy. The researcher proposed using an IPM approach which involved a primary control based on biological control agents (Orius) with support from cultural (management) techniques and only strategic support from pesticides.

The term IPM (Integrated Pest Management) had been much abused over previous years, and had been given to a range of tactics such as monitoring of pests before spraying, or combined with rotation of pesticides but with no care for the biological control agents present in the crop. IPM was primarily based on a non-chemical preventative approach, focusing on naturally occurring beneficial insects and mites, with the release of mass produced beneficial insects and mites when required, and the use of strategic chemical products only when necessary as stated by Australia’s only IPM logo accreditation scheme for growers. In some areas, Australia was lagging behind other western countries in the establishment of biologically based IPM. For example, Israel had over 2000 Ha of capsicums under IPM, compared to Australia’s 10 Ha. In other areas, such as potato production, Australia leads the world in IPM.

Western Flower Thrips, Frankliniella occidentalis, (WFT) was one of the greatest pest threats to vegetable and flower production in Australia. The challenge for growers was how to effectively manage WFT, given that it had rapidly developed insecticide resistance so that at the time, Australian populations were resistant to all major classes of insecticides, including newer chemistries released only a few years ago. Controlling WFT with insecticides was not sustainable. WFT was able to survive all insecticide sprays that were legally available to growers in the crops studied in this project.

Extensive testing of the effects of a range of insecticides on O. armatus was undertaken in this project. The results showed that the neonicitinoid group of chemicals were the most toxic products. In particular imidacloprid remained in the soil residually and completely killed all O. armatus for several years after application. This had been observed by Manchil IPM Services in Virginia South Australia, Baldivis Western Australia and also in Israel.

Extensive commercial field trials were undertaken across Western Australia, Victoria, South Australia and Tasmania. All commercial trials had good results as measured by control of WFT, with some spectacular results. For example, some growers in WA went from 2 sprays a week to no sprays for the entire season for WFT and Two-spotted mites. Understanding the impact of a range of insecticides on the survival and breeding of O. armatus survival, as well as the environmental conditions across Australia, were critical in being able to use this biological control agent in an effective way.

At the start of the project Manchil IPM Services was producing 1000 O.armatus a week which could cover 500m2 at 2 O. armatus/m2. The mass rearing of O. armatus was successfully achieved and weekly production increased to 400, 000 O.armatus. If released at 2 O. armatus/m2 this would be enough to cover 20ha/week.