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Please note that as these reports may date back as far as the 1990s, the content and recommendations within them may be superseded by more recent research.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?

The aim of this project was to develop a key component of an integrated pest management (IPM) system for strawberry production, namely the breeding of an organophosphate (OP)-tolerant predatory mite (Gaeolaelaps aculeifer) for inundative release to biologically control western flower thrips (Frankliniella occidentalis).

At the time this project was initiated because the control of western flower thrips in commercial Australian strawberry crops was largely reliant upon insecticides, which were neither cost-effective nor sustainable because of the development of insecticide resistance. Some strawberry growers were using commercially-reared biocontrol agents such as G. aculeifer to manage western flower thrips infestation levels, and achieving considerable success. However this agent was vulnerable to broad-spectrum insecticides used for the control of other pests, most notably the OPs used for Rutherglen bug control.

In this project the researcher exposed a strain of commercially-reared G. aculeifer to repeated and progressively increasing doses of dimethoate and thereby created an OP-tolerant strain. This strain provided the Australian strawberry industry with a new means of limiting the disruption to the strawberry IPM system for western flower thrips during a Rutherglen bug invasion.

The OP-tolerant G. aculeifer strain developed in this project was supplied to Biological Services (Loxton), the main Australian commercial producer of this agent. Interested growers purchased this selected strain of G. aculeifer and obtained instructions for its field release and maintenance from Biological Services (Loxton).

Further investment by Australia’s horticultural industries, through Hort Innovation (then Horticulture Australia Limited), in the development of more biological control agents to help manage the range of pests that attacked horticultural crops across a broad range of crop environments had genuine potential to reduce dependence on pesticides at the time.