Replacement technologies for managing fruit flies, Rhagoletis species, key pests of cherry in Canada

Project code: MU03-ENT3

Project Lead

Howard Thistlewood - Agriculture and Agri-Food Canada.

Objective

To assess the potential of a new bio-product, Spinosad®, applied in a bait and kill strategy to control Cherry Fruit Flies in cherry trees, and to study the impacts of this and other products on beneficial insect species

Summary of Results

Cherry production is an important part of the Canadian tree fruit industry, and the sector is growing, thanks in part to re-plant programs and better yielding cultivars. In Canada and word-wide, Cherry Fruit Fly has become the most serious pest of cherries, with no market tolerance for the insect either domestically or internationally. With the withdrawal of several broad spectrum insecticides in response to pesticide re-evaluation initiatives, management of this pest has become a serious challenge. For export-oriented growers, solutions must be found which will be acceptable internationally. Owing to the fairly recent emergence of Cherry Fruit Fly as a major pest, little information is available relating to the ecology, life-cycle and behaviour of the insect.

Scientists at Agriculture and AgriFood Canada centres in British Columbia and Quebec worked with international and university colleagues to develop and integrate reduced-risk alternative pest management tools into cherry production. The project paid particular attention to the urban/ rural interface owing to the inter-relationship of insects on trees in gardens and in orchards. The project investigated the potential of a new bio-product, GF120 Naturolyte, a Spinosad® based product which was registered by PMRA for use in Canada in 2006. The product was used in a bait and kill strategy to control Cherry Fruit Flies in and around cherry trees. At the same time, work was underway to assess the impact of both Spinosad® and other novel products, including nicotinoid insecticides, on a number of important predaceous mites and other beneficial insects so as to minimise secondary pest problems.

To ensure effective control for Cherry Fruit Flies when using soft technologies, such as bait sprays, a great deal more information about these pests is required than is currently available. A major part of this project involved improving understanding of the ecology and behaviour of the flies through field studies.

Eight species of Rhagoletis ßitalicize flies were found to be present in sweet and sour cherry orchards but only western cherry fruit fly, R. indifferens and black cherry fruit fly, R. fausta pose a threat to fruit production.

These two pest species emerge and are detected in traps for the entire growing season from early June until late September, with R. fausta populations peaking one to two weeks earlier than R. indifferens.

Monitoring of the flies with traps and lures was significantly improved, when using a Swiss Rebell trap design or an Israeli Frutect trap, than when using the industry standard yellow card trap. Furthermore, an addition of an ammonium carbonate lure (replaced every two weeks) generally doubled the mean capture of male or female R. indifferens on traps.

Surveys and collections of natural enemies of the pest were made in approximately 53 sites in British Columbia. Collection of infested cherries and rearing of up to 21,314 pupae per year from field sites showed relatively high levels (10-20%) of parasitism from at least four genera of parasitoids in seven locations.

A common landscape fabric was assessed for its potential as a physical barrier. The study found that this fabric successfully prevented (90-100% control) the movement of larvae from cherries into the ground and merit testing as a physical control method for use in some sites, in the absence of insecticides, or for private gardens.

The results of this research address the need in the industry for environmentally acceptable alternatives to organophosphate insecticides. In the long term, knowledge gained will improve pest management through better information related to pest biology and ecology, and an understanding of how best to minimize impacts on beneficial insects.

For more information about the project, please contact:

Dr. Howard Thistlewood

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