Evaluation of Met52 for the management of thrips in greenhouse ornamentals

Project Code BPR11-060

Project Lead

Les Shipp  Agriculture and Agri-Food Canada

Michael Brownbridge  Vineland Research and Innovation Centre

Objective

To develop efficacy and crop tolerance data in support of a regulatory submission for Met52 (Metarhizium anisopliae strain F52) for the control of thrips in greenhouse ornamentals (Chrysanthemum spp.)

Summary of Results

Background

During the 2010 Biopesticides Priority Setting workshop Met52 was selected as the priority biopesticide solution for the management of thrips in greenhouse ornamentals.

Thrips are considered to be the most destructive insect pest in greenhouse ornamentals and vegetables due to direct damage by feeding on plant foliage and flowers. In ornamentals, thrips cause dry, stippled or spotted leaves, deformed flowers and other symptoms affecting marketability of the crop. They are known to be difficult to control for a number of reasons, including the broad range of hosts, high reproduction capacity, rapid life cycle, and resistance to various insecticide chemical classes.

Met52 Granular Bioinsecticide is a biopesticide based on the entomopathogenic fungus Metarhizium anisopliae strain F52 (Novozymes Biologicals), which controls insects through a pathogenic mode of action. Fungal conidia which come into contact with the target pest germinate and penetrate the insect’s cuticle and infect the insect. Unlike conventional products, biopesticides based on entomopathogenic fungi normally take a few days before control is achieved, but are capable of providing prolonged activity against the target.

During this project, the efficacy of Met52 on thrips was to be evaluated on Chrysanthemum with the goal to use gathered data to support the addition of thrips management in ornamentals to the label of Met52 Granular Bioinsecticide.

Approaches

Three trials were carried out at the Vineland Research Centre and Agriculture and Agri-Food Canada's Greenhouse and Processing Crops Research Centre at Harrow, Ontario. The product was applied as a granular formulation, which was blended with or overlaid on the potting soil as a single treatment at the time of planting. The Met52 treatments were compared to an untreated control and a commercial standard treatment (spinosad). Endpoints evaluated were the impact of the treatment on the thrips population as well as damage to the crop.

Results

In all three trials, a reduction of thrips numbers was observed following the application of Met52, with the soil incorporated treatment achieving better results than the overlay application. Thrips populations in the pots treated with Met52 were reduced by between approximately 28% and 55%. Soil samples taken over the course of the trial confirmed that Metarhizium conidia remained active in the soil over the trial period, thus providing continuing protection over the course of the trial.

In trial BPR11-061 a single application of Met52 G was applied at a rate of 1500 grams per cubic meter (g/m3), mixed into the top 3 centimeter (cm) of the growing media and overlain on the top of the growing media at the time of planting, with commercial standard Success and untreated plots serving as controls. The overlay soil treatments of Met52 G granular did not significantly reduce the thrips population, however the treatment blended into the top 3 cm of potting soil did result in an up to 28% reduction of thrips.

In trial BPR11-062 thrips populations were not significantly reduced when the equivalent of 1500 g/m3 (adjusted for viability) was incorporated into only the top 3 cm of soil. The complete incorporation of Met52 G into the growing media for the chrysanthemum pots resulted in a reduction of the thrips population of 31%, though this was not statistically significant, due to relatively high variability.

Both BPR11-061 and BPR11-062 were conducted as cage trials and thus may not be representative of how a product will perform in a commercial setting.

In BPR11-063, a bench trial which more closely reflected commercial conditions, thrips movement was prevented by barriers instead of cages. Significant differences were observed in all treatments at the 1500 g/m3 rate, with thrips reductions of 45 and 55% respectively in the bulk and overlay treatments. Treatment of potting soil with Met52 Granular Bioinsecticide was demonstrated to reduce thrips by up to 50%. While this level of control is not sufficient to protect the crop from thrips damage, this reduced risk product is expected to add significant value to the integrated pest management toolbox for managing this destructive and difficult to control pest.

Published research suggests that Metarhizium can act synergistically with conventional insecticides, thus further enhancing the value of the product in an IPM (Integrated Pest Management) approach. The addition of a new mode of action will also help improve resistance management, which is of critical concern for this pest.

The Pesticide Risk Reduction Program has complemented results from this project with data from other trials with this product conducted in the United Kingdom. It has prepared and submitted a label expansion request for the addition of thrips management in ornamentals to the label of Met52 Granular Insecticide to the Pest Management Regulatory Agency (PMRA) of Health Canada.

The PMRA has completed their review of this submission and the use has been added to the label. Registration of this new use pattern will help growers reduce pesticide risk and will increase control options for this economically very significant pest.

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