Development of a biopesticide for management of wireworms in potatoes

Project code: MU03-270

Project Lead

Todd Kabaluk - Agriculture and Agri-Food Canada.

Objective

To develop a biopesticide option for the control of wireworm in potato.

Summary of Results

Wireworms (Agriotes spp and others) have a long history as pests of agricultural crops in Canada. While they can attack almost any crop, in potato the impacts are particularly severe, as feeding on daughter tubers causes a great reduction in marketable crop yield.

This project developed a biopesticide to control wireworms by making use of a known fungal pathogen of insects, Metarhizium anisopliae. A number of local isolates of M. anisopliae were investigated by AAFC researchers during the course of this project in an effort to take advantage of the natural relationship between the fungal disease agent and the insect. Experience with other crops has shown that these insect-attacking fungi are well suited for the long-term management of some insect pests. M. anisopliae is pathogenic toward Agriotes adults (click beetles) in addition to larvae, and adults are able to transmit infection from beetle to beetle.

While much of the work focussed upon isolate screening, characterization, environmental effects and virulence, the research project also drew on private sector expertise to assess the feasibility of production scale-up and commercialization of the most promising of these British Columbia lower mainland M. anisopliae isolates as a potential fungal biopesticide.

The studies undertaken have shown that there is genetic similarity of soil-acquired isolates of M. anisopliae from the lower mainland of BC. It has been determined that local (Agassiz, B.C. and vicinity) isolates are more virulent toward wireworms than are the commercially available Metarhizium isolates. Different species of wireworms exhibit differences in susceptibility to M. anisopliae infection.

A technique to genetically fingerprint M. anisopliae isolates was developed and a gene bank of M. anisopliae isolates, many of which are pathogenic to wireworms was established.

None of the non-target insects tested was infected by the Agassiz isolate of M. anisopliae, but occasionally infections by the commercial isolate F52 were observed in non-targets. Temperature ranges over which M. anisopliae exhibit maximum growth have been identified, however it was found that conidia production for the Agassiz isolate is low and large scale field trials planned for 2006 had to be curtailed as a result.

While it was demonstrated that applications of M. anisopliae infect and kill wireworms under field conditions, the efficacy of M. anisopliae as a biocontrol for wireworms is constrained by soil moisture and type, duration and temperature of exposure, and by the repellent nature of very high levels of soil conidia, the reproductive and infectious structure of the fungus. When soil applied, the biocontrol has been shown to be compatible with spray regimes for both fungicides and insecticides and, in an unexpected laboratory finding, the efficacy of M. anisopliae was synergized in the laboratory by combining it with low levels of Spinosad®.

The relevant findings from this research project support data collection in advance of registration of the biopesticide for control of wireworms in potatoes.

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