A Review of Commercial Metarhizium- and Beauveria-Based Biopesticides for the Biological Control of Ticks in the USA

Simple Summary

Microbial biopesticides containing entomopathogenic fungi have potential in tick management. In this review, we compiled a comprehensive list of the use of commercialized Metarhizium and Beauveria-based biopesticides in the USA that have been tested against ixodid ticks under laboratory and field conditions and when used as a part of integrated tick management. Despite considerable progress in the development of fungal biopesticides over the past 20 years, the establishment of commercial products available for use against ticks continues to be slow. There is a need for the development of sustainable, nonchemical tick management strategies. Until efficacious fungus-based products become more available, tick management will rely primarily on synthetic chemical acaricides, with natural-product acaricides as the alternative.

Abstract

There is a need for the development of sustainable, nonchemical tick management strategies. Mycoacaricide and mycoinsecticide product development worldwide has focused primarily on fungi in the genera Beauveria (Hypocreales: Cordycipitaceae) and Metarhizium (Hypocreales: Clavicipitaceae). Microbial biopesticides containing entomopathogenic fungi have potential in tick management. However, despite considerable progress in the development of fungal biopesticides over the past 20 years, the establishment of commercial products available for use against ticks continues to be slow. We reviewed published scientific literature and compiled a comprehensive list of reports of the effectiveness of commercial biopesticides based on the fungal genera Metarhizium and Beauveria and registered for use in the USA against ixodid ticks under laboratory and field conditions. We also report on results when these biopesticides were used as a part of integrated tick management. Until efficacious fungus-based products become more available, tick management will rely primarily on synthetic chemical acaricides, with natural-product acaricides as the alternative.

Evaluation of spray applications of Metarhizium anisopliae, Metarhizium brunneum and Beauveria bassiana against larval winter ticks, Dermacentor albipictus

Dermacentor albipictus (Acari: Ixodidae), the winter tick, is a one-host tick that parasitizes large ungulates. They can dramatically affect moose, Alces alces (Artiodactyla: Cervidae), causing significant physiological and metabolic stress and mortality among heavily parasitized individuals. Entomopathogenic fungi in the genera Metarhizium (Hypocreales: Clavicipitaceae) and Beauveria (Hypocreales: Cordycipitaceae) are promising tick biological control agents. We examined the pathogenicity of experimental and commercially formulated isolates of M. anisopliae, M. brunneum and B. bassiana sprayed at concentrations of 10⁶, 10⁷ and 10⁸ conidia/mL against the larval stage of D. albipictus and assessed the efficacy of spraying the commercial product Met52®EC, containing M. brunneum, strain F52, under laboratory conditions. Results showed larval D. albipictus mortality was significantly higher and occurred earlier when treated with M. anisopliae and M. brunneum isolates compared to B. bassiana at 10⁶, 10⁷ and 10⁸ conidia/mL. Mortality was observed as early as 3 days in the M. anisopliae and M. brunneum treatments and after 6 days in the B. bassiana treatments. After 21 days, larval mortality ranged from 74-99% when ticks were treated with M. anisopliae and M. brunneum isolates at 10⁶, 10⁷ and 10⁸ and conidia/mL. In contrast, mortality of ticks treated with B. bassiana ranged from 30 to 64%. When larvae were treated with the commercial product Met52, mortality was ~ 45% after 3 days and ~ 96% after 9 days. These results demonstrate the effectiveness of M. anisopliae and M. brunneum against D. albipictus.