Abstract
Selecting entomopathogenic fungal isolates for use as biocontrol agents requires an assessment of their growth and virulence characteristics as affected by environmental conditions. Here we demonstrate a wide temperature and moisture range for colony growth, effective conidial germination and virulence against Pissodes strobi Peck (white pine weevil) of several isolates of Lecanicillium Gams and Zare, an entomopathogenic fungus distributed worldwide and indigenous to forests on Vancouver Island, British Columbia, Canada. In order to examine the potential Lecanicillium as a biological control agent, the pathogenicity of isolates collected from different geographical locations on P. strobi cadavers was assessed, and colony growth at different temperatures was evaluated. Colony growth was evident between 5 and 30°C, with optimal growth occurring at 25°C. Various combinations of water activity (0.55, 0.76, 0.85 and 0.99 a w) and temperature (10, 15, 20, and 25°C) were also used to evaluate environmental impacts on conidial germination and cumulative mycosis of adult P. strobi. Certain Lecanicillium isolates displayed xerophilic (0.85 a w) or psychrophilic (10°C) growth optima. Ultimately, identifying the abiotic limits of this entomopathogenic fungus will be used to determine which isolates have potential for future in situ biocontrol trials.
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Acknowledgments
The authors would like to acknowledge the funding supplied by Natural Resources Canada (Canadian Forest Service, Enhanced Pest Management Methods program) for this ECOBIOM (Extended Collaboration on Biological Control of Forest Insects or Pathogenic Microorganisms) project. The authors also thank Koppert Canada Ltd. for providing Mycotal® and Vertalec® for the experiments. Technical support provided by George Brown and Lara van Akker was indispensable.
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Kope, H.H., Alfaro, R.I. & Lavallée, R. Effects of temperature and water activity on Lecanicillium spp. conidia germination and growth, and mycosis of Pissodes strobi . BioControl 53, 489–500 (2008). https://doi.org/10.1007/s10526-007-9087-z
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DOI: https://doi.org/10.1007/s10526-007-9087-z