Barry J. Hicks
College of the North Atlantic
SERG Project #2006/12
Year of Project: 2006
Report Received: 2007
Three isolates of Beauveria bassiana were obtained from three different host insects. They were tested in laboratory bioassays against the larvae of the eastern spruce budworm, Choristoneura fumiferana.
An isolate (A) originally taken from a noctuid moth larvae was effective against the larvae of the budworm but the profuse sporulation characteristic of this fungus was not evident. This may be supporting evidence for strain specificity of B. bassiana that is seen in the literature.
Two other isolates (B & C) that were originally taken from 2 different species of tortricid caterpillars, were also very effective against the budworm and showed more promise as both caused profuse sporulation in the budworm cadavers.
Beauveria bassiana showed very good storage capacity. Isolate A was stored at 5oC for 5 years and upon re-initiation, was still very effective against the budworm larvae.
The fungi’s potential increased with data showing a low impact on non-target organisms. The terrestrial isopod, Porcellio scabers was not affected and the lady beetle, Hippodamia convergens was little affected. Only the highest dosage tested (107 spores/insect) against adults of H. convergens showed an increased mortality over that in the controls. The literature suggests that lady beetles are more sensitive to the effects of entomopathogenic fungi in lab-bases bioassays mainly because of the stressful conditions and the fact that the environmental conditions experienced in the lab are unrealistic to natural habitats.
This study has shown that B. bassiana has great potential to be a biological control agent against the larvae of the eastern spruce budworm. This fungus should be explored further against this and other forest pest Lepidoptera.