Using non-woven bands impregnated with the entomopathogenic fungus Metarhizium anisopliae for biological control of the Asian longhorned beetle, Anoplophora glabripennis
Shanley, Ryan Patrick
The Asian longhorned beetle, Anoplophora glabripennis (Motschulsky), is a tree-boring cerambycid that has invaded northeastern North America, where it poses a serious threat to urban and forest trees. The use of non-woven fiber bands impregnated with Metarhizium anisopliae F 52 (fungal bands) for control of adult A. glabripennis is in development. Studies were conducted to evaluate whether conidia from fungal bands disperse in the environment and whether adult A. glabripennis can acquire infection through exposure to environments contaminated with conidia. In the field, fungal bands containing M. anisopliae were hung at a height of 3 m on 15 trees. Bark samples were taken 10, 20 and 30 cm above the bands and 10, 30, and 60 cm below the bands 2, 5, and 9 days after band placement to quantify conidial densities. There were significantly more conidia in samples taken below bands (average = 4.7 ? 1.1 conidia/sample) compared with samples taken above bands (average = 1.0 ? 0.3 conidia/sample). A significant positive correlation was found between rainfall and the occurrence of conidia on any of the bark samples. A laboratory study was conducted to determine whether conidia from Metarhizium anisopliae F 52 fungal bands could be spread to other parts of the environment, and whether A. glabripennis could become infected by conidia dispersed from fungal bands. One or five adult A. glabripennis were used to contaminate artificial environments with conidia after being exposed to fungal bands. All adults subsequently exposed to contaminated environments were killed by fungal infection. Furthermore, beetles exposed to environments that had been contaminated by five beetles died in significantly fewer days (16.2 ? 1.1 d) compared with environments contaminated by one beetle (27.9 ? 2.5 d). Beetles in both density treatments died in significantly fewer days than beetles exposed to environments without M. anisopliae conidia (114.9 ? 16.2 d). These results indicate that environmental contamination with conidia from fungal bands can occur, and that adult A. glabripennis can acquire infection from a contaminated environment. Lastly, in a laboratory bioassay, beetles were immobilized on M. anisopliae F 52 fungal bands for 30 seconds to quantify the median lethal dose, measured in number of viable conidia per square centimeter of a fungal band, for M. anisopliae F 52 fungal bands against adult A. glabripennis. Correlations were found between dose and mortality and between dose and beetle longevity for beetles presumed to have died as a result of fungal infection. A median lethal dose of 6.80 x 106 conidia/cm2 was calculated. These results suggest that M. anisopliae F 52 fungal bands, which have been shown to retain densities greater than 1 x 107 viable conidia/cm2 for at least 112 days (in New York City), would only need to be hung on trees once per season to enable exposure to the majority of adult A. glabripennis in US infestations each year.
committee members: Ann E. Hajek (chair), John D. Vandenberg
Asian longhorned beetle; Anoplophora glabripennis; Metarhizium anisopliae; biological control; fungal bands; fungus
dissertation or thesis