Emerald ash borer, Agrilus planipennis Fairmaire, an insect native to central Asia, was first detected in southeast Michigan in 2002, and has since killed millions of ash trees (Fraxinus spp.) in North America. The objectives of this study were to 1) determine an optimal sampling location on girdled ash trap trees for detection of A. planipennis larvae based on measurements of tree characteristics, and 2) develop a whole-tree estimation method for extrapolating larval densities from subsampled heights. We conducted sampling at 1-m increments, recording larval presence, height on tree bole, bolt diameter, and bark roughness for 58 infested ash trees. Analyzing height and diameter separately, generalized linear mixed models indicated the probability of A. planipennis detection was maximized at 17.2 cm for diameter and increased linearly as vertical height increased. There was also a positive relationship between intermediate bark roughness and A. planipennis presence. Stepwise regression indicated the optimal bolts for extrapolating whole tree larval densities were, in order of importance, at heights of 1–2 m, 4–5 m, 7–8 m, and 0–1 m. Subsampling with just one or two bolts explained 70% and 86%, respectively, of the variance in A. planipennis densities. Our results can be used by resource managers to improve efficiency of detection efforts and estimate infestations of A. planipennis.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 42 • No. 3