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IFQRG 2014
Ron Mack Peggy Elder
USDA – APHIS - PPQ – CPHST Otis Laboratory
Buzzards Bay, Massachusetts 02540 USA [email protected] 508-563-0960 office phone
Characterization of Emerald Ash Borer (EAB) Pupal Chamber Location
in Ash Log Sections
• To develop appropriate phytosanitary measures for sawn ash wood, it is critical that we have a clear understanding of the location of EAB life stages in logs
• If pupal chambers are restricted to bark in large
diameter (>12”) logs used in sawn wood production, simple debarking could obviate the need to consider treatments such as fumigation or heat.
Background
Current plant health regulations
• United States requires all bark and ½” of sapwood removed. Canada requires all bark and 1 cm of sapwood of ash sawn wood to be removed to prevent movement of EAB.
• EU has amended core plant health regulations to require all bark and 2.5 cm of sapwood of ash sawn wood to be removed. This regulation to be implemented October 1, 2014.
Summary of relevant literature • EAB prepupae develop in early fall (September-October), forming in chambers that the L4 excavate either in the
bark or slightly into the sapwood (Lyons et al. 2007).
• Wang et al. (2010) found pupal cells located at a range of 4-16 mm in depth under the bark, which was about 1-7 mm below the surface of the xylem sapwood.
• Location of pupal chambers varies among trees of different size; in larger trees with thick bark, they tend to form in the bark. McCullough et al. (2010) reported that “all the EAB prepupae were in the bark of logs that were larger than 12” diameter when the bark was at least ½” thick”.
• Pupal chambers have not been observed to form deeper than 16.5 mm (0.6 inches), measured from the surface of the bark to the deepest part of the pupal cell (McDonald et al. 2006, McCullough et al. 2010).
References
• Lyons, D.B., Caister, C., deGroot, P, Hamilton, B., Marchant, K., Scarr, T. and Turgeon, J.J. 2007. Survey guide for detection of emerald ash borer. Natural Resources Canada – Canadian Forest Service and Canadian Food Inspection Agency, Sault Ste. Marie, Ontario, Canada.
• McDonald, R.J., McCullough, D.G., Poland, T.M., and Steel, A. 2006. On site debarking of logs infested with emerald ash borer: A means utilization. Poster D0487. Entomological Society of America Annual Meeting. Dec 10-13 2006. Indianapolis, IN.
• McCullough, D.G., Poland, T.M and Steel, A. 2010. Debarking high value logs. USDA web report. Accessed August 30, 2014 at: http://www.nrs.fs.fed.us/disturbance/invasive species/eab/control management/debarking/
• Wang, X.Y., Yang, Z.Q., Gould, J.R., Zhang, Y.N., Liu, G.J. and Liu, E.S. 2010. The biology and ecology of the emerald ash borer, Agrilus planipennis, in China. Journal of Insect Science 10:128. Available online: insectscience.org/10.128
Measurement of EAB pupal chambers was referenced from cambium in sawn discs.
Location of field collected White Ash (Fraxinus americana) and Green Ash
(Fraxinus pennsylvanica) in Michigan, 2014.
Smaller diameter material was cut into discs on upright band saw.
Larger diameter ash bolts were cut into discs on a portable band saw mill.
Discs were sawn, marked individually, and reassembled intact for assay.
Cutting and assay of ash discs. Michigan, 2014.
Bolts were reassembled after sawing, keyed by a spray line on bark.
Individual discs were assayed by identifying and circling pupal chambers.
Digital caliper used for measuring pupal chamber depth relative to cambium.
Careful assay screened out occasional non-target insect larvae. Tylonotus bimaculatus (Ash and Privet borer).
Data table for EAB pupal chamber study. Michigan, 2014.
Diameter Range
Mean Log
Diameter (inches)
Mean Bark
Thickness (mm)
Total Number
Bark Chambers
Total Number Sapwood Chambers
Mean BARK Pupal
Chamber Depth (mm)
Mean SAPWOOD
Pupal Chamber
Depth (mm)
Number of Bolts
Mean Bark
Chambers per Bolt
Mean Sapwood Chambers per Bolt
2-3.9 3.43 3.66 39 468 2.70 4.85 71 0.5 6.6 4-5.99 5.09 4.13 85 946 3.36 5.12 77 1.1 12.3 6-7.99 7.04 5.92 354 1470 3.85 5.20 59 6.0 24.9 8-9.9 9.02 7.17 904 1488 4.13 5.42 56 16.1 26.6
10-11.99 11.17 7.76 1428 607 4.40 5.78 61 23.4 10.0 12-13.99 13.06 9.37 2138 645 4.80 6.30 85 25.2 7.6 14-15.9 14.88 11.08 993 334 4.87 5.81 52 19.1 6.4
16-17.99 16.87 12.74 414 173 4.87 5.98 24 17.3 7.2 18-19.99 18.71 12.03 524 58 5.37 5.70 12 43.7 4.8
0.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
16.00
18.00
20.00
Mean Bark Thickness (mm)
Min Bark Thickness (mm)
Max Bark Thickness (mm)
Bark Thickness (mm) for ash bolts by diameter class.
Pupal chamber depth in sapwood by diameter class.
0.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
16.00
18.00
20.00
Mean SAPWOOD PupalChamber Depth (mm)
Sapwood Pupal ChamberDepth Min (mm)
Sapwood Pupal ChamberDepth Max (mm)
Pupal chamber depth in bark by diameter class.
0.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
16.00
18.00
20.00
Mean BARK Pupal ChamberDepth (mm)Bark Pupal Chamber DepthMin (mm)Bark Pupal Chamber DepthMax (mm)
Observations
• Wang et al. (2010) “pupal cells 1-7mm below xylem sapwood”.
• McCullough et al. (2010) “all EAB prepupae were in the bark of logs that were larger than 12” diameter when the bark was at least ½” thick”.
• (McDonald et al. 2006, McCullough et al, 2010) “Pupal chambers have not been observed to form deeper than 16.5mm (0.6 inches), measured from the surface of the bark to the deepest part of the pupal cell.
• We clearly expanded the known depth
range, even in smaller diameter material.
• We found 26 examples of pupal chambers in the sapwood for material >12” diameter and bark thickness >1/2”. Total sapwood chambers 6189. Total bark chambers 6879. Total number bolts 497.
• We found 95 examples where mean bark thickness combined with sapwood chamber depth exceeded 16.5mm.
The sapwood depth removal requirement for ash sawn wood is ½” in the United States and 1cm in Canada. We found 38 examples of sapwood chambers in excess of 1 cm in sapwood for all bolts. There were 28 examples of sapwood chambers exceeding 1 cm depth in ≥ 12” diameter material.
Future Work
Measure pupal chamber depth in different geographic locations (Pennsylvania, Tennessee, etc.)
