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Northern Research Station
11 Campus Blvd., Suite 200
Newtown Square, PA 19073
(610) 557-4017
(610) 557-4132 TTY/TDD

Emerald Ash Borer

Modeling Spread of Emerald Ash Borer

Research Issue

Since its discovery near Detroit, MI, and Windsor, ON, in 2002, the emerald ash borer (EAB) has continued to spread through natural dispersal and movement of infested firewood, logs, and nursery stock into 25 states and 2 provinces as of March 2016.  Quarantine regulations restrict movement of ash woody material from regulated to un-regulated areas. However, ash material was moved freely for at least a decade after EAB likely became established (in the 1990s) before EAB was discovered and quarantine regulations were imposed. Ash material may also be moved within regulated areas. Detection of EAB is extremely difficult during the early stages of infestation, when there are few visible signs of attack. Understanding the dispersal capabilities and spread rates of EAB is necessary to predict how far from known infested trees EAB is likely to be. Dispersal and spread models are also useful for deciding where to focus survey activities and for implementing and evaluating management options. 

 Our Research

EAB on flight mill
We conducted research to determine the flight and natural spread capability of EAB males and females and to evaluate the realized dispersal of EAB at isolated infestation sites. Mated and unmated, fed and unfed, male and female EAB were tethered to flight mills and their flight behavior and distance were recorded. We also measured free flight in the laboratory with a mirror and high-speed video-recorder that allowed for precise 3-dimensional trajectory measurements. We assessed realized EAB dispersal at two discrete outlier sites that originated 1 year and 3 years earlier from infested nursery trees. Ash trees were systematically sampled within an 800-m radius of the origin of each infestation to locate galleries constructed by the progeny of dispersing EAB adults. We also gathered data on tree cover and land-use within the sampling area of each outlier site to determine if EAB dispersal was related to ash abundance and distribution and land use (wooded, residential, agricultural, or urban) within the dispersal area.

Expected Outcomes

The flight performance of mated females suggests a considerable capacity for range expansion by this invasive species. Understanding how far EAB beetles may disperse and whether site-related factors influence dispersal could help officials develop appropriate protocols for EAB detection, delimitation surveys, regulatory activities, management implementation, and evaluation of control measures. Such information is also needed to accurately predict the rate and pattern at which EAB infestations expand spatially.

Research Results

Mated females flew further per day and longer than unmated females or males. Mated females that were allowed to feed between flight periods flew an average of 1.3 km/day for 4 days; 10% flew more than 7 km/day. Free-flight speeds were approximately three times the speeds recorded by the flight mills, suggesting that tethering may have impeded flight. The median corrected distance flown by mated females was >3 km, with 20% flying >10 km and 1% flying >20 km. 

At the outlier site established 1 year before sampling, we identified 8 trees with a mean attack density of 11.6 larvae per square meter. At the outlier site established 3 years prior to sampling, we found 12 trees with a mean attack density of 25.8 larvae per square meter. Colonized trees were found out to 638 and 540 m from the epicenters at the 1 year and 3 year sites, respectively. Ash phloem abundance and distance from the epicenter strongly influenced the distribution of EAB attacks. Prevailing wind and land use type did not strongly influence EAB dispersal.

Taylor, R.A.J.; Bauer, L.S.; Poland, T.M.; Windell, K. 2010.  Flight performance of Agrilus planipennis (Coleoptera: Buprestidae) on a flight mill and in free flight.   Journal of Insect Behavior 23: 128-148. 

Siegert, N.W.; McCullough, D.G.; Williams, D.W.’ Fraser, I.; Poland, T.M.; Pierce, S.J.  2010.  Dispersal of Agrilus planipennis (Coleoptera: Buprestidae) from discreet epicenters in two outlier sites.  Environmental Entomology39:253-265.

Siegert, N.W.; Mercader, R.J.; McCullough, D.G.; Liebhold, A.M.; Poland, T.M.; Heyd, R.L.; 2009. Manipulating spread and predicting dispersal of isolated emerald ash borer populations. In: McManus, K.A; Gottschalk, K.W., eds. Proceedings, 20th USDA Interagency Research Forum on Invasive Species. 2009 January 13-16; Annapolis, MD. GTR-NRS-P-51. Newtown Square, PA: USDA Forest Service, Northern Research Station: 54-55.

Research Participants

Principal Investigator

  • Therese Poland, US Forest Service, Northern Research Station, Research Entomologist

Research Partners

Last Modified: 03/07/2016