Developing methods to detect parasitoids released for biological control of the emerald ash borer

USDA Forest Service Forest Health Protection (Northeastern Area); USDA Forest Service Northern Research Station; USDA Animal and Plant Health Inspection Service Plant Protection and Quarantine; USDA Agricultural Research Service; Michigan State University; University of Massachusetts

SUMMARY: Researchers developed and tested methods to detect three introduced emerald ash borer (EAB) biological control agents (parasitoids) in the interest of optimizing release strategies.

At parasitoid-release sites with moderate EAB densities in Michigan, researchers made and deployed 1) “egg sentinel logs” by exposing ash logs to egg-laying EAB females,  2) “larval sentinel logs” by inserting EAB larvae into similar logs, and 3) yellow pan traps that could collect adults of the three parasitoid species. At each field site, researchers released relatively large numbers of each parasitoid species at multiple time intervals during the field season to facilitate parasitoid establishment and reproduction. Egg sentinel logs, larval sentinel logs, and yellow pan traps were evaluated to see if they would be valuable tools in surveying for established and impact of the three parasitoids. Information on parasitoid dispersal distances and population densities would help optimize parasitoid release frequencies and numbers.

Overall, egg sentinel logs (ESLs) were an effective monitoring tool for the egg parasite Oobius  agrili, although production of ESLs is labor intensive. Seasonal deployment of ESLs, provided valuable data on O. agrili biology in the United States. Parasitized EAB eggs were first detected in late June and early July [~940 degree days base 50 (DD50)]. Egg parasitism increased through the summer and peaked in early August [~2000 DD50] and declined thru September.

Larval sentinel logs were a powerful tool to track the establishment and prevalence of the larval parasite Tetrastichus planipennisi and interactions with a native parasitoid Atanycolus spp. Spathius agrili, the third non-native parasite released on these sites rarely parasitized larvae in larval sentinel logs

Yellow pan traps were useful in trapping both S. agrili and T. planipennisi but not O. agrili. The usefulness of pan traps in trapping S. agrili was an important discovery, and resulted in the expansion of yellow pan trapping to additional release sites in MI and to other states including IL, PA, and NY by APHIS and state land managers. As a result, S. agrili and T. planipennisi have been detected at release sites in several additional states.

EFETAC'S ROLE: This project is supported by EFETAC funding.

STATUS: Completed. Some additional follow-up survey work is underway using funds from the Northern Research Station.

PROGRESS: In addition to the work described above, researchers and cooperators are deploying yellow pan traps at EAB biocontrol release sites as a simple and inexpensive method to determine parasitoid establishment. Researchers expanded the known establishment and distribution of Spathius agrili at three study sites in Michigan. The yellow pan trap method was provided to the EAB Biocontrol Program, and the traps were deployed in 2011and 2012 by land managers in Michigan, Illinois, and West Virginia, and by researchers in Indiana to determine parasitoid establishment at release sites.

Abell K, Bauer LS, Duan J, Van Driesche R. The seasonal and spatial distribution of Oobius agrili (Hymenoptera: Encyrtidae) parasitizing emerald ash borer eggs in Michigan. Manuscript planned after this field season.

Bauer LS, Hansen J, Gould J. 2011. Yellow Pan Traps: A Simple Method for Trapping Larval Parasitoids Released for Biological Control of the Emerald Ash Borer.

Bauer, LS, JJ Duan, J Gould.  Emerald ash borer (Agrilus planipennis Fairmaire) (Coleoptera: Buprestidae).  Saving Trees, Saving Forests: Use of Classical Biological Control to Preserve Native US and Canadian Forests. 56 pp. Book Chapter. In press.

Duan, J.J., L.S. Bauer, M.D. Ulyshen, J.R. Gould, and R. Van Driesche. 2011. Development of methods for the field evaluation of Oobius agrili (Hymenoptera: Encurtidae) in North America, a newly introduced egg parasitoid of emerald ash borer (Coleoptera: Buprestidae). Biological Control 56:170-174.

Duan, J. J., L. S. Bauer, J. A. Hansen, K. J. Abell, R.Van Driesche. 2012. An improved method for monitoring parasitism and establishment of Oobius agrili (Hymenoptera: Encyrtidae), an egg parasitoid introduced for biological control of the emerald ash borer (Coleoptera: Buprestidae) in North America.  Biological Control 60: 255-261.

Duan, J. J., L. S. Bauer, K. J. Abell, and R. Van Driesche. 2012. Population responses of hymenopteran parasitoids to the emerald ash borer (Coleoptera: Buprestidae) in recently invaded areas in north central United States. BioControl 57: 199–209.

Hansen J, Bauer LS, Duan J. Field detection of introduced emerald ash borer (Agrilus planipennis) parasitoids using larval sentinel logs and yellow pan traps:  a proof of concept study. Great Lakes Entomol. Manuscript in prep.

Ulyshen MD, Duan JJ, Bauer LS, Gould J, Taylor P, Bean D, Holko C, Van Driesche R. 2011. Field-cage methodology for evaluating climatic suitability for introduced wood-borer parasitoids: Preliminary results from the emerald ash borer system. Journal of Insect Science 11: 1-10.


Steve Katovich, Northeastern Area Forest Health Protection, or (651) 649-5264

Updated December 2012

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