2009 Annual Report
1a.Objectives (from AD-416)
The purpose of this agreement is to quantify the impact of introduced parasitoids on the survival of emerald ash borer (EAB), Agrilus planipennis Fairmaire, populations. The work will be done in the US, using one species of American ash (Fraxinus pennsylvanica). Evaluations will be based on life tables developed from marked cohorts of eggs and larvae at six field sites in natural forests where the parasitoids imported to the US to control EAB either have already been released or will be released in the first year of the study. Specific objectives will be:
1. Locate 3 control and 3 treatment sites. At the treatment sites, release the three EAB parasitoids imported from China (Oobius agrili, Tetrastichus planipennisi , Spathius agrili).
2. At all sites, assess the impact of parasitoids on cohorts of EAB eggs and larvae/pupae in green ash (F. pennsylvanica)
3. Use data from EAB cohort studies to develop life tables for EAB populations and compare stage specific survival rates and other life table parameters.
1b.Approach (from AD-416)
We will test whether parasitoids introduced from China will greatly reduce survival of emerald ash borer cohorts on green ash trees (F. pennsylvanica) in U.S. Work will be done in Michigan at three control and three treatment sites, the latter where three introduced EAB parasitoids either have been or will be released. Cohorts of EAB eggs and larvae/pupae will be created at each site, and used for construction of site-specific life tables for measuring the impact of released parasitoids.
Cohorts of approximately 1500 EAB eggs and 300 larvae were established on 60 ash trees at six selected sites (three treatment sites and three control sites) during the summer months of 2008 and 2009. In collaboration with USDA APHIS and FS, over 3,000 individuals of three introduced parasitoids (T. planipennisi, S. agrili, and O. agrili) were released into each of the three treatment sites following the establishment of EAB cohorts. Field observations of the established cohorts in both 2008 and 2009 indicated that there was a high proportion (30 - 70%) of the EAB eggs preyed upon possibly by ants and other arthropod predators, whereas the percent parasitism by the egg parasitoid (O. agrili) was low (< 1%). No cohorts of EAB larvae established in 2008 were parasitized by any of the released parasitoids; however approximately 10% of late EAB larvae collected in July of 2009 from the randomly selected trees in the treatment (parasitoid release) sites were successfully attacked by the introduced larval parasitoid (T. planipennisi). In addition, more cohorts of EAB eggs and larvae have been established in the summer of 2009, and will be sampled in the summer of 2010 to further measure the impact of the introduced EAB parasitoids. This research documents research conducted under a Reimbursable Agreement between ARS and the University of Massachusetts.