Evaluating Impacts of Indigenous and Introduced Parasitoids on Populations of the Invasive Emerald Ash Borer, Agrilus Planipennis Fairmaire
Beneficial Insects Introduction Research
2012 Annual Report
1a.Objectives (from AD-416):
To assess the establishment and impact of exotic and indigenous parasitoids on EAB populations in Maryland.
1. Establishment of at least four parasitoid release / research sites.
2. Determine the establishment and dispersal of released parasitoids at each of the release sites via general surveys.
3. Quantify EAB egg and larval survival and mortality factors via experimentally established cohorts and wild EAB populations.
1b.Approach (from AD-416):
Evaluations of egg and larval survival and mortality factors will be based on EAB life tables developed from marked cohorts of eggs and larvae on common American ash trees at a minimum of four field sites in natural forests, where some indigenous parasitoids may have become associated with EAB, and the three introduced Chinese parasitoids (Oobius agrili, Tetrastichus planipennisi, Spathius agrili) either have already been released or will be released in the first year of the study. Naturally occurring native species (if any) in each of the study sites will be treated as sequential and/or contemporary factors inflicting mortality of EAB along with the previously introduced Chinese parasitoids. If work from associated EAB projects leads to successful discovery and introduction of new species of parasitoids from Russia and/or China, these species will be introduced and then included in the evaluation studies.
Surveys of numerous field sites around Maryland were conducted in spring 2012 to determine the baseline condition of ash trees present, and therefore their suitability for use in the emerald ash borer (EAB) life-table study. Twelve sites were selected, and throughout May and June 2012, 10 trees per site were infested with EAB eggs. 30 eggs were individually attached to each tree, for a total of 3600 EAB eggs. The construction of woodpecker exclusion fences is ongoing, and the releases of the larval parasitoids Tetrastichus planipennisi and Spathius agrili are scheduled to occur in the near future as the EAB larvae reach the 3rd/4th instars. Established EAB egg/larval cohorts in the twelve sites will be sampled in the late fall of 2012 when the parasitoids associated with immature stages EAB are in diapauses for overwintering or early spring of 2013 before the emergence of adults.