Comparing sentinel larval log preparation methods for Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) larval parasitoid monitoring

Three Asiatic larval parasitoid species, Spathius agrili Yang (Hymenoptera: Braconidae), Spathius galinae Belokobylskij & Strazanac, and Testrastichus planipennisi Yang (Hymenoptera: Eulophidae) have been released in North America for emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) biological control.  One or more of these species have been released in at least 30 U.S. states and 3 Canadian provinces.  Effective monitoring tools for introduced parasitoids are crucial for the success of the EAB biological control program.  Small ash logs containing EAB larvae (i.e., sentinel larval logs) can be an effective method for recovering EAB larval parasitoids.  However, their preparation can be labor intensive, and availability of certain host materials may be limited.  We compared recovery of EAB larval parasitoids using different sentinel larval log preparation methods that varied in labor and host material requirements.  These included: dissected EAB larvae inserted into green ash (Fraxinus pennsylvanica) logs, EAB larvae reared directly from eggs placed on green ash logs, or EAB larvae reared directly from eggs placed on tropical ash (Fraxinus uhdei) logs.  Sentinel larval logs were deployed at sites throughout the growing season in Michigan where EAB larval parasitoids were established.  Each log remained in the field for 3-4 weeks, after which it was brought back to the laboratory and monitored in rearing containers for parasitoid emergence.  After emergence was complete, logs were dissected to examine for EAB larval parasitism.  Pros and cons of each sentinel larval log preparation method and recovery efficacy will be discussed.