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Evaluation of tree mortality and parasitoid recoveries on the contiguous western invasion front of emerald ash borer
Author(s) -
Johnson Todd D.,
Lelito Jonathan P.,
Pfammatter Jesse A.,
Raffa Kenneth F.
Publication year - 2016
Publication title -
agricultural and forest entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.755
H-Index - 55
eISSN - 1461-9563
pISSN - 1461-9555
DOI - 10.1111/afe.12164
Subject(s) - emerald ash borer , agrilus , biology , buprestidae , fraxinus , botany , parasitoid , ecology , biological pest control
A recent invader to N orth A merica, emerald ash borer A grilus planipennis F airmaire ( B uprestidae), is expanding its western range into new habitats. We examined how site factors affect the emergence and damage caused by this beetle on the western edge of its contiguous population in eastern W isconsin, U.S.A . We characterized forest structure and quantified signs and symptoms of A . planipennis from 2010 to 2013. We evaluated the potential for establishment of three host‐specific parasitic H ymenoptera, released as biological control agents of A . planipennis . During J une to S eptember 2011, we conducted releases of 1500 O obius agrili Z hang and H uang ( E ncyrtidae), 1900 S pathius agrili Y ang ( B raconidae) and 2700 T etrastichus planipennisi Y ang ( E ulophidae) at the same location. Signs and symptoms of A . planipennis increased in abundance during the present study. Emergence of A . planipennis was greater in larger diameter trees and in subplots with more ash trees. More epicormic shoots were on the upper halves of trees in subplots with a higher percentage of ash. F raxinus nigra exhibited a higher incidence of ruptured bark than F raxinus pennsylvanica . In J anuary 2013, we felled four infested ash trees and censused insect emergence from the entire trees. We recovered 441 A . planipennis, 41 T . planipennisi and no other released parasitoids. These results suggest that, of these three parasitoids, T . planipennisi has the highest likelihood of contributing to biological control in W isconsin, although ash mortality will proceed rapidly and likely supersede the effects of the parasitoids. The best opportunity for introduced parasitoids to benefit W isconsin may arise in post‐outbreak, recovering forests.