ORIGINAL PAPER The mating and oviposition behavior of the invasive emerald ash borer (Agrilus planipennis), with reference to the influence of host tree condition David E. Jennings • Philip B. Taylor • Jian J. Duan Received: 12 June 2013 / Accepted: 22 November 2013 / Published online: 1 December 2013 Ó Springer-Verlag Berlin Heidelberg (outside the USA) 2013 Abstract Emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is an invasive wood- boring beetle first detected in North America in 2002. Relatively little is known about the factors affecting the mating and oviposition behavior of EAB, even though they could have implications for the management of this spe- cies. Consequently, we conducted field surveys in Michi- gan to observe the diurnal behavior of EAB adults, in addition to examining how their behaviors associated with reproduction varied in relation to the size and condition of host trees. We observed most EAB adults between 11:00 and 15:00, and this pattern was the same for both sexes and for all of the specific behaviors examined (feeding, flying, mating, resting, and walking). Regarding host tree size and crown condition, we consistently found that the most EAB eggs, adults, mating pairs, and ovipositing females were observed on intermediately stressed trees with 40–60 % crown reductions (likely resulting from earlier EAB infestations). Additionally, host tree crown condition appeared to be a more important factor than diameter at breast height. Our results therefore provide support to the hypothesis that host tree crown (stressing) condition influences EAB oviposition behavior. Determining which trees are likely to contain the most EAB eggs should help to guide efforts for releasing and promoting the establishment of parasitoids utilized in biologic control. However, future work should attempt to experimentally test the hypothesis that host tree condition (e.g., crown reduction) drives EAB oviposition behavior, and investi- gate the fitness implications of these host choices. Keywords Biologic control Á Crown condition Á DBH Á EAB Á Host selection Introduction Emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is an invasive wood-boring beetle that is responsible for killing millions of ash trees (Fraxinus spp.) in North America after being accidentally introduced from northeastern Asia. First identified in the United States in Michigan in 2002 (Cappaert et al. 2005b; Poland and McCullough 2006), as of October 2013 EAB has spread to a further 20 states and two Canadian prov- inces (USDA-APHIS 2013). Future treatment and/or removal of affected ash trees is projected to cost more than $10 billion over the next decade (Kovacs et al. 2010), and the loss of ash stands will likely have a myriad of other ecological impacts (Gandhi and Herms 2010; Hausman et al. 2010; Ulyshen et al. 2011; Flower et al. 2013a). Consequently, suppressing populations of EAB will have clear benefits both economically and environmentally. However, we still know relatively little about the repro- ductive behavior of this species or how host trees affect their mating and oviposition behavior, which could have implications for predicting EAB spread and biologic control. Understanding the life-cycle of EAB could provide some insight into what factors influence their reproductive Communicated by M. Traugott. D. E. Jennings (&) Department of Entomology, University of Maryland, 4112 Plant Sciences Building, College Park, MD 20742, USA e-mail: dejennin@umd.edu P. B. Taylor Á J. J. Duan USDA-ARS, Beneficial Insects Introduction Research Unit, Newark, DE 19713, USA 123 J Pest Sci (2014) 87:71–78 DOI 10.1007/s10340-013-0539-1