|JENNINGS, DAVID - University Of Maryland|
Submitted to: Journal of Pest Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/22/2013
Publication Date: 12/1/2013
Citation: Jennings, D.E., Taylor, P.B., Duan, J.J. 2013. The mating and oviposition behavior of the invasive emerald ash borer (Agrilus planipennis), with reference to the influence of host plant condition. Journal of Pest Science. (2014) 87:71–78.
Interpretive Summary: Emerald ash borer (EAB) is an insect pest that has killed millions of ash trees (Fraxinus spp.) in North America since being discovered in Michigan in 2002, and the management of EAB is projected to cost over $10 billion in the coming decade. Knowing how the behavior of EAB adults varies over the course of a day, and how tree health and size affects where they choose to mate and lay eggs should enable us to more effectively control this pest. For example, it will allow us to better predict how EAB will spread, and to determine the best locations for releasing parasitoids for biological control. Toward that end, we surveyed EAB behavior on ash trees in Michigan in 2008 and 2009. EAB adults were most frequently observed on trees in late-morning and early-afternoon. When examining the influence of tree health and size on EAB behavior, we found that trees experiencing intermediate levels of stress (caused by previous EAB infestation) appeared to be preferred by EAB adults for mating and laying eggs. However, the size of ash trees has a less important influence on where EAB adults mated and laid eggs. These findings should help future biological control efforts, as they suggest that egg parasitoids might have the greatest chance for establishing populations on previously infested ash trees. Future research should test our results using an experimental approach, and also investigate how tree health and size affects larval development.
Technical Abstract: The emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) is an invasive wood-boring beetle accidentally introduced to North America from northeastern Asia. While our knowledge of EAB ecology has increased greatly over the past decade, we still know relatively little about the factors influencing their behavior and host selection. To address these issues, we conducted field surveys in Michigan examining the diurnal behavior of EAB, as well as how host size and crown condition affected mating and oviposition behavior. Observations of diurnal behavior were recorded over two days in the summer of 2008, while our surveys of eggs, mating, and oviposition behavior were conducted in the summer of 2009. We found that most EAB adults were observed between 11:00 am and 3:00 pm, and this pattern was the same for females and males and for all five of the specific behaviors we examined (feeding, flying, mating, resting, and walking). In terms of the influence of host plant 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 (mostly due to earlier EAB infestations). Additionally, host crown condition appeared to be a more important factor than DBH alone. Our results therefore provide support to the hypothesis that host crown (stressing) condition strongly influences EAB oviposition behavior. Knowing which trees are likely to contain the most EAB eggs will help to guide efforts for releasing and promoting establishment of parasitoids utilized in biological control. However, future work should attempt to experimentally test the hypothesis that host condition (e.g., crown reduction) drives EAB oviposition behavior, and also investigate the fitness implications of these host choices.