Oviposition Preferences ofAgrilus planipennis(Coleoptera: Buprestidae) for Different Ash Species Support the Mother Knows Best Hypothesis

Abstract

AbstractThe “mother knows best” hypothesis states that adults should choose hosts for oviposition on which their offspring will best perform, maximizing their own fitness. It has been hypothesized that this preference—performance relationship for wood-boring insects is especially important because larvae are not able to switch hosts, although no study has examined oviposition choices for these insects. We examined oviposition preferences of the emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), in two common gardens, one on the campus of Wright State University in Dayton, OH, and the other at the Michigan State University Tollgate Research Farm in Novi, MI, by wrapping cheesecloth around ash trunks to assess passive oviposition patterns.Wefound that in both gardens, ash species native to North America, which are highly susceptible to the emerald ash borer, consistently received more ova than Manchurian ash, which is indigenous to Asia and more resistant to the emerald ash borer. Susceptible trees in the Novi garden received 93 times the number of ova and susceptible trees at the Wright State garden received up to 25 times the number of ova that were received by Manchurian ash in each of their respective gardens. Neither tree size nor vigor affected oviposition choice. There were also higher numbers of adult exit holes on North American than Manchurian ash in both common gardens. The observed oviposition preferences in this study align with patterns of adult feeding preference, ash host mortality, and exit hole numbers from other studies. These observations also suggest that oviposition preferences may contribute to interspecific patterns of host resistance and mortality. Collectively, our results demonstrate that the emerald ash borer prefers to oviposit on species on which its offspring will best perform, suggesting that there is strong selection for the ability to recognize host cues that predict better larval survival and performance.