Emerald ash borer (Agrilus planipennis Fairmaire, EAB) is causing widespread ash (Fraxinus spp.) mortality as it invades North America and Eastern Europe. Resistance of its coevolved hosts, including Manchurian ash (Fraxinus mandshurica Rupr.), is considered to limit EAB outbreaks and ash mortality in its native Asia, although an understanding of resistance mechanisms is still developing. Such knowledge may facilitate breeding for resistance and management of EAB in its invaded ranges. In the present study, controlled egg inoculations were used to investigate resistance mechanisms impacting larval performance, as well as to characterize the effects of water and nutrient availability on inter- and intra-specific variation in resistance phenotypes based on larval outcomes. Larval survival and growth rates were lower on coevolved Manchurian ash than on evolutionarily naïve white ash (Fraxinus americana L.). Water stress decreased tree growth and resistance of Manchurian ash to EAB, although it had little effect on resistance of the already highly susceptible white ash. High nutrient availability increased tree growth but had no effect on larval performance. These results show that the higher resistance of Manchurian ash to EAB is conferred by phloem traits that decrease larval performance, in addition to lower oviposition preference.
Bibliographical noteFunding Information:
Robert Hansen, Alejandro Chiriboga, Amilcar Vargas, Ellie Shoup, Diane Hartzler, Paul Snyder, Sara Rudowsky, Christian Bonilla, Bryant Chambers, Amy Hill, Anna Conrad, Patrick Sherwood, Michael Falk and Amy Itnyre (The Ohio State University) assisted in the set-up, maintenance and harvest of the experiments. Jonathan Lelito and Scott Whitehead (USDA-APHIS-PPQ Biological Control Rearing Facility, Brighton, Michigan) provided EAB eggs. Funding for the project was provided by the USDA APHIS/USDA Forest Service Accelerated Emerald Ash Borer Research Program (GRT00011769/ 60016270), and by State and Federal funds appropriated to the Ohio Agricultural Research and Development Center and The Ohio State University. DS designed, conducted, analyzed and wrote up the experiments. CV designed and conducted the experiments. DH and PB designed and wrote up the experiments.
- Agrilus planipennis
- host plant resistance
- larval performance
- resistance phenotyping
- resource availability