Dryocosmus kuriphilus (Hymenoptera: Cynipidae) is non-native to North America and induces formation of galls on petioles and leaves of all chestnut (Castanea spp., Fagales: Fagaceae). We investigated the interactions between the gall wasp D. kuriphilus, a native parasitoid, Ormyrus labotus (Hymenoptera: Ormyridae), and a non-native parasitoid, Torymussinensis (Hymenoptera: Torymidae). Galls were collected monthly from May to August and in January from four locations in the United States consisting of orchard-grown hybrid chestnuts (Hiram, OH and Meadowview, VA), suburban-grown ornamental Chinese chestnuts (C. mollissima) (Broadview Heights, OH), or forest-grown American chestnuts (C. dentata) (Bowling Green, KY). Parasitoids were removed from galls and T. sinensis and O. labotus were identified using PCR-markers. The relative abundance of each parasitoid was compared in relation to collection date, habitat, presence of alternative hosts, and gall characteristics. T. sinensis was collected from each location and date, and was dominant in the orchard and suburban locations. However, relatively more O. labotus were collected within the forest, which had significant oak component and alternative cynipid hosts. O. labotus was only collected in spring and early summer, indicating the use of different summer and winter hosts. Observations suggest that in addition to parasitizing D. kuriphilus, O. labotus hyperparasitizes T. sinensis. T. sinensis has a longer ovipositor than O. labotus, and parasitized larger galls. This study improves our understanding of interactions between an invasive gall wasp, an introduced parasitoid, and native parasitoids, and illustrates novel relationships that may form as exotic species expand their geographic range.
|Number of pages||10|
|State||Published - Oct 2011|
Bibliographical noteFunding Information:
Acknowledgments We thank Fred Hebard (American Chestnut Foundation), Steve Hartman, Edgar Stehli, and Bob Stehli for plant material. Melonie Antonik, Fabrice Curtis and Luke Dodd provided assistance with gall collections and dissections, and Abbe Kesterson and Dr. Chris Schardl of the University of Kentucky’s Advanced Genetic Technology Center provided assistance with DNA sequencing. This research was funded by the Northern Nut Growers Association, American Chestnut Foundation, and McIntire Stennis funds from the Kentucky Agricultural Experimental Station, and is published as Experiment Station Project 10-08-120. Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the United States Department of Agriculture. USDA is an equal opportunity provider and employer.
ASJC Scopus subject areas
- Agronomy and Crop Science
- Insect Science