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Biological Improvement of Chestnut Through Technologies That Address Management of the Species, Its Pathogens and Pests
Department of Entomology
The overall impact of this project will be to further the progress being made toward the restoration of chestnut as a tree in North American forests and as a nut in the American marketplace.
2011 Project Description
American chestnut restoration efforts, and chestnut production, are under threat from the invasive Asian chestnut gall wasp Dryocosmus kuriphilus. We are evaluating developing ecological interactions associated with this exotic invasive gallmaker as it expands its geographic range in North America.
Expanding populations of the exotic gall wasp are recruiting native and introduced natural enemies in North America. Consequences of this recruitment are being investigated in the context of potential biological control of the gall wasp, which could affect commercial chestnut production and American chestnut restoration efforts.
I am characterizing the expanding natural enemy complex of the gall wasp. Parasitization is a primary cause of mortality, and parasitoid recruitment is being evaluated, with eight parasitoid species documented as gall wasp associates. Gall-inducing insects are obligate plant parasites, making them difficult to manipulate under laboratory conditions.
I've developed a means of rearing gall wasp populations under controlled conditions and am evaluating the interactions between the gall wasp and stem-cankering fungi such as the non-native chestnut blight fungus, Cryphonectria parastica. My ultimate goal is to gain an understanding of the ecological interactions, dispersal patterns, and mechanisms regulating gall wasp populations in eastern North America.
The gall wasp is now found in eleven states in the U.S. Eight previously unreported parasites have been collected, and the introduced parasite is well established. The fecundity of adult female wasps declines with wasp age, as does the size of individual eggs (a measure of fitness). Interactions between the gall wasp and a stem cankering fungus reduces the fitness of the host, enhances the fitness of the fungus, but has no impact on gall wasp fitness.
Cooper, W.R. and L.K. Rieske. 2011. A native and introduced parasitoid utilize an exotic gall-maker host. Biological Control 56: 725-734.
Cooper, W.R. and L.K. Rieske. 2011. Chestnut species and jasmonic acid treatment influence development and community interactions of galls produced by the Asian chestnut gall wasp, Dryocosmus kuriphilus. Journal of Insect Science 11:140; available online: insectscience.org/11.140.