The American chestnut (Castanea dentata) and the Allegheny and Ozark chinkapins (both Castanea pumila) have been attacked in succession by three different exotic pests: chestnut gall wasp, phytophthora root rot, and chestnut blight.
Efforts to reintroduce American chestnut will probably be hampered by another pest, the chestnut gall wasp, which was first reported in 1974 (Payne et al., 1975). This pest was illegally imported into the country on smuggled budwood and became established in a chestnut orchard in southern Georgia. Chestnut gall wasps lay eggs in bud and flower tissue. Feeding by the larvae results in the tree forming a characteristic gall. Branch die-back can occur, possibly from toxins produced by the larvae, and severe infestations can result in tree mortality. Although there are biological controls for the chestnut gall wasp, none has been evaluated in North America (Murakami et al., 1995; Yara et al., 2000). Chinkapins appear to be resistant or immune to chestnut gall wasp and may be a source of resistance for breeding programs.
Murakami, Y., N. Ohkubo, S. Moriya, Y. Gyoutoku, C. H. Kim, and J. K. Kim. 1995. Parasitoids of Dryocosmus kuriphilus (Hymenoptera: Cynipidae) in South Korea with particular reference to ecologically different types of Torymus (Syntomaspis) sinensis (Hymenoptera: Torymidae). Appl. Entomol. Zool. 30: 277-284.
Payne, J. A., A. S. Menke, and P. M. Schroeder. 1975. Dryocosmus kuriphilus Yasumatsu, (Hymenoptera: Cynipidae), an oriental chestnut gall wasp in North America. U. S. Dept. Agr. Coop. Econ. Insect Report 25(49-52): 903-905.
Yara, K., E. Yano, T. Sasawaki, and M. Shiga. 2000. Detection of hybrids between introduced Torymus sinensis and native T. beneficus (Hymenoptera: Torymidae) in central Japan, using malic enzyme. Applied Entomol. Zool. 35: 201-206.