Asian chestnut gall wasp
Drycosmus kuriphilus Yasumatsu (Hymenoptera: Cynipidae)
Orientation to pest
The Asian chestnut gall wasp, Drycosmus kuriphilus Yasumatsu, is a gall making cynipid that is specific to chestnut (Castanea spp.). The gall wasp is native to China but invasive in many countries around the world, including parts of the USA. Galling disrupts shoot and twig growth, impedes normal flowering, and weakens infested trees. Adult females (there are no males) emerge from galls in early-to-mid summer and lay several eggs in each chestnut bud they attack. Eggs hatch in mid-to-late summer, and young larvae feed a little and then overwinter in the infested buds. When buds begin to grow in spring, galls are formed. Galls have one to several chambers, each with a developing gall wasp larva. Larvae eat the tissue within the galls and pupate there. New gall wasps emerge soon after. After adults emerge, galls turn brown and woody and may remain on the tree for several years and are a clear sign of infestation. In China, pest outbreaks occur about every 10 years and last 2-3 years. There is one generation per year.
Hosts commonly attacked
This species is specific to species of chestnuts (Castanea).
Distribution
Asian chestnut gall wasp is native to China, but is also present in Korea, Japan, Nepal, Europe (Italy, France, Slovenia, Hungary, Switzerland, and Croatia) and the USA as an invasive pest.
Figure 1. Distribution of the chestnut gall wasp in the United States |
Images of Asian chestnut gall wasp
Figure 2. Adult of Asian chestnut gall wasp, Drycosmus kuriphilus | Figure 3. Young gall of Asian chestnut gall wasp in spring (left) and old gall after wasp emergence (right), which may remain on trees for several years |
Figure 4. Interior view of gall in cross section, showing multiple chambers and a one gall wasp pupa | Figure 5. View of old galls on leafless chestnut tree in winter |
Important biological control agents related to this pest species
Classical biological control programs focusing on the parasitoid Torymus sinensis Kamijo (Hymenoptera: Torymidae) have been implemented in several countries, including Japan and the United States. Several native species also utilize the gall wasp as a host.
Web links for information on Asian chestnut gall wasp
- Quarantined Pest Data Sheet | European & Mediterranean Plant Protection Organization
- Biological Control Publication | Federal Office for Agriculture, Switzerland
"Evaluating the use of Torymus sinensis against the chestnut gall wasp Dryocosmus kuriphilus in the Canton Ticino, Switzerland"
Articles
- Moriya, S., K. Inoue, A. Otake, M. Shiga, and M. Mabuchi. 1989. Decline of the chestnut gall wasp population, Dryocosmus kuriphilus Yasumatsu (Hymenoptera, Cynipidae) after the establishment of Torymus sinensis Kamijo (Hymenoptera, Torymidae). Applied Entomology and Zoology 24: 231-233.
- Aebi, A., K. Schonrogge, G. Melika, A. Quacchia, A. Alma, and G. N. Stone. 2007. Native and introduced parasitoids attacking the invasive chestnut gall wasp Dryocosmus kuriphilus. EPPO Bulletin 37: 166-171.
- Cooper, W. R. and L. K. Rieske. 2007. Community associates of an exotic gallmaker, Dryocosmus kuriphilus (Hymenoptera: Cynipidae), in eastern North America. Annals of the Entomological Society of America 100: 236-244.
- Cooper, W. R. and L. K. Rieske. 2007. Review of the historic and current status of the Asian chestnut gall wasp in North America. Journal of the American Chestnut Foundation 11: 26-33.
- Rieske, L. K. 2007. Success of an exotic gallmaker, Dryocosmus kuriphilus, on chestnut in the USA: a historical account. Bulletin of the European and Mediterranean Plant Protection Organization (EPPO Bulletin) 37: 172-174.