Environmental Entomology (2009) 38, 417-424

W.R. Cooper and L.K. Rieske (2009)
Woody stem galls interact with foliage to affect community associations
Environmental Entomology 38 (2), 417-424
Abstract: Gall wasps (Hymenoptera: Cynipidae) hijack the physiology of their host plant to produce galls that house wasps throughout their immature stages. The gall-maker-host plant interaction is highly evolved, and galls represent an extended phenotype of the gall wasp. We evaluated two-way interactions between stem galls produced by Dryocosmus kuriphilus Yasumatsu on Castanea spp. (Fagales: Fagaceae) and foliage directly attached to galls (gall leaves) using gall leaf excision experiments and herbivore bioassays. Early season gall leaf excision decreased the dry weight per chamber (nutritive index) and thickness of the protective schlerenchyma layer and increased the number of empty chambers and the occurrence and size of exterior fungal lesions. Leaf excision also caused a modestly significant (alpha = 0.1) increase in the incidence of feeding chamber fungi and herbivory by Curculio sayi Gyllenhal (Coleoptera: Curculionidae), and a modest decrease in parasitoids. This study shows that gall leaves are important for stem gall development, quality, and defenses, adding support for the nutrient and enemy hypotheses. We also evaluated the effects of stem galls on the suitability of gall leaves to Lymantria dispar L. (Lepidoptera: Lymantriidae) herbivory to assess the extent of gall defenses in important source leaves. Relative growth rate of L. dispar larvae was greater on gall leaves compared with normal leaves, indicating that, despite their importance, gall leaves may be more suitable to generalist insect herbivores, suggesting limitations to the extended phenotype of the gall wasp. Our results improve our knowledge of host- cynipid interactions, gall source-sink relations, and D. kuriphilus community interactions.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Lynne K. Rieske, W. Rodney Cooper

Research topic(s) for pests/diseases/weeds:
environment - cropping system/rotation

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Lymantria dispar	Chestnut (Castanea)
	Dryocosmus kuriphilus	Chestnut (Castanea)
	Curculio sayi	Chestnut (Castanea)