Economic Impact Of Galls

The majority of plant galls harm the host plant only by diverting plant resources and thus have little economic impact. The economic impacts of gallmaking insects include the benefits of fig pollination as well as some negative economic effects in the form of crop losses.

Three examples of gallmaking insects with negative economic impacts are the Hessian fly (Diptera: Cecidomyiidae), the grape phylloxera (Homoptera: Phylloxeridae), and the oriental chestnut gall wasp (Hymenoptera: Cynipidae). The Hessian fly, Mayetiola destructor, is well known for the damage it causes to wheat crops. This fly does not cause galls on wheat, but rather exhibits a kind of facultative cecido-genesis by inducing galls only when the eggs are laid on barley, where the galls are much more damaging to the host plant than the necroses it forms on wheat. Grape phylloxera, D. vitifoliae, nearly destroyed the wine industries of Europe in the late 19 th century. Although the leaves of European vines are resistant and are not infested with the leaf- and stem-galling forms, generations of wingless females gall the roots, eventually killing the vines. The only successful treatment has been to graft grapes onto certain resistant root strains. The economic impact of the oriental chestnut gall wasp, Dryocosmus kuriphilus, results from the loss of nut crop as galls form on the buds and flowers of chestnut trees (Castanea spp.), although the trees remain healthy.

See Also the Following Articles

Agricultural Entomology • Commercial Products from Insects • Host Seeking, for Plants • Phytotoxemia

Further Reading

Ananthakrishnan, T. N. (1984). "The Biology of Gall Insects." Oxford &

IBH, New Delhi. Csoka, G. (1997). "Plant Galls." Forest Research Inst., Budapest. Csoka, G., Mattson, W. J., Stone, G., and Price, P. (1998). "The Biology of

Gall-Inducing Arthropods." Forest Service, USDA, St. Paul. Darlington, A. (1975). "The Pocket Encyclopaedia of Plant Galls in

Colour." Blandford Press, Poole. Meyer, J. (1987). "Plant Galls and Gall Inducers." Gebrüder, Borntraeger, Stuttgart.

Redfern, M., and Askew, R. R. (1992). "Naturalists' Handbooks." 17.

"Plant Galls." Richmond Pub., Slough, England. Shorthouse, J. D., and Rohfritsch, O. (1992). "Biology of Insect-Induced

Galls." Oxford University Press, New York. Williams, M. A. J. (1994). "Plant Galls: Organisms, Interactions, Populations," Special Vol. 49 of the Systematics Association. Clarendon Press, Oxford.

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