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Title: BIOLOGICAL CONTROL OF WHEAT STEM SAWFLIES: PAST AND FUTURE

Author
item Shanower, Thomas
item Hoelmer, Kim

Submitted to: Joaur Agricult. & Urban Pest Management (Invited Review Article)
Publication Type: Review Article
Publication Acceptance Date: 10/21/2004
Publication Date: 10/1/2004
Citation: Shanower, Thomas G., Hoelmer, Kim A. Biological Control of Wheat Stem Sawflies: Past and Future. J. Agric. Urban Entomol. 21(4):197-221.

Interpretive Summary:

Technical Abstract: Grass-feeding stem sawflies (Hymenoptera: Cephidae) include several pests of wheat and other grain crops. Species reported as pests include Cephus cinctus (North America), C. fumipennis (China), C. cultratus (central Asia), and C. pygmaeus and Trachelus tabidus (Europe and Mediterranean region). The latter two were introduced into North America over 100 years ago. Cephid biology is similar: females oviposit in stems, and larvae feed within the stem, moving to the base of the plant as they mature. A groove is cut inside the stem and a plug created beneath, forming a chamber in which larvae diapause during the winter or dry season. Increased temperatures, moisture and/or photoperiod terminate diapause. Pupation occurs within the stub. Weakened stems break at the groove, leaving stubs. Yield losses of up to 35% have been reported from larval feeding and loss of fallen grain. Annual damage by C. cinctus in North America is estimated at $100 million. Biological control efforts were initiated against C. cinctus in 1930-40. Parasitoids from England and the eastern US were released in Canada. Another attempt in the western US in 1952-55 utilized parasitoids from France. Both failed. Biological control efforts against C. pygmaeus were carried out 1935-38 (US) and 1937- 40- (Canada). These resulted in the establishment of Collyria coxator which plays an important regulatory role. The USDA-ARS recently initiated a new project for biological control of C. cinctus in the western US. We review biological control efforts against wheat stem sawflies, discuss reasons for earlier failures, and outline the approach of the new project.