Author
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Submitted to: Encyclopedia of Entomology
Publication Type: Book / Chapter Publication Acceptance Date: 12/16/2003 Publication Date: 4/1/2004 Citation: Shanower, T.G. 2004. History of biological control of wheat stem sawflies (hymenoptera: cephidae). Encyclopedia of Entomology. 2:1090-1093. Interpretive Summary: Wheat stem sawflies are important pests of wheat in the northern hemisphere, particularly in North America. Host plant resistance and cultural control strategies offer partial control, though both have significant drawbacks. Attempts at biological control using exotic parasitoids have been variably successful. For Cephus pygmaeus and Trachelus tabidus in eastern North America, an ichneumonid parasitoid (Collyria coxator) was successfully established and contributes to reduced population levels now observed in these two sawflies. In contrast, biological control for Cephus cintus has been attempted unsuccessfully three times. Several factors may have contributed to the lack of establishment of natural enemies in the western US and Canada. A key factor may have been that the parasitoids selected for release were collected from a different sawfly host and perhaps they were unable to complete development in this new host. A second problem may have been that the parasitoids were not adapted to the colder, drier climate they were released into. The release protocol may also have contributed to the lack of establishment. Adults were transported across the country (Canada or the US) and released immediately into the field. This may have resulted in injury or death to the adult parasitoids due to shipping and handling, and poor timing and/or synchronization between C. cinctus populations and the parasitoids. Technical Abstract: Wheat stem sawflies are important pests of wheat in the northern hemisphere, particularly in North America. Host plant resistance and cultural control strategies offer partial control, though both have significant drawbacks. Attempts at biological control using exotic parasitoids have been variably successful. For Cephus pygmaeus and Trachelus tabidus in eastern North America, an ichneumonid parasitoid (Collyria coxator) was successfully established and contributes to reduced population levels now observed in these two sawflies. In contrast, biological control for Cephus cintus has been attempted unsuccessfully three times. Several factors may have contributed to the lack of establishment of natural enemies in the western US and Canada. A key factor may have been that the parasitoids selected for release were collected from a different sawfly host and perhaps they were unable to complete development in this new host. A second problem may have been that the parasitoids were not adapted to the colder, drier climate they were released into. The release protocol may also have contributed to the lack of establishment. Adults were transported across the country (Canada or the US) and released immediately into the field. This may have resulted in injury or death to the adult parasitoids due to shipping and handling, and poor timing and/or synchronization between C. cinctus populations and the parasitoids. |
