Foreign Exploration for Natural Enemies of Cephid Sawflies

摘要

Sawflies which feed and develop in the stems of grasses are widespread throughout the northern hemisphere, particularly in the Palearc-tic region. Wheat is the primary crop impacted, but these sawflies also attack rye, barley and timothy, as well as various native, noncrop grasses. Several cephid species that cause significant damage to crops have been extensively studied. However, their ecology in wild grass hosts is virtually unknown, including the occurrence and impact of natural enemies. Following the introduction and establishment of European parasitoids against Cephus pygmaeus (Hymenoptera: Cephidae) in North America, unsuccessful attempts were made during the early to midtwentieth century to establish European parasitoids against Cephus cinctus in North America. The failures were attributed to a lack of adaptation to C. cinctus or to the lack of proper synchronization with suitable host stages. Further collections and introductions were not pursued at that time. However, uncertainty exists regarding the identity and taxonomic relationship of various species of Cephus. Natural enemy taxa are also in need of revision. Further field collections and biological studies are warranted, especially for species in central and eastern Asia for which information is particularly sparse, and which may be closely related to C. cinctus. Such collections would provide new study material for taxonomic revisions, and possibly new populations and/or species of natural enemies for biological control evaluations. New opportunities exist for the discovery and collection of better-adapted parasitoid populations in regions with climates that are very similar to those of the desired areas of introduction.