Propagation of Agapeta zoegana L. (Lepidoptera: Cochylidae) for Biological Control of Spotted Knapweed: Procedures and Cost

Agapeta zoegana L. is a root-boring moth introduced from Eurasia for biocontrol of spotted knapweed, Centaurea maculosa Lamarck, in Montana and the Pacific Northwest. Because of low populations of spotted knapweed in Eurasia, field collections have yielded very few insects. Consequently, a propagation effort using field cages was initiated to hasten the population increase and the subsequent distribution of the moth throughout the knapweed-infested areas of Montana. Procedures for propagating the moth in field cages are described. Methods to improve production are suggested. The direct cost of rearing 20,000 A. zoegana adults for field release was $26,350, an average of $1.32/insect. Primary cost factors were labor and cages. This field-cage approach is effective and the cost appropriate for providing A. zoegana for initial colonization in the western United States.