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Progress Report - 1991

Ralph E. Berry, Joyce Takeyasu, Department of Entomology
Oregon State University and Mark Morris, A. M. Todd Company
Jefferson, OR

Note: this information is considered unpublished work and should not be used as final or finished results. It has been included in IPMP 3.0 because it may not be available from other sources, and in some cases may include information that may not reach final publication.

Monitoring Adult Mint Root Borer with Sex Pheromone Traps Research

The sex pheromone of the MRB was evaluated in 1991 to determine if it could be used to monitor emergence of adult male MRB. MRB sex pheromone caps, provided by Dr. Harry Davis (USDA, Yakima, WA), were placed in Pherocon 1C traps manufactured by Trece Inc. (Salinas, CA) and placed in 12 different peppermint fields throughout the Willamette Valley in western Oregon. The traps were monitored on a weekly basis beginning May 20 and continuing through August 12. Trap counts indicate a peak in male moth emergence during the week of July 15, 1991. MRB was found for the first time in central Oregon. The use of pheromone traps to monitor adult emergence and an understanding of the reproductive biology of MRB will allow us to design a management program for MRB.

Laboratory studies focused on adult emergence pattern, number of eggs laid per female, length of the pre-oviposition and oviposition periods, length of the incubation period prior to egg hatch and percent egg hatch. These experiments were conducted in a 75 °F growth chamber under a 16:8 light:dark cycle using hibernacula collected from both the Willamette Valley and Sunnyside, WA.

Laboratory studies shows that the male:female sex ratio is approximately 50:50, with male moths emerging a few days earlier than females. Under laboratory conditions, female moths laid an average of 217 eggs (SD + 79.8), predominantly on the lower leaf surface. At a constant temperature of 75 °F, females were able to mate and begin laying eggs within 24 hours of emerging. Egg laying continued for up to six days. Eggs hatched in approximately six and a half days with an average of 82.5% (SD + 10.0) of the eggs hatching.