||Biology and Management of
Arthropods in Peppermint
Report - 1991
Ralph E. Berry, Joyce Takeyasu, Department of Entomology
Oregon State University and Mark Morris, A. M. Todd Company
Note: this information is considered unpublished work and should not be used as final or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
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.