Mating disruption of two sympatric, orchard-inhabiting tortricids, Choristoneura rosaceana and Pandemis limitata (Lepidoptera: Tortricidae), with pheromone components of both species' blends

In British Columbia several pheromone blends were tested as possible mating disruptants for 2 sympatric, orchard-inhabiting leafrollers (Lepidoptera: Tortricidae), the oblique-banded leafroller, Choristoneura rosaceana (Harris). and the threelined leafroller, Pandemis limitata (Robinson). Z9-tetradecenyl acetate (Z9-14:OAc), a minor pheromone component of the P. limitata pheromone and known pheromone antagonist of C. rosaceana, was tested alone and in combination with Z11-tetradecenyl acetate (Z11-14:OAc), the major pheromone component of both species, and additional minor components of the C. rosaceana pheromone, as mating disruptants of both species. Disruption of mating, assessed using tethered virgin females of both species, was tested in 0.1-ha plots (33.3 by 33.3 m), using fiber-tape dispensers releasing approximate to 10 mg/ha per hour. Z9-14:OAc applied alone did not significantly disrupt mating of either species. All treatments containing Z11-14:OAc and Z9-14:OAc in a approximate to 1:1 ratio equally reduced mating of both species. Furthermore, an approximate to 91:6 ratio of Z11-14:Oac : Z9-14:OAc, which is highly attractive to P. limitata, was no more effective than 3 less attractive pheromone blend containing a, approximate to 1:1 ratio of these components. Unattractive blends combining the major component, Z11-14:OAc and the inhibitor, Z9-14:OAc, disrupted mating of C. rosaceana as effectively as the major component alone. These results indicate that false-trail following was not an important mechanism of mating disruption for either of these species in this experimental setting. We conclude that Z11-14:OAc could be used alone or in combination with Z9-14:OAc to disrupt mating in both leafrollers simultaneously.