Disruption of Pheromone Communication in Platynota stultana (Lepidoptera: Tortricidae) in Grape Vineyards

Abstract

Leafroller, Platynota stultana Walsingham, pheromone–communication–disruption experiments were conducted in grape vineyards in the San Joaquin Valley in California during 1993. Four synthetic pheromone components were released, either singly or in various mixtures, into the atmosphere of the vineyards at predetermined rates from evaporation sources. These sources were attached to grape stakes at specified heights and spacings, in grids of 36 (6 × 6) evaporators. The numbers of male moths that located and were caught in female-baited traps in the centers of the evaporator arrays, compared with the numbers captured in similar female-baited traps in untreated control areas, were used to calculate the effectiveness of communication disruption. Most of the disruptive activity of the P. stultana pheromone was provided by the 2 components that are found in greatest amounts in living female moths, (E)-11-tetradecenyl acetate and (Z)-11-tetradecenyl acetate. These components, combined in a 9: 1 ratio, disrupted pheromone communication more effectively than did either component displayed alone. The extent of communication disruption was proportional to the amount of the pheromone components released per hectare per day and was a function of both separation between evaporators and pheromone release rate from each evaporator. Ninety-nine percent disruption was obtained with the release of 6.4 mg per hectare per day of the 9:1 blend of the 2 components. Most male P. stultana moths were active in the upper 3rd of the grapevine structure, and evaporators placed at this height were most effective in preventing males from locating females.