MATING DISRUPTION OF CODLING MOTH (LEPIDOPTERA, TORTRICIDAE) WITH POLYETHYLENE TUBE DISPENSERS - DETERMINING EMISSION RATES AND THE DISTRIBUTION OF FRUIT INJURIES

Emission characteristics of three sex pheromone components of codling moth, Cydia pomonella (L.), from a polyethylene tube dispenser used fo r mating disruption were determined and regression models predicting t he emission rate of each component as a function of temperature and ac cumulated degree hours above 0 degrees C were developed. Field experim ents were conducted in small plots of apple during 1989-90 to measure intraseasonal changes in the distribution of fruit injury within phero mone-treated blocks. Fruit injury was < 0.5% in 0.4 ha plots treated w ith 1,000-4,000 dispensers per ha in 1989 except in plots situated alo ng the border of the orchard adjacent to a non-pheromone-treated orcha rd with high levels of fruit injury. In a separate orchard in 1990, th e differential application of pheromone dispensers (2,000 per ha) and insecticides was used to create four 1-ha plots with moderate to high population densities of codling moth larvae during the first generatio n (50-fold range in densities of injured fruits per tree). Subsequentl y, all plots were treated with pheromone prior to the second generatio n. Fruit injury at harvest was < 1.0% for 'Delicious' in all plots exc ept the highest density (HD) plot (4.0%), but was ca. 1.0% or higher f or 'Golden Delicious' in all plots (14% in the HD plot). The mean numb er of injured fruits per tree for 'Delicious' and 'Golden Delicious' i ncreased 10 and 25 fold between generations in the plot adjacent to an d within 100 m of the HD plot, respectively. Results from both years d emonstrated the effectiveness of mating disruption in suppressing the population buildup of codling moth in plots of apple not exposed to im migration of moths.