Creating point sources for codling moth (Lepidoptera: Tortricidae) with low-volume sprays of a microencapsulated sex pheromone formulation.

Studies were conducted to examine the deposition of microcapsules and the attractiveness of treated apple leaves, Malus domestica Borkhausen, for codling moth, Cydia pomonella L., after low-volume concentrated sprays [24.7 g (AI) in 12 liters of water/ha] of a microencapsulated (MEC) sex pheromone formulation (CheckMate CM-F). Nearly 30% of leaves collected from sprayed zones within tree canopies had no microcapsules, whereas 20% had >20 microcapsules. Microcapsule density was correlated with leaf area, and significant differences in the density of microcapsules per leaf were found because of both height and depth in the canopy relative to the sprayed zone and leaf surface. In general, the highest concentration of microcapsules was deposited on the underside of leaves in the sprayed zone. However, deposition was greater on the upper than the bottom surface of leaves in the canopy below the spray zone and in the tops of trees on the opposite side of the canopy. Field-aged MEC-treated apple leaves elicited upwind flight and moth contact in flight tunnel tests for at least 5 wk. Precipitation reduced the attractiveness of leaves, particularly for leaves treated only on their upper versus bottom surface. Traps in unsprayed orchards baited with MEC-treated artificial leaves were attractive for 5 wk. Moth catches in similar traps placed in MEC-sprayed plots were low but increased significantly over 3-4 wk. These data suggest that, after a brief initial period of sensory disruption, low-volume MEC sprays create point sources of sex pheromone (leaves) within the orchard that may enhance mating disruption through competitive attraction.