975 Research Article Received: 3 September 2010 Revised: 29 December 2010 Accepted: 17 January 2011 Published online in Wiley Online Library: 24 March 2011 (wileyonlinelibrary.com) DOI 10.1002/ps.2141 Effects of reservoir dispenser height on efficacy of mating disruption of codling moth (Lepidoptera: Tortricidae) in apple David L Epstein, a* Lukasz L Stelinski, b James R Miller, a Matthew J Grieshop a and Larry J Gut a Abstract BACKGROUND: The effect of varying the height of reservoir dispensers for mating disruption of codling moth, Cydia pomonella (L.), was investigated. The goal was to improve the effectiveness of C. pomonella mating disruption through improved understanding of adult distribution within the tree canopy and the impact of pheromone dispenser placement on disruption. Two dispensers per tree were placed at 2 m and 4 m and/or one dispenser at each height on the tree at a label rate of 1000 units ha -1 . Monitoring traps and tethered female moths were deployed in plots at 2 and 4 m heights to assess treatment effects by catches or matings respectively. RESULTS: Fewest male moths were captured with all dispensers placed at 4 m. Female mating was lowest, and with least variation between females tethered at 2 and 4 m, when dispensers were placed simultaneously at 2 and 4 m (28% mated). Mating was 32% with both dispensers at 4 m, 38% with both dispensers at 2 m and 46% in the no disruption control. Mating was highest across treatments when females were tethered at 2 m and dispensers placed at 4 m (40%), and when females were tethered at 4 m with dispensers placed at 2 m (46%). CONCLUSION: Traps at 4 m in trees captured more male moths than traps at 2 m, regardless of disruption dispenser positioning. Female mating was lowest when dispensers were placed simultaneously at 2 and 4 m, suggesting that current recommendations for placement of reservoir dispensers in tree crowns may be suboptimal. c  2011 Society of Chemical Industry Keywords: codling moth; pheromone disruption; dispenser height; competitive attraction 1 INTRODUCTION Mating disruption of codling moth [Cydia pomonella (L.)] using various hand-applied dispensers has become an accepted prac- tice. Approximately 162 000 ha of apple and pear are treated worldwide. 1 Investigations using pheromone-baited sticky traps have indicated that flight of males is concentrated in the top third of the tree canopy. This finding has resulted in the recommenda- tion that dispensers of synthetic pheromone be applied within the top meter of the tree canopy. 2–4 Witzgall et al. directly observed male moths flying and ‘searching’ in branches in the upper half of tree crowns, providing further support for deployment of mating disruption dispensers near the top of the tree canopy. 5 Epstein et al. developed a vacuum sampling technique for direct measurement of the spatial distribution of resting male and female C. pomonella within the tree canopy in orchards with and without pheromone mating disruption. 6 In pheromone-disrupted plots, significantly more males were found in the combined lower two-thirds of the tree canopy (0–3.0 m) than in the top third of canopy (3.0–4.5 m). However, female moth distribution was approximately equivalent between the top third and middle third (1.5–3.0 m) of tree canopies (42 and 46% in the top and middle respectively). In plots not treated with pheromone, more male C. pomonella were found in the upper two-thirds of trees (1.5 – 4.5 m) than at lower locations. An equal percentage of females were collected from the top and middle thirds of the tree canopies in non-disrupted plots. 6 Recent work by Miller et al. 7–9 provides strong evidence that competitive attraction is a primary mechanism by which pheromone mating disruption operates for C. pomonella with hand-applied reservoir dispensers of pheromone. Disruption should be optimal when dispensers of synthetic pheromone are deployed in areas within the trees where females typically call. Thus, if the distribution of female C. pomonella is similar between the upper, middle and lower parts of the tree canopy, then placement of dispensers solely in the top third of the tree canopy may be suboptimal. 6 The above results, indicating that female C. pomonella occur throughout the tree canopy in both disrupted and non-disrupted ∗ Correspondence to: David L Epstein, Michigan State University, B18 FST, East Lansing, MI 48824, USA. E-mail: epstei10@msu.edu a Department of Entomology, Michigan State University, East Lansing, Michigan, USA b Department of Entomology and Nematology, University of Florida, Citrus Research and Education Center, Lake Alfred, FL, USA Pest Manag Sci 2011; 67: 975–979 www.soci.org c  2011 Society of Chemical Industry