Mating Disruption of Citrus Leafminer Mediated by a Noncompetitive Mechanism at a Remarkably Low Pheromone Release Rate L. L. Stelinski & J. R. Miller & M. E. Rogers Received: 7 January 2008 / Revised: 29 April 2008 / Accepted: 9 May 2008 / Published online: 26 June 2008 # Springer Science+Business Media, LLC 2008 Abstract The citrus leafminer, Phyllocnistis citrella Stain- ton (Lepidoptera: Gracillariidae), is a worldwide pest of citrus. A season-long investigation was conducted that evaluated mating disruption for this pest. Effective disrup- tion of the male P. citrella orientation to pheromone traps (98%) and reduced flush infestation by larvae was achieved for 221 d with two deployments of a 3:1 blend of (Z,Z,E)- 7,11,13-hexadecatrienal/(Z,Z)-7,11-hexadecadienal at a re- markably low rate of 1.5 g active ingredient (AI)/ha per deployment. To gain insight into the mechanism that mediates the disruption of P. citrella, male moth catch was quantified in replicated plots of citrus treated with varying densities of pheromone dispensers. The densities of septum dispensers compared were: 0 (0/ha, 0.0 g AI/ha), 0.2 (one every fifth tree or 35/ha, 0.05 g AI/ha), 1 (215/ha, 0.29 g AI/ha), and 5 per tree (1,100/ha, 1.5 g AI/ha). Profile analysis by pre- viously published mathematical methods matched predictions of noncompetitive mating disruption. Behavioral observations of male P. citrella in the field revealed that males did not approach mating disruption dispensers in any of the dis- penser density treatments. The current report presents the first set of profile analyses combined with direct behavioral observations consistent with previously published theoretical predictions for a noncompetitive mechanism of mating disruption. The results suggest that disruption of P. citrella should be effective even at high population densities given the density-independent nature of disruption for this species and the remarkably low rate of pheromone per hectare required for efficacy. Keywords Phyllocnistis citrella . Mating disruption mechanisms . Desensitization . Camouflage . Competitive attraction . Citrus Introduction The citrus leafminer, Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae), originated from India (Stainton 1856) and is a major citrus pest throughout the world (Heppner 1993). It was first recorded in Florida in 1993 (Heppner 1993) and since has spread throughout the US Gulf Coast as well as to California (Gill 1999) and Hawaii (Nagamine and Heu 2003). Although this species infests all varieties of citrus, as well as other Rutaceae and certain ornamental plants, grape- fruit, tangerine, and pumello are the preferred hosts (Legaspi and French 2003). Mated female P. citrella oviposit on host leaves, and emerging larvae tunnel within young leaves to feed. Infes- tations greater than 16% leaf area damage reduce yield on “Tahiti” lime (Peña et al. 2000). Control of the leafminer with chemical sprays is often ineffective in Florida because of the prolonged and sporadic leaf flush (immature leaves as described by Hall and Albrigo 2007) influenced by frequent rain and the fact that larvae are concealed within feeding galleries. Consequently, to be effective, sprays need to be applied biweekly (Peña et al. 2002; Rogers and Stelinski, unpublished data). The association of P. citrella with citrus bacterial canker, Xanthomonas axonopodis pv. citri, a major disease affect- J Chem Ecol (2008) 34:1107–1113 DOI 10.1007/s10886-008-9501-8 L. L. Stelinski (*) : M. E. Rogers Entomology and Nematology Department, Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850, USA e-mail: stelinski@ufl.edu J. R. Miller Department of Entomology, Michigan State University, East Lansing, MI 48824, USA