Suppression of citrus leafminer, Phyllocnistis citrella, with an attract-and-kill formulation

Abstract The citrus leafminer, Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae), is a worldwide pest of citrus crops and is responsible for proliferation of citrus bacterial canker,Xanthomonas axonopodis (Hasse) pv. citri (Gamma Proteobacteria: Xanthomonadaceae). We developed and evaluated an attracticide formulation, termed MalEx, for control of P. citrella. MalEx is a viscous paste with UV-protective properties that is dispensed as 50-ll droplets using custom-made calibrated pumps. A formulation containing 0.016 % P. citrella pheromone [3:1 blend of (Z,Z,E)-7,11,13-hexadecatrienal and (Z,Z)-7,11-hexadecadienal] and 6 % permethrin was found to suppress male response to phero-mone in the field better than formulations containing 10 · less pheromone. Although formulations without permethrin showed some suppression of male activity because of mating disruption, addi-tion of 6%permethrin to the formulation was required for optimal efficacy.WhenMalEx, containing 0.016 % pheromone and 6 % permethrin, was applied at 3 000 point sources ha)1, the application height did not influence efficacy of male P. citrella suppression within mature 4-m tall citrus trees. Decreasing the rate of MalEx from 3 000 to 1 500 droplets ha)1 reduced efficacy as measured by both male P. citrella activity and larval infestation. Although 4 500 droplets ha)1 did not result in statistically better efficacy than 3 000 droplets ha)1, there was a noticeable trend for higher efficac