Mating disruption of citrus leafminer, Phyllocnistis citrella Stainton, (Lepidoptera: Gracillariidae) in California citrus nursery and small orchard settings

Citrus Leaf Miner (CLM), Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae), is a relatively new pest in California causing extensive damage to young citrus trees. Pheromone disruption methods have shown varying levels of efficacy for CLM control in field studies in Florida. Two experiments were developed to test the efficacy of CLM pheromone disruption under California conditions. Both trials employed SPLAT® (ISCA Technologies, Inc. Riverside, CA), a sustained-release product containing 0.15% active ingredient of artificial female CLM pheromone, (Z, Z, E)-7, 11, 13-Hexadecatrienal. A seedling trial using Frost-Lisbon stock was set up with each treatment seedling receiving a one-gram application of SPLAT. Additionally, a 10-acre lemon grove was divided into two blocks with each tree in the 5-acre treatment section receiving a one-gram application of SPLAT. Two plots with seedlings were placed at either end of the grove to simulate a seedling nursery. Traps with CLM monitoring lures, were used to record male numbers and leaf mining on shoots was observed and recorded weekly throughout the experiments. Significantly more males were observed in traps in the control plots; a mean of 13.8 males in the treatment traps versus 94.5 in the control traps (p=0.0058). Trials in the lemon grove showed significantly fewer mines per leaf and number of leaves mined in the treatment portion versus the control, with the treatment having a p-value of 0.0001. The mean number of leaves mined was significantly higher when no treatment was applied, than when treatment was applied, by 1.17 leaves (p<0.0001).