GC-EAD and GC-MS analyses of a pheromone gland extract from virgin females of the citrus leafminer (CLM, Phyllocnistis citrella Stainton) confirmed that the male attractant previously found by random screening tests in a field, (7Z,11Z)-7,11-hexadecadienal (Z7,Z11-16:Ald), is a real pheromone component of CLM. While a field test of lures mixed with extra compounds structurally related to Z7,Z11-16:Ald did not inform candidates for a minor component having a synergistic effect, some compounds, particularly monoenyl derivatives, strongly inhibited the activity of the dienyl pheromone component. Furthermore, two experiments were carried out in citrus orchards to develop a method for disrupting the mating of CLM. In order to estimate the disruptive ability of Z7,Z11-16:Ald and some derivatives, pheromone traps surrounded with septa impregnated with these test compounds were used. However, this first trial was fruitless because the number of captured males actually increased due to the effect of the surrounding compounds such as Z7,Z11-16:Ald. On the other hand, another experiment with polyethylene dispensers containing Z7,Z11-16:Ald revealed a good ability to disrupt the male's orientation, although CLM eggs and larvae on a citrus tender flush did not show any significant difference in the control and treated fields. Monitoring traps caught 27-127 males in one night in control fields from July to September, but hardly any males were caught in either field treated with the dispensers at a density of 500 or 1300 tubes/ha.

Toxicity of insecticides to the citrus leafminer, AbstractThe experiments were conducted to learn about the relative toxicity of insecticides against the two parasite wasps of citrus leafminer (CLM), Phyllocnistis citrella. The relative toxicity of 12 common insecticides against the eggs and first instar larvae of the pest, and its parasitoids of Chrysocharis pentheus and Sympiesis striatipes, which are dominant species in Ehime Prefecture, was compared in 2003. Corrected mortalities were evaluated by dipping or spraying methods for the CLM eggs and larvae, and by clip-cage bioassay for the parasitoid wasps. All the insecticides tested showed almost over 90% mortality to the first instar larvae of citrus leafminer, but a lesser effect to the eggs. Against the adult parasitoids, imidacloprid (a.i. 0.005%), thiamethoxam (a.i. 0.003%) and acetamiprid (a.i. 0.005%) of the nicotinoide insecticides were less toxic, but dinotefuran (a.i. 0.02%) showed rather high mortalities. Of the IGRs, teflubenzuron (a.i. 0.05%) and diflubenzuron (a.i. 0.012%) were safe or less toxic to adult wasps. These three nicotinoide and two IGRs insecticides will be suitable candidates for use in the IPM program. Isoxathion (a.i. 0.025%) and primiphose-methyl (a.i. 0.056%) of the organophosphate and alanycarb (a.i. 0.04%) of carbamate were highly toxic. Bifenthrin (a.i. 0.0015%) of the pyrethroid and petroleum oil (a.i. 1.05%) were moderate in toxicity. Clothianidin (a.i. 0.005%) of the nicotinoide showed low toxicity to Chrysocharis pentheus but moderate toxicity to Sympiesis striatipes.

Seasonal abundance and parasitism of the citrus leafminer, Phyllocnistis citrella Stainton were investigated in controlled and uncontrolled citrus groves from June 2001 through May 2002 on Citrus iyo (iyotangor) in Ehime Prefecture. No significant difference in mean monthly frequency of P. citrella infestation and its parasitoids was found between controlled and uncontrolled groves. There were two peaks of P. citrella infestation, in July and October. These peaks were strongly related to favorable temperature for P. citrella development and continuous flushing of new shoots. At least seven species of the parasite wasps of P. citrella were observed, of which Chrysocharis pentheus (Walker) and Sympiesis striatipes (Ashmead) were the predominant species. The population drastically increased from July to August, and also from October to November, which coincided with heavy infestation of P. citrella in the iyotangor grove. In spite of a high percentage of parasitism (about 70%) in summer and autumn, the damage to tender leaves was noticeable, because all native parasitoids attacked mature larvae and pupae of P. citrella after they had nearly completed their feeding period.