The Resistance of the Citrus Leafminer, Phyllocnistis citrella STAINTON, to Insecticides and a Laboratory Bioassay Method

The susceptibility of two populations of the citrus leafminer, Phyllocnistis citrella, collected from Matsubase in Kumamoto Prefecture and Naruto in Tokushima Prefecture, to several insecticides was determined by field tests and laboratory bioassay. Citrus leaves infested with 1st and 2nd instar larvae were dipped into insecticide solutions and kept in petri dishs containing wet filter paper at 25°C. The mortalities were determined 48h. The Matsubase population was resistant to fenvalerate (LC50=30.1ppm) and permethrin (LC50=5.27ppm), but the Naruto population was susceptible. The susceptibility to phosmet was low in the Matsubase (LC50=3, 212ppm) and Naruto populations (LC50=150ppm). These results are consistent with the trend found in field tests with insecticides to control P. citrella.