EVALUATION OF THE INSECTICIDAL ACTIVITIES OF THREE EUCALYPTUS SPECIES CULTIVATED IN IRAN, AGAINST HYPHANTRIA CUNEA DRURY (LEPIDOPTERA: ARCTIIDAE)

摘要

In the current study, the larvicidal activity of leaf essential oils from three eucalyptus species (Eucalyptus largiflorens Meull, Eucalyptus oleosa Meull, and Eucalyptus spathulata Hook) against American white moth, Hyphantria cunea Drury 1773 (Lepidoptera: Arctiidae), was investigated. Mortality was recorded daily for three days after treatment. Leaf disc bioassays revealed that all three oils had strong insecticidal activity on the experimental insects insofar as 50% lethal concentrations (LC50) for E. oleosa, E. spathulata, and E. largiflorens at 24 h exposure time were 0.36, 0.61, and 1.24%, respectively. The time needed to kill 50% (LT50) values were calculated as 9.09 h with E. largiflorens, 11.03 h with E. oleosa, and 13.03 h with E. spathulata at the highest concentrations (2.5% for E. largiflorens, 2% for E. oleosa, and 2.5% for E. spathulata). Based on probit analysis, an increase in the susceptibility of the insect was associated with an increase in the different concentrations of all oils and the increase in the time of exposure. The results of this study show that leaf essential oils of E. largiflorens, E. oleosa, and E. spathulata might be considered as a potent source for the production of fine natural larvicides.