Toxicity and individual mound treatment effect of d-limonene on red imported fire ant（Solenopsis invicta Buren）

D-limonene is a Rutacea plant-derived monoterpene with pesticide properties. A formulation containing d-limonene（as active ingredient） and edible plant oil was assessed on its efficacy on red imported fire ant（Solenopsis invicta Buren）. The toxicity of mixtures containing 80%，85% and 90% d-limonene on fire ants was evaluated in laboratory. All mixtures demonstrated excellent insecticidal effects on reproductive alates，workers，eggs and pupae of fire ants，and the effect of the mixture containing 90% d-limonene was the best. The time of all mixtures for killing workers was much shorter than that for killing alates. The effect of the mixture containing 90% d-limonene as an individual mound treatment was then evaluated. The mixture was applied by a unique method，that a sponge soaking up 10 mL mixture was immediately put into the core of ant mound after rapidly poking a Φ 3 cm hole into