Assessment of Repellency of Nine Phthalates against Red Imported Fire Ant (Hymenoptera: Formicidae) Workers Using Ant Digging Behavior

Repellency of nine phthalates against red imported fire ant workers, Solenopsis invicta Buren, was evaluated using ant digging behavior. Test compounds included dimethyl, diethyl, dipropyl, dibutyl, dipentyl, dihexyl, diheptyl, dioctyl, and dinonyl phthalates. The active ingredient was incorporated into sand within a liquid scintillation vial with an entry hole on the cap. Fire ant workers dug and removed sand from the vial through the entry hole. The differences in amount of sand removed from the treated and control vials were used to evaluate chemical repellency. Of the 9 phthalates, dimethyl and diethyl phthalates were most repellant to red imported fire ant workers. The minimum repellant concentration within 24 h was 100 ppm for both dimethyl and diethyl phthalates.