Effects of boric acid,fipronil, hydramethylnon,and diflubenzuron baits on colonies of ghost ants (Hymenoptera: Formicidae)

Laboratory colonies of the ghost ant, Tapinoma melanocephalum (F.) were administered sugar solution (10%) baits containing the insecticides boric acid, fipronil (REGENT), hydramethylnon (SIEGE), or diflubenzuron (DIMILN). Colonies were exposed to the baits for 21 d, and development of workers, queens, and brood (larvae and pupae) was observed for 4 wk. Fipronil (0.05%) caused 100% mortality in all colonies the first week. With boric acid (0.5%), 100% mortality of workers, queens, and brood was reached at the end of the third week. With hydramethylnon (2%), 83% of the colonies disappeared at the end of the fourth week, but some queens were still alive 9 wk after the trial started. Diflubenzuron (1%) behaved similarly to the control, although in some colonies, the brood production increased, whereas in other colonies, the queens disappeared. In the control colonies, workers, queens, and brood were always observed even up to 9 wk.