The fire ant decapitating fly, Pseudacteon bifidus (Diptera: Phoridae): host specificity and attraction to potential food items

The tropical fire ant, Solenopsis geminata (F.) (Hymenoptera: Formicidae), is an invasive pest throughout most of the tropics, especially on islands in the Pacific. Natural enemies such as the fire ant decapitating fly, Pseudacteon bifidus Brown and Morrison (Diptera: Phoridae), offer the potential for use as self-sustaining biological control agents provided they are host specific and do not cause other unintended problems. This paper provides details of sequential field and laboratory choice tests with host and non-host ants, as well as tests with a variety of potential food items to which adult flies may be attracted. Results of these tests showed that P. bifidus flies are highly host specific to tropical fire ants and that they are not attracted to ants in other genera. Even other species of fire ants are unlikely to be parasitized by this fly in the field. Furthermore, tests with a variety of food items demonstrated that P. bifidus is not likely to be a nuisance to humans because it is not attracted to carrion, feces, fruits, or various kinds of human food items. In short, P. bifidus would not likely cause unintended problems if it were used as a self-sustaining biological control agent of invasive tropical fire ants.