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

Authors: Porter, Sanford; PLOWES, ROBERT - University Of Texas; CAUSTON, CHARLOTTE - Charles Darwin Foundation

Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/15/2018
Publication Date: 3/22/2018
Citation: Porter, S.D., Plowes, R.M., Causton, C.E. 2018. The fire ant decapitating fly Pseudacteon bifidus (Diptera: Phoridae): host specificity and attraction to potential food items. Florida Entomologist. 101(1):55-60. https://doi.org/10.1653/024.101.0111.
DOI: https://doi.org/10.1653/024.101.0111

Interpretive Summary: The tropical fire ant, Solenopsis geminata, is an invasive pest throughout most of the tropics, especially on Hawaii, Guam, and other Pacific islands. Natural enemies, like the fire ant decapitating fly Pseudacteon bifidus, offer the potential for use as self-sustaining biological control agents provided they are host specific and do not cause other unintended problems. Scientists at the USDA-ARS, Center for Medical, Agricultural and Veterinary Entomology in Gainesville, FL, the University of Texas at Austin, and the Charles Darwin Foundation, Galapagos, Ecuador cooperated in conducting sequential field and laboratory choice tests with host and non-host ants, as well as tests with a variety of potential food items adult flies might feed on. Results of these tests showed that these 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 this decapitating fly 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. These results are important because they show that field release of this decapitating fly as a self-sustaining biocontrol agent of invasive tropical fire ants would not cause unintended problems.

Technical Abstract: The tropical fire ant, Solenopsis geminata (F.) is an invasive pest throughout most of the tropics, especially on islands in the Pacific. Natural enemies, like the fire ant decapitating fly Pseudacteon bifidus Brown and Morrison, 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 adult flies might feed on. 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 was used as a self-sustaining biological control agent of invasive tropical fire ants.