Field Studies of the Parasitic AntSolenopsis daguerrei(Hymenoptera: Formicidae) on Fire Ants in Argentina

Abstract

Listen

Translate article

The workerless parasitic ant Solenopsis daguerrei (Santschi) has been considered a potential candidate for biological control of imported fire ants in the United States since the 1970s. We estimated the detrimental effects of S. daguerrei in fire ant colonies from Argentina by comparing the composition of parasitized and nonparasitized field colonies of the black imported fire ant S. richteri Forel. We recorded mound density and volume, incidence of polygyny, number of queens per colony, queen weight, and presence and abundance of brood and sexuals. Also, we studied aspects of the parasite’s biology such as parasitization rates, presence of sexuals, abundance and weight of queens, and sex ratio. S. daguerrei occurred in 1.2–23.7% of the colonies at 21 collecting sites. The mound density at parasitized sites was significantly lower than in parasite-free sites (161 versus 239 mounds per hectare). Parasitized colonies had significantly fewer host queens than nonparasitized ones (2.9 versus 5.5 queens per colony). The percentage of colonies with worker brood was significantly lower (in fall) in parasitized than in nonparasitized colonies. Also, worker brood was significantly less abundant (in fall and spring) in parasitized colonies. A short delay in the production of sexual brood by the host was observed in parasitized colonies. These detrimental effects look promising but should be evaluated in the long-term and confirmed in other areas. A better understanding of the host and parasite is required to introduce S. daguerrei into the United States to control imported fire ants.