Field Studies of the Parasitic Ant Solenopsis daguerrei

LUIS A. CALCATERRA, JUAN A. BRIANO, AND DAVID F. WILLIAMS

ENVIRONMENTAL ENTOMOLOGY

ENTOMOLOGICAL SOC AMER

Año: 1999 vol. 28 p. 88 - 95

0046-225X

The workerless parasitic ant Solenopsis daguerrei (Santschi) has been considered a potential candidate for biological control of imported Þre ants in the United States since the 1970s. Weestimated the detrimental effects of S. daguerrei in Þre ant colonies from Argentina by comparing the composition of parasitized and nonparasitized Þeld colonies of the black imported Þre 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 parasiteÕs biology such as parasitization rates, presence of sexuals, abundance and weight of queens, and sex ratio. S. daguerrei occurred in 1.2Ð23.7% of the colonies at 21 collecting sites. The mound density at parasitized sites was signiÞcantly lower than in parasite-free sites (161 versus 239 mounds per hectare). Parasitized colonies had signiÞcantly fewer host queens thannonparasitized ones (2.9 versus 5.5 queens per colony). The percentage of colonies with worker brood was signiÞcantly lower (in fall) in parasitized than in nonparasitized colonies. Also, worker brood was signiÞcantly 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 conÞrmed in other areas. A better understanding of the host and parasite is required to introduce S. daguerrei into the United States to control imported Þre ants.Solenopsis daguerrei (Santschi) has been considered a potential candidate for biological control of imported Þre ants in the United States since the 1970s. Weestimated the detrimental effects of S. daguerrei in Þre ant colonies from Argentina by comparing the composition of parasitized and nonparasitized Þeld colonies of the black imported Þre 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 parasiteÕs biology such as parasitization rates, presence of sexuals, abundance and weight of queens, and sex ratio. S. daguerrei occurred in 1.2Ð23.7% of the colonies at 21 collecting sites. The mound density at parasitized sites was signiÞcantly lower than in parasite-free sites (161 versus 239 mounds per hectare). Parasitized colonies had signiÞcantly fewer host queens thannonparasitized ones (2.9 versus 5.5 queens per colony). The percentage of colonies with worker brood was signiÞcantly lower (in fall) in parasitized than in nonparasitized colonies. Also, worker brood was signiÞcantly 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 conÞrmed in other areas. A better understanding of the host and parasite is required to introduce S. daguerrei into the United States to control imported Þre ants.