SÁNCHEZ RESTREPO AndrÉs Fernando
congresos y reuniones científicas
The invasive tawny crazy ant, Nylanderia fulva, in the southern limit of its native distribution range
FERNÁNDEZ, MARÍA BELEN; SÁNCHEZ, ANDRÉS F.; VARGO, ED; JOHNSON, L.; SHOEMAKER, D.D.; CONFALONIERI, VIVIANA; CALCATERRA, LUIS
Congreso; XXIII Simpósio de Mirmecologia An International Ant Meeting; 2017
Ants comprise 5% of the world?s 100 worst invasive species. Increasing global commerce facilitates their distribution throughout the world; such is the case of the tawny crazy ant (TCA), Nylanderia fulva, introduced into the US in 2002 from an unknown site within its native southern South America. TCA is a major urban and ecological pest that has dispersed throughout Texas, Florida, and southern Louisi-ana and Mississippi. Recent studies in the Gulf Coast of Texas showed that the TCA quickly reaches densities of up to two orders of magnitude greater than all other ant species pooled together, likely due to its strong poison and supercolonial social structure across southern US; yet nothing is known about TCA in its native range. The objectives of this study are to know the distribution of TCA in Argentina, the putative source population introduced into the US, using a COI marker of 794 bp; to investigate its social structure using paired tests of aggression between nests; and to infer its reproduction system (sexual or clonal), using microsatellite markers. Initial surveys were mostly concentrated in northeast-ern Argentina. Samples of workers, alates and/or queens were collected for behavioral assays and molecular analyses. TCA nests were found across the entire surveyed area. As observed in popula-tions in the US, native populations did not show evidence of aggressive behavior between nests at local scale. COI sequences from the native range were compared with published sequences from the US. As expected, the number of COI haplotypes in the native range was several times higher and more diverse than in the US. A Neighbor Joining Distance Tree recovered three haplogroups. All intro-duced populations grouped in a single haplogroup in which a haplotype from Misiones, Paraguay, and Brazil was similar to a haplotype found in Texas and Louisiana, and a haplotype from Entre Ríos was similar to a haplotype from Florida and Texas, and closely related to the haplotype from US Virgin Is-lands. These findings suggest the introduction could have originated from northeastern Argentina and/or from nearby areas of Paraguay and Brazil. Colonies found in Argentina appear to have much lower numbers of queens than colonies in the US. Population genetic analysis from Argentine populations revealed differences in allele frequencies: queens were homozygous in more loci than workers, which were mostly heterozygotes. These unusual genotype frequencies could have resulted from a combina-tion of sexual and clonal reproduction, as in other highly invasive ants. (CONICET, PICT-FONCyT, ARS-USDA, Texas A&M University).