LAUSR

Two species of imported fire ants, the red imported fire ant, Solenopsis invicta Buren, and the black imported fire ant, Solenopsis richteri Forel, were introduced into the United States from South America at the port of Mobile, Alabama in 1918 and 1930s, respectively. Although S. richteri was introduced and established in the United States more than one decade earlier than S. invicta, the latter has gradually displaced S. richteri throughout most of its distribution. However, S. richteri still persist in areas along the northern boundary of S. invicta’s distribution range, including northern Alabama, north Mississippi and southern Tennessee (Streett et al., 2006; Tschinkel, 2006; Oliver et al., 2009). Hybridization occurs between these 2 species in the United States (Vander Meer et al., 1985). In 1958, the USDA Animal and Plant Health Inspection Service (APHIS) enacted a Federal Imported Fire Ant Quarantine (7CFR301) for both species and their hybrid. Like virtually all ants, both S. invicta and S. richteri are well equipped with exocrine glands producing a wide variety of secretions, the chemistry of which has been subjected to rigorous studies (Vander Meer, 1983, 1997; Chen et al., 2009; Chen & Fadamiro, 2009a,b; Vander Meer et al., 2010; dos Santos Pinto et al., 2012). These 2 species show many similarities in exocrine gland chemistry, but also some apparent differences. For example, significant similarity was found in venom alkaloid chemistry of alate queens between these 2 species, which was speculated as a sign of reproductive compatibility (Chen et al., 2012). On the other hand, the difference in the profiles of piperidine alkaloids and cuticular hydrocarbons