Residues in Nontarget Ants 1 , Species Simplification and Recovery of Populations Following Aerial Applications of Mirex 2

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Abstract
Varying levels (0.029-12.12 ppm) of mirex (dodedaclorooctahydro-1,3,4-metheno-1 H -cyclobuta[ cd ]pentalene) were found in nontarget ants after aerial applications of mirex bait to control the red imported fire ant, Solenopsis invicta Buren, in Grimes and Brazos Counties, TX. Fourteen species of ants were monitored in the 2 plots. A fall treatment to the Brazos Co. area just recently invaded by S. invicta had the most pronounced effect. Those ants that are generally omnivorous and highly predacious were the first to be affected and were eliminated within 2 wk: these species included S. invicta, Solenopsis geminata (F.), Monomorium minimum (Buckley), Pheidole dentata Mayr, as well as a fungus-growing ant, Trachymyrmex septentrionalis (McCook). The highest levels of mirex were observed in Pogonomyrmex barbatus (F. Smith) and Conomyrma insana (Buckley). After 8 wk, only 2 species could be found in the Brazos Co. study plot, P. barbatus and Camponotus pennsylvanicus (DeGeer), and samples of both contained mirex. The population of P. barbatus and C. pennsylvanicus was fairly stable both pre and posttreatment. Populations of S. invicta were reestablishing in the Brazos Co. plot 7 mo posttreatment as were C. insana and Leptogennys elongata Mayr. Fourteen mo posttreatment, C. insana and S. invicta were the most prolific reinvaders reaching populations based on mound numbers and mound size much greater than pretreatment populations. Populations of M. minimum, Iridomyrmex pruinosum and P. dentata were reduced a year later over pretreatment levels.