ARS | Publication request: Usefulness of fire ant genetics in insecticide efficacy trials

Submitted to: Southern Nursery Association Research Conference
Publication Type: Proceedings
Publication Acceptance Date: January 10, 2011
Publication Date: September 1, 2011
Citation: Rinehart, T.A., Oliver, J. 2011. Usefulness of fire ant genetics in insecticide efficacy trials. Southern Nursery Association Research Conference. 56:104-108.

Interpretive Summary: Red (Solenopsis invicta Buren) and black (Solenopsis richteri Forel) imported fire ant and their hybrids have spread throughout the southeastern United States after being introduced in Mobile, Alabama in the late 1930’s. New infestations can be caused by infested sod and nursery stock that is shipped outside the ant’s current range. Nursery items, such as balled nursery stock, that are shipped to areas outside of the quarantine zone must be certified and compliant with USDA-APHIS regulations. Control measures generally include insecticide treatments, which are updated and revised as new research and products are available to improve the management of imported fire ants. Our objective here is to better understand the results of pesticide efficacy trials by analyzing the genetic background of fire ants in colonies being treated.

Technical Abstract: Mature fire ant colonies contain an average of 80,000 worker ants. For this study, eight fire ant workers were randomly sampled from each colony. DNA fingerprints for each individual ant were generated using 21 simple sequence repeats (SSR) markers that were developed from fire ant DNA by other laboratories. Workers from eight different colonies were tested for a total of 64 individual ants. Samples were labeled with number corresponding to the colony and letter for each individual ant. All colonies were then treated with Onyx Pro Insecticide or Scimitar GC as part of pesticide efficacy trials. Among the eight colonies sampled, colonies that survived from 3 – 8 weeks post treatment included colony numbers 30, 32, 87, 130, and 181. Colonies eliminated during the 1 week after treatment included 7, 160, and 190. Our objective was to look for evidence of a genetic basis for survival following pesticide treatment by comparing genetic diversity between colonies that survived and those that were eliminated within the first week. DNA fingerprints were compiled for all samples and analyzed for similarities. The genetic relationships among ants and colonies were visualized using an unrooted neighbor-joining tree that shows clustering of more closely related ants.