Reduction in the number of Formosan subterranean termite colonies contributing to alate swarms in the French Quarter, New Orleans

The National Formosan subterranean termite (FST) program has conducted area-wide termite management in New Orleans, La. since 1998. Sustained control of FST requires colony-level elimination. Therefore, it is important to assess treatment success, not only by monitoring changes in the numbers of flying reproductives (alates) within the program area, but also in the numbers of colonies which are contributing alates to the swarms. The current study is part of a long-term investigation into the numbers of colonies contributing to alate swarms as compared over time and location. Alates were collected from April to July of 2007 to 2009 via light traps placed throughout the French Quarter, New Orleans. Genomic DNA from 40 individual alates from each trap, at each peak (i.e. swarm events with at least 50 alates found in the trap), was extracted and then genotyped at seven microsatellite loci. The effective number of colonies contributing alates to each single trap was estimated as the average within-colony relatedness of FSTs from previous studies (r=0.58) divided by the observed relatedness among alates sampled in each trap. The average number of colonies per trap was 7 in 2007, 2 in 2008 and just over 2 in 2009. This is a clear reduction from 2003 data, which indicated that alates in a trap originated from an average of 13 colonies during a single mass swarm event. Further results will be presented which compare data across multiple traps to determine whether the same colonies contribute alates to multiple traps over time.