The impact of imidacloprid on subterranean termite (Reticulitermes spp.) colonies located inside and around residential structures

Abstract:
This ongoing study in central North Carolina is making use of DNA technology (microsatellite genotyping) and long term monitoring to observe the immediate and prolonged effects of imidacloprid on subterranean termite colonies (Reticulitermes spp.) located inside and around residential structures. A set of 12 termite-infested houses in Raleigh, NC with active and accessible termites were selected for study and placed into a multi-year monitoring program. Termite infestations inside and around each house were extensively monitored and genotyped at 10 microsatellite loci to determine colony identity for a period of several months before treatment to develop a map of colony location and activity across each property. A licensed PMP applied imidacloprid as a liquid treatment (Premise® 75 WSP) at 0.05% by trenching and rodding around the outside of the foundation, and in some cases making limited interior applications. Initial results from the first four treated houses show that there can be numerous subterranean termite colonies (up to eight) in close proximity to structures and that attacks on a single house can originate from two different colonies simultaneously. The application of imidacloprid resulted in a rapid decline of termites inside each building with complete elimination of all known interior infestations within 7-85 d. Termite activity in the soil monitors placed along the foundation and in the yard of each property were also severely impacted following treatment with imidacloprid. In fact, all active monitors at each of these test sites became inactive at 21 - 80 d after treatment, even those located 17 - 50 ft. from the foundation wall. It was even observed that termite colonies detected in the outer ring of monitors, and distinct from colonies inside the structure, also disappeared following treatment. Long-term monitoring and genotyping over the next 2-3 yr will provide the best assessment of the effect of imidacloprid on the original termite colonies present at each site and the effect on new colonies that may try to recolonize the study area following application. The current status of results will be reported at this meeting.