DEVELOPMENT AND EVALUATION OF A TRANSMISSIBLE COATING FOR CONTROL OF SUBTERRANEAN TERMITES

Soil termiticides control subterranean termites by acting as chemical barriers, but they do not substantially suppress termite populations. Therefore, an effective termite population suppression technique is vi ewed as a highly desirable complement to soil treatment. Baiting strat egies have attempted to suppress termite populations by administering slow-acting toxicants to termite feeding substrates. As an alternative to baits, this paper describes a new approach for delivering slow-act ing toxicants, namely, via a transmissible coating which is applied di rectly to the cuticle of trapped termites. The coated termites are the n released, the coating is groomed off by untreated termites, and the material is further circulated in the population by trophallaxis. Vari ous toxicants were tested in a resin-based transmissible coating again st the eastern subterranean termite, Reticulitermes flavipes (Kollar) (Isoptera: Rhinotermitidae). Of the 11 compounds tested in the transmi ssible coating formulation, sulfluramid was the most effective. Petri dish tests demonstrated that a single resin-sulfluramid coated termite could kill up to 1,394 untreated termites. Further lab tests in soil cups and soil trays with up to 50,000 termites per test, consistently demonstrated greater than 95% mortality when 5% or 10% of the termites were treated with the coating. Twenty urban field trials were initiat ed in 1993. The termite populations at these sites were characterized by the mark-release-recapture technique and other population estimator s. Population estimates for the 20 sites ranged from 100,572 to 11,422 ,441 with an average mean estimate of 1,931,917. Greater than 60% supp ression was achieved at 19 of the 20 sites after treatments in the fir st year. Surviving populations were further suppressed with smaller fo llow up treatments in 1994 and 1995. At 12 of the 20 sites which had n ot been expanded, the average number of termites trapped per visit in 1995 declined by 92.6% compared to 1993. At the other 8 sites which we re expanded, new termite activity was mainly located in expanded areas and was largely suppressed by the end of 1995. Two block trials were initiated in 1994 on two heavily infested, residential, city blocks. T rap activity was strongly suppressed within both blocks by the end of 1994. Low trap activity and low termite yields were seen on both block s In 1995 and further suppressed by small follow up treatments. The nu mber of termites trapped in 1995 had declined by 90.4% on one block an d had declined by 95.4% on the other block. The field trials documente d here are the largest ever reported for an alternative termite contro l system. In total, the 22 field trials encompassed 151 residential pr operties including two city blocks, tyro apartment complexes, two apar tment buildings, one public housing complex and one park. A total of 1 ,282 traps were monitored, of which 631 traps were active. By the end of 1995 only 16 traps continued to be active at 9 of the 22 sites. The se tests establish the field efficacy of a transmissible coating conta ining sulfluramid as a viable strategy for subterranean termite popula tion suppression under diverse urban conditions.