Toxicity and horizontal transfer of chlorantraniliprole in the eastern subterranean termite

Toxicity and horizontal transmission of chlorantraniliprole were measured against field-collected eastern subterranean termites, Reticulitermes flavipes (Kollar). Chlorantraniliprole was highly toxic to termite workers in brief and continuous exposure assays across arange of concentrations from 5 to 100 ppm. All doses tested resulted in 100% mortality in the termites in 14 d. The effect of exposure route (topical, oral, or both) was investigated by exposing termites to treated substrate only, treated food only, or both. Results indicate that exposure route has no significant effect on chlorantraniliprole toxicity and demonstrate that chlorantraniliprole is highly active by feeding and contact. Results of feeding assays (paper consumption tests) demonstrate that as little as 5-ppm chlorantraniliprole applied to sand prevents termites from consuming cellulose that is in contact with the treated sand. Termites on untreated soil consumed 79 +/- 3% of the available paper in 3 d, whereas termites on chlorantraniliprole-treated did not consume any paper before they became symptomatic and died. Results of transfer tests demonstrate that chlorantraniliprole is transferred efficiently among the termites. The rate and the level of secondary mortality in the recipient termites depend on both the concentration of chlorantraniliprole and the duration of exposure in the donors. Little secondary mortality was observed with the lowest dose of 5 ppm, which was effective at killing the donor termites, but insufficient to cause mortality in the recipient termites. In contrast, highly efficient transfer was observed with 25 and 50 ppm chlorantraniliprole. Both doses resulted in 100% mortality in the donors and the recipients at 21 d after exposing the recipients to the treated donors. These data demonstrate that chlorantraniliprole has dose-independent toxicity, delayed toxicity, and is readily transferred in eastern subterranean termites.