LABORATORY AND FIELD EVALUATIONS OF SELECTED CHEMICAL TREATMENTS FOR CONTROL OF DRYWOOD TERMITES (ISOPTERA, KALOTERMITIDAE)

A 1-m board bioassay was used to assess the efficacy of spinosad, diso dium octaborate tetrahydrate (DOT), calcium arsenate, and chlorpyrifos on the mortality and fecal pellet production of 2 drywood termite spe cies, Incisitermes snyderi (Light) and Cryptotermes brevis (Walker), u nder unforced exposure and simulated field conditions. Spinosad suspen sion concentrate at 2,300 or 5,000 ppm, 35% calcium arsenate, and chlo rpyrifos aerosol at 5,000 ppm were more toxic and reduced pellet produ ction compared with DOT treatments at 4 wk. Of DOT treatments, only 98 % dust caused higher mortality than controls at 8 wk Spinosad suspensi on concentrate and chlorpyrifos had an effect an termite location in b ioassay boards. Acoustic emissions activity of 55 C. brevis infestatio ns in 2 buildings was determined before intragallery injection of liqu ids and dusts tested above, with the exception of arsenate dust, and s urface application of 10% DOT. After treatment, acoustic emission acti vity was recorded for each infestation at 1, 2, 3, 5, 8, and 12 mo. At 4 mo, one building was fumigated with sulfuryl fluoride. Posttreatmen t readings taken 3 mo or earlier for infestations treated with spinosa d suspension concentrate, chlorpyrifos, and DOT surface showed reducti ons in acoustic emission activity. Only spinosad SC treatment yielded significant acoustic emission reductions at 5 mo or later. Results sug gest that chemical toxicity, formulation, and application method, as w ell as drywood termite behavior and gallery system architecture, influ enced the performance of local chemical treatments. Sulfuryl fluoride fumigation resulted in cessation of acoustic emission activity in all colonies monitored in the fumigated building.