DEVELOPMENT AND EVALUATION OF A METHOD FOR THE DESIGN OF SPRAY APPLICATIONS - AERIAL TEBUFENOZIDE APPLICATIONS TO CONTROL THE EASTERN SPRUCE BUDWORM, CHORISTONEURA-FUMIFERANA (CLEM)

A novel approach to the design of insecticide spray applications was d eveloped and evaluated in field trials to assess the efficacy of the i nsect moulting hormone analog tebufenozide (Mimic (R)) against the eas tern spruce budworm, Choristoneura fumiferana (Clem.). The pest biolog y, and habitat and pesticide characteristics were used as a basis to d erive the required active ingredient (a.i.) and deposit density. Inges tion is the primary exposure route; an LD95 acquisition through foliag e consumption by fourth-instar larvae was used to establish a target d ose of 15 ng a.i. cm(-2) in one drop per needle (2.5 cm(-2)). A range of a.i. and volume application rates were selected based on the requir ed densities, canopy leaf area index and projected spray losses to the understorey and by drift; application rates of 35, 70 and 140 g a.i. l ha(-1) were employed, with volume application rates of 1, 2 and 4 L ha(-1). Coniferous forest plots were aerially treated, resulting in av erage deposit densities (droplets cm(-2)) on artificial foliage betwee n 0.8 and 3.7, with averge volumetric deposits between 7 and 30% of vo lume application rates. Population control was satisfactory, except fo r those applications at 35 g a.i. in 2 L and 70 g in 4 L ha(-1) for wh ich low deposit densities were observed. This approach to spray applic ation design was found to be of scientific value and is adaptable to o ther insecticide applications. (C) 1997 Elsevier Science Ltd.