Development and evaluation of a method for the design of spray applications: aerial tebufenozide applications to control the eastern spruce budworm, Choristoneura fumiferana (Clem.)
1997
Payne, N. | Retnakaran, A. | Cadogan, B.
A novel approach to the design of insecticide spray applications was developed and evaluated in field trials to assess the efficacy of the insect moulting hormone analog tebufenozide (Mimic) against the eastern spruce budworm, Choristoneura fumiferana (Clem.). The pest biology, and habitat and pesticide characteristics were used as a basis to derive the required active ingredient (a.i.) and deposit density. Ingestion is the primary exposure route; an LD95 acquisition through foliage consumption by fourth-instar larvae was used to establish a target dose 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 required 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 average deposit densities (droplets cm-2) on artificial foliage between 0.8 and 3.7, with averge volumetric deposits between 7 and 30% of volume application rates. Population control was satisfactory, except for those applications at 35 g a.i. in 2 L and 70 g in 4 L ha-1 for which low deposit densities were observed. This approach to spray application design was found to be of scientific value and is adaptable to other insecticide applications.
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