Effects of Moisture Before and After Laboratory Spray Application of Insecticides to Western Spruce Budworm (Lepidoptera/ Tortricidae)

1988

S. 1678-1680

2 Tab., 9 Lit. Ang.

Unselbständiges Werk

200042611

Under laboratory greenhouse conditions, moisture on Douglas-fir, Pseudotsuga menziesii (Mirbel) Franco, foliage at the time of spray application enhanced toxicity of acephate, carbaryl, methomyl sulprofos, and thiodicarb to western spruce budworm, Choristoneura occidentalis Freeman, approximately 2 to 14 times at LC50. Toxicity of acephate increased the most (14.2 times). Possibly, moisture permitted a more even distribution of toxicant so that theprobability of all larvae receiving a lethal concentration increased. When a p recisely estimated LC90 (wet) of each of the five chemicals was applied to misted foliage and subjected to 0.76 cm of simulated rainfall at 0, 3, 7, or 14 d after spray application, time of rainfall application was not a significant factor in resultant mortality. Rainfall seemed to decrease mortality by the same average amount regardless of time of application. These results suggest that the application of sprays early in the morning when dew is present on foliage may be advantageous compared with applications to totally dry foliage.