The fate of fenitrothion in a stream environment and its effect on the fauna,following aerial spraying of a Scottish forest

In order to control an infestation of Pine Beauty moth (Panolis flammea Schiff.) fenitrothion was applied at a rate of 300 g ha^?1 to a forest plantation consisting primarily of Lodgepole Pine (Pinus contorta Loud.) and Sitka Spruce (Picea sitchensis Carriere) using the ultra-low volume spraying technique. The concentration of fenitrothion in the forest stream rose to a maximum of 18μgl^?1 within the treated area an hour after spraying, but fell to 0.5 μgl^?1 after 24 hs. There was no evidence that the resident fish population was disturbed by the treatment and no short term effects were noticeable in caged fish. The concentration—time profile in the fish followed closely the profile in the water, and in each of the four fish tissues studied fell to 0.02 mg kg^?1 after 24 hs. Invertebrate drift increased markedly 12–16 hs after spraying, but decreased to around pretreatment levels within 48 hs. Caged insects remained alive during the five-day post-spray observation period, suggesting that drifting insects were displaced rather than killed by the insecticide. Concentration of fenitrothion in Willow Moss (Fontinalis antipyretica) fell from 0.139 mg kg^?1 to 0.003 mg kg^?1 (wet weight) after 48 hs. Fenitrothion was not detected in sediment but his was possibly due to the low surface area/weight ratio of the particles.