Fate of aminocarb insecticide in the aquatic components of a mixed‐wood boreal forest environment after aerial application of two matacil^® 180 flowable formulations

Abstract

The aminocarb flowable formulation, Matacil®180F, was mixed in water (180FE) and in an oil‐based diluent (180FO) and both formulations were applied as double applications at 70 g active ingredient (AI) in 1.5 L/ha. An aircraft (TBM Avenger) equipped with 1010 flat fan (Teejet^®) nozzles was used to spray the insecticide over a mixed‐wood boreal forest in eastern Canada. The amount deposited (g Al/ha) and percent deposited varied considerably among the four applications. The average amount of aminocarb deposited (g Al/ha) and the percent of the applied dosage found on the forest floor were 18.1 and 22.9, respectively. The emulsion formulation, 180FE, usually produced a higher deposit on the forest floor and in stream waters than the oil‐based 180FO. The 1 h postspray peak concentrations of aminocarb found in the stream waters sprayed with 180FO and 180FE were 3.06 and 22.64 ppb, respectively. The residues dissipated rapidly within 24 h. The small amount of the chemical (5.8 ppb) that was found in sediment also dissipated quickly. Concentrations of aminocarb found in watercress (880 ppb) and moss (210 ppb) were significantly higher than the peak concentrations found in the water. Peak concentrations in plants usually occurred at 1 or 3 h postspray sampling time, and in all cases decreased gradually thereafter. Highest residues in fish were 6.1 and 13.8 ppb, but they were eliminated rapidly. No mortality or behavioural changes were observed in fish. At the dosage rate used, aminocarb does not pose any undue hazard to the aquatic environment.

Key words:

• Aminocarb
• Matacil^®
• flowable formulation
• aerial spray
• deposition
• persistence
• half‐life
• fate