Toxicity and risk of permethrin and naled to non-target insects after adult mosquito management.
We derived laboratory LC50 values, assessed non-target insect risks, and conducted a field bioassay for ultra-low-volume (ULV) aerosol applications of insecticides used to manage adult mosquitoes. The house cricket, Acheta domesticus (L.), was used as an indicator species for medium- to large-bodied ground dwelling insects. The 24-h LC(50) values for Permanone (formulated product of permethrin), Permanone + piperonyl butoxide (PBO), technical grade permethrin, and technical grade permethrin + PBO ranged from 0.052 to 0.9 microg/cm(2). The 24 h LC(50) for technical grade naled and Trumpet((R)) (formulated product of naled) were 0.038 and 0.44 microg/cm(2), respectively. The synergist ratio was 2.65 for Permanone + PBO and 1.57 for technical grade permethrin + PBO. The toxicity of technical grade permethrin was about 10-fold greater than Permanone. A risk assessment using modeled estimated environmental concentrations resulted in risk quotients (RQ) that exceeded regulatory levels of concern, but when compared to field-derived actual environmental concentrations RQs did not exceed a regulatory level of concern, except in the case of technical grade naled. These results were expected because higher tiered risk assessments using field-verified data generally lead to lower risk estimates. Field bioassays using caged crickets showed no significant mortality for permethrin or naled after a single truck-mounted ULV application. The results of the risk assessment using actual environmental concentrations are supported by the field bioassays and suggest that a single ULV application of synergized or unsynergized permethrin and naled most likely will not result in population impacts on medium- to large-bodied insects.
Schleier
Jerome J
JJ
Department of Land Resources and Environmental Sciences, Montana State University, 334 Leon Johnson Hall, Bozeman, MT 59717-3120, USA. jeromes@montana.edu
Peterson
Robert K D
RK
D000818:Animals; D004785:Environmental Pollutants / Q000633:toxicity*; D006135:Gryllidae / Q000187:drug effects*; D007928:Lethal Dose 50; D009032:Mosquito Control; D009267:Naled / Q000633:toxicity*; D026023:Permethrin / Q000633:toxicity*; D018570:Risk Assessment
D004785:Environmental Pollutants; D026023:Permethrin; D009267:Naled