Effects of the organophosphate azinphos-methyl on birds of potato fields and apple orchards in Quebec, Canada

Abstract

Although considered to be a highly toxic insecticide, no adverse effect on wildlife has ever been demonstrated for azinphos-methyl. In the province of Quebec, approximately 20 000 kg of this insecticide are used annually with the major use crops being apples and potatoes. This study examined the potential impact of azinphos-methyl on birds inhabiting sprayed apple orchards and potato fields. Lethal impacts were considered by examining reproductive success and survivorship of banded territorial males. No such impacts were noted; some banded territorial males were present on their territories for at least 2 or 3 years. Decreases in cholinesterase activity in brain and blood samples can be used to document exposure and physiological impacts. No statistical effect could be demonstrated for birds in the potato fields but decreases in cholinesterase activity were highly significant for the three species studied in apple orchards. Behavioural impacts were examined by looking at changes in activity patterns (in potato fields). Data were inconclusive but did serve to show that the fields themselves were rarely used and that overall activity levels did not seem to be related to spray events. The lack of a measurable impact in potato fields is largely attributed to the lower dose rate and to behavioural attributes of the resident birds which led them to avoid sprayed areas. Exposure to the insecticide was irrefutably demonstrated for the residents of the apple orchards but this could not be associated with any other measurable impact. There is obviously a potential that under some environmental conditions vulnerable individuals could be adversely affected. It is concluded however that there was no evidence from this study to support the contention that the use of azinphos-methyl in Quebec has a measurable effect on birds at a population or community level.