Cholinesterase Inhibition in Tree Swallows (Tachycineta Bicolor) and Eastern Bluebirds (Sialia Sialis) Exposed to Organophosphorus Insecticides in Apple Orchards in Ontario, Canada

Abstract

Abstract-Apple orchards occupy approximately 12,565 ha of land in Ontario, Canada, and are treated with the greatest number and applications of pesticides among all agricultural crops within the province. The potential for exposure to wildlife from frequent organophosphorus (OP) spray applications is therefore considerable. This study investigated the impact of agricultural spray applications of azinphos-methyl, diazinon, phosalone, and phosmet in apple orchards on the cholinesterase (ChE) activity of wild birds nesting in orchards. These four OP pesticides ranked among the most widely used insecticides used on all fruit crops in Ontario in 1988. Tree swallows (Tachycineta bicolor) and eastern bluebirds (Sialia sialis) were chosen as monitor species because they commonly breed and forage within apple orchards, utilize different feeding strategies, and are readily attracted to nest boxes. Brain and plasma ChE activities were determined for nestling bluebirds and swallows, and plasma ChE was measured in adult swallows for comparison with nestling data. In adult tree swallows, mean plasma ChE levels were significantly inhibited 41% compared to controls 12 h after a second application of azinphos-methyl. Mean plasma ChE activity in another group of adult tree swallows dropped by 21 and 19% following a multiple phosmet application. In nestlings, brain ChE activities obtained postspray often fell below predicted activities calculated from control siblings. This trend was especially apparent in the younger nestlings, less than 6 d old. However, for bluebirds the rates of increase of brain ChE with age in nestlings from treated sites was significantly lower than in nestlings from control sites. Brain ChE activity of two nestlings found dead following a phosalone application gave no indication that insecticide exposure was responsible. No other dead or moribund birds were discovered during the course of the study. Sequential plasma sampling of siblings, before and after OP application, was beneficial in reducing the required number of nests sampled by one half, but plasma ChE was less reliable overall than brain ChE in indicating exposure. Results of depressed ChE levels in tree swallows and eastern bluebirds inhabiting apple orchards are consistent with avian species in other orchard monitoring studies. No indication was found that OP exposure due to agricultural spraying in apple orchards adversely affected the survival of the birds we monitored.

Effect of lambda cyhalothrin (pyrethroid) and monocrotophos (organophosphate) on cholinesterase activity in liver, kidney and brain ofRana cyanophlyctis

“…Nizam (1993) reported 49% and 57% inhibition of AchE after Nfb and nimocinol treatment in subject animal. Burgees et al (1999) observed that organophosphate decreased cholinesterase activity in birds and these insecticide also produced tremors loss of Table 3. Activity of cholinesterase in brain of Rana cyanophyctis treated with lambda cyhalothrin 65.9 muscular control and paralysis.…”

Cholinesterase activity as a biomarker of pesticide exposure inAllolobophora chloroticaearthworms living in apple orchards under different management strategies

“…A classical biomarker of exposure to OP or CA is the inhibition of cholinesterase (ChE) activity. This biomarker was successfully applied to birds in apple orchards [3,4].…”

The Influence of Study Species Selection on Estimates of Pesticide Exposure in Free-Ranging Birds

“…These environments present complex exposure scenarios for birds because orchards receive multiple pesticides per application and multiple applications per season. Additionally, orchards attract many species of birds because they provide habitat for nesting and other resources (Bishop et al 2000;Boutin et al 1999;Bouvier et al 2011;Burgess et al 1999;Fluetsch and Sparling 1994;Johnson et al 1976;Wilson et al 2001). Anti-ChE insecticides, which inhibit acetylcholinesterase, are still used in these and other agricultural environments, and because of their toxicity and nonselective mode of action, adverse effects have been observed over a wide taxonomic spectrum, including birds (e.g., Elliott et al 2008;Gill et al 2004;Parsons et al 2010;Strum et al 2010).…”

“…However, little empirical data or guidance exists for choosing indicator species for contaminant studies with labile chemicals that have the potential for short-term but highly acute effects (Greig-Smith 1990). Indicator species used in field studies with pesticides are often selected on the basis of abundance and convenience in collecting data with that species (e.g., Millikin and Smith 1990; see also Bouvier et al 2005;Burgess et al 1999;Greig-Smith 1990;Jones 2003;Patnode and White 1991;Rondeau and DesGranges 1995). Selection of a species based on its abundance may provide greater numbers of individuals for study and analysis, but a species may be abundant because it is less sensitive or does not receive the exposure necessary to result in a toxic effect.…”