Effects of insecticide use on breeding birds in Christmas tree plantations in Quebec

Abstract

: This research, which was carried out in the spring of 1989 and 1990 in seven balsam fir (Abies balsamea) plantations in southeastern Quebec, examines potential deleterious effects of three insecticides (i.e. dimethoate, diazinon and insecticidal soap) on breeding American Robins (Turdus migratorius) (n=87 nests) and Song Sparrows (Melospizsa melodia) (n=41 nests). Through analyses of blood serum cholinesterases (AChE and BChE) activity both prior to and the second day following applications of the two organophosphorus insecticides, we showed that adult American Robins, Song Sparrows and Chipping Sparrows (Spizella passerina) breeding in the treated plantations were exposed to diazinon and dimethoate (p<0.05). Signs of exposure to diazinon (p<0.05) were also found in young American Robins. However, despite sharp reductions in blood ChE (and, in some cases, marked inhibition confirmed by 2-PAM reactivation), no cases of adult mortality were recorded following the treatments. Cases of complete or partial mortality were recorded in American Robin and Song Sparrow nests, even among control birds (non-exposed birds). No mortality was recorded for broods exposed to the insecticidal soap. Abandonment of nests and egg infertility were ruled out as possible causes of mortality. The cases of total mortality observed in American Robin and Song Sparrow broods exposed to dimethoate were similar to those recorded for control nests (18 and 25% compared to 14 and 21%, respectively). However, among American Robin and Song Sparrow nestlings exposed to diazinon, essentially twice as many cases of total mortality (31 and 38%, respectively) were recorded as for the control nests. It appears that American Robin eggs are sensitive to diazinon and dimethoate, particularly when spraying is carried out early in the incubation stage. In the case of the Song Sparrow, it is mainly the nestlings that succumb after diazinon is sprayed on them or when dimethoate applications are made during the egg stage.

Variation in plasma cholinesterase activity in the clay-colored robin (Turdus grayi) in relation to time of day, season, and diazinon exposure

“…The American Robin, a relative of the clay-colored robin, is one of the species that has been most commonly affected. Rondeau and Desgranges (1995) found 48% ChE inhibition in blood serum of American robins from christmas tree plantations which had been sprayed with diazinon at 0.625 kg ai/ha. Also, ChE inhibition up to 72% was reported in the same species due to exposure to 2.2 kg ai/ha diazinon on ornamental trees (Decaire et al 1993).…”

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

“…Robins have frequently been the focus of orchard pesticide studies, and significant effects have been Environmental Management (2014) 53:416-428 425 observed in this species (Cobb et al 2000;Fluetsch and Sparling 1994;Gill et al 2000;Graham and DesGranges 1993). However, Graham and DesGranges (1993) and Rondeau and DesGranges (1995) both reported significant plasma ChE depression in both chipping sparrows and robins in areas treated with OPs, but chipping sparrows were the only species to demonstrate significant brain ChE depression in Christmas tree plantations. The findings of these studies corroborate some of our results and contrast others.…”

“…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.…”

A Review and Analysis of Study Endpoints Relevant to the Assessment of “Long Term” Pesticide Toxicity in Avian and Mammalian Wildlife

“…For example, Putera and colleagues (1985) found that 89% of Mourning doves on eggs during a spray event (unspecified whether this was an insecticide or fungicide spray) failed whereas all nests with chicks were successful. Rondeau and Desgranges (1995) found that exposure to diazinon during laying or early incubation was particularly damaging. No adult toxicity was seen in the latter study; it was not looked for by Putera and colleagues. (c) Eggshell quality endpoints (Endpoints equivalent to: eggshell thickness, proportion of eggs cracked).…”