Stress and immune responses of nestling tree swallows (Tachycinet bicolor) and eastern bluebirds (Sialia sialis) exposed to nonpersistent pesticides and p,p′‐dichlorodiphenyldichloroethylene in apple orchards of southern ontario, canada

Abstract

To determine the relative effects of pesticides in current use and persistent residues of p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE), we examined endocrine and immune responses in tree swallow (Tachycineta bicolor) and eastern bluebird (Sialia sialis) chicks from pesticide-sprayed apple orchards and reference sites in southern Ontario, Canada, during 2000 to 2001. Nests were exposed to as many as seven individual pesticide applications and up to five mixtures of pesticides during the egg-incubation and chick-rearing stage. Eggs collected from sprayed orchards contained higher p,p'-DDE concentrations than eggs from reference sites. In 16-d-old tree swallows, no significant differences were found in body mass, basal corticosterone concentration, or the corticosterone stress response following a 10-min restraint of chicks sampled from sprayed orchards and reference sites. Challenge with adrenocorticotrophic hormone (ACTH), however, produced a higher level of corticosterone secretion in tree swallow chicks from sprayed orchards relative to chicks from reference sites. Multiple regression analysis revealed no correlation between corticosterone concentrations and exposure to pesticide sprays or p,p'-DDE in tree swallow chicks. In contrast, bluebird chicks from sprayed orchards were less responsive to challenge with ACTH and a significant negative association was found between the response to ACTH challenge and p,p'-DDE concentration in eggs. The phytohemagglutinin (PHA)-induced cutaneous basophil hypersensitivity response was similar between exposure groups in both tree swallow and bluebird nestlings. Examination of immune organs revealed that tree swallow chicks from sprayed orchards had significantly greater thymic lymphocyte density and cortical/ medullary ratios and significant splenic B-cell hyperplasia relative to reference chicks. Our results indicate that modulation in the hypothalamus-pituitary-adrenal axis in songbird chicks tested are most associated with high p,p'-DDE egg concentrations. An alteration in the endocrine or immune system may compromise songbird survival immediately after fledging or during migration.

Reproductive success of three passerine species exposed to dioxin-like compounds near Midland, Michigan, USA

“…Researchers have monitored birds exposed to contaminants for molecular (Custer et al 2005, 2001; Papp et al 2005), immune (Dods et al 2005; Martinovic et al 2003; Mayne et al 2004), morphometric (Custer et al 2005; DeWitt et al 2006; Henshel et al 1997), and genetic (Stapleton et al 2001) responses with mixed results. The predominant limitation of these measurement endpoints is relating them to altered survival or reproductive performance in field studies, while similar measurement endpoints are useful in laboratory studies to determine dose–response relationships (Head and Kennedy 2007).…”

“…Tree swallows (TRES; Tachycineta bicolor ), which eat primarily emergent aquatic invertebrates, are linked to contaminated sediments (Echols et al 2004; Neigh et al 2006a), and have been extensively utilized in field studies (Custer et al 2005; Echols et al 2004; Froese et al 1998). House wrens (HOWR; Troglodytes aedon ) and eastern bluebirds (EABL; Sialia sialis ) eat primarily terrestrial insects and have been used to assess contaminated soils (Mayne et al 2004; Neigh et al 2006a, 2007). …”

Multiple Lines of Evidence Risk Assessment of Terrestrial Passerines Exposed to PCDFs and PCDDs in the Tittabawassee River Floodplain, Midland, Michigan, USA

“…Site-specific assessments of exposures and related effects for a variety of terrestrial passerine species have been conducted (Ankley et al 1993; Bishop et al 1995; Custer et al 2001; Henning et al 2003; Arenal et al 2004; van den Steen et al 2006, 2007), but more commonly, tree swallows have been selected as target species in assessments of risk in aquatic-based studies (Shaw 1983; DeWeese et al 1985; Beaver 1992; Ankley et al 1993; Bishop et al 1995; Froese et al 1998; Custer et al 1998; Secord et al 1999; Custer et al 2000; Harris and Elliott 2000; Custer et al 2002, 2003; Echols et al 2004; Custer et al 2005; Smits et al 2005; Neigh et al 2006b; Spears et al 2008). However, house wrens and eastern bluebirds have been effectively used as receptors at terrestrially contaminated study sites (Thiel et al 1988; Burgess et al 1999; Custer et al 2001; Mayne et al 2004; Neigh et al 2006a). …”

Passerine Exposure to Primarily PCDFs and PCDDs in the River Floodplains Near Midland, Michigan, USA

“…Eastern bluebirds prefer open grassland habitats and feed by dropping on prey from an elevated perch, whereas house wrens primarily glean insects off foliage in brushy/forested habitats. Several studies of contaminants have used eastern bluebirds and house wrens (Burgess et al 1999; Custer et al 2001; Henny et al 1977; Mayne et al 2004; Neigh et al 2006a, 2007). …”