68
et al. 1996). Red-winged blackbirds (Agelaius phoeniceus) exposed to sublethal
dose of organophosphate for longer duration was found to affect the feeding behaviour of the species (Nicolaus and Lee 1999). As sublethal exposure of these pesticides is often associated with anorexia, a common consequence of exposure is
reduction in the body weight (Grue et al. 1991; Maitra and Mitra 2008; Moye and
Pritsos 2010). A single dose of dicrotophos leads to 55–77% inhibition of brain
acetylcholinesterase in European Starlings that can be correlated with weight loss
(Grue and Shipley 1984). According to Kuenzel (1994), pesticide-induced lesion in
lateral hypothalamus leads to food avoidance causing significant body weight
reduction in birds. Pigeons exposed experimentally to sublethal dose of chlorpyrifos
and aldicarb showed abnormal flight and improper navigation (Moye and Pritsos
2010). Mc Carty et al. (2009) reported that buff-breasted sandpiper (Tryngites subruficollis), a species of migratory shorebird that sojourn in spring at the agricultural
fields near Rainwater Basin area of Nebraska, is subjected to extensive exposure to
pesticide that led the bird to debilitate social and courtship behaviour (Mc Carty
et al. 2009).
Organophosphates and carbamates affect thermoregulatory ability in birds causing inability to withstand in cold seasons (Martin and Solomon 1991). Acute exposure of organophosphate at sublethal level showed pronounced but transient
hypothermia (Grue et al. 1991). Anticholinesterase-directed hypothermia in birds is
often coupled with more than 50% inhibition in brain acetylcholinesterase activity
(Clement 1991). The higher mortality rate in American kestrels (Falco sparverius)
exposed to cold temperature was due to poor thermoregulatory ability (Rattner and
Franson 1983).
3.4.3 Effects on Endocrine System and Reproduction
Organophosphates and carbamates are among the endocrine-disrupting chemicals
(EDCs) that can cause altered patterns of behaviour by mimicking the action of
hormones. Although effects of exposure to EDCs vary from species to species, the
bird species at the top of the food chain are particularly vulnerable (Carere et al.
2010). EDCs can interrupt redox homeostasis causing oxidative stress and imbalance between pro-oxidants and antioxidants. Redox balance shifted toward more
oxidant condition instigates oxidative damage, anticipating several degenerative
pathologies (Abdollahi et al. 2004).
Damstra et al. (2002) suggested that some unique characteristics of birds make
them more vulnerable to potential endocrine-disrupting chemicals including consumption of large amount of food and higher metabolic rates, periods of starvation
that mobilize lipid reserves, hormone-dependent behaviours, developmental
scheme, and regulation of sexual differentiation. Physiological and metabolic processes of a bird can be considerably affected by very delicate changes in the balance
of the endocrine system (Damstra et al. 2002; Fernie et al. 2015).
A. Mitra et al.
et al. 1996). Red-winged blackbirds (Agelaius phoeniceus) exposed to sublethal
dose of organophosphate for longer duration was found to affect the feeding behaviour of the species (Nicolaus and Lee 1999). As sublethal exposure of these pesticides is often associated with anorexia, a common consequence of exposure is
reduction in the body weight (Grue et al. 1991; Maitra and Mitra 2008; Moye and
Pritsos 2010). A single dose of dicrotophos leads to 55–77% inhibition of brain
acetylcholinesterase in European Starlings that can be correlated with weight loss
(Grue and Shipley 1984). According to Kuenzel (1994), pesticide-induced lesion in
lateral hypothalamus leads to food avoidance causing significant body weight
reduction in birds. Pigeons exposed experimentally to sublethal dose of chlorpyrifos
and aldicarb showed abnormal flight and improper navigation (Moye and Pritsos
2010). Mc Carty et al. (2009) reported that buff-breasted sandpiper (Tryngites subruficollis), a species of migratory shorebird that sojourn in spring at the agricultural
fields near Rainwater Basin area of Nebraska, is subjected to extensive exposure to
pesticide that led the bird to debilitate social and courtship behaviour (Mc Carty
et al. 2009).
Organophosphates and carbamates affect thermoregulatory ability in birds causing inability to withstand in cold seasons (Martin and Solomon 1991). Acute exposure of organophosphate at sublethal level showed pronounced but transient
hypothermia (Grue et al. 1991). Anticholinesterase-directed hypothermia in birds is
often coupled with more than 50% inhibition in brain acetylcholinesterase activity
(Clement 1991). The higher mortality rate in American kestrels (Falco sparverius)
exposed to cold temperature was due to poor thermoregulatory ability (Rattner and
Franson 1983).
3.4.3 Effects on Endocrine System and Reproduction
Organophosphates and carbamates are among the endocrine-disrupting chemicals
(EDCs) that can cause altered patterns of behaviour by mimicking the action of
hormones. Although effects of exposure to EDCs vary from species to species, the
bird species at the top of the food chain are particularly vulnerable (Carere et al.
2010). EDCs can interrupt redox homeostasis causing oxidative stress and imbalance between pro-oxidants and antioxidants. Redox balance shifted toward more
oxidant condition instigates oxidative damage, anticipating several degenerative
pathologies (Abdollahi et al. 2004).
Damstra et al. (2002) suggested that some unique characteristics of birds make
them more vulnerable to potential endocrine-disrupting chemicals including consumption of large amount of food and higher metabolic rates, periods of starvation
that mobilize lipid reserves, hormone-dependent behaviours, developmental
scheme, and regulation of sexual differentiation. Physiological and metabolic processes of a bird can be considerably affected by very delicate changes in the balance
of the endocrine system (Damstra et al. 2002; Fernie et al. 2015).
A. Mitra et al.