Adverse effects of thiram‐treated seed ingestion on the reproductive performance and the offspring immune function of the red‐legged partridge

Abstract

Pesticide research traditionally has focused on compounds with high acute toxicity or persistence, but the adverse sublethal effects of pesticides with different properties also may have important consequences on exposed wildlife. The authors studied the effects of thiram, a fungicide used for seed coating with known effects as endocrine disruptor. Red-legged partridges (Alectoris rufa; n = 15 pairs per treatment group) were fed wheat treated with 0%, 20%, or 100% of the thiram application rate used in autumn (25 d) and late winter (10 d) to mimic cereal sowing periods. The authors studied the effects on reproductive performance, carotenoid-based ornamentation and cellular immune responsiveness of adult partridges, and their relationship with changes in oxidative stress biomarkers and plasma biochemistry. The authors also studied the effect of parental exposure on egg antioxidant content and on the survival, growth, and cellular immune response of offspring. Exposure to thiram-coated seeds delayed egg laying, reduced clutch size, and affected egg size and eggshell thickness. Partridges exposed to the 20% thiram dose exhibited reduced egg fertility and brood size (55% and 28% of controls, respectively). Chick survival was unaffected by parental exposure to treated seeds, but adverse effects on their growth rate and cellular immune response were apparent. These effects on reproduction and immune function may have important demographic consequences on farmland bird populations.

Specific carotenoid pigments in the diet and a bit of oxidative stress in the recipe for producing red carotenoid-based signals

“…In agreement with this, redder integuments have also been observed in red-legged partridges exposed to other chemicals (i.e. pesticides and heavy metals) that induce oxidative stress (Lopez-Antia et al, 2015a; Lopez-Antia et al, 2015b; Vallverdú-Coll et al, 2015) or in zebra finches enduring experimentally reduced antioxidant (glutathione) levels (Romero-Haro & Alonso-Alvarez, 2015). The findings support the view that oxidative stress is not only a constraint for the expression of optimal phenotypes, but that mild levels are involved in many functions (Jones, 2006; Metcalfe & Alonso-Alvarez, 2010; Isaksson, Sheldon & Uller, 2011).…”

Copper exposure reduces production of red carotenoids in a marine copepod

“…The ultimate goal of this study was to determine if red carotenoid production was sensitive to environmental stressors. Carotenoid content and color in other taxa have been used as bio-indicators of environmental stress (Isaksson et al, 2005;Lopez-Antia et al, 2015;Vallverdú-Coll et al, 2016). In this study, we used copper exposure as a source of pro-oxidant stress, but our findings are consistent with those from studies that examined the effect of other pro-oxidants on carotenoids including lead (Vallverdú-Coll et al, 2016, testosterone (Alonso-Alvarez et al, 2008), and other pollutants (Isaksson et al, 2005;Pérez-Rodríguez et al, 2010).…”

“…Conversely a recent study on the same species found an positive relationship between red coloration and pesticide-induced oxidative stress (Lopez-Antia et al, 2015). Thiram-exposed red-legged partridges had higher levels of circulating yellow carotenoids and redder beak coloration than un-exposed partridges (Lopez-Antia et al, 2015). Clearly, more research is needed to deduce the complex relationships of oxidative stress, antioxidant systems, carotenoid metabolism, and carotenoid coloration.…”

“…Alonso-Alvarez et al (2008) found that testosterone-supplemented red-legged partridges (Alectoris rufa) had higher levels of yellow circulating carotenoids and decreased red coloration of their red carotenoid-pigmented facial mask (De Blas et al, 2014). Conversely a recent study on the same species found an positive relationship between red coloration and pesticide-induced oxidative stress (Lopez-Antia et al, 2015). Thiram-exposed red-legged partridges had higher levels of circulating yellow carotenoids and redder beak coloration than un-exposed partridges (Lopez-Antia et al, 2015).…”

Factors Affecting Red-Legged PartridgeAlectoris rufaAbundance on Big-Game Hunting Estates: Implications for Management and Conservation

“…According to several studies, the most harmful factor for partridge distribution is habitat change resulting from agricultural intensification (Vargas et al, 2006;BlancoAguiar et al, 2007), which has had direct effects, such as the deterioration of suitable nesting sites (Newton et al, 2004), a reduction in food availability, an increase of predation risk owing to habitat simplification (Benton et al, 2003) and exposure to toxic biocides, for example through ingestion of dressed seeds (Mineau and Palmer, 2013;López-Antia et al, 2015). In addition, other factors such as overhunting and releases of farmed partridges have also been identified as harmful to wild partridges (Caro et al, 2014).…”