A non-invasive method to monitor farmland bird exposure to triazole fungicides.

The treatment of seeds with pesticides is an extended practice in current agriculture. There is a high risk of exposure in granivorous birds, such as the red-legged partridge (Alectoris rufa), that can consume those seeds remaining on the surface during sowing. Fungicide exposure could in turn affect bird reproductive capacity. To better understand to what extent triazole fungicides are a threat to granivorous birds, we need an easy and reliable method to quantify field exposure. In this study, we tested a novel non-invasive method to detect the presence of triazole fungicide residues in farmland bird faeces. We experimentally exposed captive red-legged partridges to validate the method, and then applied it in a real scenario to assess exposure of wild partridges. We exposed adult partridges to seeds treated with two formulations containing triazole fungicides as active ingredients: Vincit®Minima (flutriafol 2.5%) and Raxil®Plus (prothioconazole 25% and tebuconazole 15%). We collected two types of faeces (caecal and rectal samples) immediately after exposure and 7 days later and quantified the concentrations of the three triazoles and their common metabolite (1,2,4-triazole). The three active ingredients and 1,2,4-triazole were only detected in faeces collected immediately after exposure. Triazole fungicide detection rates in rectal stool were 28.6%, 73.3% and 80% for flutriafol, prothioconazole and tebuconazole, respectively. In caecal samples, detection rates were 40%, 93.3% and 33.3%, respectively. 1,2,4-triazole was detected in 53% of rectal samples. For an applied use of the method in the field, we collected 43 faecal samples from wild red-legged partridges during autumn cereal seed sowing and found detectable levels of tebuconazole in 18.6% of the analysed wild partridges. The results of the experiment were then used to estimate actual exposure levels from this prevalence value found in wild birds. Our study shows that faecal analysis can be a useful tool to assess farmland bird exposure to triazole fungicides, when samples are fresh and the method has been validated for the detection of target molecules.

Egg Overspray with Herbicides and Fungicides Reduces Survival of Red-Legged Partridge Chicks.

Within the environmental risk assessment conducted for pesticide registration in the European Union (EU), avian reproductive toxicity is characterized after exposing adults. However, eggs of ground-nesting species can be exposed when pesticide applications occur during laying or incubation. We simulated environmentally realistic exposure of red-legged partridge (Alectoris rufa) eggs to an herbicide (2,4-D) and a fungicide (tebuconazole) applied to winter cereal crops during the breeding season of most farmland birds. We analyzed the effects on hatching success, offspring survival, and physiology. Exposure by overspray led to greater pesticide accumulation in the eggshell or content than exposure through contact with treated soil (3.1-13.7 times higher, depending on the pesticide and target sample). Egg overspray with tebuconazole significantly increased chick mortality, which was 26% higher than that of controls. 2,4-D caused a similar but a close to significant increase (chick mortality 24% higher than controls). Exposure to either pesticide through contact with treated soils did not affect chick survival but altered some biochemical parameters posthatching. Our experiment shows that egg spraying with pesticides should be considered as a relevant exposure scenario in risk assessment procedures, given its potential to affect the reproductive success of ground-nesting farmland birds.

Evidence for BTV-4 circulation in free-ranging red deer (Cervus elaphus) in Cabañeros National Park, Spain.

Bluetongue (BT) is an infectious disease of wild and domestic ruminants caused by bluetongue virus (BTV). BTV-4 spread through southern Spain from 2004 to 2006, whereas a BTV-1 outbreak that started in southern Spain in 2007 is still ongoing. Vaccination and movement restriction regulations are applied to domestic ruminants to control BT, but the potential reservoir role of wild European ungulates has not been clarified so far. The aim of this study was to describe the epidemiology of BTV in the wild free-ranging red deer (Cervus elaphus) population of Cabañeros National Park (CNP) in central Spain during the BTV-4 and BTV-1 epizootics, assessing the potential role of this deer population as a BTV reservoir. Blood samples from 2885 (2542 adults, 208 calves and 135 undetermined) wild red deer were collected from 2005 to 2010 in CNP and surrounding hunting estates. All sera were tested for antibodies against the BTV VP7 protein by ELISA. Ninety-four of the ELISA-positive samples were analysed by serum neutralization to detect BTV-4 and BTV-1 specific antibodies, and 142 blood samples were analysed by RT-PCR for BTV RNA. A total of 371 (12.9%) out of the 2,885 deer (35/208 calves, 307/2,542 adults, and 29/135 undetermined) were positive for antibodies against BTV. Prevalence increased in adult deer from 2005-2006 to 2008-2009, declining thereafter. No positive samples for BTV-1 were found by serum neutralization, whereas 43 deer (38 adults, four calves and one undetermined) were positive for BTV-4 specific antibodies. No BTV RNA positive deer were found by RT-PCR. Antibody detection throughout the study period suggests a maintained circulation of BTV in red deer. However, the lack of BTV RNA detection suggests a minor transmission risk to livestock.

Spatial and temporal evolution of bluetongue virus in wild ruminants, Spain.

We confirmed the emergence of bluetongue virus (BTV) in 5 wild ruminant species in Spain. BTV seroprevalence was high and dispersed with time, with a south-to-north gradient. Our results suggest a complex epidemiology of BTV and underline the need for additional research on wildlife in Europe.