Biochemical and immunological effects of coated seed ingestion on red-legged partridge (Alectoris rufa)

Resumen del póster presentado al XXXth International Union of Game Biologists and Perdix XIII, celebrados en Barcelona (España) del 5 al 9 de septiembre de 2011.Pesticide application is suspected to be a major cause of population decline in farmland birds. Seeds coated with fungicides or insecticides constitute a main part of the diet of species such as the red-legged partridge (Alectoris rufa) during sowing seasons. The aim of this study was to test the effects of coated seed ingestion on A. rufa physiology and fitness. We tested an insecticide (imidacloprid) and two fungicides (difenoconazole and thiram). Each experiment consisted in two groups of six pairs of partridges exposed at two doses: a dose corresponding to the recommended for seed coating and another dose twice as high as the recommended one. Seed administration was prolonged for a 10-day period, after which all animals were transferred to an untreated diet and monitored for an additional 12 days. We took measures on mass, ventilation rate, ornamentation, hematocrit, plasma levels of hormones, vitamins and carotenoids, oxidative stress parameters and immunocompetence, which was analysed by testing primary and secondary cellular responses (PHA test), as well as humoral response (SRBC-agglutination test). High levels of the three tested pesticides had an effect on ornamentation by reducing the percentage of eye ring pigmentation. Low concentrations of imidacloprid and high doses of thiram induced significant weight loss and reduced body condition, although animals recover quickly once the exposure was terminated. These two pesticides also induced oxidative stress; percent of oxidized glutathione was significantly increased by thiram, whereas imidacloprid reduced the retinol concentration in plasma. Imidacloprid and thiram showed also an immunosuppressive effect, impairing the primary cellular immune response. Interestingly, this effect was only reported for males in both cases. Coated seed consumption may compromise health of farmland birds, especially during seasons when little alternative food sources are available in the field.Peer Reviewe