Detoxification and elimination of nicotine by nectar-feeding birds

摘要: Many dilute nectars consumed by bird pollinators contain secondary metabolites, potentially toxic chemicals produced plants as defences against herbivores. Consequently, nectar-feeding birds are challenged not only frequent water excess, but also the toxin content of their diet. High turnover, however, could be advantageous to nectar consumers enabling them excrete metabolites or transformation products more easily. We investigated how alkaloid nicotine, naturally present in Nicotiana species, influences osmoregulation white-bellied sunbirds Cinnyris talatala and Cape white-eyes Zosterops virens. examined metabolic fate nicotine these two species shed light on post-ingestive mechanisms that allow tolerate nicotine. A high concentration (50 µM) decreased cloacal fluid output increased its osmolality both due reduced food intake led dehydration. White-eyes excreted a higher proportion ingested nicotine-containing diet than sunbirds. However, sugar did affect detoxification elimination. Both metabolised excreting very little unchanged mainly through cotinine pathway, with norcotinine being most abundant metabolite excreta, while nornicotine. utilized phase II conjugation reactions detoxify depending mercapturic acid pathway found white-eyes, despite having similar tolerance, responded differently used different nicotine-derived