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Argentine ants harm nestlings of the blue tit

The consequences of ant invasions on ecosystems may only become apparent after long periods. In addition, predicting how sensitive native fauna will respond is only possible if the underlying proximate mechanisms of their impact are identified. The attraction of the native and invasive ant community to artificial bird nests was studied, together with reproduction of a wild native songbird over five consecutive breeding seasons in relation to the presence of an invasive ant species. Biometric, reproductive and individual blood parameters of great tits Parus major breeding in invaded as compared to uninvaded sites by Argentine ants Linepithema humile were analysed. Great tits bred preferably in uninvaded territories by the Argentine ant. Moreover, Argentine ants were more abundant at nests in invaded sites, than any native ant species were at uninvaded sites. Further, Argentine ants recruited at the artificial nests more intensively and responded to a larger variety of nest (intact eggs, cracked eggs, faeces, and cracked eggs plus faeces) contents than native species. Although breeding success and adult condition did not vary in relation to invasion status, offspring quality was negatively affected by the presence of Argentine ants. Nestlings reared in invaded sites were lighter, with lower wing/tarsus length ratio and had a reduced nutritional condition and altered oxidative stress balance as measured from several blood parameters. The interspersed distribution and small distance between invaded versus uninvaded territories suggest that ant presence affects nestling condition through direct interference at the nest. These results highlight the importance of evaluating the proximate effects like physiological parameters of the native fauna, when studying invasive ant-native bird interactions. informacion[at] Álvarez et al (2020) Breeding consequences for a songbird nesting in Argentine ant' invaded land. Biol Invasions
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Tropical bat as mammalian model for skin carotenoid metabolism

Tropical bat as mammalian model for skin carotenoid metabolism

Animals cannot synthesize carotenoid pigments de novo, and must consume them in their diet. Most mammals, including humans, are indiscriminate accumulators of carotenoids but inefficiently distribute them to some tissues and organs, such as skin. This limits the potential capacity of these organisms to benefit from the antioxidant and immunostimulatory functions that carotenoids fulfill. Indeed, to date, no mammal has been known to have evolved physiological mechanisms to incorporate and deposit carotenoids in the skin or hair, and mammals have therefore been assumed to rely entirely on other pigments such as melanins to color their integument. Here high-performance liquid chromatography (HPLC) in combination with time-of-flight mass spectrometry (HPLC-TOF/MS) is used to show that the frugivorous Honduran white bat Ectophylla alba colors its skin bright yellow with the deposition of the xanthophyll lutein. The Honduran white bat is thus a mammalian model that may help developing strategies to improve the assimilation of lutein in humans to avoid macular degeneration. This represents a change of paradigm in animal physiology showing that some mammals actually have the capacity to accumulate dietary carotenoids in the integument. In addition, the majority of the lutein in the skin of Honduran white bats is present in esterified form with fatty acids, thereby permitting longer-lasting coloration and suggesting bright color traits may have an overlooked role in the visual communication of bats. informacion[at] Galvan et at (2016) Tropical bat as mammalian model for skin carotenoid metabolism. Proc Natl Acad Sci USA doi: 10.1073/pnas.1609724113