Artificial light at night (ALAN) has become a pervasive anthropogenic stressor for both humans and wildlife. Although many negative impacts of ALAN on human health have been identified, the consequences for infectious disease dynamics are largely unexplored. With the increase in popularity of energy efficient light-emitting diodes (LEDs), the effects of spectral composition of ALAN have also come into question. Previous studies showed that exposure to low levels of incandescent ALAN extended the infectious period of House Sparrows (Passer domesticus) infected with West Nile virus (WNV) without affecting mortality rates, thus increasing the pathogen initial reproductive rate (R0) by ∼41%. Here, we asked whether exposure to broad-spectrum (3000 K [Kelvin; unit of color temperature]) ALAN suppressed melatonin, a hormone implicated in ALAN-induced physiological consequences, in House Sparrows. We then asked whether amber-hue bulbs (1800 K) could ameliorate the effects of WNV on individual sparrows, and whether broad-spectrum or blue-rich bulbs (3000 K and 5000 K, respectively) could exacerbate them. We found that exposure to low intensity (∼5 lux) broad-spectrum (3000 K) ALAN significantly suppressed melatonin levels throughout the night. Second, we found that exposure to broad-spectrum and blue-rich (3000 + 5000 K) lights did not affect WNV viremia but did increase WNV-induced mortality. Conversely, birds exposed to amber-hue (1800 K) ALAN had lower viremia and mortality rates similar to controls (i.e. natural light conditions). This study demonstrates that ALAN affects melatonin regulation in birds, but this effect, as well as ALAN influences on infectious disease responses, can be ameliorated by particular lighting technologies.
|State||Published - Aug 1 2020|
Bibliographical noteFunding Information:
We thank Haley Hanson, Kyle Koller, Bilal Koussayer, Sarah Guzinski, and Samantha Oakey for input on the experimental design and experimental execution. We also thank Erik Hofmeister for sharing the WNV NY’99 strain. Funding statement: We thank USF College of Public Health and NSF 1257773 for funding. Ethics Statement: All experimental work was pre-approved by and performed according to IACUC #2716 and IBC #1323. Author contributions: M. E. Kernbach contributed to the design and execution of the experiment, data collection, data analysis, and manuscript writing. V. M. Cassone contributed to the design of the melatonin administration. T. R. Unnasch contributed to the design of BSL3 work and funding. L. B. Martin contributed to the design and execution of the experiment, data analysis, manuscript revision, and funding. Data depository: Analyses reported in this article can be reproduced using the data provided by Kernbach et al. (2020). Conflict of interest statement: We declare that we have no competing interests. Supplementary material: Supplementary material is available at The Auk: Ornithological Advances online.
We thank USF College of Public Health and NSF 1257773 for funding.
© 2020 Published by Oxford University Press for the American Ornithological Society 2020.
- House Sparrow
- Light pollution
- West Nile virus
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Animal Science and Zoology