Title:
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Insects and lighting : how green is white light?
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Life on Earth has evolved under regular cycles of light and dark. Only in the
past two centuries have humans begun altering habitats with electric lighting. The
use of artificial light at night (ALAN) is growing annually and broad-spectrum 'white'
_ lighting is taking centre stage. Many new-technology 'white' lights are described as
'environmentally friendly' or 'green' due to their reduced energy use relative to
traditional technologies. While use of low-energy lighting may help reduce overall
carbon emissions and therefore the severity of climate change, little is known about
their impact on animal behaviour and ecology. Determining the ecological effects
of light pollution has high policy relevance in the UK as it is a potential driver of
recent insect declines. Understanding how ALAN affects insects will be key for
effective conservation biology. I used experimental approaches to investigate the
impact of new technology lighting, specifically 'white' light-emitting diodes (LEOs),
on insect behaviour and ecology.
LEOs attracted fewer insects and a smaller diversity of insect families than
competing 'white' metal halide street lights. LEOs did not attract a greater
abundance or diversity of insects than traditional narrow-spectrum high-pressure
sodium street lights. Slight alterations to the spectral distribution of domestic LED
light bulbs ('cool-white' and 'warm-white') did not result in any significant difference . .
in insect .. attraction. Overall LEOs attracted significantly fewer insects than
competing (fluorescent) lights which emitted ultraviolet light. I found that moths are
less likely to respond to predatory bat calls in the presence of LED lighting,
suggesting that white light can have nuance effects on insect behaviour affecting
speGies in unforeseen ways.
I suggest ways to mitigate for the impacts of ALAN on insects and I
recommend legislative action to prevent overuse of lighting. An improved
understanding of how insects respond to new white lighting will have far reaching
benefits via their roles as pollinators, vectors of disease, nutrient recyclers,
decomposers, predators and prey items.
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