[Pollinator] DISTRACTED WHILE POLLINATING: THE HIDDEN DANGER OF ARTIFICIAL LIGHT

[Scott Black]

http://conservationmagazine.org/2016/06/artificial-light-disrupts-pollination/



*Distracted while pollinating: The hidden danger of artificial light *

*June 7, 2016Conservation This Week
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Everyone knows moths are attracted to light, but scientists are just now
learning that this attraction may have negative consequences for other
parts of the ecosystem. Moths drawn to artificial sources of light may do
less work pollinating plants, according to research published last week in
the journal *Global Change Biology*.

Researchers sampled moths at 40 sites along hedgerows bordering
agricultural fields in Oxfordshire, England. Half of the study sites were
lit with streetlights and half were not. Surprisingly, no one had
previously investigated how this very common source of artificial lighting
affects the behavior and ecological function of moths.

They used three different methods to sample the moth community at each
site: by capturing moths along 25-meter-long transects at night; by shining
a bright flashlight vertically and counting the moths that flew through the
beam over the course of a minute; and by setting out light traps, which
provide a light source and capture moths attracted to it.

Light traps are a standard method for sampling moths, but the researchers
argue, logically, that it doesn’t make much sense to study the effects of
artificial lighting with light traps. And indeed, the light traps detected
fewer differences between lit and unlit sites than transects did.

Still, the three methods together yielded a clear picture. “Moth abundance
at ground level was halved at lit sites, species richness was >25% lower,
and flight activity at the level of the light was 70% greater,” the
researchers write. In other words, at lit sites more moths are flying up
high, around streetlight level. At dark sites more moths are flying low,
near the plants.

“Where there are street lights, our research indicates that the moths are
being attracted upwards, away from the fields and hedgerows,” says lead
author Callum Macgregor, a graduate student at Newcastle University. “This
is likely to cause disruption of night-time pollination by moths, which
could be serious for the flowers which rely upon moths for pollination, and
of course there could be negative effects on the moths themselves as well.”

To explore whether this altered moth behavior affects pollination, the
researchers analyzed the abundance and diversity of pollen on the
proboscides of the captured moths.

About a quarter of all moths collected were carrying pollen. These moths
represented 83 species and 10 families, and only 1% of the individual
pollen-carrying moths belonged to the family (Sphingidae) most associated
with pollination. The pollen came from at least 28 different types of
flowers, including several not previously known to be moth-pollinated. All
this contributes to mounting evidence that moths make a more significant
contribution to pollination than previously assumed.

But the data also suggest that overall, pollen transport by moths is lower
at lit sites compared to unlit sites. In the light-trap samples there were
fewer moths carrying pollen at lit sites, and in the transect samples fewer
pollen types were found on moths at lit sites.

More research would be required to confirm that this reduced pollen
transport corresponds to reduced pollination services. Still, the findings
are worrisome, the researchers say.

“There is a great deal of concern at the moment about our falling
pollinator populations and the knock-on effect on plant pollination,” says
study team member Darren Evans, a reader in ecology and conservation at
Newcastle University. “Our research suggests that it’s a process that is
being damaged on two fronts – night and day – and together the impact could
be significant.” *– Sarah DeWeerdt | 7 June 2016*

*Source: *Macgregor C.L. *et al.* “The dark side of street lighting:
impacts on moths and the disruption of nocturnal pollination.” *Global
Change Biology* DOI: 10.1111/gcb.13371
<http://onlinelibrary.wiley.com/doi/10.1111/gcb.13371/full>





*Scott Hoffman Black*

Executive Director

     The Xerces Society for Invertebrate Conservation

Chair

     IUCN Butterfly Specialist Group



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*Protecting the Life that Sustains Us*



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