Dim the lights for some natural pollination


Even a bit of darkness has ecological as well as environmental benefits, research suggests. Nick Carne reports.


When the lights go down the moths behave as we want them to.

When the lights go down the moths behave as we want them to.

iStock/SanderStock

Switching off street lights helps restore the natural behaviour of moths, scientists say, and that’s important because the humble moth supplements the daytime work of bees and other pollinating insects.

Now a new study by researchers from Newcastle and York universities in the UK has shown we don’t need an all-night blackout to get results. In a paper published in the journal Ecosphere they report that there is no difference in pollination success between part-night lighting and full darkness.

"Often, as conservationists, we have to make difficult trade-offs between development and environmental protection,” says York’s Callum Macgregor.

"However, our study suggests that turning off street lights in the middle of the night is a win-win scenario, saving energy and money for local authorities whilst simultaneously helping our nocturnal wildlife."

In the last decade, many local authorities have changed their street lighting regime in a bid to cut costs and save energy. This includes switching off or dimming the lights at certain times of the night as well as replacing traditional high-pressure sodium (HPS) bulbs with energy-efficient light-emitting diodes (LEDs).

In the study, Macgregor and colleagues analysed the impact of a range of scenarios on the pollination of moth-pollinated flowers placed underneath street lights. These included both HPS and LED lighting, run either all night or switched off at midnight. Results were compared to pollination under natural darkness.

They found that regardless of the type of light, full-night light caused the greatest ecological disruption. There was no difference between LED and HPS bulbs in the part-night scenarios and in both cases, the disruption to the plants' pollination was minimal compared to full darkness.

  1. https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/ecs2.2550
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