{"id":130,"date":"2015-02-12T23:51:06","date_gmt":"2015-02-12T23:51:06","guid":{"rendered":"https:\/\/kitenet.wordpress.com\/?p=130"},"modified":"2015-02-12T23:51:06","modified_gmt":"2015-02-12T23:51:06","slug":"lightness-falls","status":"publish","type":"post","link":"https:\/\/kitenet.co.uk\/wp\/2015\/02\/12\/lightness-falls\/","title":{"rendered":"Lightness falls"},"content":{"rendered":"

New research suggests that\u00a0light pollution can reduce mating success in Winter Moths<\/em><\/strong><\/p>\n

\"Light<\/a>
Light pollution map from CPRE’s Dark Skies project<\/figcaption><\/figure>\n

Moths are in trouble – evidence is accumulating (see Butterfly Conservation<\/a> and Conrad et al<\/em>. 2006<\/a>) to show that many moth species are in decline, especially in the southern half of\u00a0Britain. But what are the causes? Research is showing that\u00a0a combination of factors is likely to be involved (Fox et al<\/em>. 2014<\/a>), with habitat change or loss and climate change likely to be a large part of the story. But another\u00a0factor that could be impacting on\u00a0moths is\u00a0‘light pollution’, the tendency for humans to want their own habitat to be lit up at night, so we can work, play and feel safe walking the streets. The night-time glow of towns and cities\u00a0is\u00a0visible from miles away, and even in rural areas roads, shops and houses may be illuminated.<\/p>\n

Could all this light be\u00a0affecting the lives of nocturnal creatures such as moths? It seems plausible, but it’s hard to prove, not least because the way most of us go out and look for moths is by putting bright lights out to attract them. How to find out\u00a0what light pollution does to moths\u00a0when they’re hard to observe\u00a0in the dark?<\/p>\n

\"\"<\/a>
Mating Winter Moths by F. Lamiot via Wikimedia Commons<\/figcaption><\/figure>\n

A newly published paper (“Artificial light at night inhibits mating in a Geometrid moth”\u00a0Van Geffen et al<\/em>. 2015<\/a>) has used an ingeniously simple method to investigate this, and the results\u00a0suggest that we should indeed be worried about what light is doing to moths. Koert van Geffen and colleagues carried out their study in\u00a0the Netherlands, and chose Winter Moth as their subject. Why Winter Moth? One reason\u00a0why they\u00a0make good study subjects is that their habits\u00a0are a bit more predictable than for many moths: female Winter Moths are flightless, and one they emerge from their cocoons under ground they ascend the nearest oak tree and wait for the males to find them. And there is an established method for trapping them, by setting up ‘funnel traps’ that steer the females into a container once they climb far enough up the oak tree.<\/p>\n

So Winter Moths\u00a0are going to be climbing their oak trees, and if you shine a light on the tree the females can’t fly away. The Dutch team set up a series of different lighting regimes directed at oak trees, using green, white and red light, plus unlit trees for comparison. They counted the females on each tree, and checked them to see if they had mated. The results seem to me to be quite dramatic.<\/p>\n

\"Mean<\/a>
Mean number of female Winter Moths caught per night on trees with different light treatments, from Van Geffen et al. 2015<\/figcaption><\/figure>\n

By far the greatest number of female moths were caught from the unlit trees. Of the illuminated trees, white had fewer than red, and green fewest of all. All lit trees had more moths on the shaded side than the lit side, but only under red light did even the shaded side produce anywhere near as many moths as the unlit trees. And there was a big difference in mating success: 53% of females caught from the unlit trees had mated, but only 28% of the females under red\u00a0illumination, 16% under white, and 13% under green.<\/p>\n

Van Geffen et al<\/em>. also studied male moths using pheromone traps positioned under different lights. The differences here were less dramatic but still apparent, with\u00a0fewest males caught under red light, more\u00a0under white, more again under green, and the greatest number from unlit traps.<\/p>\n

This is of course just one study of one moth species, but it showed that in this instance\u00a0artificial light reduces the activity of female moths, and also reduces the male response to female pheromones, resulting in decreased mating success. The lights used in the experiment were LEDs with a light intensity of 10 lux – street lighting can be much brighter than this, up to 60 lux (Gaston et al<\/em>. 2012<\/a>).<\/p>\n

Relatively simple and effective research, providing\u00a0more evidence of the pressures on moth populations. Can we do anything to reduce the effects of light pollution?\u00a0Gaston et al<\/em>. 2012<\/a>\u00a0review possible ways of\u00a0preventing too much light escaping into the wider environment.\u00a0Further\u00a0useful information and advice is available from\u00a0Buglife’s research<\/a>\u00a0and Campaign to Protect Rural England’s “Dark Skies” pages<\/a>. For instance, we can reduce the intensity of artificial lighting, direct it more precisely so there is less overspill, and leave lights on for shorter periods so that they are only illuminated when they are actually needed. This not only has the potential to help wildlife, but to reduce energy use and costs as well – moving lighting in this direction has got to be a no-brainer.<\/p>\n

By taking action at home and encouraging local authorities and businesses to do likewise we can all help shed some darkness and take moths out of the spotlight.<\/p>\n","protected":false},"excerpt":{"rendered":"

New research shows how light pollution stops moths mating<\/p>\n","protected":false},"author":1,"featured_media":134,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[12,27,28,34,45,1],"tags":[],"class_list":["post-130","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-conservation","category-lepidoptera","category-light-pollution","category-moths","category-research","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/kitenet.co.uk\/wp\/wp-json\/wp\/v2\/posts\/130","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/kitenet.co.uk\/wp\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/kitenet.co.uk\/wp\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/kitenet.co.uk\/wp\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/kitenet.co.uk\/wp\/wp-json\/wp\/v2\/comments?post=130"}],"version-history":[{"count":0,"href":"https:\/\/kitenet.co.uk\/wp\/wp-json\/wp\/v2\/posts\/130\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/kitenet.co.uk\/wp\/wp-json\/wp\/v2\/media\/134"}],"wp:attachment":[{"href":"https:\/\/kitenet.co.uk\/wp\/wp-json\/wp\/v2\/media?parent=130"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kitenet.co.uk\/wp\/wp-json\/wp\/v2\/categories?post=130"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kitenet.co.uk\/wp\/wp-json\/wp\/v2\/tags?post=130"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}