Spotlight on danger

Spotlight on danger

Fruit flies, turtles and humans at risk from bright lights

Have you ever been dazzled when someone takes your photo with a flash? Do you think animals would feel the same?

To find the answer, we carried out a research project into the relationship between light and fruit fly larvae in a new programme, "Addicted to Discoveries", at City University.

We observed a surprising phenomenon: fruit fly adults always fly towards light, while larvae react by burrowing. But why does this happen?

Our experiments used three different coloured lights - red, blue and white - all of equal intensity, to see if they negatively affected a larvae's growth, development and reproduction. The experiment looked at a period after pupation - the three-day period when the insect turns from a larva into a fly.

Tests showed the number of adult flies collected, and the average weight of the pupa, under blue light were both significantly less than those that were treated with the red light and white light.

We concluded that the time for pupation may be prolonged, and so the life cycle of fruit fly may be reduced, by a blue light.

Related research in Florida by American scientists showed sea turtles are threatened by artificial lighting. Normally, turtle eggs hatch on beaches. The baby turtles reaches the safety of the sea by navigating towards the brightest light - often moonlight.

However, the development of cities means turtles often get confused by artificial lighting. Some baby turtles become attracted by car headlights on busy main roads and are killed by traffic, or become lost far from the sea and die from exposure to the hot sun.

What is more, human's can also be victims. Researchers in Nanjing have identified possible health problems for people caused by light. Different wavelengths, periods of exposure, or intensity have an impact on things such as the body's circadian rhythms which decide things like how long we need to sleep, our heart rate, attention spans and energy levels.

Similar US research shows extended exposure to light at night increases our food intake and reduces glucose tolerance, leading to health problems such as obesity and diabetes.

From these findings, we conclude that excessive lighting is a problem for living organisms, which is why light pollution is a hot issue today.

Humans can play an important role in solving this problem; it is vital to eliminate the overuse of lighting.


How does blue light affect fruit flies?

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