Читать книгу Extreme Insects - Richard Jones - Страница 23

NAME	Jamaican fire beetle Pyrophorus noctilucus
LOCATION	Central and South America
ATTRIBUTE	brightest light production by any insect

Several groups of insects can generate light, including the springtails, true bugs, fly larvae and especially the beetles. The well-known glow-worms and fireflies are neither worms nor flies, but beetles, and many species occur worldwide. Light-generating beetles use their lights to attract or communicate with potential mates. Some flash to a secret rhythm, while others emit a continuous pale glow. There has long been debate about which beetle species might be brightest and until recently comparisons were rather subjective, usually describing the similarity to a candle at some set distance as seen by the naked eye or to stars of various brightnesses. Supremely accurate photometers can now measure light production down to the atomic level, and a clear winner has been found – Pyrophorus noctilucus, a click beetle found in forests in the West Indies.

It is auspicious that this species should rank highest. In 1885 the French physiologist Raphael Dubois first isolated the compounds luciferin and luciferase by dissecting the glowing spots on the thorax of P. noctilucus. Similar chemicals are found in all light-emitting organisms. Light generation by living organisms (known as bioluminescence) is remarkable because it is ‘cold’. Using the old candle analogy, a firefly produces 1/80,000th of the heat that would be created by a candle of the same brightness.

The chemical reactions that produce light are based on the enzyme luciferase, which combines luciferin with oxygen and adenosine triphosphate (ATP). The significance of Dubois’s discovery was not fully understood for nearly 60 years until ATP was identified as the energy-carrying molecular currency in every living thing. In photosynthesis, light energy is captured by green plants and transformed into chemical energy in the form of ATP. This is used to make basic sugars and other substances from carbon dioxide in the atmosphere and water taken up by the roots. Photosynthesis absorbs light; bioluminescence releases light. The two reactions are equal, but the reverse of each other.