Category Archives: Physiology

Bank Holiday Special – Why insects are so colourful: The complex business of survival

Mastering Entomology

In the desperate struggle to evade predators, many insects have evolved toxic or bad-tasting skin, a camouflaged body (‘crypsis’), or a startle response to scare away predators. In this “evolutionary arms race”, adaptations on one side call forth counter adaptations on the other side. One such defensive adaptation is to appear toxic using brightly coloured (‘conspicuous’) body coloration- this is known as ‘aposematism’ (“Ay-PO-Sematism”). This idea that signals are sent by prey to predators to indicate toxicity was first suggested by Wallace to Darwin in 1861- they theorised that this evolved to stop predators attacking toxic prey to benefit both sides.

Aposematic warning coloration is a widely utilised form of defence used in all the animal kingdom (not just insects) and has evolved separately from many different evolutionary lines (convergent evolution). It can warn predators of defences such as a painful sting, repellent spray (such as a Bombardier beetle’s noxious…

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Cells from Insects could Create Everlasting Paint.

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Durable, cheap and environmentally friendly paint may soon be on sale since scientists at the Natural History Museum in London have unlocked the key to paint that never fades, using unique cells from butterflies and other insects. The Blue Morpho butterfly, Morpho peleides, is just one of many insects that have transparent, iridescence wings created by small three-dimensional structures that alter the way light is reflected.

The phenomenon is created by ‘structural colouration’. The wing is made up of transparent scales that have intricate shapes, which scatter light when it hits them. This is what creates the vibrant colour that changes when looking at it from different angles. Professor Andrew Parker, Oxford University, has grown cells from butterfly wings and weevil shells that have this nano-property.

Cells dissected from the blue morpho chrysalis were used to culture an entire forewing. The team attempted to convert the cells to scales, but part of the original cell was lost, so that the cells couldn’t be used to produce more scales. This means that butterfly cells are suitable for mass production of coloured scales, but other insects like the Blue Weevil, genus Metapocyrtus, could be used instead. These weevils use a different type of cell, also found in the opal gemstone, which can be used to make any colour.

Traditional dyes and pigments fade over time, whereas paints, clothes and make-up that use structural colouration could retain their colour and vibrancy forever. Cosmetic and paint industries would require huge quantities for commercial use, which may only be achievable using the weevil cells. With a sufficient supply of nutrients and growth hormones, cells from weevils could be used to make industrial quantities of everlasting paint.

Source: Natural History Museum.