August 20, 2012
European Paper Wasp Never Cries Wolf
European paper wasps (Polistes dominula) advertise the size of their poison glands to potential predators, finds a new study published in BioMed Central's open access journal Frontiers in Zoology. The brighter the color, the larger the poison gland.
Aposematism is used by many different animals to warn potential predators that they are poisonous. Usually this takes the form of distinctive coloration or patterns which predators quickly learn to avoid. Paper wasps have conspicuous yellow and black patterns covering their bodies and researchers from University of Granada and the University of AlmerÃa found that when they compared the size of a wasp's poison gland to the brightness of its color there was a direct relationship.
Dr Gregorio Moreno-Rueda, who led this study explained, "It might be thought that bigger wasps have bigger poison glands, and this is indeed true, but even when the data was adjusted to take in to account the size of the insect, a positive correlation between gland size and brightness remained."
But producing both the poison and the distinctive coloration is costly to the wasp. To get around this problem some species, such as hoverflies, have learnt to mimic poisonous ones. But other animals use coloration as a truthful (Zahavian) signal. In this case the wasp would be signaling that it is so strong and healthy that it can waste energy producing bright color; and a strong and healthy wasp will contain a lot of poison.
Dr Moreno-Rueda continued, "A second possibility is that the pigment is also an antioxidant that helps protect the insect from its own poison or from the by-products of poison production. Consequently an insect which has a lot of poison will also have a lot of colour."
Either way predators need to beware — a bright wasp will leave a nasty taste in the mouth.
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