Bugs resort to several colors to protect themselves from predators
Colorful bugs look very different as young and adults, but why?

Date:
June 25, 2020
Source:
University of Melbourne
Summary:
New research has revealed for the first time that shield bugs use a
variety of colors throughout their lives to avoid predators. For
years it has been thought that animals living in the same
environment -- like nymphs and adults of the same species --
should use similar warning colors, not different ones.



FULL STORY ==========================================================================
New research has revealed for the first time that shield bugs use a
variety of colours throughout their lives to avoid predators.


========================================================================== Shield bugs are often bright, colourful insects that use colours to
warn off their distastefulness to predators. The paper, published in Proceedings of the Royal Society B, found that it is impossible to
predict how an adult bug will look like based on their colour when young.

"We found that in most species, the same individual bug will use different colour combinations as nymphs -- young bugs -- and adults, going for
example from red and green to yellow and green," said lead author and ecologist, Dr Iliana Medina, from the University of Melbourne's School
of Biosciences.

"This is significant because many of these species use colour to warn
predators that they are distasteful, and for years it has been thought
that animals living in the same environment -- like nymphs and adults of
the same species - - should use similar warning colours, not different
ones." The joint research between scientists at the University of
Melbourne and the Australian National University combined information
on colour in young and adults for more than 100 species of shield bugs worldwide. They then used field work in Canberra, with white-winged
choughs, to measure how likely these birds were to attack adult and
nymphs of one Australian species of shield bug, the cotton harlequin bug.

Experiments were also conducted in the aviary, training two-week-old
chicks to see how fast they learned to avoid nymphs and adults, then
testing whether their previous experience with adults could reduce attack
rates on nymphs.

"Our experiments with the cotton harlequin bug showed that predators
could quickly learn to avoid both types of colour signals from nymphs
and adults, but nymphs get a larger benefit," Dr Medina said.

"Although young and adult cotton harlequin bugs have different colours, previous experience with adults make chicks less likely to attack
the nymphs.

Also, chicks and wild predators that have never seen the insects before
do not show much interest in eating them. The colours in these insects
are a great strategy against predators." Many animals such as frogs,
insects and sea slugs use bright colourations to advertise toxicity or distastefulness. In theory, warning signals of prey that live in the
same environment should be the same because predators can learn more effectively to avoid one type of pattern, instead of many different ones.

While this idea has been used to explain the great examples of mimicry in nature, and why distantly related species end up having the same warning colours, such as black and red, or black and yellow, researchers say
there are multiple examples of variation in local warning signals and
an overlooked type of variation is that across life stages.

"If predators were able to learn to avoid only one type of warning colour,
we would expect nymphs and adults to look similar in many species," Dr
Medina said. "What our findings show, however, is that the wide colour variation in shield bugs is probably the result of predators being able
to learn to avoid different types of colourful signals."

========================================================================== Story Source: Materials provided by University_of_Melbourne. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Iliana Medina, Regina Vega-Trejo, Thomas Wallenius, Damien
Esquerre',
Constanza Leo'n, Daniela M. Perez, Megan L. Head. No link between
nymph and adult coloration in shield bugs: weak selection by
predators.

Proceedings of the Royal Society B: Biological Sciences, 2020;
287 (1929): 20201011 DOI: 10.1098/rspb.2020.1011 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/06/200625102519.htm

--- up 22 weeks, 2 days, 2 hours, 34 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1337:3/111)