Natures wonders: moth chemical defenses (Introduction)

by David Turell @, Wednesday, September 27, 2017, 21:03 (880 days ago) @ David Turell

Tiger moths produce two repellent chemicals to protect themselves against birds and ants:

"Wood tiger moths protect themselves from multiple predators using different chemical defences. Choosing the right defence can be tricky as predators come in many forms, and from many directions.

"Now the researchers from the Department of Biological and Environmental Science at University of Jyväskylä have shown that one moth species, the Wood Tiger Moth, has found a clever way around this. The moth, which is brightly coloured to signal to predators that it is not to be messed with, has not one but two defensive fluids. One of them is targeted towards bird predators, who may try to catch the moth on the wing. A chemical compound in it, pyrazine, has one of the most repulsive odours known and can make the bird refrain from consuming the moth before even tasting it.

"The second type of fluid works against invertebrate predators, such as ants, on the ground. This defence is particularly handy in situations where the moth cannot flee due to low temperatures, or when it is coming out of its pupa and its wings are not yet fully extended. The research, published in Proceedings of the Royal Society B: Biological Sciences on September 27th, 2017, used a series of assays with live predators to reveal the first evidence of a single species producing separate chemical defences targeted to different predator types."

The abstract:

"Animals have evolved different defensive strategies to survive predation, among which chemical defences are particularly widespread and diverse. Here we investigate the function of chemical defence diversity, hypothesizing that such diversity has evolved as a response to multiple enemies. The aposematic wood tiger moth (Arctia plantaginis) displays conspicuous hindwing coloration and secretes distinct defensive fluids from its thoracic glands and abdomen. We presented the two defensive fluids from laboratory-reared moths to two biologically relevant predators, birds and ants, and measured their reaction in controlled bioassays (no information on colour was provided). We found that defensive fluids are target-specific: thoracic fluids, and particularly 2-sec-butyl-3-methoxypyrazine, which they contain, deterred birds, but caused no aversive response in ants. By contrast, abdominal fluids were particularly deterrent to ants, while birds did not find them repellent. Our study, to our knowledge, is the first to show evidence of a single species producing separate chemical defences targeted to different predator types, highlighting the importance of taking into account complex predator communities in studies on the evolution of prey defence diversity."

Comment: Unless these moths had these chemicals from the beginning of their species, they would not be here now. I think they were designed to be protected this way.

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