Research Group Biochemical Ecology and Molecular Evolution

Clever defence – use of another‘s toxin for your own benefit

Higher mating success, higher chance of survival for the offspring, or a potent counteragent against predators: what sound like a miracle cure is the fascinating adaptation of specific insect species to the toxic pyrrolizidine alkaloids produced by plants. The toxins are produced as part of the chemical defence of the plant against plant-feeding animals. But some insects have developed specific adaptations to cope with pyrrolizidine alkaloids and are able to accumulate them in a pre-toxic form.

The cinnabar moth as survivalist

The larvae of the cinnabar moth, Tyria jacobaeae, feed almost exclusively on the common ragwort (Jacobaea vulgaris). Though this plant accumulates high levels of toxic pyrrolizidine alkaloids, they have no negative effects on the insect. In contrast, the larvae modify the alkaloids into a pre-toxic form. In the case that a predator feeds on the insects, the alkaloids become toxic again. The striking yellow-black pattern of the larvae signals this toxicity.

Toxin-based pheromones

Some species of the arctiid moths that are related with the cinnabar moth go even step ahead. They produce pheromones from the plant-derived toxins. The more pheromone they produce, the higher is the mating success for the males. During mating, a proportion of the plant-derived compounds are transferred to the female that uses the alkaloids to protect its eggs.

Not only moths use pyrrolizidine alkaloids for their own benefit. A similar use of these compounds was already described for certain species of the leaf beetles and for specific grasshoppers.

Further background informations

Here you find a short introduction to aspects related to our research.

icon-secondary metabolism
Secondary
metabolism
Symphytum_icon
Pyrrolizidine
alkaloids (PAs)
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Insect
adaptations