Friday Beetle Blogging: A Buttload of Hydrogen Cyanide

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A Paropsisterna sp. eucalyptus leaf beetle larva everts its hindgut to expose its volatile defensive chemicals.

Among the more conspicuous insects we encountered during our Australian travels were Paropsisterna eucalyptus leaf beetles. Most trees I looked at in southern Australia hosted clusters of pudgy yellow larvae hanging around in plain view, munching on the aromatic leaves in happy abandon.

The beetles have good reason to be seen: they are toxic. Unusually among insects, this beetle’s arsenal includes hydrogen cyanide. By advertising this fact to would-be predators, they avoid becoming a bird’s lunch.

An aggregation of Paropsisterna sp. eucalyptus leaf beetle larvae.

source: Moore, B. P. 1967. Hydrogen Cyanide in the Defensive Secretions of Larval Paropsini (Coleoptera: Chrysomelidae). Australian Journal of Entomology 6: 36-38.

3 thoughts on “Friday Beetle Blogging: A Buttload of Hydrogen Cyanide”

  1. I’m surprised cyanide as a defense hasn’t popped up more across insect taxa as a means of defense. The disparate taxa in which it has shown up (and other invertebrates also, eg millipedes) suggests the evolutionary potential is there – once it does show up you’d think it would ‘spread like wildfire’ (in an evolutionary sense).

    Anyway, great photos – chemical defense in insects is perhaps my favorite non-systematic subject.

    1. Chemical defense and offense certainly has become a major evolutionary pathway in plants. I would suggest that insects are just not as capable a biochemical development forge. Consider that most ‘poisonous’ insects actually get their poisons by sequestering plant poisons.

      Perhaps insects have just concentrated on other, more profitable solutions. Whatever they are, they seem to work pretty well, especially in beetles and flies, LOL.

  2. Pingback: Chemical Warfare and Evolution | Ask an Entomologist

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