Cocoon or not cocoon? That is the question.



Hi Ant folk:

I am interested in finding out if ants in the Myrmicinae tribe produce silken cocoons as I am trying to get hold of some samples. Do you know anyone who has Acromyrmex echinator, Atta cephalotes, Pogonomyrmex barbatus or Solenopsis invicta in culture who might have some cocoon samples hanging around (if they exist)?

Thanks for your help.
Cheers, Holly

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Hello Holly:

No ant in the subfamilies Myrmicinae, Pseudomyrmecinae or Dolichoderinae is known to produced larval silk. The adaptive significance of this fact, and the metabolic fate of their silk production genes and anatomy is not well studied (unknown?), though perhaps one of the others on our team may know more.

Mature larvae of most species in the other subfamilies normally do spin a cocoon before pupating, so those are where you'll have to seek the materials in question, I suppose.

Just wondering, how did you arrive at this particular list of species?

Best regards, James C. Trager of the AskAnt Team.

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Hi James,

Very interesting. I came across the list of ants as I have been looking for the silks genes from the genome projects. Our lab has done a bit of work on silks from Formicinae and Myrmeciomorphs in the past and I am looking to add to the dataset.

It's interesting that you say Dolichoderinae also don't produce silk as Argentine ants have also been sequenced. Do Myrmicinae, Pseudomyrmecinae or Dolichoderinae have unique domiciles? Are they weaker than other subfamilies?

Thank you for your response and I look forward to having a few more ant conversations.

Cheers, Holly

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Hello Holly:

Myrmicinae and Dolichoderinae are diverse taxonomically and ecologically, with a wide range of nesting habitats, about which no generalizations may be made. Pseudomyrmecinae are almost all inhabitants of cavities in plants, and interestingly, species in the huge genus of Formicinae called Camponotus vary in cocoon production in a way that may be interesting to you. Soil and dead and rotten wood inhabiting ones typically have pupae in cocoons, while many that inhabit the tight confines of plant stems, notably the subgenus Colobopsis, lack cocoons.

Nonetheless, I rather think that lack of cocoons could be more of a nutritional matter than a matter of where particular ants live. A diet dominated by nectar, honeydew and fruit juice, or by seeds, is low in protein, so perhaps it was adaptive for the mainly nectarivorous or granivorous ancestors of these groups to eliminate silk production in order to conserve amino acids for growth and development. Many Formicinae are evidently more carnivorous than at some of the Dolichoderinae and Myrmicinae, and at least some have nitrogen-fixing, internal bacterial symbionts that could mitigate the nitrogen compound deficiency. I hope that my making this sweeping, and perhaps wrong guess/generalization will stimulate commentary from some others, and perhaps other myrmecologists can be brought into the discussion . . .

Do let us know if you hear from them.

Regards, James C. Trager of the AskAnt Team

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