Baileya multiradiata and Trigonorhinus fungus weevils

When collecting seeds of desert marigold (Baileya multiradiata for you latin fans) I more often than not run across fused clumps of seeds in the seedheads that have been partially eaten and abandoned leaving a chamber and frass behind. This week as I was gathering some I found larvae and later adult fungus weevils (Trigonorhinus) in those chambers. The best match looks to be Trigonorhinus griseus, but being out of my field I'm reluctant to call a species.

As noted the chambers are quite common. This morning I collected and dissected ten likely seedheads (well-dried and shedding old flowers), and found the following:

Larva 2
Pupa 0
Adult 5
Empty chamber 2
No chamber 1

Nine of the ten had chambers. Larvae and adults were alive and were returned to their hosts.

If you have access to plants with mature seedheads (see attached photos), I'd be interested in a count of ten looking for evidence of a chamber (some of the seeds firmly clumped). If you want to go further and open them looking for occupants all the better.

Posted on 07 de novembro de 2021, 04:07 AM by stevejones