Are the Dotted Paopsine Leaf Beetles (Parapsis atomaria) a Problem in SoCal?

https://www.inaturalist.org/observations/239617796

With all of our nonnative but established Eucalyptus trees (look around - they're everywhere), it's no wonder that we are finding this Australian beetle that eats these trees. I've observed three in the last month. Four, if you count the one being caught and (presumably) eaten by a local Native Predator, the Orbweaver Spider (Species ID pending).

I saw the beetle caught in the web and the orbweaver grabbing it. I didn't stay to witness what happened, unfortunately. Did the beetle get eaten? Were there toxic juices from the Eucalyptus that deterred or poisoned the spider? Not sure. But later when I went back to look, the spider and beetle were gone.

Immediately nearby, a meter or so, there is a larger older Eucalyptus tree and plenty of evidence of herbivory on the leaves, as well as a beetle and many groups of eggs.

So my questions are around how "Invasive" this beetle is or might become, and although I'm not a big fan of our nonnative Eucalyptus at several levels, I can see the concern that municipal planners may be confronted with if the beetles increase their population and activity enough to damage and/or kill these trees. I don't want dead branches falling on my patio, a theoretical situation if there is a mass die-off of Eucalyptus. Additionally in wild places like Marshall Canyon where there are many of these trees (which I will go survey for these beetles), my concern would be deadfalls and/or fire hazard.

Is anyone interested in looking into this further?

Posted on September 9, 2024 07:17 PM by