I’ve been noticing that one of the plants in my backyard here in Orlando is getting totally mauled by insects. I didn’t know what this vine with heart-shaped leaves was, but I thought it looked like a wild yam species. The level of herbivory damage is often intense.
Then Isa Betancourt (@isabetabug) on her bug-themed livestream challenged her viewers to find and observe an insect for 1 minute. Always a great activity and something I do all the time but it was a good motivation to get into my backyard to discover what was causing all the damage. Here’s what I found:
I knew the beetle I found was a leaf beetle (family Chrysomelidae) so I headed online and searched for wild yam + leaf beetle + Florida. And I quickly found an answer, this plant is called air potato (Dioscorea bulbifera) which is an invasive plant introduced from China in the early 1900’s and is now swallowing up huge areas in South and Central Florida. They reproduce primarily by producing above-ground tubers (called bulbils) that look like little potatoes, which explains both the common and scientific names.
The air potato leaf beetle (Lilioceris cheni) is also an introduced species, but this one is not a nuisance, it’s beneficial. They were introduced specifically as a biocontrol of air potato in 2012, and from what I can see they’re kicking ass. Introducing new species on purpose can be risky, what if they start devouring a native plant species? The best biocontrol species are highly specialized and only feed on the pesky invasive plant, and studies on air potato beetles showed exactly that. They strongly prefer to eat air potato over other closely related plant species and there is no evidence that they can complete their lifecycle on any other species native to Florida. The perfect enemy of a noxious weed!
I’ve always liked herbivores and I think that leaf beetles may be my favorite group of animals. Unfortunately they have a bad reputation since a few of them are serious crop pests like the colorado potato beetle, cucumber beetles, and flea beetles. I’m excited that there is no reason not the celebrate the voracious appetites of these beautiful beetles and that they are working hard to reduce the outbreak of an invasive vine in my backyard and across the state. Here’s one in action: