There is a new non-native species in North America, and researchers are working quickly to find out its potential impacts.
Smaller than a grain of rice, Phyllotreta ochripes (fill-uh-TREE-tuh OKE-rih-peez), is not an easy species to detect. But it is important to pay attention to these tiny insects because they may have big implications when it comes to managing invasive garlic mustard (Alliaria petiolata) plants.
Phyllotreta ochripes is a type of flea beetle, a group of insects named for their small size and ability to jump. Though some kinds of flea beetles are native to North America, Phyllotreta ochripes is native to western Europe and parts of Asia. In 2017, however, they were detected in North America.
Following their initial detection in Michigan, researchers (Douglas et al., 2024) found Phyllotreta ochripes flea beetles in Illinois, Maryland, Michigan, Ohio, and Pennsylvania. They even sifted through over 700 flea beetle observations on iNaturalist, spanning from Newfoundland to Texas, to see if any were Phyllotreta ochripes. And some were! The researchers confirmed 29 observations, mostly from the Midwestern United States but also from Ontario. A commonality among the observations was that the Phyllotreta ochripes flea beetles were found on or near garlic mustard.
Garlic mustard is a well-known and widespread invasive plant in North America, often growing in dense patches along trails and in woodlots. Phyllotreta ochripes flea beetles feed on garlic mustard, but they are not alone in having an appetite for the plant.
Another tiny insect, a type of weevil called Ceutorhynchus scrobicollis (soo-toh-RINK-us skroh-bih-KOLL-iss), also feeds on garlic mustard. Just like the Phyllotreta ochripes flea beetles, these weevils are not native to North America. But these weevils did not arrive on garlic mustard by chance. In Ontario, they are released intentionally as approved biological control, or “biocontrol”, agents.
The goal of biocontrol is to restore the ecological balance between invasive plants, like garlic mustard, and their host-specific natural enemies, like C. scrobicollis, by reuniting them in their new habitat. In this case, hungry weevils are literally eating away at populations of invasive garlic mustard, making space for native flora and fauna to move back into Ontario’s ecosystems.
These weevils, Ceutorhynchus scrobicollis, are also incredibly picky eaters: they only eat garlic mustard! The adults feed on the leaves while the larvae feed inside the plant. The Phyllotreta ochripes flea beetle is less picky, and eats multiple species of plants, including invasive garlic mustard.
For this reason, a team of researchers at University of Toronto are working swiftly to better understand the current distribution of Phyllotreta ochripes in Ontario and its potential impact on both invasive garlic mustard and the approved biological control agents that feed on it. And they are seeking your help!
How You Can Help
There are two ways that you can help researchers study Phyllotreta ochripes in Ontario.
First, members of the public can submit observations of the Phyllotreta ochripes flea beetle to iNaturalist. So long as the observation is flagged as the correct species (“Phyllotreta ochripes”) and is in Ontario, it will automatically be added to the U of T team’s iNaturalist project, “Finding Phyllotreta ochripes in Ontario”. Make sure to take photos that are clear and that include important features of the insect.
They are particularly interested in photos of Phyllotreta ochripes on garlic mustard, but any observations of this species are helpful.
Second, if you are planning to conduct any garlic mustard removal this year, you can also participate by collecting first-year garlic mustard plants with signs of Phyllotreta ochripes flea beetle feeding for the team to later dissect for evidence of Phyllotreta ochripes eggs and larvae.
Please reach out to the team directly (Dr. Jenn Baici, [email protected]) before collecting garlic mustard plants for contribution to the project so that they can provide more detail about collection, storage, and pick-up.
Their tiny size makes Phyllotreta ochripes flea beetles easy to miss, but they are worth a closer look. As researchers continue their work on these insects, your observations could help reveal their spread in Ontario and what impacts they could have on garlic mustard and the weevils helping to control it.
If you have questions, please reach out to members of the research team:
- Jenn Baici, University of Toronto, [email protected]
- Ian Jones, University of Toronto, [email protected]
- Kenneth Dearborn, University of Toronto, [email protected]
- Sandy Smith, University of Toronto, [email protected]
- Rob Bourchier, University of Toronto, [email protected]
- Hume Douglas, Agriculture and Agri-Food Canada (AAFC), [email protected]
Additional Reading
Douglas H, Hammond G, Smith T, Mutz J, Konstantinov A (2024) Palaearctic flea beetle Phyllotreta ochripes (Curtis) (Coleoptera, Chrysomelidae, Galerucinae), herbivore of Alliaria petiolata (garlic mustard), new to North America. Biodiversity Data Journal 12: e135576. https://doi.org/10.3897/BDJ.12.e135576
