(10/29/24) BATON ROUGE, La. — Throughout the southeastern United States, an invasive species, Chinese privet, has been entering and taking over land at an exceptional rate. The shrub produces thousands of small, green and purple fruits that are eaten by animals and spread with notable efficiency. In south Louisiana, these plants are not hard to find on the side of the road and in areas of overgrowth.
An LSU graduate student, Brandi Misiaszek, is researching ways to control Chinese privet and thinks she has found one in the ligustrum weevil.
“My first objective is to characterize all the herbivores associated with the Chinese privet in Louisiana. Since we're interested in the biocontrol of Chinese privet, we also want to know what else is eating it,” Misiaszek said. “My second objective is to understand broadly the impact of the ligustrum weevil on Chinese privet.”
Misiaszek has been studying the weevil and Chinese privet since 2023 along with Rodrigo Diaz, an LSU AgCenter entomologist. The ligustrum weevil has been difficult to find in Louisiana, which has been a challenge, but the researchers have been able to find it around LSU, at Baton Rouge parks and at a greenhouse at the AgCenter Doyle Chambers Central Research Station.
The ligustrum weevil has been observed to eat privets and other ornamentals, but there is much that scientists still do not know about the insect. Currently, many scientists view it as a pest and have recommendations for getting rid of it, as it is known to eat all kinds of privets, which are often used for show in home gardens.
An objective of Misiaszek’s research is to find what other plants the weevil eats as well as where they lay their eggs through a process called host-range testing.
This is an important distinction to research because it could make or break the effectiveness of the weevil to control the privet, Diaz said. If the privet-munching weevils lay eggs only in the fruits of the Chinese privet, it could make it even harder for the invasive plant to spread and guarantee that the weevil can control the plant without impacting other plants.
“I think that the egg laying, or the oviposition, of the weevils is more important than what they feed on because this basically means that the weevil can limit the reproduction of a plant because they lay the eggs into the seeds, the larvae eat that seed and it makes it so the seed can't grow into a plant,” Misiaszek said.
Misiaszek also is asking for the public’s help in finding more examples of the privet and the weevil in nature. Researchers have been using the app and website iNaturalist to locate where the plant is located around Baton Rouge and Louisiana. By understanding the geographic distribution of both plant and insect, Misiaszek and Diaz can detect patterns in the weevil's seasonal activity, habitat preferences, and spread across different regions of the state.
The ligustrum weevil sitting on a leaf in a lab in the Life Sciences Building. Photo by Anthony Bailey/LSU AgCenter
LSU graduate student Brandi Misiaszek standing around different privets and ornamentals that she has used to study the habits of the ligustrum weevil at a greenhouse at the LSU AgCenter Doyle Chambers Central Research Station. Photo by Anthony Bailey/LSU AgCenter
The fruits of Chinese privet before they turn purple. Chinese privet is prevalent throughout much of the southeastern United States. Photo by Anthony Bailey/LSU AgCenter