By Andi Anderson
An invasive pest, Thrips parvispinus—also known as pepper thrips—is becoming a serious threat in Michigan greenhouses. First identified in Florida in 2020, it’s now detected in multiple U.S. states and has appeared in Michigan since 2023.
This tiny insect damages plants by scraping tissues, causing severe deformation, brown scarring, and brittle growth. Its presence can render floriculture crops like Mandevilla, orchids, poinsettias, and even specialty crops like peppers and strawberries unsellable.
Unlike western flower thrips, T. parvispinus has a distinct dark abdomen, beige thorax, and yellow legs. Females appear two-toned and larger than the light-colored males. This species completes its lifecycle in about 13 to 14 days and cannot survive Michigan’s outdoor winters, making greenhouse environments a key concern.
Dr. Alexandra Revynthi at the University of Florida leads extensive studies on this pest, testing 21 conventional insecticides and 11 biopesticides. While some products, like Mainspring, affect thrips feeding rather than killing them instantly, oils like sesame and thyme have shown strong results in reducing crop damage.
Research on microbial insecticides also shows promise. Products like Ancora and Isarid have been effective in lab settings. Entomopathogenic nematodes—particularly Heterorhabditis bacteriophora and Steinernema carpocapsae—perform well against soil stages of the pest.
Biological control agents like predatory mites (Amblyseius swirskii, A. degenerans) and minute pirate bugs effectively target thrips larvae. Early detection and intervention are essential, especially as most predators target young thrips.
Collaborative research is ongoing across North America, including in Canada and multiple U.S. states. While more trials are needed under real greenhouse conditions, combining chemical, biological, and cultural tactics offers the best approach to protect crops from this emerging pest.
Photo Credit: gettyimages-zoran-zeremski
Categories: Michigan, Rural Lifestyle, Farm Safety