The Latest Thrips Parvispinus Research Reveals New Greenhouse IPM Strategies

New research into Thrips parvispinus is giving growers more information about how to monitor and manage the persistent greenhouse pest.

A recent article published by ONfloriculture, written by Jessie deHaan of the Vineland Research and Innovation Centre, summarizes collaborative research on T. parvispinus from the Ontario Ministry of Agriculture, Food and Agri-Business, Agriculture and Agri-Food Canada, and Vineland. The research focuses on the biology and behavior of T. parvispinus, which was first detected in southern Ontario in 2021. Researchers found that conventional monitoring and biological control approaches used for western flower thrips may not work as effectively against T. parvispinus, making species-specific scouting and integrated pest management (IPM) strategies important.

Plant Host Preferences Can Guide Scouting

Research comparing beans, peppers, and Mandevilla found that T. parvispinus preferred some host plants over others. Reproduction was highest, and development was fastest, on beans, while survival was lowest on Mandevilla. Researchers also observed that thrips often preferred younger leaves for egg-laying, although preferences varied among Mandevilla varieties.

Therefore, scouting should focus on susceptible crops and varieties, particularly growing tips and younger foliage. Still, some varieties may require inspection of both younger and older leaves because thrips pressure can be more evenly distributed.

Host plants also may influence biological control. The study found that Orius insidiosus consumed more T. parvispinus than western flower thrips when feeding on peppers. However, predation was lower when T. parvispinus had developed on Mandevilla, suggesting that the host plant may affect predator-prey interactions.

Thrips Flight and Defensive Activity Provides IPM Clues

Researchers also identified defensive behaviors that could help explain challenges with predatory mites. Preliminary AI-based tracking showed that T. parvispinus used defensive movements more frequently than western flower thrips when exposed to Amblyseius swirskii, and that the pest also moved faster when predators were present.

Timing is another important finding. Unlike onion thrips, which are more active in the morning, or western flower thrips, which remain active throughout the day, T. parvispinus showed peak flight activity between 2 and 6 p.m. The establishment of this pattern could influence pesticide application timing.

Color Preference in Monitoring Tools

The findings also point to better monitoring tools. Dark blue sticky cards outperformed yellow cards in commercial hibiscus trials and previous greenhouse studies. However, sticky cards primarily detect adults. Plant washes provided the most accurate population estimates because they captured both adults and larvae, although they require more labor and a microscope.

For additional information on new Thrips parvispinus research and pest management insights, please read the original report here.