D3457: Advances in thrips management using UV-C

Western flower thrips, Frankliniella occidentalis (WFT), are a major pest in the ornamental greenhouse industry. Chemical pesticides are used by most growers to manage them; however, rapid resistance has limited their effectiveness. A promising and viable alternative for controlling thrips in greenhouses is ultraviolet-C (UV-C) radiation. Our current research has progressed to studies in actual greenhouse environments, focusing on infested marigolds, Tagetes patula.

Noting that WFT primarily reside and oviposit eggs on the underside of leaves, we have developed a novel UV-C greenhouse applicator (UVGA) prototype to target this behavior. The apparatus consists of modular panels that can be aligned in tandem with horizontally positioned UV-C lamps. The number of lights in the panels, the number of panels and the position of the panels can be adjusted to different plant tray sizes, row numbers, and plant heights. This allows for UV-C exposure to all plant surfaces, with an emphasis on the underside of leaves.

We evaluated the effect of UV-C on the fecundity of WFT using marigolds and the new applicator. We demonstrated that WFT larvae can be significantly reduced after 30 seconds of exposure, with minimal damage to the plants. Our findings indicate that UV-C has promise as a complementary tool for integrated pest management (IPM) programs against WFT in commercial greenhouses.