UV-C irradiation as a management tool for Tetranychus urticae on strawberries.

Background: Tetranychus urticae Koch, the two-spotted spider mite, is a highly polyphagous and worldwide pest of many agricultural crops, including fruit, vegetables, and ornamentals. Typical methods of control include applications of acaricides and biological control agents. Here, we present a non-chemical technology for management of T. urticae on strawberry plants through the use of a nightly short-duration ultraviolet-C (UV-C) irradiation treatment.

Results: Potted strawberry plants infested with T. urticae that received a nightly 60-s exposure of UV-C irradiation had significantly fewer live mites per mid-canopy leaflet (fewer than five) than untreated control plants (> 175). Furthermore, none of the UV-C irradiated strawberry plants had any spider mite webbing; whereas, 65% of untreated plants were webbed. Tetranychus urticae feeding on untreated plants caused significant yellowing of the leaves compared with UV-C-treated plants.

Conclusion: The UV-C irradiation treatment maintained mite populations below the accepted economic threshold of five mites per mid-canopy leaflet. No phytotoxic effects were visible on plants exposed to the short-duration nightly UV-C irradiation treatments. Further discussion is provided on the potential benefits of UV-C irradiation for mite management. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.