Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/10/2018
Publication Date: 4/24/2018
Citation: Short, B.D., Janisiewicz, W.J., Takeda, F., Leskey, T.C. 2018. UV-C irradiation as a management tool for Tetranychus urticae on strawberries. Pest Management Science. https://doi.org/10.1002/ps.5045.
Interpretive Summary: The two-spotted spider mite (TSSM), Tetranychus urticae Koch, is an important pest of many agronomic crops worldwide. Feeding injury from TSSM causes yellowing and browning of leaves and a reduction in photosynthesis. Additionally, mites produce a silk that webs over leaf and other plant material creating a further aesthetic issue. UV-C irradiation technology has been shown to be effective for management of fungal pathogens and surface sterilization. In this study, we evaluated the effect of UV-C irradiation on management of TSSM on potted strawberry plants in a Phytotron. Strawberry plants were infested with 50 adult and 50 immature TSSM and then exposed to nightly, 60-s bouts of UV-C irradiation or left unexposed for four weeks. After the four-week-period, the number of mites were recorded on treated and untreated plants. Exposure of the UV-C irradiation resulted in >97% reduction in TSSM with no yellowing or webbing compared with untreated plants. Based on these results, UV-C irradiation is a promising technology for management of TSSM on strawberry plants.
Technical Abstract: 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 UV-C irradiation treatment. 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 (<5) 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. 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.