Optimization of UV-B radiation to suppress egg hatching of Western flower thrips (Frankliniella occidentalis) in tomato leaves

Ultra-violet (UV) light is known as being potentially harmful to living organisms. With continuous research development in LED (light emitting diode) technologies, LED-based use of UV light is being tested and implemented into pest management programs. Here, we describe use of UV-B (main spectral peak at 300 nm) as an approach to suppress hatching of eggs by western flower thrips (WFT) (Frankliniella occidentalis). WFT-infested tomato leaves were exposed to UV-B light at two time points (day or night) and onto adaxial or abaxial leaf sides, and results were compared with untreated controls (five treatments). Hatching percentage of WFT eggs was determined seven days after a single 4-hour UV-B exposure. We found that, for all four treatment combinations, UV-B exposure significantly decreased hatching rate of WFT eggs. UV-B may have adverse effects on tomato plant growth. Thus, optical sensing was used to examine leaf reflectance profiles from all five treatments. The reflectance data indicated that plants from all treatments recovered from initial stress elicited by UV-B exposure. Our results suggested that UV-B light can be utilized as an efficient and sustainable control of WFT populations. Presented results may also be potentially beneficial in developments of effective and sustainable pest management programs of other important greenhouse pests.