Efficacy of LED-enhanced blue sticky traps combined with the synthetic lure Lurem-TR for trapping of western flower thrips (Frankliniella occidentalis)

Pest monitoring is an important tool for successful integrated pest management programmes. Blue sticky traps are important for monitoring western flower thrips, Frankliniella occidentalis, in greenhouses. However, blue sticky traps have three major weak points: (1) efficacy depends on reflection of light, which varies in intensity with fluctuating light conditions (season, diurnal rhythmic pattern), (2) they reflect broad wavelength pattern not optimally matching with maximum sensitivity of WFT photoreceptors, and (3) they offer no olfactory cues which are important for thrips orientation. This study explored the most attractive wavelength range for WFT using broad range of narrow-bandwidth light-emitting diodes (LEDs) in order to improve the attractiveness of blue sticky traps. Subsequently, trapping efficacy of the most attractive blue LED in combination with blue sticky trap and addition of an attractive lure (Lurem-TR) was evaluated in flight cages under greenhouse conditions. Release-capture studies revealed that LEDs with peak emission of 445 nm were clearly more effective than conventional blue sticky traps. In choice experiments, up to 2.7-fold and in no-choice experiment up to 2.1-fold more WFT were captured by LED-blue sticky traps compared to conventional reflecting blue sticky traps. Lurem-TR improved the performance of blue sticky traps and LED-blue sticky traps 2.3-fold and 2.0-fold, respectively, as compared to those without Lurem-TR. The addition of LEDs and kairomone lure to blue sticky traps seems promising for improving WFT trapping, specifically at low population densities especially during early infestation. However, these results should be further validated under more complex, large field conditions.