Colour shade and chemical influences on the capture of adults Frankliniella occidentalis (Thysanoptera: Thripidae) in blackberry crops

Western flower thrips (WFT) are a major pest for blackberry crops in Mexico, causing economic damage. To monitor this pest, yellow and blue sticky traps are commonly used during the blossom season. However, the impact of different shades of yellow and blue on adult WFT capture has not been well understood. The study tested different shades of yellow and blue to determine their influence on capturing of Frankliniella occidentalis in infested blackberry crops. Additionally, diverse geometric shapes in bright blue (the most appealing shade from the initial test) set against a dark green backdrop were examined. Furthermore, the potential synergy between the bright blue sticky traps and commercial attractants was investigated. Bright blue (blue 3; 59% reflectance to 548 nm) and fluorescent yellow (yellow 4; 98% reflectance to 522 nm) traps were effective in capturing adult WFT in high numbers, however, the bright blue traps displayed a numerical superiority (5.6%-12.8% more) over the fluorescent yellow traps. Furthermore, the introduction of various geometric shapes in bright blue against a dark green background showed a significant effect on the capture of adult WFT, with the traps consisting of a triangle and the semicircle yielding the highest captures (standardized data with respect to the blue area of the trap). However, the results indicate that a trap without contrast (>blue area) can be used if it is placed in contrast to the crop foliage (non-standardized data). Lurem-TR, a commercial attracts, significantly increased adult WFT capture rates, doubling or tripling the capture to traps without bait, and 2 mg of eugenol increased captures by 1.5-2.5 times. The findings are crucial for improving the monitoring and control of WFT blackberry crops. By optimizing trapping strategies, the agricultural sector can better manage the impact of this pest on blackberry cultivation.