Potential of blue light-emitting diodes (LEDs) to disturb whiteflies on the crop: a new push–pull strategy?

Mass trapping can be a crucial component of a push–pull strategy, which involves deterrence of pests from a crop (push), while luring them toward an attractive source e.g., a trap (pull). In this study, we explored the effect of blue and blue + UV LEDs on the dispersal of greenhouse whiteflies settled on tomato plants (“push” factor) and the contribution of a yellow sticky trap (YST) and a green LED-enhanced YST (green LED trap) on their recapture after take-off (“pull” factor), in controlled conditions. In following scaling-up experiments in the greenhouse, we tested the effect of different blue spotlight arrangements and intensities on whitefly dispersal, in the presence of a green LED trap. Number of dispersed and trapped whiteflies was counted and the results revealed that blue and blue + UV LEDs increased the dispersed whiteflies by twofold compared to the control without deterrent LEDs and 87–90% of them were captured on a green LED trap. In the greenhouse, high-intensity blue spotlights (186 μmol/m²/s) deterred nearly 50% of whiteflies from the plants and more than half of them were recaptured, regardless the different arrangement of the blue spotlights. The green LED trap was at least twice as attractive as the YST, and in the greenhouse, it captured nearly 12 times more whiteflies in the presence of high-intensity deterrent blue spotlights, compared to the control. These findings provide significant implications for improving targeted whitefly control techniques and can lead to the development of new push–pull strategies.