The effect of blue and UV light-emitted diodes (LEDs) on the disturbance of the whitefly natural enemies Macrolophus pygmaeus and Encarsia formosa

Recent studies demonstrated that blue and UV light effectively disturb greenhouse whiteflies (Trialeurodes vaporariorum) from a host plant (“push”), enhancing their capture on attractive traps after dispersal (“pull”). This push–pull technique could contribute to whitefly biocontrol and lead to the development of mass trapping. However, the impact of these wavelengths on the behavior of whitefly natural enemies, commonly deployed for biocontrol, remains underexplored. This study investigated the response of two important whitefly biocontrol agents, Macrolophus pygmaeus and Encarsia formosa, to blue and UV light. Initial experiments were conducted under artificial conditions (no prey/host and plant present) to isolate their visual behavior to these lights, excluding other stimuli. In follow up experiments, the effect of these lights was assessed in a more complex scenario, involving prey/host (whitefly nymphs) on tomato leaves. Results revealed that both M. pygmaeus and E. formosa exhibited avoidance behavior under blue and UV LEDs in the artificial setup, irrespective of ambient light or dark conditions. Contrastingly, in presence of prey/host on tomato leaves, only M. pygmaeus was significantly disturbed by UV light, whereas in all other scenarios there was little to no effect of blue and UV LEDs on the behavior of these natural enemies. These findings enhance our understanding on the visual behavior of crucial biocontrol agents and highlight the importance of refining targeted whitefly control techniques that minimize impacts on beneficial insects and optimize the use of LEDs in integrated pest management (IPM).