Ultraviolet and violet light enhance the attraction efficacy of semiochemicals for the Asian longhorned beetle

The Asian longhorned beetle Anoplophora glabripennis attacks healthy trees and semiochemicals are used for monitoring, although no optimal efficacy has been achieved. To develop monitoring strategies, we compared the attraction rates of 14 monochromatic light-emitting diodes (LEDs) for A. glabripennis adults, and determined the relative attraction capacity of most attractive wavelengths: the attraction rates were higher at 365-nm and 420-nm than other wavelengths. Subsequently, we evaluated whether 365-nm and 420-nm lights could enhance the attraction rates of sex pheromones or host kairomone, alone or in combination. We assessed the attraction rates of combinations of LEDs and sex pheromones or host kairomones, and showed that attraction rates of combinations of light cues and [4-(n-heptyloxy) butanol and 4-(n-heptyloxy) butanal], (Z)-3-hexen-1-ol, (Z)-3-hexenol acetate or (-)-linalool were higher than those of single chemicals. Finally, we studied the influence of LED light, sex pheromones and host kairomone mixtures on attraction for A. glabripennis and found that combinations of cues attracted were more attractive than LED cues or semiochemicals alone. When 420-nm light was combined with mixtures of [4-(n-heptyloxy) butanol:4-(n-heptyloxy) butanal:(-)-linalool = 1:1:1], the attraction rates for adult females increased by 212% (vs. LED cues alone) and by 5321% (vs. semiochemicals alone). We demonstrated that ultraviolet and violet lights could enhance the attraction efficacy of semiochemicals for A. glabripennis and combination cues provided a promising strategy.