UV light attracts Diaphorina citri and its parasitoid

Diaphorina citri Kuwayama (Hemiptera: Psyllidae) transmits the bacteria associated with Huanglongbing, an incurable and lethal disease affecting citrus productivity and fruit quality worldwide. This vector is prominently phototactic and uses visual cues to find host plants. Yellow sticky traps are used for its monitoring, but their efficiency is limited, especially at low population densities. Diaphorina citri can be captured at night when light is provided and it is attracted to UV light. One way to increase the attraction of D. citri is therefore combining sticky traps with LEDs of specific colors at night, but more information about attractiveness of UV and colors combined with UV is needed. Moreover, information on the attraction of the main parasitoid of D. citri, Tamarixia radiata Waterson (Hymenoptera: Eulophidae) to UV and other light colors is lacking. We examined the attraction of males and females of D. citri to LED lights of different colors but comparable intensities separately or combined with ultraviolet (UV). The non-UV colors alone did not differ in attractiveness, whereas green, light blue and red light became more attractive when combined with UV. However, none of these color combinations were more attractive than UV alone. The parasitoid T. radiata was also attracted to UV LEDs. Female parasitoids were equally attracted to UV during day and night, but males were more attracted at night. These results suggest that the effectiveness of the commonly used yellow sticky traps can be increased by combining them with UV LEDs at night, and the parasitoid of D. citri may also be attracted. On the one hand, attraction of parasitoids to the traps may help monitoring their presence, but on the other hand, it may affect biological control by this natural enemy.