Visual cues attract adult Tunga penetrans (Siphonaptera: Tungidae)

Tunga penetrans (Linnaeus, 1758) (Siphonaptera: Tungidae) is an ectoparasitic flea whose adult females cause tungiasis by embedding into the host's skin. Environmental, social and financial challenges in tungiasis endemic areas have left this disease neglected and lacking locally available control measures. One possible approach for controlling T. penetrans targets its off-host stages; however, surveillance tools for adult fleas are still lacking. Moreover, host-seeking cues and behaviour of adult T. penetrans remain largely unknown. In this study, we show that visual cues are attractive to adult T. penetrans. Newly emerged T. penetrans responded to light stimuli across a broad spectrum, ranging from 375 nm to 690 nm. Within this range, significantly stronger attraction was observed at 430 nm over 375 nm, at 490 nm over 610 nm, and at 610 nm over 690 nm. Attraction did not differ significantly between 430 nm and 490 nm or between 535 nm and 490 nm. Overall, wavelengths between 430-535 nm induced stronger attraction in both sexes under constant electrical current conditions. In contrast, although host odor and body temperature attracted more than half of the tested adult fleas on average, the observed responses were not statistically significant. These findings suggest that visual cues in this spectral range could serve as promising attractants for capturing adult fleas. Incorporating these insights into trap strategies could support improved monitoring, surveillance, and potentially contribute to control efforts.