Carnivorous plants are adapted to growing in areas of poor soil nutrition and are able to derive some of their nutrients by trapping animals. Unlike most other predators, carnivorous plants lack mobility thus they must attract their prey through a combination of visual and olfactory cues. UV-fluorescence has long been thought to be a potential attractant utilized by carnivorous plants, however previous work has suggested that visual cues may be more important for avoiding capture. In this study, the relative importance of UV fluorescence was tested using artificial fruit fly traps with either UV absorptive or UV reflective features. Two strains of Drosophila melanogaster were used; a wild type (Oregon R) and a visually impaired mutant (w1118). This study addressed three different questions regarding the effect of UV fluorescence on D. melanogaster. 1) Are there differences in capture rates between wild type and visually impaired fruit flies? (2) Is there a preference for UV absorptive or UV reflective artificial traps? (3) Are there sex differences in capture rates between male and female fruit flies?
A total of 269 D. melanogaster were captured in the experiment, with 160 fruit flies caught in the UV absorptive traps and 109 caught in the UV reflective traps. There was no significant difference in the number of captures between the Oregon R wild type and w1118 mutant fruit flies (t = 0.00, df = 22, p = 1.00). Within genotypes, more w118 mutant fruit flies chose the UV absorptive traps than the UV reflective traps (t = -3.034, df = 10, p = 0.013). The Oregon R wild type fruit flies did not display a significant difference in capture rates between the UV reflective and UV absorptive traps (t = -1.345, df = 10, p = 0.208). While only 119 males were captured compared to 150 females, differences in sex captures were not significantly different (t = -1.242, df = 46, p = 0.221). When sex and trap preference were compared in a mosaic plot, both male and female fruit flies had similar trap preferences (= 0.198, df = 1, p = 0.656). This study further supported the hypothesis that visual cues are not as important as olfactory cues in attracting and trapping fruit flies. The results also suggest that the visually impaired w1118 mutant fruit flies can actually use visual cues.