Ultraviolet inflorescence cues enhance attractiveness of inflorescence odour to Culex pipiens mosquitoes

Abstract

Inflorescence patterns of ultraviolet (UV) absorption and UV-reflection are attractive to many insect pollinators. To understand whether UV inflorescence cues affect the attraction of nectar-foraging mosquitoes, we worked with the common house mosquito, Culex pipiens and with two plant species exhibiting floral UV cues: the tansy, Tanacetum vulgare , and the common hawkweed Hieraciumm lachenalii . Electroretinograms revealed that Cx . pipiens eyes can sense UV wavelengths, with peak sensitivity at 335 nm. Behavioural bioassays divulged that UV inflorescence cues enhance the attractiveness of inflorescence odour. In the presence of natural floral odour, female Cx . pipiens were attracted to floral patterns of UV-absorption and UV-reflection but preferred uniformly UV-dark inflorescences. Moreover, Cx . pipiens females preferred UV-dark and black inflorescence models to UV-dark and yellow inflorescence models. With feathers and pelts of many avian and mammalian hosts also being UV-dark and dark-coloured, foraging Cx . pipiens females may respond to analogous visual cues when they seek nectar and vertebrate blood resources.

Not Just from Blood: Mosquito Nutrient Acquisition from Nectar Sources

“…The most recent studies on mosquito color vision have confirmed that mosquitoes, like other dipterans, can sense colors in the ultraviolet light ranges. Moreover, the detection of plant odors is enhanced in the presence of visual cues that included UV light when compared with assays lacking UV inflorescence [7]. Although there is much more to be explored, vision is likely to play a key role in mosquito nectar-seeking and uncovering the contribution of this sense merits further investigation.…”

“…Although females are less susceptible to rapid mortality caused by sugar deprivation, their survival rate and fecundity can be compromised by reduced energy reserves [1,4]. The sensory cues that enable nectar-feeding include odors [1,2], tastants [5], and visual stimuli [6,7], but the molecular mechanisms of how these cues are perceived, as well as their relative contribution to the detection of a nectar source, are poorly understood (Figure 1). This review highlights the role of sugar feeding in the life cycle of mosquitoes, the plant sources they prefer, the volatiles that attract them, and the contribution of vision, olfaction, and gustation to this behavior.…”

Artificial light and biting flies: the parallel development of attractive light traps and unattractive domestic lights

“…This UV/blue/green sensitivity is highly conserved in insects [ 30 ]. For biting flies, spectral sensitivity data exist for Aedes aegypti [ 31 ], Culex pipiens [ 32 ], Lutzomyia longipalpis [ 33 ], Glossina morsitans [ 34 ], Tabanus nigrovittatus [ 35 ], simuliid blackflies (species not provided) [ 36 ], Stomoxys calcitrans [ 37 ] and Haematobia irritans [ 37 ]. These taxa all show dual peaks in sensitivity, with one peak in the UV and another in the blue/green, and minimal sensitivity to longer wavelengths (Fig.…”

Mosquito phytophagy – sources exploited, ecological function, and evolutionary transition to haematophagy

“…Many insects including mosquitoes sense UV light (Muir et al, ; Briscoe & Chittka, ; Shimoda & Honda, ) and can read the pattern of UV‐absorptive and ‐reflective petals. UV‐absorptive (UV‐dark) petals are attractive to mosquitoes (Peach et al, ) which may explain the apparent contradiction that host‐seeking mosquitoes are attracted to dark colours, whereas nectar‐foraging mosquitoes reportedly visit human‐visual white/yellow inflorescences.…”