Light-coloured and strongly-scented inflorescences are often pollinated by crepuscular or nocturnal moths 23, 24, 25, 26, and sometimes are co-pollinated by mosquitoes 27. Mosquitoes frequent mostly light-coloured inflorescences 1, 2, or dark inflorescence mimics in the presence of a human observer 22, but the underlying mechanisms are not known 2, 22. The role of visual inflorescence cues for mosquito attraction has barely been explored. Plant CO 2 mediates insect attraction in many plant-insect interactions 14 and serves as a foraging cue for nectar-feeding insects 20 including the haematophagous sand fly, Phlebotomus papatasi 21. The plants’ transition from net CO 2 sinks to net CO 2 producers coincides with peak nectar foraging activity of many mosquito species 2, 8. During diurnal photosynthesis, plants are net CO 2 sinks but at dusk cease photosynthesis and become net CO 2 producers, thus increasing ambient CO 2 concentrations 17, 18, 19. In mosquitoes, CO 2 interacts with other host cues 15, 16 however, CO 2 originates not only from vertebrate hosts but also from plants that emit CO 2 as a metabolite of cellular respiration 17. CO 2 also attracts, or prompts host-seeking behaviour of, other haematophagous insects including tsetse flies ( Glossina spp.), kissing bugs, biting midges ( Culicoides spp.) and black flies (Diptera: Simuliidae) 14. Important olfactory cues are CO 2 10, L-lactic acid 11 and other carboxylic acids 12, 13. Mosquitoes use olfactory, visual, and thermal cues to locate vertebrate hosts, including humans. As pollinators 4, 5 or nectar thieves 6, mosquitoes seek the inflorescences of many plant species 7, 8, responding to floral semiochemicals (message-bearing chemicals) that apparently guide them to floral resources 9. However, both male and female mosquitoes also consume plant sugars, primarily as floral nectar 1, 2, that provide essential energy for flight and survival 1, 2, 3, thus enabling populations even of highly synanthropic mosquitoes to persist 3. Overlapping cues between plants and vertebrates support the previously postulated concept that haematophagy of mosquitoes may have arisen from phytophagy.įemales of many mosquito species require the nutrients obtained from a vertebrate blood meal for egg development.
Our data support the hypothesis that the entire inflorescence Gestalt of olfactory, CO 2 and visual cues is more attractive to mosquitoes than floral odorants alone. The “human-odorant-blend” attracted mosquitoes but was less effective than the entire 20-odorant floral blend. This blend included nine odorants found in human headspace. We established that tansies become net producers of CO 2 after sunset, and that CO 2 enhances the attractiveness of a floral blend comprising 20 synthetic odorants of tansy inflorescences. In laboratory experiments, we demonstrated that visual and olfactory inflorescence cues in combination attract more mosquitoes than olfactory cues alone. Using common tansies, Tanacetum vulgare L., northern house mosquitoes, Culex pipiens L., and yellow fever mosquitoes, Aedes aegypti (L.), we tested the hypothesis that the entire inflorescence Gestalt of olfactory, CO 2 and visual cues is more attractive to mosquitoes than floral odorants alone. Heretofore, nectar-foraging mosquitoes were thought to be guided solely by floral odorants. Male and female mosquitoes also consume floral nectar that provides essential energy for flight and survival. He is Editor Emeritus of The Asia-Pacific Education Researcher.Female mosquitoes exploit olfactory, CO 2, visual, and thermal cues to locate vertebrate hosts. His research interest relate to lay theories and intergroup relations, socioeconomic inequality and mobility, hope, gratitude and other positive psychological experiences, and the cultural dimensions of learning and academic achievement. Bernardo is a Professor of Psychology at the University of Macau. He presently serves as an editorial board member for Contemporary Educational Psychology and The Asia Pacific Education Researcher, and is currently serving as a guest editor for a special issue on culture and motivation in the British Journal of Educational Psychology.Īllan B. His research interests are on student motivation and well-being.
He finished his PhD in Educational Psychology at The University of Hong Kong under the supervision of David Watkins. Prior to this, he was a Research Scientist at the National Institute of Education, Nanyang Technological University in Singapore. King is an Assistant Professor at the Department of Curriculum and Instruction, The Hong Kong Institute of Education.