New data on mosquito vision could help avoid being bitten by these known disease vectors.
Scientists from the University of Washington conducted a new study. It turned out that when ordinary species of mosquitoes detect the gas that we exhale (CO₂), they fly only towards certain colors. They are attracted to red, orange, black and blue. At the same time, mosquitoes ignore other colors – green, purple, blue and white.
The researchers believe that these results of the new work will help explain how mosquitoes detect people. These insects seem to “see” human skin, despite pigmentation, as a red-orange object.
“Mosquitoes seem to use scent to distinguish between nearby objects,” explains senior study author Jeffrey Riffell, professor of biology at the University of Washington. – Insects smell certain compounds such as CO₂ from our breath. This, in turn, stimulates their eyes to scan for certain colors and other visual patterns that are associated with a potential host and head towards them.”
The results, published Feb. 4 in Nature Communications, show how a mosquito’s sense of smell affects how a mosquito responds to visual cues. Knowing which colors attract hungry mosquitoes and which don’t can help develop more effective insect repellants, traps, and other insect repellent methods. Mosquitoes are known to carry West Nile virus, Zika virus and the parasites that cause malaria.
Earlier a team of researchers (Joop J. A. van Loon, Renate C. Smallegange, Gabriella Bukovinszkiné-Kiss, Frans Jacobs, Marjolein De Rijk, Wolfgang R. Mukabana, Niels O. Verhulst, David J. Menger, and Willem Takken) re-assessed the role of carbon dioxide in attraction of the African malaria mosquito An. coluzzii Coetzee & Wilkerson sp. n. (renamed from An. gambiae sensu stricto molecular ‘M-form’; Coetzee et al. 2013) to odor blends composed of C4-compounds, which have previously been reported to be attractive or inhibitory in the absence of carbon dioxide. Anopheline mosquitoes feed on humans as blood hosts, enabling the transmission of Plasmodium parasites from infected to uninfected hosts. Vector-host contact is achieved through chemoreception of volatile cues emitted by the blood host (Zwiebel and Takken 2004). Host volatiles are perceived by olfactory organs located on the head of the mosquito, in particular the antennae and maxillary palps (Qiu and Van Loon 2010). In recent years, the molecular basis of olfactory perception of mosquitoes has been elucidated by the discovery of a suite of olfactory receptor (OR) genes that recognize volatile host cues (Carey et al. 2010; Liu et al. 2010). Binding of the host-derived volatile organic molecules to ORs trigger signal transduction in olfactory receptor neurons, which transmit electrophysiological activity to the olfactory lobe in the brain ultimately leading to a behavioral response (Qiu and Van Loon 2010). Recently, significant progress has been made in the identification of a number of these odorants, resulting in the creation of odor blends that are as attractive as a human host (Menger et al. 2014; Mukabana et al. 2012; Okumu et al. 2010). These blends have been formulated during an iterative process involving molecular, physiological, and behavioral assays on anopheline mosquitoes in vitro and in vivo (Carey et al. 2010; Carlson and Carey 2011; Qiu et al. 2011; Rinker et al. 2012; Smallegange et al. 2010, 2012).
In the present study, we re-assessed the role of carbon dioxide in attraction of the African malaria mosquito An. coluzzii Coetzee & Wilkerson sp. n. (renamed from An. gambiae sensu stricto molecular ‘M-form’; Coetzee et al. 2013) to odor blends composed of C4-compounds, which have previously been reported to be attractive or inhibitory in the absence of carbon dioxide (Smallegange et al. 2012; Verhulst et al. 2011a). This finding led us to augment the three-component blend of ammonia, lactic acid, and tetradecanoic acid that we reported before as an effective kairomone blend mimicking the attraction of human subjects (Smallegange et al. 2009, 2012) with butan-1-amine and 3-methyl-1-butanol, a volatile produced by microbiota on the human skin (Verhulst et al. 2009, 2011a).
Source: van Loon, Joop J A et al. “Mosquito Attraction: Crucial Role of Carbon Dioxide in Formulation of a Five-Component Blend of Human-Derived Volatiles.” Journal of chemical ecology vol. 41,6 (2015): 567-73. doi:10.1007/s10886-015-0587-5
