A new study has identified the specific colors that attract mosquitoes.
In addition to being attracted to the carbon dioxide emitted more by adults, especially pregnant women and taller people, than children, a new study suggests that mosquitoes fly towards certain colors after detecting CO2.
Color is important for object detection and location when it comes to mosquitoes. A study published in the magazine Nature Communications has discovered that yellow fever-transmitting mosquitoes (Aedes aegypti) fly towards certain colors, such as red, orange, black, and cyan, but ignore colors like green, purple, blue, and white.
Aedes aegypti mosquitoes can also transmit the dengue virus, chikungunya, and the Zika virus, and remember that it is the females of the species that need blood.
The scientists monitored the mosquitoes’ responses to visual and olfactory stimuli in a test chamber. They tested how the insects responded to different colored dots on the bottom of the chamber, with or without CO2 injection. They found that mosquitoes fly towards a specific location if it is red, orange, black, or blue and if they smell CO2 first.
Due to the lack of carbon dioxide emissions, the insects ignored these areas, regardless of the colors. However, they still ignored the green, blue, white, and cyan areas, even after being sprayed with CO2.
“Mosquitoes appear to use scent to distinguish what is nearby, such as the host that will bite,” explains Jeffrey Riffell, the lead author of the study. “When we smell certain compounds in our breath, such as CO2, this odor stimulates the eyes to search for and target specific colors and other visual patterns associated with potential hosts.”
The results show how the mosquito’s sense of smell (which humans cannot smell, but mosquitoes can) influences the mosquito’s response to visual cues. These findings help explain how mosquitoes find hosts to bite because human skin, regardless of overall pigmentation, emits a strong orange-red “signal” to mosquitoes’ eyes, regardless of our skin tone.
“I said that mosquitoes are attracted by three main signals: breath, sweat, and skin temperature. In this study, we discovered a fourth signal: the color red,” commented the author.
Although we don’t know if these insects perceive color in the same way as human eyes, this finding shows that most of the colors that mosquitoes prefer after smelling CO2 (orange, red, and black) correspond to longer wavelengths. Additionally, knowing which colors attract hungry mosquitoes and which don’t could help us develop more effective repellents, traps, and other methods to repel mosquitoes, especially in hot climates.