New Research on Mosquito Odorant Receptors Advances Understanding of Feeding Behaviors

Contact: Shelby Cefaratti-Bertin, 254-327-8012
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Mosquitoes may be annoying, biting pests, but they also are considered to be the deadliest creatures in the world. More than 700,000 people die each year from vector-borne diseases transmitted by mosquitoes, including yellow fever, Zika, Chikungunya, dengue, malaria and West Nile.

Baylor University mosquito researchers, led by Jason Pitts, Ph.D., who specializes in vector biology and global health, have researched the complex odor-receptors – or sense of smell – of mosquitoes to help understand how they find meals. Their latest research – “Odorant receptors for floral- and plant-derived volatiles in the yellow fever mosquito, Aedes aegypti” – is published in the journal, PLOS ONE.

The study identified how odorant receptors (ORs) in Aedes aegypti mosquitoes – a known vector often called the yellow fever mosquito – are activated by plant-based chemicals, which help mosquitoes locate food sources crucial to survival and reproduction. The findings advance understanding of the role of ORs in mosquitoes’ nectar foraging (sugar meals), which could be used to develop new mosquito control methods, ultimately leading to a decrease in vector disease transmission around the world.

“By more fully understanding the sensory mechanisms that drive innate behaviors, we can conceptualize novel ways to reduce the impact of mosquitoes and other disease-transmitting insects (and ticks) on human health,” Pitts said.

Mosquito sense of smell 

The way mosquitoes smell and the way humans smell are similar, Pitts said. Humans have nerves in their nasal passages that – if tuned – will send signal receptors to the brains – the same process for mosquitoes. For mosquitoes, this chemical or odor detection is crucial for virtually all aspects of their life cycle, Pitts said.

By studying how ORs work in yellow fever mosquitoes, the researchers were able to learn more about what food sources mosquitoes are attracted to, where they feed and how female mosquitoes, in particular, target blood meals. Hungry mosquitoes are attracted to humans for blood meals, especially if their sweat contains certain carboxylic acids, a key component in human sweat, Pitts said.

“All mosquitoes nectar feed from flowers and other sources, but female mosquitoes are the only ones to blood-feed or bite humans and other mammals and use the blood for egg development in reproduction,” Pitts said. “They find their host through attractive odors. As we sweat, we emit volatile orders – or strong smells – which can be very attractive to mosquitoes.” 

Better Mosquito Surveillance and Control 

Pitts and his team hope their research provides valuable information that aids the design of more efficient odor-baited traps for mosquito surveillance or local population control. It also could help with the development of innovative repellents that are more environmentally friendly than current active ingredients to reduce biting.

Since 15 to 20% of all infectious diseases come from mosquitoes, controlling and mitigating mosquito populations remains a global health challenge.

“While there are not as many of these vector diseases in the U.S., there are many areas around the world where you have less infrastructure, less healthcare,” Pitts said. “When people are infected by pathogen-carrying mosquitoes, they are affected dramatically in their ability to work, their ability to earn their incomes is reduced, so that just keeps exacerbating the problem.” 

Research team

In addition to Pitts, the research team included: 

• Heidi Pullmann-Lindsley, doctoral candidate, Arthropod Sensory Biology & Neuroethology Lab, Department of Biology, Baylor University
• Robert Mark Huff, doctoral candidate, Arthropod Sensory Biology & Neuroethology Lab, Department of Biology, Baylor University
• John Boyi, doctoral candidate, Arthropod Sensory Biology & Neuroethology Lab, Department of Biology, Baylor University

Funding

The recent research was funded by two grants from the National Institute of Allergy and Infectious Diseases (No. 1R01AI148300-01A1 and 1R15AI156684-01).

ABOUT JASON PITTS, PH.D.

Jason Pitts, Ph.D., associate professor and director of the Biology of Global Health 4+1 Program,  researches arthropod disease vectors, specifically investigating mosquitoes and other arthropods in behaviors such as host-seeking, nectar feeding and more. His work has been featured in journals such as the Journal of Medical Entomology, Chemical Senses and Insect Biochemistry and Molecular Biology and a book chapter in Sensory Ecology Of Disease Vectors. He works to find ways to address vector disease transmission to lead to a reduction in diseases, like Malaria, Dengue and Zika. 

Pitts sees his students – undergraduates and graduate students – as pivotal in driving research. His graduate students take on lead roles in experimental design, data collection and science communication. They also mentor undergraduates who assist with research projects. These experiences, he said, are invaluable in preparing students for their future careers as postdoctoral fellows, graduate/professional students or academic researchers. 

ABOUT ARTHROPOD SENSORY BIOLOGY & NEUROETHOLOGY LAB

Baylor University’s Arthropod Sensory Biology & Neuroethology Labinvestigates the sensory neuronal basis for behaviors in disease-transmitting arthropods, especially mosquito vectors of arboviruses like Dengue and Zika. Of particular interest are the pathways that contribute to chemical- and temperature-oriented behaviors such as host-seeking, nectar feeding and oviposition site selection. A long-term objective of the lab’s efforts will be to contribute to reductions in human and animal disease transmission at local, national and regional levels by developing novel methods of arthropod surveillance and control that can be integrated into existing pest management programs.

ABOUT BAYLOR UNIVERSITY

Baylor University is a private Christian University and a nationally ranked Research 1 institution. The University provides a vibrant campus community for more than 20,000 students by blending interdisciplinary research with an international reputation for educational excellence and a faculty commitment to teaching and scholarship. Chartered in 1845 by the Republic of Texas through the efforts of Baptist pioneers, Baylor is the oldest continually operating University in Texas. Located in Waco, Baylor welcomes students from all 50 states and more than 100 countries to study a broad range of degrees among its 12 nationally recognized academic divisions.