Grant: Discovery Grants Program - Individual

Canadians are no strangers to mosquitoes - there are more than 80 species of these blood-sucking insects found in our country. Insect repellents represent our first and most important line of defense against mosquitoes, with a global market forecasted to exceed CAD$10 billion annually by 2031. Applied topically to the skin and/or clothing, repellents deter mosquitoes from approaching and/or settling, and ultimately provide temporary protection from bites. Although a wide variety of insect repellents are commercially available, the vast majority are formulated from a single active ingredient - DEET. Developed by the U.S. military nearly eight decades ago, Health Canada has approved the oily synthetic substance as a safe and effective mosquito repellent at concentrations up to 30%. Despite its rampant use, we know surprisingly little about how DEET actually works. Its repellency effect appears to have a strong genetic component, but much more research is needed to understand the mechanisms by which this occurs. Evidence is also accumulating that indicates continued widespread use of repellents formulated from only one or a few active ingredients significantly increases the risk of mosquito populations to develop "insensitivity", that is, the diminished effect of repellents in preventing mosquitoes from taking a human blood meal. The proposed research therefore aims to identify and validate the function of behaviourally relevant genes that confer mosquito insensitivity to DEET. We will also determine how common DEET insensitivity is among natural populations of Canadian mosquitoes. To do this research, my laboratory has selected DEET-insensitive and DEET-sensitive populations of Culex tarsalis, a mosquito pest species commonly found in Canada. The proposed research is "low risk and high reward". As I have extensive experience and expertise in the mosquito species and all of the methodologies proposed, minimal technical hurdles are expected. The work is original and innovative, as no other studies have undertaken the proposed cutting-edge combinational genomics approach or integrated both insect smell and taste into the same DEET experiments. Further, no studies have determined how prevalent DEET insensitivity is in Canadian mosquitoes. The research outcomes represent a huge advancement for the field and are impactful because they 1) will allow for the rational development of novel, effective and safe repellents; 2) could lead to completely novel control strategies that alter or block key mosquito behaviours in nature; and 3) will provide insights into how Canadian mosquitoes may evolve in response to spatial repellents, thus allowing for the formulation, distribution and monitoring strategies that minimize the chances of insensitivity spreading in natural populations. The proposed research will train several highly qualified personnel, provide extensive outreach opportunities and result in publications in high-quality, peer-reviewed journals.