Antennal Lobe Comparison in Anthropophagic and Zoophilic Mosquitoes

Abstract

Mosquitos are one of the most dangerous vectors of disease in tropical areas. They are particularly adept at spreading malaria and dengue fever, two major public health threats. As our climate continues to warm and mosquitoes breeding ranges extend, it will become more vital to understand effective solutions that work to curb the mosquito population and their attraction to humans. Current methods target the mosquito olfactory systems by interfering at some level of mosquito host detection. One population of mosquitoes known as Aedes aegypti aegypti have diverged from their zoophilic ancestors by laying eggs in areas with high human population. Over time, they have appeared to take advantage of the abundance of human hosts around them. Previous studies have identified odorant receptors that respond to human volatiles and are more highly expressed in human preferring mosquitos (McBride et al., 2014). This connects to other stud-ies that have found larger antennal lobe glomeruli connected to neurons that express receptors used for detecting favorable odorants. This lead me to hypoth-esize that human preferring mosquitoes will have larger glomeruli if the higher expression in receptors responsive to human odor has led to an increase in olfactory sensory neurons. I stained and imaged the brains of two strains of mosquitoes, one that is human preferring and one that is a generalist. Contrary to my hypothesis, I only found glomeruli that were significantly smaller in the hu-man-preferring mosquito. Also, although the generalist mosquitoes have smaller bodies, the size of their antennal lobe was larger on average. It appears that human preferring mosquitoes may have lost the need to sense a diverse group of hosts, and this is reflected in their neuronal architecture. My results have provided an initial glimpse of antennal lobe targets for future studies while updating the Aedes antennal lobe model. My work represents a small part of the complete functional picture of mosquito olfactory circuits that can be used to more suc-cessfully design mosquito deterrents.