My research has shown that a comprehensive understanding of animal behavior requires studying animals in great detail in as naturalistic but highly controlled environments as possible. By leveraging field work, wet-lab work, genetic tools, engineering models, and theoretical concepts, my research on insect olfaction and search behavior already constitutes an interdisciplinary career bridging the gap between neuroscience, ecology, engineering, and theory.

The effect of neonicotinoid pesticides on insect olfactory processing

The persistence of wild pollinators is critical to the long-term security of our food supply, but many populations show alarming declines, including one-third of bumblebee species categorized as threatened. In this project, we explore the interactions between two major factors that impact bee health: exposure to neonicotinoid pesticides and nutrition. Combining behavioral and electrophysiological techniques, we will ask how these pesticides alter bees’ abilities to evaluate the composition of their food (nectar and pollen) via smell and taste. Our results, so far, demonstrated that imidacloprid–a commonly used neonicotinoid pesticide–exposure significantly reduced the activity of a single focal olfactory neuron and delayed the return to baseline activity of the whole antenna. Insects exposed to imidacloprid had a greater relative preference for ethanol-laced pineapple juice than control flies, demonstrating that neuronal shifts induced by imidacloprid are associated with changes in relative preference.

Collaborator: Dr. Anne Leonard (Dept. of Biology)

Funding: USDA-NIFA (Leonard (PI), Mathew (Co-PI); $431,899 (2018-2021)

Publication: Tatarko A, Leonard A, and Mathew D. A neonicotinoid pesticide alters Drosophila olfactory processing (2023) under review at Scientific Reports. 

Novel strategies to target key mosquito host-seeking factors governing human host preference

Long-lasting insecticide-treated bed nets and indoor residual spraying have reduced malaria transmission by targeting mosquitoes with habits highly tied to feeding on humans (primarily Anopheles gambiae). However, vectors with a wider host feeding range and less human-centered behavioral traits are scarcely impacted by these strategies and remain a barrier to complete malaria elimination. Novel strategies are needed for these vectors, and one of these is to drive modified traits that govern host preference into the vector population so that these vectors no longer seek or actively avoid humans. Therefore, the goal of this project is to modify mosquito odorant receptors in an effort to generate human-avoiding mosquitos. The specific goal is to identify potential human-specific odorant receptors in Anopheles stephensi (a mosquito species endemic to south-east Asia), confirm candidate odorant receptor specificity, and finally modify mosquito odorant receptor genes and test transformant receptivity to humans versus other animals. So far, we identified and characterized an An. stephensi odor receptor AsOr8. The responsiveness of AsOr8 to odorants was highly similar to the An. gambiae Or8 (AgOr8) with subtle differences. Subtle differences in receptor sensitivity to specific odorants may provide clues to species- or strain-specific approaches to host-seeking and host selection.

Collaborator: Dr. Andrew Nuss (Dept. of Animal Nutrition & Veterinary Science)

Funding: DARPA (Nuss (PI), Mathew (Co-PI); $500,000 (2017-2020))

Publication: Speth Z, Kaur G, Mazolewski D, Sisomphou R, Sia DDC, Pooraiiouby R, Vasquez-Gross H, Peterit J, Gulia-Nuss M, Mathew D, Nuss AB. Characterization of Anopheles stephensi Odorant Receptor 8, an abundant component of the mouthpart chemosensory transcriptome (2021) Insects 12(7):593