I am interested in studying biological questions that tie together ecology, engineering, and neuroscience. At the intersection of these topics is animal behavior, and with insects comprising over a third of all animal biomass, I have made them my focus. Another reason I have focused on various insects is because olfaction is an important sensory modality for most insects as it is required for locating food sources and mates and for avoiding predators. Thus, apart from the main focus of my lab on Drosophila (fruit-fly) olfaction, we have also focused on olfaction in other insects like mosquitos, bumble bees, and butterflies. Fortunately, because of the inclusive and collaborative environment across the UNR campus, I have developed productive collaborations with colleagues in the Biology, ANVS, Philosophy, and Mechanical Engineering departments. Some of these collaborations have already resulted in extramural grant funding and manuscripts under review/preparation.
Explore how neonicotinoid pesticides affect the sensory mechanisms underlying wild bee nutrition
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. We will 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. Some of the highest exposure to neonicotinoids occurs via plants growing in agricultural margins and backyards; we will determine whether this inadvertent dosing of non-target plants alters their reward chemistry and broader ecological interactions. We will address some basic questions that might help mitigate possible routes of exposure for native bees.
Collaborator: Dr. Anne Leonard (Dept. of Biology)
Funding: USDA-NIFA (Leonard (PI), Mathew (Co-PI); $431,899 (2018-2021)
Develop strategies to target key mosquito host-seeking factors governing human host preference
Long-lasting insecticide treated bed nets in conjunction with 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. A greater understanding of mosquito odorant binding proteins and their specific role in human host selection over other vertebrate hosts is required for this. The goal of this project is to modify mosquito odorant receptors in an effort to generate human-avoiding mosquitos. To do so, we will 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.
Collaborator: Dr. Andrew Nuss (Dept. of Animal Nutrition & Veterinary Science)
Funding: DARPA (Nuss (PI), Mathew (Co-PI); $500,000 (2017-2020))
Manuscripts under preparation:
- Gurlaz K, Sisomphou R, Mazolewski D, Speth Z, Siao D, Pooraiiouby R, Mathew D, Nuss AB “Antennal transcriptome profiles in Anopheles stephensi: host-seeking females, blood-fed females, and males”
- Yim W, Ponce-Alvarez D, Mathew D, Nuss AB “Evolution rates of odorant receptor genes in anthropophilic Anophelines”
Investigate ecological and physiological factors that determine oviposition preference
plays an important role as insects navigate to appropriate resources for food and reproduction. The olfactory environment of herbivorous insects can show large spatial and temporal variability. It has been suggested that prior experience influences adult preference for oviposition sites. Variations in adult preference for oviposition sites are common. However, the causes leading to these variations are not understood. Moreover, an experience based learning process can be costly to the individual as it increases investment of energy resources into neural tissue at the expense of important fitness-related traits, such as reproduction and immunity. This collaboration seeks to fully understand how prior host plant experience modulates preference for oviposition sites in adult Lepidoptera.
Collaborators: Dr. Angela Smilanich (Dept. of Biology), Dr. Lora Robinson (Dept. of Biology)
Optogenetic control of a Flying Fly’s sense of smell
All moving organisms exhibit search behavior in order to find food, mates, or places to raise their young. These behaviors often require extended decision making sequences in response to variable stimuli with complex process represents a critical step towards bridging the gap between sensory systems, neural processing, behavior, ecology, and evolution. A classic example of natural search behavior is that of insects following turbulent odor plumes towards their source. However, because neither odors nor the turbulent structures that carry them are visible to the naked eye, many open questions still remain. To answer these questions, we will build the technology and methodology that will make it possible to separate the olfactory experience from the wind, making it possible to independently control these two stimuli to systematically study how they are integrated in the brain. We will do this using a combination of real-time 3D tracking of freely-flying fruit flies and optogenetics, which makes it possible to remotely activate small populations of olfactory neurons. These new methods will enable experiments that provide transformative insight into how insects navigate complex multi-sensory environments.
Collaborator: Dr. Floris van Breugel (Dept. of Mechanical Engineering)
Overall, 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 inter-disciplinary career bridging the gap between neuroscience, ecology, engineering, and theory, a key emerging frontier in systems biology.