Date of Award

May 2020

Document Type


Degree Name

Master of Science (MS)


Biological Sciences

Committee Member

Matthew Turnbull

Committee Member

Francis Reay-Jones

Committee Member

Andrew Mount


The midgut is the main point of interaction between a lepidopteran larva and its environment, so understanding how the gut functions is important not just for understanding gut physiology but also the ecology and evolution of these organism. The midgut of these larvae is a fascinating system in which to study developmental, regeneration, and immune physiology. The midgut can exhibit up to a 200-fold increase in size through ontogeny, primarily through addition of new cells at molt, while damaged cells are replaced throughout intermolt periods. In the midgut of lepidopteran larvae, mature cells are produced from stem cells, localized in pockets underneath the mature cells.

Several regulators of stem cell activity are known, but no integrative model has been established. In numerous animal taxa, bioelectric phenomena regulate stem cell activity, including duplication and differentiation. Here, we are using the tobacco budworm, Heliothis virescens, to characterize bioelectric patterns in the lepidopteran larval gut. We adapted a method to isolate stem and mature gut cells from physiologically staged fourth instar larvae and assay their membrane potential. As bioelectric phenomena are highly important in gut physiology, our results may be useful in regulating lepidopteran pests. Finally, our results could help further our understanding of how physiology and an organism’s environment interact.



To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.