Publication Date


Document Type


Committee Members

David Goldstein (Committee Member), Lynn Hatrzler (Advisor), Barbara Hull (Committee Member)

Degree Name

Master of Science (MS)


Breathing in most insects is controlled through a negative feedback loop consisting of signals (O2, CO2, pH), sensors (chemoreceptors), integrators (neural ganglia), and effectors (spiracles over tracheae). I hypothesized that mealworms and their adult counterparts Darkling beetles, Tenebrio molitor, can sense anoxic and hyperoxic environments and preferentially avoid these environments. I also hypothesize that mealworms are attracted to hypercarbia while Darkling beetles avoid hypercarbia. I constructed a test arena to create an O2 or CO2 gradient. Velocity, total distance traveled, and time spent in each area of the O2 or CO2 gradients were compared for 0%, 21% and 100% O2, and 0.04%, 1% and 5% CO2. Air flow alone decreased velocity and distance traveled by Darkling beetles compared to the no air flow protocol (p<0.05, one-way ANOVA). Darkling beetles spent more time in 21% O2 than in 100% O2 than in 0% O2 (p<0.05, one-way ANOVA). There was no evidence that the Darkling beetles preferred any portion of the CO2 gradient over another. I infer from my data that Darkling beetles prefer to avoid anoxic and to a lesser extent hyperoxic environments. Mealworms spent more time in anoxia than normoxia (p<0.05, one-way ANOVA). Mealworms spent more time in 5% CO2 than 1% CO2 and 0.04% CO2 (p<0.05, one-way ANOVA). I infer from my data that mealworms prefer anoxia over normoxia and are attracted to hypercarbia. Darkling beetles and mealworms are able to sense their gaseous environments and appear to avoid environments that may be insalubrious to them.

Page Count


Department or Program

Department of Biological Sciences

Year Degree Awarded


Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

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