Field and Laboratory Approaches to Understanding Gas Exchange in Solenopsis invicta Nests Restricted; Files Only

Abstract

Much of life on Earth lives in soil. Many animals that construct subterranean

nests use passive or active airflow mechanisms to be able to live underground. Fire

ants (Solenopsis invicta) build complex nest structures that go up to two meters

underground. It is not well understood how they are able to breathe within their nests,

and we do not know the mechanisms they utilize to allow for air exchange. Through

field and laboratory measurements on fire ants, we can to begin to understand their

possible oxygen requirements. From the field measurements, we found a range of

CO2 production rates between 0.4 ± 0.1 and 3.1 ± 0.3μL CO2/s coming from a nest

of volume 617mL. This range, we believe, may be due to the effects of temperature

or circadian rhythm. The laboratory measurements, which recorded the rate of fire

ants’ oxygen consumption and carbon dioxide production, we found the mean CO2

production rate to be 516 ± 24μLh−1g−1 and the mean O2 consumption rate to be

612 ± 5μLh−1g−1 at early times. These findings have some agreement with published

values. Furthermore, we found that fire ants are able to survive in hypoxic and

hypercarbic conditions with oxygen levels as low as 11.84 ± 0.01% and carbon dioxide

levels up to 6.61 ± 0.36% for at least 200hrs. We also found that the possible minimum

amount of oxygen fire ants can live in is 0.78 ± 0.01%.

Table of Contents

1 Introduction 1

1.1 Air Exchange in Subterranean Nests . . . . . . . . . . . . . . . . . . 1

1.2 Fire Ants and Their Nests . . . . . . . . . . . . . . . . . . . . . . . . 4

1.3 Ants Breathing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

1.4 Insects, Oxygen, and Carbon Dioxide . . . . . . . . . . . . . . . . . . 8

1.5 Goals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2 Field Experiments 11

2.1 Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2.1.1 Measurements of Field Data . . . . . . . . . . . . . . . . . . . 11

2.1.2 Quantification of Nest Volume . . . . . . . . . . . . . . . . . . 13

2.2 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3 Lab Experiments 19

3.1 Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

3.1.1 Collecting Fire Ants and Initial Conditions . . . . . . . . . . . 19

3.1.2 The Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

3.2 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

4 Comparing and Integrating Results 28

5 Conclusions and Future Directions 30

5.1 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

5.2 Limitations and Future Directions . . . . . . . . . . . . . . . . . . . . 31

Appendix A Other Field Data Plots 34

Appendix B Other Lab Data Plots 40

Bibliography 42

About this Honors Thesis

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School	Emory College
Department	Physics
Degree	B.S.
Submission	Honors Thesis
Language	English
Research Field	Biophysics, General Physics, General
Keyword	respiration fire ants nest ventilation
Committee Chair / Thesis Advisor	Jennifer Rieser, Emory University
Committee Members	Eri Saikawa, Emory University Alexander Avramov, Emory University

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