THE MECHANISMS REGULATING CO2 NARCOSIS IN BOMBUS IMPATIENS
Open Access
- Author:
- Cressman, Anna
- Graduate Program:
- Entomology
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- October 20, 2022
- Committee Members:
- Gary Felton, Program Head/Chair
Etya Amsalem, Thesis Advisor/Co-Advisor
Rudolf Johannes Schilder, Committee Member
Heather M Hines, Committee Member - Keywords:
- carbon dioxide
insects
reproduction
metabolism
anesthesia - Abstract:
- Carbon dioxide (CO2) is commonly used to immobilize insects and to induce reproduction in bees. However, despite its wide use and potential off-target impacts, its underlying mechanisms are not fully understood. Here I used Bombus impatiens to examine whether CO2 impacts are mediated by anoxia and whether these mechanisms differ between female castes or following mating. I examined the behavior, physiology, and gene expression of workers, mated and virgin queens following exposure to anoxia (lack of oxygen), hypoxia (reduced oxygen levels), full and partial hypercapnia (elevated carbon dioxide levels), and control. Hypercapnia and anoxia caused immobilization, but only hypercapnia resulted in behavioral, physiological, and molecular impacts in bees. Recovery from hypercapnia resulted in increased abdominal contractions and took longer in queens. Additionally, hypercapnia activated queens’- but inhibited workers’ ovaries in a dose-dependent manner and caused a depletion of fat-body lipids in both. All responses of hypercapnia were weaker following mating in queens. Analysis of gene expression related to hypoxia and hypercapnia supported the physiological findings in queens, demonstrating that the overall impacts of CO2, excluding virgin queen ovaries, were unique and were not induced by anoxia. This study contributes to our understanding of the impacts and the mechanistic basis of CO2 narcosis in insects and its impacts on bees’ physiology.