Effects of Carbon Dioxide and Oxygen on Heart Contraction Rate of Navel Orangeworm, Amyelois transitella (Walker) (Lepidoptera: Pyralidae)

Fifth instars of navel orangeworm, Amyelois transitella (Walker), were exposed to controlled atmospheres to measure the effects of elevated carbon dioxide and reduced oxygen concentrations and temperature on heart contraction rate. The atmospheres contained varying concentrations of oxygen, carbon dioxide and nitrogen and were produced by blending air with carbon dioxide or nitrogen. Carbon dioxide concentrations between 50% and 99.5% caused immediate cardiac arrest in A. transitella, but the heart contractions restarted after a transient delay. The length of this delay was directly proportional to the concentration of carbon dioxide, and contraction rate following restart was inversely proportional to the concentration of carbon dioxide. Cardiac arrest was irreversible in 100% carbon dioxide. Heart contraction rate of A. transitella was directly proportional to both temperature and oxygen content of the atmosphere through a range of 15°C to 50°C.