Effects of caste on critical PO2 and flight metabolic rate in the bumble bee, Bombus impatiens

Authors: WALTER, RIKKI - North Dakota State University; DAVIS, GEORGIA - North Dakota State University; Rinehart, Joe; GREENLEE, KENDRA - North Dakota State University

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/24/2019
Publication Date: 11/17/2019
Citation: Walter, R., Davis, G., Rinehart, J.P., Greenlee, K.J. 2019. Effects of caste on critical PO2 and flight metabolic rate in the bumble bee, Bombus impatiens [abstract]. Entomological Society of America Annual Meeting. Nov. 17-20, 2019. St. Louis, MO. Poster No. D3102.

Interpretive Summary:

Technical Abstract: Bombus impatiens are a social bumble bee species used in commercial pollination. Bumble bee queens overwinter underground. Underground burrows may be a hypoxic (low oxygen) environment, which could be detrimental to bees. Although many insects are tolerant of hypoxia, this is not known for B. impatiens. The tracheal system of B. impatiens workers is positively correlated with body size. However, queens have tracheal systems that are much smaller than would be expected for their large body size, suggesting that overwintering queens may have lower hypoxia tolerance than workers. To determine how queens and workers tolerate low oxygen, we measured the critical PO2. The critical PO2 is the oxygen level below which metabolic rate cannot be maintained. Critical PO2 was measured by exposing bees to decreasing levels of oxygen via respirometry during rest; flight metabolic rate was measured at different oxygen levels individually. Queens and workers did not have significantly different critical PO2 values either at rest or during flight. Together, these data suggest that the queens’ small tracheal system volume may not negatively affect their ability to tolerate hypoxia. Knowing that bumble bees are tolerant of hypoxia may help to use this in commercial storage, as has been successful in other bee species.