Appetite is correlated with octopamine and hemolymph sugar levels in forager honeybees
- 152 Downloads
Insects have rapidly changing energy demands, so they primarily rely on hemolymph and other carbohydrates to carry out life activities. However, how gustatory responsiveness and hemolymph sugar levels coordinate with one another to maintain energetic homeostasis in insects remains largely unknown for the highly social honeybee that goes through large physiological and behavioral changes. The potential role of biogenic amines and neuropeptides in the connection between the regulation of appetite and fluctuating sugar levels in the hemolymph, due to starvation, as the bee ages, was investigated. The largest appetite increase due to the starvation treatment was within the forager age class and this corresponded with an increase in octopamine levels in the brain along with a decline in hemolymph sugar levels. Adipokinetic hormone (AKH) was found in very small quantities in the brain and there were no significant changes in response to starvation treatment. Our findings suggest that the particularly dynamic levels of hemolymph sugar levels may serve as a monitor of the forager honeybee energetic state. Therefore, there may be a pathway in forager bees via octopamine responsible for their precise precipitous regulation of appetite, but to determine cause and effect relationships further investigation is needed.
KeywordsStarvation Aging Biogenic amines Trehalose Hemolymph
Gas chromatography–mass spectrometry
Generalized linear model
Gustatory response score
High-performance liquid chromatography
Multivariate analysis of variance
- PER assay
Proboscis extension response assay
We thank Mariann Pü, Brian Shields, Rebecca Zhou, Victor Le, and Elizabeth Eppley for assistance with hemolymph extractions, brain dissections, and data collection. The authors would also like to thank Dr. Kathleen Howard for providing access to her lyophilizer and assisting with its use. This work was supported by an Alexander von Humboldt Foundation Fellowship award to CM, a Swarthmore College Surdna Summer Research Fellowship to KC, and a Howard Hughes Medical Institute Fellowship to NP.
The datasets generated during the current study are available in the Open Science Framework repository, https://osf.io/h4c6e/.
Compliance with ethical standards
All honeybees were handled humanely in accordance with current ethical standards. Special ethical approval is not required to carry out this study.
Conflict of interest
The authors declare that there are no competing interests.
- Evans JD, Schwarz RS, Chen YP, Budge G, Cornman RS, Rua P, Miranda J, Foret S, Foster L, Gauthier L, Genersch E, Gisder S, Jarosch A, Kucharski R, Lopez D, Lun CM, Moritz RFA, Maleszka R, Muñoz I, Pinto MA (2013) Coloss beebook volume I: standard methods for Apis mellifera research, 1st edn. Ibra Publications, Bristol, p 636Google Scholar
- Klowden M (2013) Physiological systems in insects, 3rd edn. Academic Press, New York, p 677Google Scholar
- Lee GH, Park JH (2004) Hemolymph sugar homeostasis and starvation-induced hyperactivity affected by genetic manipulations of the adipokinetic hormone-encoding gene in Drosophila melanogaster. Genetics 167(1):311–323. https://doi.org/10.1534/genetics.167.1.311 CrossRefPubMedPubMedCentralGoogle Scholar
- Linn CE, Roelofs WL (1993) Levels of biogenic amines and peptides in individual corn earworm moths, Helicoverpa zea, using high performance liquid chromatography with electrochemical detection. Insect Biochem Mol Biol 23(3):367–373. https://doi.org/10.1016/0965-1748(93)90020-S CrossRefPubMedGoogle Scholar
- Nisimura T, Seto A, Nakamura K, Miyama M, Nagao T, Tamotsu S, Yamaoka R, Ozaki M (2005) Experiential effects of appetitive and nonappetitive odors on feeding behavior in the blowfly, Phormia regina: a putative role for tyramine in appetite regulation. J Neurosci 25:7507–7516CrossRefPubMedGoogle Scholar