title: Pollen feeding in the butterfly Heliconius charitonia: isotopic evidence for essential amino acid transfer from pollen to eggs.
abstract: Heliconius and Laparus butterflies exhibit a unique pollen-collecting behaviour that enhances lifespan and fecundity. The specific nutritional contribution of pollen, however, had not been previously demonstrated. We used stable isotope variation to trace the carbon flow into eggs from corn pollen provided experimentally to ovipositing female Heliconius charitonia, and to evaluate the use of isotopically contrasting nectar sugars in egg amino acids. The delta(13)C of individual amino acids from pollen, larval host plant and the eggs from experimental butterflies was measured with gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS), to evaluate amino acid transfer. The delta(13)C of egg essential amino acids indicated a transfer of essential amino acids from pollen to butterfly eggs. However, the delta(13)C of non-essential amino acids reflected the isotopic composition of the artificial nectar, indicating that H. charitonia synthesizes non-essential amino acids from dietary sugars. This, to our knowledge, is the first direct demonstration of amino acid transfer from pollen to butterfly eggs, and suggests that essential amino acids in particular are a key resource for extending lifespan and fecundity in Heliconius butterflies.
authors.affiliation: Center for Conservation Biology, Department of Biology, Stanford University, Stanford, CA 94305, USA. dobrien@wellesley.edu
authors.forename: Diane M
authors.initials: DM
authors.lastname: O'Brien
authors.forename: Carol L
authors.initials: CL
authors.lastname: Boggs
authors.forename: Marilyn L
authors.initials: ML
authors.lastname: Fogel
mesh_terms: D000601:Amino Acids, Essential / Q000493:pharmacokinetics*; D000704:Analysis of Variance; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002080:Butterflies / Q000378:metabolism* / Q000502:physiology*; D002247:Carbon Isotopes; D003364:Costa Rica; D005247:Feeding Behavior / Q000502:physiology; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D008800:Mexico; D009587:Nitrogen Isotopes; D010063:Ovum / Q000737:chemistry*; D011058:Pollen / Q000737:chemistry*; D003313:Zea mays
chemical_list: D000601:Amino Acids, Essential; D002247:Carbon Isotopes; D009587:Nitrogen Isotopes