Fatty acid and carbon isotopic data for: Use of essential vs. non-essential fatty acids during flight in monarch butterflies: Implications for the importance of nectaring during migration

Many insect species are migratory, but migration is energetically costly,
leading to a tradeoff between migration and subsequent
reproduction. Of importance to the allocation of resources to
migration and reproduction is the relative use of essential and
non-essential fatty acids. How different ecological conditions
experienced by individuals affect the differential allocation of nutrients
has not been well explored, especially in insects. Our goal was
to evaluate how reproductive (summer) and migratory (fall) rearing
conditions affect the source and allocation patterns of fatty acids used
during experimental flights (0-6h) in monarch butterflies (Danaus
plexippus L.). We used larval and adult diets manipulated
isotopically (δ13C) and chromatographic analyses to determine fatty acid
composition and source in the fat body. C4 vs. C3 carbohydrate
feeding increased the δ13C value of lipids in monarchs (-31.2 vs -22.1‰)
and increased total fatty acid concentrations reflecting lipid synthesis
during adult feeding. Fuel use during flight differed with
essential fatty acids being more conserved in fall vs. summer conditions
(21% vs 32% loss respectively) indicating that the environmental cues
responsible for the onset of migration result in physiological changes
that modify lipid use. Frequency of stopovers for nectar and
nectar quality available during migration will influence the capacity of
monarchs to conserve essential fatty acids up to and through migration and
overwinter period.