Meeting Abstract
Flower nectar is more than just water and sugar; it also contains other macro nutrients such as amino acids (AAs) and sometimes fatty acids (FAs). A previous study has suggested that AAs in nectar are not incorporated into eggs by Lepidoptera. Another study showed that carbon from nectar sucrose can be synthesized into non-essential AAs that are then allocated into eggs, whereas carbon from nectar sucrose is not incorporated into essential AAs, suggesting that essential AAs in lepidopteran eggs are derived solely from larval resources. Here we use a new technique of real-time respirometry coupled with real-time stable carbon isotope analysis to test the allocation and metabolic use of essential and non-essential AAs and FAs in the adult nectar diet to reproduction, adult flight muscle and adult metabolic fuel in female Manduca sexta hawk-moths. We used artificial nectar (25% sugar in water) enriched with one of the 13C-labeled essential AAs (leucine, phenylalanine) or non-essential AA (glycine), or one FA (palmitic acid). Our results show that both essential and non-essential AAs in the nectar diet are allocated to eggs, and can still be detected in 1st and 2nd instar larvae as well as in the adult flight muscle. Nectar FAs, however, were not allocated to either offspring or flight muscle, but were oxidized for energy by the adult at rest. Real-time measures show that nectar AAs and FAs are metabolized within minutes after feeding and continues for several hours. The ability to 13C-label specific AAs and FAs and track their metabolism in real time provides an abundance of opportunities to study macronutrient allocation in a diversity of organisms and life history contexts.
