Amino Acids in Artificial Nectar: Feeding Preferences of the Flesh Fly Sarcophaga bullata

Abstract

We presented flesh flies (Sarcophaga bullata) with a choice between artificial nectar (10 % sucrose) and artificial nectar containing one of 20 amino acids. Flies tested immediately after eclosion did not consistently prefer either solution. Flies maintained on a sugar only diet for 8 days preferred the amino acid solution in six of 19 trials. This preference was particularly marked in the case of histidine. Flies maintained on a liver only 1iet suffered high mortality, but preferred the amino acid solution in four of 10 trials, and the sugar solution in one trial. Flies avoided solutions containing histidine and lysine, but preferred glycine, at concentrations much higher than those normally found in nectar. Thus flesh flies preferred solutions containing some amino acids at concentrations comparable to those occurring in floral nectar. We suggest that such preferences are likely to have selected for the high amino acid contents in the nectars of some fly-pollinated flowers, and form a basis for at least some correlations between pollination syndrome and amino acid levels in nectar.