Can Inachis io detect nectar amino acids at low concentrations?

This study tested Inachis io L. butterflies' preference for nectar amino acids using a dilution series (100, 75, 50, 25 and 0%) of the amino acid concentration of Lantana camara to determine how sensitive the insects are to low concentrations of amino acids, such as those found in the flowers of many plant species. Female butterflies clearly detected and preferred nectar amino acids even at the lowest concentration offered, whereas males did not. These results further support the hypothesis that female butterflies detect and select for nectar with amino acids at levels found in the field.