[Blues' larvae as sugar suppliers for ants]

Abstract

The larvae of the Provence chalk-hill Blue (Lysandra hispana) are visited regularly in the field by ants which lay trails to the caterpillars and recruit new members from their colony. The Blues' larvae secrete a fluid from an abdominal gland which serves as food for the ants. Large larvae are able to release the secretion in intervals of less than 2 min for at least 1 h. In addition to water, the main constituents of the secretion are fructose, sucrose, trehalose, and glucose-the total concentration of these sugars being more than 10% (13.1% and 18.7%). The haemolymph of the caterpillars, however, has a total carbohydrate content of only about 2%. Other than minor quantities of protein, only one amino acid could be detected in the secretion. The relationship between sugar-donating Lycaenid larvae and ants is discussed and interpreted as symbiosis.