Sucrose‐dependent increase in oligosaccharide production and associated glycosidase activities in the potato aphid Macrosiphum euphorbiae (Thomas)

Osmotic stress due to high sucrose concentration was imposed on the potato aphid, Macrosiphum euphorbiae (Thomas), in an artificial diet situation. Thin layer chromatography resolved melezitose and six additional honeydew oligosaccharides. Significantly higher levels of these oligosaccharides were recovered from the honeydew of this species in response to feeding on increased dietary sucrose concentrations, pointing to an osmoregulatory response. In addition, carbohydrase activities from the potato aphid were described. A degree of specificity toward hydrolysis of the sucrose substrate over other α‐glucosyl sugars was demonstrated. Also, sucrose was optimal for the formation of the oligosaccharides. A strong α‐galactosidase activity was found and transgalactosylation ability was indicated. These major trends in carbohydrase activity were also found in the foxglove aphid, Acyrthosiphon solani (Kaltenbach), and the oleander aphid, Aphis nerii Fonscolombe.