Sucrose Triggers Honeydew Preference in the Ghost Ant, Tapinoma melanocephalum (Hymenoptera: Formicidae).

Honeydew produced by hemipterans mediates mutualistic interactions between ants and hemipterans. Previous studies demonstrated that the mealybug Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) and the aphid Myzus persicae (Sulzer) (Hemiptera: Aphididae) produce abundant honeydew and attract a large number of tending ants. Ghost ants, Tapinoma melanocephalum (F.) (Hymenoptera: Formicidae), show a significant preference for mealybug honeydew over aphid honeydew. Although many studies have indicated that the honeydew produced by hemipterans plays an important role in ant-hemipteran interactions, we know little about what triggers ants' foraging preferences. Our results showed that the honeydew produced by both mealybugs and aphids contained fructose, sucrose, trehalose, melezitose, raffinose, and rhamnose. There were no significant difference in the concentrations of the various sugars between mealybugs and aphids, except sucrose. Xylose was present only in mealybug honeydew, and glucose was present only in aphid honeydew. We also found no substantial difference in the excretion frequency and the total weight of honeydew produced per 24 h between mealybugs and aphids. Ghost ants preferred sucrose. In addition, attractiveness of sucrose solutions increased significantly with increasing concentration. These results suggest that sucrose is the trigger for ghost ants' honeydew preference. [ABSTRACT FROM AUTHOR]