Adjustment of nectar loading in honeybee foragers

Abstract

Honeybee foragers often return to the nest before filling their crop with nectar. A series of studies conducted in the 1980's considered the mass-dependent metabolic cost of nectar load and suggested that their partial filling is a strategy to optimize the energetic efficiency of foraging. However, some researchers did not agree with this idea and, instead, proposed an alternative hypothesis arguing promotion of communication concerning other potential food sources by frequent returning to the nest. Recent studies revealed that foragers also show a similar adjustment in nectar loading when they leave the nest. The volume and concentration of nectar loaded in the nest as fuel for flight and material for pollen load can be influenced by several factors such as the distance to food source, informational state concerning food source and certainty of foraging. This article reviews studies concerning the two types of nectar adjustment and discusses their underlying mechanisms and function.