Nectar loads as fuel for collecting nectar and pollen in honeybees: adjustment by sugar concentration

Abstract

When honeybee foragers leave the nest, they receive nectar from nest mates for use as fuel for flight or as binding material to build pollen loads. We examined whether the concentration of nectar carried from the nest changes with the need for sugar. We found that pollen foragers had more-concentrated nectar (61.8 %) than nectar foragers (43.8 %). Further analysis revealed that the sugar concentration of the crop load increased significantly with waggle duration, an indicator of food-source distance, in both groups of foragers. Crop volume also increased with waggle duration. The results support our argument that foragers use concentrated nectar when the need for sugar is high and suggest that they precisely adjust the amount of sugar in the crop by altering both volume and nectar concentrations. We also investigated the impact of the area where foragers receive nectar on the crop load concentration at departure. Although nectar and pollen foragers tend to load nectar at different areas in the nest, area did not have a significant effect on crop load concentration. Departing foragers showed an average of 2.2 momentary (<1 s) begging trophallactic contacts before leaving the nest. They might be rejecting nectar with inappropriate concentrations during these contacts.

Probabilistic assessment of nectar requirements for nectar-foraging honey bees

“…Further, the fraction of trip spent flying, F i , a parameter found in the Agencies' model, is a supposition that is not documented to be based on any real-world data. The proportion of sugar content of nectar during trip i , P i , is also a problematic variable, given the evidence that foragers take concentrated nectar from the hive to fuel part or all of their foraging trips (Harano and Nakamura 2016). In part, the similarity between the predictions of the RARI and RP models can be attributed to the fact that many of the data used to parameterize the models were acquired from the same studies.…”

“…In their proposed exposure assessment, conservatively, it is assumed that there is no degradation or dissipation of the pesticide between application and ingestion. Available data from Harano and Nakamura (2016) demonstrate that foragers acquire fuel for foraging from processed nectar in the hive in advance of departure. The Agencies' model was based on sparse input data and was not subject to a sensitivity analysis.…”

Dietary requirements of individual nectar foragers, and colony-level pollen and nectar consumption: a review to support pesticide exposure assessment for honey bees

“…The main source of energy for foraging trips is a mixture of nectars at variable sugar concentrations (Beutler 1950;Visscher et al 1996;Harano and Nakamura 2016). Some nectar may be acquired from in-coming foragers as part of recruitment communication, but most provisioning comes from hive bees so that the amount and sugar concentration needed can be controlled (Harano and Nakamura 2016).…”

“…The amount and the concentration of sugar taken by foragers before a trip depends on the anticipated total energy required for the round trip (Beutler 1950;Brandstetter et al 1988;Harano and Nakamura 2016). The amount provisioned appears to be based on information from bee dances as well as olfactory and trophallactic signals that communicate the distance, identity, and quality of the food source (Beutler 1950;Harano et al 2013;Harano and Sasaki 2015;Harano and Nakamura 2016). The volume and sugar concentration of fluid provided by the hive bees to the foragers is achieved by mixing nectar at different stages of evaporation, from freshly collected nectar to honey.…”

A Review of Native Wild Bee Nutritional Health

“…Sugar concentrations in nectar may increase foraging distances for bees but has been studied only in honey bees. They have been found to adjust sugar concentrations in their crop depending on foraging distance and foraging task and the energetic requirements [47]. Eusocial insects with nectar stores may be able to use those stores to increase thoracic temperatures and allow for flight in suboptimal temperatures.…”