Bees Pack More Food If Rewards Are Uncertain

When faced with uncertain rewards from their foraging journeys, honey bees reduce the risk of starvation by carrying more food with them.

AsianScientist (Nov. 16, 2015) – In a study published in Scientific Reports, researchers have found that honey bees (Apis cerana) prepare for uncertain journeys by bringing along more food.

According to risk sensitive foraging theory, animals forage in ways that not only maximize net caloric intake, but also minimize their probability of starvation (i.e. minimum food requirement). Previous studies have shown that honey bee foragers prefer constant rewards over variable rewards.

The amount of food (used as ‘fuel load’) taken by a foraging bee on her outward journey may be an objective measure of her perception of the riskiness of the foraging trip she is embarking on. A team of researchers led by Professor Tan Ken of the Xishuangbanna Tropical Botanical Garden (XTBG) studied the risk sensitivity of honey bees by studying the risk mitigation strategy as they travel between their nest and a food source.

The researchers trained honey bee foragers to a feeder located 1.2 km from each of four colonies. They hypothesized that an individual bee that perceived her foraging trip as being risk should carry more fuel as she perceived that the energy budget of the trip may place her at risk of starvation before she can return to the nest.

They found that crop concentration and volume were influenced by feeder variability. When a feeder offered variable rewards, honey bees carried 12.7 percent greater volume of fuel than that they carried when a feeder offered constant reward.

The study showed that when honey bee foragers were faced with variable rewards at a feeding site, they reduced the risk by increasing the volume, and possibly the concentration of the fuel load they carried. Fuel load volume seemed to provide a direct measure of a forager’s perception of the riskiness of a foraging trip, and may provide a novel experimental tool for determining how foragers rank riskiness.

The article can be found at: Tan et al. (2015) Individual Honey Bee (Apis cerana) Foragers Adjust Their Fuel Load to Match Variability in Forage Reward.


Source: Chinese Academy of Sciences.
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