Colony foraging allocation is finely tuned to food distance and sweetness even close to a bee colony

摘要

Social bee colonies can allocate their foraging resources over a large spatial scale, but how they allocate foraging on a small scale near the colony is unclear and can have implications for understanding colony decision-making and the pollination services provided. Using a mass-foraging stingless bee, Scaptotrigona pectoralis (Dalla Torre) (Hymenoptera: Apidae: Meliponini), we show that colonies will forage near their nests and allocate their foraging labor on a very fine spatial scale at an array of food sources placed close to the colony. We counted the foragers that a colony allocated to each of nine feeders containing 1.0, 1.5, or 2.0M sucrose solution [31, 43, and 55% sucrose (wt/wt), respectively] at distances of 10, 15, and 20m from the nest. A significantly greater number of foragers (2.6-5.3 fold greater) visited feeders placed 10 vs. 20m away from the colony. Foraging allocation also corresponded to food quality. At the 10-m feeders, 4.9-fold more foragers visited 2.0M as compared to 1.0M sucrose feeders. Colony forager allocation thus responded to both differences in food distance and quality even when the travel cost was negligible compared to normal colony foraging distances (10 m vs. an estimated 800-1710m). For a nearby floral patch, this could result in unequal floral visitation and pollination.