Gil Mariana, De Marco Rodrigo J
Free University of Berlin, Department of Biology/Chemistry/Pharmacy, Institute of Biology - Neurobiology, Koenigin-Luise-Strasse 28/30, 14195 Berlin, Germany.
J Exp Biol. 2009 Sep 1;212(17):2830-4. doi: 10.1242/jeb.032623.
In this study, we asked whether honeybees learn the sign and magnitude of variations in the level of reward. We designed an experiment in which bees first had to forage on a three-flower patch offering variable reward levels, and then search for food at the site in the absence of reward and after a long foraging pause. At the time of training, we presented the bees with a decrease in reward level or, instead, with either a small or a large increase in reward level. Testing took place as soon as they visited the patch on the day following training, when we measured the bees' food-searching behaviours. We found that the bees that had experienced increasing reward levels searched for food more persistently than the bees that had experienced decreasing reward levels, and that the bees that had experienced a large increase in reward level searched for food more persistently than the bees that had experienced a small increase in reward level. Because these differences at the time of testing cannot be accounted for by the bees' previous crop loads and food-intake rates, our results unambiguously demonstrate that honeybees adjust their investment of time/energy during foraging in relation to both the sign and the magnitude of past variations in the level of reward. It is likely that such variations lead to the formation of reward expectations enhancing a forager's reliance on a feeding site. Ultimately, this would make it more likely for honeybees to find food when forage is scarce.
在本研究中，我们探究了蜜蜂是否能学习奖励水平变化的信号及幅度。我们设计了一项实验，让蜜蜂首先在一个提供不同奖励水平的三朵花的花丛中觅食，然后在没有奖励且经过长时间觅食停顿后，在该地点寻找食物。在训练时，我们向蜜蜂展示奖励水平的降低，或者相反，展示奖励水平的小幅或大幅提高。测试在训练后的第二天蜜蜂一访问花丛时就进行，此时我们测量蜜蜂的食物搜索行为。我们发现，经历奖励水平提高的蜜蜂比经历奖励水平降低的蜜蜂更持续地寻找食物，并且经历奖励水平大幅提高的蜜蜂比经历奖励水平小幅提高的蜜蜂更持续地寻找食物。由于测试时的这些差异不能用蜜蜂之前的嗉囊负载量和食物摄入率来解释，我们的结果明确表明，蜜蜂在觅食过程中会根据过去奖励水平变化的信号和幅度来调整它们的时间/能量投入。这种变化很可能导致奖励期望的形成，增强觅食者对觅食地点的依赖。最终，这将使蜜蜂在食物稀缺时更有可能找到食物。
