Fearful foragers: honey bees tune colony and individual foraging to multi-predator presence and food quality

PLoS One. 2013 Sep 30;8(9):e75841. doi: 10.1371/journal.pone.0075841. eCollection 2013.

Abstract

Fear can have strong ecosystem effects by giving predators a role disproportionate to their actual kill rates. In bees, fear is shown through foragers avoiding dangerous food sites, thereby reducing the fitness of pollinated plants. However, it remains unclear how fear affects pollinators in a complex natural scenario involving multiple predator species and different patch qualities. We studied hornets, Vespa velutina (smaller) and V. tropica (bigger) preying upon the Asian honey bee, Apis cerana in China. Hornets hunted bees on flowers and were attacked by bee colonies. Bees treated the bigger hornet species (which is 4 fold more massive) as more dangerous. It received 4.5 fold more attackers than the smaller hornet species. We tested bee responses to a three-feeder array with different hornet species and varying resource qualities. When all feeders offered 30% sucrose solution (w/w), colony foraging allocation, individual visits, and individual patch residence times were reduced according to the degree of danger. Predator presence reduced foraging visits by 55-79% and residence times by 17-33%. When feeders offered different reward levels (15%, 30%, or 45% sucrose), colony and individual foraging favored higher sugar concentrations. However, when balancing food quality against multiple threats (sweeter food corresponding to higher danger), colonies exhibited greater fear than individuals. Colonies decreased foraging at low and high danger patches. Individuals exhibited less fear and only decreased visits to the high danger patch. Contrasting individual with emergent colony-level effects of fear can thus illuminate how predators shape pollination by social bees.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Analysis of Variance
  • Animals
  • Appetitive Behavior / physiology*
  • Bees / physiology*
  • Choice Behavior / physiology*
  • Fear*
  • Nutritive Value
  • Plant Nectar / chemistry
  • Predatory Behavior / physiology
  • Social Behavior*
  • Statistics, Nonparametric
  • Time Factors
  • Wasps / physiology

Substances

  • Plant Nectar

Grants and funding

This work was supported by the Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, and the CAS 135 program (XTBG-T01) of Chinese Academy of Science, China National Research Fund (31260585) to Ken Tan. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.