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Box 1: bite recruitment in polybia wasps

Colonies of the paper wasp Polybia are much smaller than most honeybee colonies. They also have a distinctly unique method of forager recruiting completely dissimilar to the honeybee waggle dance. The paper wasp’s approach to recruiting foragers to food sources is much more aggressive. As Sean O’Donnell shows in his study, the wasp recruiters bite one another, a signal that was used by scouts to recruit other wasps to begin foraging. He found that bitten wasps have an increased likelihood to initiate foraging. In order to test his hypothesis, he removed active foragers from nest sites and found that in relation to the control sites, foraging greatly decreased throughout the following days. This, he noted caused a marked decrease in food gathering and as he had predicted a drastic increase in the rate at which non-foraging worker wasps were bitten. Those that were bitten often began a foraging role soon after. It is important to note that just as the honeybees cope with inaccuracy of waggle dances by deferring to prior knowledge on food sources, some paper wasps initiated foraging even without being bitten (O’Donnell 2006).

Olfactory communication proves to be even more advanced in honeybees and also plays an important role in the recruitment process. In addition to scents gathered from the environment, Thom et al. in their experiments proved that the returning recruiters secrete as many as four complex pheromones while engaging in the waggle dance. They showed, by injecting one such chemical into a test population, that it increased the number of recruits that left the hive after the waggle-dance. As many as four distinct chemical signals, produced only by waggle-dancers during their runs have been shown to increase the number of recruits that begin foraging (Thom et al. 2007). Von Frisch’s experiments also showed that a nectar scent carried by a forager can be traced by a dance-observer to a particular flower, thereby increasing the accuracy of the recruitment process (Von Frisch 1974).

The variability of waggle-dance communication

The effectiveness of the waggle-dance is highly variable within individual honeybee colonies. Colonies with eggs fertilized by multiple males (multiple-patriline) have been shown to increase foraging rates, larger stores of food and higher individual health compared to single-patriline colonies (Mattila et al. 2008). That is to say, queens that breed with more than one male increase the productivity of their nest. It is strange that decreased relatedness within the brood would in fact increase productivity, but the reasons are clear. What Mattila and her colleagues discovered was that in a genetically diverse population, worker efficiency was improved by the genetic variability of communicational behaviors. They showed that multiple-patriline colonies had an increase in foraging rates of 27-78% and engaged in 36% percent more waggle dances daily than genetically uniform colonies (Matilla et al. 2008). Not only does genetic diversity increase resistance to diseases in the hive, but it also allows for varying degrees of specificity in waggle dances. Decreased relatedness creates an increased need for more highly specific communication, as well as an increased variability in the waggle-dance. This increased variety of dance, according to the Tuned Error Hypothesis, may also lead to a larger search area. This is not necessarily a negative outcome. It occurs also when workers witness only a limited number of incomplete waggle runs and perhaps could allow bees, even at a short range, to find unexplored food resources next to the one being indicated by the dancer. Since the dances that indicate more remote locations are more precise and last longer, the search area at both close and far distances should theoretically be comparable (Tanner et al. 2008).

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Source:  OpenStax, Mockingbird tales: readings in animal behavior. OpenStax CNX. Jan 12, 2011 Download for free at http://cnx.org/content/col11211/1.5
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