Editing Quorum sensing (section)

==Social insects==
Social insect colonies are an excellent example of a [[decentralized system]], because no individual is in charge of directing or making decisions for the colony. Several groups of social insects have been shown to use quorum sensing in a process that resembles collective decision-making.

===Examples===

====Ants====
Colonies of the ant ''[[Temnothorax albipennis]]'' nest in small crevices between rocks. When the rocks shift and the nest is broken up, these ants must quickly choose a new nest to move into. During the first phase of the decision-making process, a small portion of the workers leave the destroyed nest and search for new crevices. When one of these scout ants finds a potential nest, she assesses the quality of the crevice based on a variety of factors including the size of the interior, the number of openings (based on light level), and the presence or absence of dead ants.<ref>{{cite journal | vauthors = Franks NR, Dornhaus A, Metherell BG, Nelson TR, Lanfear SA, Symes WS | title = Not everything that counts can be counted: ants use multiple metrics for a single nest trait | journal = Proceedings. Biological Sciences | volume = 273 | issue = 1583 | pages = 165–169 | date = January 2006 | pmid = 16555783 | pmc = 1560019 | doi = 10.1098/rspb.2005.3312 }}</ref><ref>{{cite journal | vauthors = Franks NR, Hooper J, Webb C, Dornhaus A | title = Tomb evaders: house-hunting hygiene in ants | journal = Biology Letters | volume = 1 | issue = 2 | pages = 190–192 | date = June 2005 | pmid = 17148163 | pmc = 1626204 | doi = 10.1098/rsbl.2005.0302 }}</ref> The worker then returns to the destroyed nest, where she waits for a short period before recruiting other workers to follow her to the nest that she has found, using a process called [[tandem running]]. The waiting period is inversely related to the quality of the site; for instance, a worker that has found a poor site will wait longer than a worker that encountered a good site.<ref>{{cite journal | vauthors = Mallon EB, Pratt SC |title=Individual and collective decision-making during nest-site selection by the ant ''Leptothorax albipennis'' |journal=[[Behavioral Ecology and Sociobiology]] |volume=50 |issue=4 |pages=352–9 |year=2001 |doi=10.1007/s002650100377|bibcode=2001BEcoS..50..352M |s2cid=15360262 |display-authors=etal}}</ref> As the new recruits visit the potential nest site and make their own assessment of its quality, the number of ants visiting the crevice increases. During this stage, ants may be visiting many different potential nests. However, because of the differences in the waiting period, the number of ants in the best nest will tend to increase at the greatest rate. Eventually, the ants in this nest will sense that the rate at which they encounter other ants has exceeded a particular threshold, indicating that the quorum number has been reached.<ref>{{cite journal |author=Pratt, S.C. |title=Quorum sensing by encounter rates in the ant ''Temnothorax albipennis'' |journal=[[Behavioral Ecology (journal)|Behavioral Ecology]] |volume=16 |issue=2 |pages=488–96 |year=2005 |doi=10.1093/beheco/ari020|citeseerx=10.1.1.598.6340 }}</ref> Once the ants sense a quorum, they return to the destroyed nest and begin rapidly carrying the brood, queen, and fellow workers to the new nest. Scouts that are still tandem-running to other potential sites are also recruited to the new nest, and the entire colony moves. Thus, although no single worker may have visited and compared all of the available options, quorum sensing enables the colony as a whole to quickly make good decisions about where to move.

====Honey bees====
[[Honey bee]]s (''Apis mellifera'') also use quorum sensing to make decisions about new nest sites. Large colonies reproduce through a process called [[swarming (honeybee)|swarming]], in which the queen leaves the hive with a portion of the workers to form a new nest elsewhere. After leaving the nest, the workers form a swarm that hangs from a branch or overhanging structure. This swarm persists during the decision-making phase until a new nest site is chosen.

The quorum sensing process in honey bees is similar to the method used by ''[[Temnothorax]]'' ants in several ways. A small portion of the workers leave the swarm to search out new nest sites, and each worker assesses the quality of the cavity it finds. The worker then returns to the swarm and recruits other workers to her cavity using the honey bee [[waggle dance]]. However, instead of using a time delay, the number of dance repetitions the worker performs is dependent on the quality of the site. Workers that found poor nests stop dancing sooner, and can, therefore, be recruited to the better sites. Once the visitors to a new site sense that a quorum number (usually 10–20 bees) has been reached, they return to the swarm and begin using a new recruitment method called piping. This vibration signal causes the swarm to take off and fly to the new nest location. In an experimental test, this decision-making process enabled honey bee swarms to choose the best nest site in four out of five trials.<ref>{{cite journal | vauthors = Seeley TD, Visscher PK |title=Group decision making in nest-site selection by honey bees |journal=[[Apidologie]] |volume=35 |issue=2 |pages=101–16 |year=2004 |doi=10.1051/apido:2004004|doi-access=free }}</ref><ref>{{cite journal | vauthors = Seeley TD, Visscher PK |title=Group decision making in honey bee swarms |journal=[[American Scientist]] |volume=94 |issue=3 |pages=220–9 |year=2006 |doi=10.1511/2006.3.220|doi-broken-date=24 February 2025 }}</ref>