Collective decision making through food recruitment

Abstract

A sér i es of exper i ments shows how the ant Lasius nige r uses i ts tra i l recru i tment System to select between two food sources. S i mu i taneously presented w i th two IM sucrose solut i ons i t concentrâtes on one of them. When offered a IM solut i on together w i th a O.IM soluti on i t sélects the r i cher source, un i ess the tra i l to the O.IM source had become welldeveloped before the IM source was i ntroduced. In the same s i tuat i on, however, the group/mass recrut i ng ant Tet r amo r ium caespitum uses i ts more i nd i v i dual transm i ss i on of i nformat i on to sw i tch to the IM source. A mathemati cal model descr i bes thèse processes and i ts dynam i cs reflect the expér i mental results. RESUME La pris e de décision collective à travers le recrutement alimentaire Nous présentons une sér i e d'expér i ences qu i montrent comment la fourm i Lasius nige r peut uti li ser son système de recrutement par pi ste afi n de sélect i onner une des deux sources de nourr i ture. S i on leur offre s i multanément deux solut i ons IM de saccharose, la soc i été concentre son act i v i té sur l'une des deux. S i l'on offre deux solut i ons, une de IM et l'autre de O.IM, elle sélect i onne la plus r i che, à mo i ns que la p i ste qu i mène à la source O.IM so i t déjà b i en développée au moment où l'on i ntrodu i t la source IM. Face à la même s i tuat i on, la fourm i Tet r amo r ium caespitum, qu i recrute par groupe/masse, ut i l i se son mode de transm i ss i on d' i nformat i on plus i nd i v i duel pour changer son explo i tat i on vers la source IM. Un modèle mathémati que décr i t ces processus, dont la dynam i que correspond b i en aux observat i ons expér i mentales.

A halictid bee with sympatric solitary and eusocial nests offers evidence for Hamilton's rule

“…Foraging T. tsushimae employ a mass recruitment system headed by a scout that searches for food items along the crevices of the ground's surface. The scout recruits numerous nestmates using a pheromone trail to tag a large food item 27 .…”

Negative feedback in ants: crowding results in less trail pheromone deposition

“…If one food source is recruited to slightly more strongly, then the small initial difference will result in more individuals reaching that food source, leading to yet more individuals recruiting to the food source. Small initial differences in recruitment can arise by chance, or may be due to differential recruitment as a result of resource quality [2,[4][5][6][7][8] or other factors [9][10][11]. Such positive feedback loops lead to rapid group-level decisions, but can result in colonies becoming 'trapped' in suboptimal decisions, as the signal to one food source becomes too strong to be overcome [6,12].…”

Ants estimate area using Buffon's needle

“…How the behaviour of individual workers translates into collective decisions by the whole or large parts of a colony is now a major area of interest in the study of social insects (Franks 1989;Beckers et al 1993;Bourke & Franks 1995;Seeley 1995;Bonabeau et al 1997;Detrain & Deneubourg 1997;Pratt 1998;Detrain et al 1999). However, relatively little work has been done on the information gathering which provides the options for these decision-making processes (but see Seeley 1977;Lumsden & HÎlldobler 1983;Beckers et al 1990Beckers et al , 1992Franks et al 1991).…”