Christine Errard

Postpharyngeal gland secretion as a modifier of aggressive behavior in the myrmicine ant Manica rubida

The role of postpharyngeal gland secretion in nestmate recognition was tested inManica rubida. Behavioral tests comprised two consecutive encounters between five ants and their color-marked nestmate. The first encounter utilized an untreated ant constituting a control, whereas in the second encounter the marked ant was treated with postpharyngeal gland exudate. Scoring was done using an aggression index obtained by direct observation and an agitation index deduced from a frame-by-frame analysis of videotapes of the various tests. When the glandular secretion originated from an alien ant, the ants became very agitated and were aggressive toward their nestmate. When the exudate originated from a nestmate, the ants generally remained calm, although their rates of self-grooming increased.

Development of interspecific recognition behavior in the antsManica rubida andFormica selysi (Hymenoptera: Formicidae) reared in mixed-species groups

The purpose of this study was to determine the role of early social experience on the ontogeny of kin and nestmate recognition in ants by means of both behavioral and chemical analysis. Workers of two ant species,Manica rubida (Myrmicinae) andFormica selysi (Formicinae), were reared in homospecific groups (control) or in artificial heterospecific groups (mixed), created less than 5 h after their emergence. Recognition was evaluated between unfamiliar individuals of different species reared in control and mixed groups for periods of 5, 12, 24, 48, and 72 h and 8, 15, 30, 60, or 90 days after emergence. Heterospecifically reared individuals of both species gradually became tolerant of allospecific individuals from control groups. Moreover, homospecifically reared individuals did not aggress allospecific individuals reared in mixed groups. During the course of familiarization between the species, there were modifications of the chemical recognition signals. In mixed groups, hydrocarbon profiles of both species acquire gradually some of the components characteristic of their heterospecific nestmates. These experiments showed that allospecific recognition required the acquisition of a minimal quantity of allospecific cues. The phenomenon provided an another example of the relationship between tolerance and the chemical cues displayed by both species. The results suggested that the individual recognized the allospecific cues borne on each individuals body surface and/or that each individual learned and memorized allospecific cues during its early life. Therefore, each individual might develop a template encoding the allospecific and the conspecific cues to characterize nestmates.

Effects of early experience on interactions between the parasite ant Formicoxenus provancheri and its host Myrmica incompleta (Hymenoptera: Formicidae)

Abstract The influence of early experience on interspecific recognition in the parasite ant Formicoxenus provancheri and its host Myrmica incompleta was studied by investigating the interactions of each species with adults and with larvae. The adults tested were reared heterospecifically (host and parasite together) or homospecifically (with or without mature conspecific ergates). Adults of each species were tested with both conspecific and allospecific larval brood. Homospecifically reared M. incompleta were more aggressive towards their parasite than when reared with the latter. Formicoxenus provancheri were always attracted to M. incompleta brood and adults. This parasite thus prefers to rear the hostbrood, especially when the parasites early experience has been either of its own species or where it has been reared alone.

Species polyethism in heterospecific groups of Myrmicinae ants

We studied species polyethism in heterospecific queenless and queenright groups of ants by associating Manica rubida (olygogynous) individuals with Myrmica rubra (polygynous) and Myrmica ruginodis (monogynous) individuals, respectively. In queenless and queenright groups, Myrmica workers specialized in brood care and guarding the nest while Manica workers performed activities normally reserved for the oldest workers (especially outside activities). This might be due to a more rapid ethogenesis in workers of the genus Manica. Myrmica workers appeared more plastic in their behaviour and more sensitive to early environment than Manica workers: their ability to learn was greater, leading them to care for more allospecific brood than Manica workers, who demonstrated a preference for conspecific brood, in all groups studied. These experiments also showed great variability in the expression of species polyethism among different groups of ants according to the degree of polygyny of the queens species. The behavi...

Interindividual Distances in Mixed-Species Groups of Ants: an Estimation of Cohesion in Social Groups

Spatial organization was estimated in mixed-species groups of ants with interindividual distance measures as a function of: (1) the age of the workers when associated; and (2) the presence of the brood. Workers ofManica rubida (Myrmicinae) andFormica selysi (Formicinae) were reared in single-species groups (control) or in artificial, mixed-species groups, created 5 h, 12 h or 22 h after emergence, with or without brood. By recording the location of each individual in the nest during the 10 days following the creation of the groups, we evaluated the spatial organization and the interindividual distances between homocolonial or allospecific workers, and between workers and homocolonial or allospecific brood. The cohesion of the group, depend on the age of the workers when associated: the younger the individuals are when the groups are created, the smaller are the interindividual distances. Moreover, homocolonial individuals aggregated with brood, when present, which improves the overall cohesion of the group. However, in mixed groups, both species associated preferentially with members of their own species. This suggests that newly-emerged ants do not depend totally on the odors of their nestmates to construct their recognition template and that they also possess an innate, specific template.

Phylogenesis / biotope interactions among formicidae.

The development of interspecific recognition and the expression of behavioral plasticity as a function of phyletic distance and the natural environment in which the ants live were investigated. An experimental model involving artificial mixed societies was used in this study. These mixed societies were produced by combining ants from two out of the 11 investigated species. The possibilities thus ranged from situations in which phylogenetically similar ants that live in the same biotype were combined, to those in which the species differ significantly in terms both of phyletic distance and of biotope. The interspecific groups were established in a neutral environment with adult ants less than 24 hours old. The results concerned agonistic and non-agonistic behaviors during the first 15 days. Both the frequency and types of interaction were shown to vary according to the type of group. Two species that share a common habitat are less aggressive and display more non-agonistic behavior than when the species come from different habitats. On the other hand, although aggressive behaviors increase with greater phyletic distance between the species, non-agonistic interactions remain constant. As a general rule, interactions between species from differing environments seem to be determined by the phyletic distance, whereas those between species from the same biotope are controlled by interspecific competition. There is a gradual change in these interactions dependent on the duration of the mixed association.