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Specialized parasites can modify host behavior to benefit transmission and reproduction. Such behavior is considered an extended phenotype of the parasite. The interactions between certain ant species and fungi of the genus Ophiocordyceps form an evident example. Once infected by Ophiocordyceps camponoti-atricipis, Camponotus atriceps ants die, biting at specific sites where abiotic conditions are optimal for fungal development. For many species of free-living fungi, light is needed to induce g [ABSTRACT FROM AUTHOR]

Environmental conditions exert strong selection on animal behavior. We tested the hypothesis that the altered behavior of hosts due to parasitic manipulation is also subject to selection imposed by changes in environmental conditions over time. Our model system is ants manipulated by parasitic fungi to bite onto vegetation. We analyzed the correlation between forest type (tropical vs. temperate) and the substrate where the host bites (biting substrate: leaf vs. twigs), the time required for the fungi to reach reproductive maturity, and the phylogenetic relationship among specimens from tropical and temperate forests from different parts of the globe. We show that fungal development in temperate forests is longer than the period of time leaves are present and the ants are manipulated to bite twigs. When biting twigs, 90% of the dead ants we examined had their legs wrapped around twigs, which appears to provide better attachment to the plant. Ancestral state character reconstruction suggests that leaf biting is the ancestral trait and that twig biting is a convergent trait in temperate regions of the globe. These three lines of evidence suggest that changes in environmental conditions have shaped the manipulative behavior of the host by its parasite. [ABSTRACT FROM AUTHOR]

Many arthropods mimic ants to avoid predation risk from visual predators. Our study of ant-mimicking arthropod diversity revealed 10 sympatric myrmecomorphs including spiders, mantids, bugs and grasshoppers. All, except one, were found predominantly on extrafloral nectary-bearing and homopteran harbouring plants. Of the five plant-visiting ant species, Camponotus compressus, Camponotus paria, Camponotus sericeus, Crematogaster subnuda and Tapinoma melanocephalum, only C. compressus showed significantly high occurrence and abundance on these plants. Except for a small spider morph, the remaining nine myrmecomorphic species resembled C. compressus and apparently use this common and abundant ant species as their model. [ABSTRACT FROM AUTHOR]

Symbiotic relationships between hosts and bacteria are common in nature, and these may be responsible for the evolutionary success of various groups of animals. Among ants, these associations have been well studied in some genera of the Camponotini, but several questions remain regarding the generality of the previous findings across all the members of this ant tribe and if bacterial communities change across development in these hosts. This study is the first to characterize the bacterial community associated with a colony of the recently recognized genus Colobopsis and three colonies of Camponotus (two distinct species) and show how different the composition of the bacterial community is when compared across the different genera. Our data reveal that Colobopsis (species: Co. riehlii) and Camponotus (species: Ca. floridanus and Ca. planatus) have distinct microbiota, and we were able to verify that the identity of the species contributes more to the bacterial diversity. We also demonstrated that there were no significant differences between colonies of the same species (Camponotus planatus), and between stages of development from different colonies. We did find that some developmental stages have distinct bacteria, confirming that each stage of development could have a specific microbiota. Our results show species are one of the factors that shape the bacterial community in these Camponotini ants. Additional studies of the intra-colonial microbiome of other hosts and across development may reveal additional clues about the function and importance of bacteria in colony recognition, individual and colony health, and nutritional upgrading. [ABSTRACT FROM AUTHOR]

Emotional state may influence cognitive processes such as attention and decision-making. A cognitive judgement bias is the propensity to anticipate either positive or negative consequences in response to ambiguous information. Recent work, mainly on vertebrates, showed that the response to ambiguous stimuli might change depending on an individual’s affective state, which is influenced by e.g. the social and physical environment. However, the response to ambiguous stimuli could also be affected by the individual’s behavioural type (personality), a question that has been under-investigated. We studied the link between individual differences in exploratory activity and the response to an ambiguous stimulus in the ant Camponotus aethiops . Exploratory behaviour, quantified with an open-field test, was variable among individuals but consistent over time within individuals. Individual ants learned to associate a spatial position to a reinforcement and another spatial position to a punishment. Once the ants had acquired this discrimination, cognitive judgement bias was tested with the stimulus in an intermediate position. Fast explorers in the open-field took significantly more time to approach the ambiguous stimulus compared to slow explorers, suggesting a negative judgement bias for fast explorers and a positive bias for slow explorers. This previously unknown link between individual difference in exploratory activity and cognitive bias in a social insect may help understanding the evolution and organization of social life. [ABSTRACT FROM AUTHOR]

In the present study, we investigated whether single-file traffic of the ant Camponotus japonicus would exhibit a transition to traffic-jamming with increasing density under stress conditions. Previous work indicated that this transition did not occur in non-stressed ants, in contrast to data from pedestrians and vehicular traffic. Citronella oil was used to elicit ant movement from one end of a unidirectional passage to the other. The movements were recorded with a video camera, and the speed and distance travelled were extracted using image processing. We provided fundamental diagrams of ant traffic for small and large ants under stress conditions. Examination of the relationship between flow rate and density revealed no evidence of jamming, different from pedestrian and vehicular traffic. Concerning the speed-density relationship, surprisingly, in contrast with human fundamental diagrams (vehicular and pedestrian), we found that speed seemed to be constant with density within the experimental error. This study provided novel experimental data on ant traffic and might inform future studies of collective behavior of social insects and traffic systems. [ABSTRACT FROM AUTHOR]

Behavioural differences between intranidal and extranidal major workers from a laboratory colony of an African carpenter ant species Camponotus maculatus reared from a foundress captured in Cameroon were investigated by means of dyadic nestmate reunion tests. Prior to the test, the ants were subjected to social isolation (48 h) in test tubes containing water reservoirs and carbohydrate food. Each test (20 min) involved a confrontation between a dyad of nestmates (two intranidal workers or two extranidal ones) placed in a set of two connected test tubes in which they had been isolated. Intranidal major workers showed higher propensity for resting behaviour and lower propensity for behavioural responses to elements of physical environment than extranidal ones. Similar behavioural differences between intranidal and extranidal minor workers (nurses and foragers) from the same colony were reported earlier in a companion study by our group. However, in contrast to minor nurses and foragers, intranidal and extranidal major workers of C. maculatus did not differ with respect to propensity for locomotion, self-grooming and social behaviour. Our findings provide a new clear-cut example of behavioural differences between nestmates related to differences in both worker morphology and worker specialisation in intranidal versus extranidal tasks. [ABSTRACT FROM AUTHOR]

In order to investigate the effect of the distance between two exits on ant evacuation efficiency and the behavior of ants escaping from a two-exit room, we conducted ant egress experiments using Camponotus japonicus in multiple situations. We found that the ants demonstrated the phenomenon of “symmetry breaking” in this stress situation. It was also shown that different locations for the exits obviously affected the ants’ egress efficiency by measuring the time intervals between individual egress and flow rate in eight repeated experiments, each of which contained five different distance between the two exits. In addition, it is demonstrated that there are differences between the predictions of Social Force Model of pedestrians and the behaviors of ants in stress conditions through comparing some important behavioral features, including position, trajectory, velocity, and density map. [ABSTRACT FROM AUTHOR]

Despite the growing number of experimental studies on mechanisms of social immunity in ant societies, little is known about how social behavior relates to disease progression within the nests of ants. In fact, when empirically studying disease in ant societies, it is common to remove dead ants from experiments to confirm infection by the studied parasite. This unfortunately does not allow disease to progress within the nest as it may be assumed would happen under natural conditions. Therefore, the approach taken so far has resulted in a limited knowledge of diseases dynamics within the nest environment. Here we introduced a single infectious cadaver killed by the fungus Beauveria bassiana into small nests of the ant Camponotus castaneus. We then observed the natural progression of the disease by not removing the corpses of the ants that died following the first entry of the disease. Because some behaviors such as social isolation of sick individuals or the removal of cadavers by nestmates are considered social immune functions and thus adaptations at the colony level that reduce disease spread, we also experimentally confined some sub-colonies to one or two chamber nests to prevent the expression of such behaviors. Based on 51 small nests and survival studies in 1,003 ants we found that a single introduced infectious cadaver was able to transmit within the nest, and social immunity did not prevent the collapse of the small sub-colonies here tested. This was true whether ants did or did not have the option to remove the infectious cadaver. Therefore, we found no evidence that the typically studied social immunity behaviors can reduce disease spread in the conditions here tested. [ABSTRACT FROM AUTHOR]

Eusocial insects organize themselves into behavioral castes whose regulation has been proposed to involve epigenetic processes, including histone modification. In the carpenter ant Camponotus floridanus, morphologically distinct worker castes called minors and majors exhibit pronounced differences in foraging and scouting behaviors. We found that these behaviors are regulated by histone acetylation likely catalyzed by the conserved acetyltransferase CBP. Transcriptome and chromatin analysis in brains of scouting minors fed pharmacological inhibitors of CBP and histone deacetylases (HDACs) revealed hundreds of genes linked to hyperacetylated regions targeted by CBP. Majors rarely forage, but injection of a HDAC inhibitor or small interfering RNAs against the HDAC Rpd3 into young major brains induced and sustained foraging in a CBP-dependent manner. Our results suggest that behavioral plasticity in animals may be regulated in an epigenetic manner via histone modification [ABSTRACT FROM AUTHOR]

To study the rules of ant behavior and group-formation phenomena, we examined the behaviors of Camponotus japonicus, a species of large ant, in a range of situations. For these experiments, ants were placed inside a rectangular chamber with a single exit that also contained a filter paper soaked in citronella oil, a powerful repellent. The ants formed several groups as they moved toward the exit to escape. We measured the time intervals between individual escapes in six versions of the experiment, each containing an exit of a different width, to quantify the movement of the groups. As the ants exited the chamber, the time intervals between individual escapes changed and the frequency distribution of the time intervals exhibited exponential decay. We also investigated the relationship between the number of ants in a group and the group flow rate. [ABSTRACT FROM AUTHOR]

Many studies have investigated how social insects behave when a parasite is introduced into their colonies. These studies have been conducted in the laboratory, and we still have a limited understanding of the dynamics of ant-parasite interactions under natural conditions. Here we consider a specialized parasite of ant societies (Ophiocordyceps camponoti-rufipedis infecting Camponotus rufipes) within a rainforest. We first established that the parasite is unable to develop to transmission stage when introduced within the host nest. Secondly, we surveyed all colonies in the studied area and recorded 100% prevalence at the colony level (all colonies were infected). Finally, we conducted a long-term detailed census of parasite pressure, by mapping the position of infected dead ants and foraging trails (future hosts) in the immediate vicinity of the colonies over 20 months. We report new dead infected ants for all the months we conducted the census – at an average of 14.5 cadavers/month/colony. Based on the low infection rate, the absence of colony collapse or complete recovery of the colonies, we suggest that this parasite represents a chronic infection in the ant societies. We also proposed a “terminal host model of transmission” that links the age-related polyethism to the persistence of a parasitic infection. [ABSTRACT FROM AUTHOR]

Introduction: Systematic surveys of macrofaunal diversity within ant colonies are lacking, particularly for ants nesting in microhabitats that are difficult to sample. Species associated with ants are generally small and rarely collected organisms, which makes them more likely to be unnoticed. We assumed that this tendency is greater for arthropod communities in microhabitats with low accessibility, such as those found in the nests of arboreal ants that may constitute a source of cryptic biodiversity. Materials and Methods: We investigated the invertebrate diversity associated with an undescribed, but already threatened, Neotropical Camponotus weaver ant. As most of the common sampling methods used in studies of ant diversity are not suited for evaluating myrmecophile diversity within ant nests, we evaluated the macrofauna within ant nests through exhaustive colony sampling of three nests and examination of more than 80,000 individuals. Results: We identified invertebrates from three classes belonging to 18 taxa, some of which were new to science, and recorded the first instance of the co-occurrence of two brood parasitoid wasp families attacking the same ant host colony. This diversity of ant associates corresponded to a highly complex interaction network. Agonistic interactions prevailed, but the prevalence of myrmecophiles was remarkably low. Conclusions: Our data support the hypothesis of the evolution of low virulence in a variety of symbionts associated with large insect societies. Because most myrmecophiles found in this work are rare, strictly specific, and exhibit highly specialized biology, the risk of extinction for these hitherto unknown invertebrates and their natural enemies is high. The cryptic, far unappreciated diversity within arboreal ant nests in areas at high risk of habitat loss qualifies these nests as ‘hot-points’ of biodiversity that urgently require special attention as a component of conservation and management programs. [ABSTRACT FROM AUTHOR]

Myrmecophily is widespread in lycaenid butterflies, in which ants receive food resources and, in turn, protect caterpillars against natural enemies. This interaction ranges from obligate myrmecophily, in which immatures are invariably associated with ants and are dependent on ants for survival, and facultative myrmecophily, in which larvae are not dependent on ants for survival, but the presence of the latter may increase larvae survival. Lycaenids also include non-myrmecophilous butterflies, which do not have positive associations with ants and have developed strategies to avoid being attacked or preyed upon by them. In this study, we examined the relationship between the lycaenid Michaelus ira and two ant species associated with Distictella elongata (Bignoniaceae). This plant has extrafloral nectaries and is patrolled by Camponotus crassus and Ectatomma tuberculatum. Morphological analyses revealed that M. ira larvae have ant organs, such as dorsal nectary organs and perforated cupolas, structures associated with myrmecophily. We performed larval exposure experiments in the field, predicting that, in the absence of myrmecophily, the butterfly larva would present strategies to avoid ant attack. Results showed that larvae were attacked by both ant species. To escape ant molestation, larvae lived and fed inside silk-sealed D. elongata flower buds. We concluded that the M. ira bud-sheltering behavior was a defensive strategy against these ant species, while the dorsal nectary organs were apparently nonfunctional. Nonetheless, myrmecophily, in general, cannot be excluded in M. ira since relationships with other ant species may exist. [ABSTRACT FROM AUTHOR]

Ants live in organized societies with a marked division of labor among workers, but little is known about how this division of labor is generated. We used a tracking system to continuously monitor individually tagged workers in six colonies of the ant Camponotus fellah over 41 days. Network analyses of more than 9 million interactions revealed three distinct groups that differ in behavioral repertoires. Each group represents a functional behavioral unit with workers moving from one group to the next as they age. The rate of interactions was much higher within groups than between groups. The precise information on spatial and temporal distribution of all individuals allowed us to calculate the expected rates of within- and between-group interactions. These values suggest that the network of interaction within colonies is primarily mediated by age-induced changes in the spatial location of workers. [ABSTRACT FROM AUTHOR]

Ants exhibit impressive olfactory learning abilities. Operant protocols in which ants freely choose between rewarded and non-rewarded odours have been used to characterise associative olfactory learning and memory. Yet, this approach precludes the use of invasive methods allowing the dissection of molecular bases of learning and memory. An open question is whether the memories formed upon olfactory learning that are retrievable several days after training are indeed based on de novo protein synthesis. Here, we addressed this question in the ant Camponotus fellah using a conditioning protocol in which individually harnessed ants learn an association between odour and reward. When the antennae of an ant are stimulated with sucrose solution, the insect extends its maxilla-labium to absorb the solution (maxilla-labium extension response). We differentially conditioned ants to discriminate between two long-chain hydrocarbons, one paired with sucrose and the other with quinine solution. Differential conditioning leads to the formation of a long-term memory retrievable at least 72 h after training. Long-term memory consolidation was impaired by the ingestion of cycloheximide, a protein synthesis blocker, prior to conditioning. Cycloheximide did not impair acquisition of either short-term memory (10 min) or early and late mid-term memories (1 or 12 h). These results show that, upon olfactory learning, ants form different memories with variable molecular bases. While short- and mid-term memories do not require protein synthesis, long-term memories are stabilised via protein synthesis. Our behavioural protocol opens interesting research avenues to explore the cellular and molecular bases of olfactory learning and memory in ants. [ABSTRACT FROM AUTHOR]

Background: Timely decision making is crucial for survival and reproduction. Organisms often face a speed-accuracy tradeoff, as fully informed, accurate decisions require time-consuming gathering and treatment of information. Optimal strategies for decision-making should therefore vary depending on the context. In mammals, there is mounting evidence that multiple systems of perceptual discrimination based on different neural circuits emphasize either fast responses or accurate treatment of stimuli depending on the context. Methodology/Principal Findings: We used the ant Camponotus aethiops to test the prediction that fast information processing achieved through direct neural pathways should be favored in situations where quick reactions are adaptive. Social insects discriminate readily between harmless group-members and dangerous strangers using easily accessible cuticular hydrocarbons as nestmate recognition cues. We show that i) tethered ants display rapid aggressive reactions upon presentation of non-nestmate odor (120 to 160 ms); ii) ants' aggressiveness towards non-nestmates can be specifically reduced by exposure to non-nestmate odor only, showing that social interactions are not required to alter responses towards non-nestmates; iii) decision-making by ants does not require information transfer between brain hemispheres, but relies on side-specific decision rules. Conclusions/Significance: Our results strongly suggest that first-order olfactory processing centers (up to the antennal lobes) are likely to play a key role in ant nestmate recognition. We hypothesize that the coarse level of discrimination achieved in the antennal lobes early in odor processing provides enough information to determine appropriate behavioral responses towards non-nestmates. This asks for a reappraisal of the mechanisms underlying social recognition in insects. [ABSTRACT FROM AUTHOR]

We analyzed the structure of a multispecific network of interacting ants and plants bearing extrafioral nectaries recorded in 1990 and again in 2000 in La Mancha, Veracruz, Mexico. We assessed the replicability of the number of interactions found among species and also whether there had been changes in the network structure associated with appearance of new ant and plant species during that 10-year period. Our results show that the nested topology of .the network was similar between sampling dates, group dissimilarity increased, mean number of interactions for ant species increased, the frequency distribution of standardized degrees reached higher values for plant species, more ant species and fewer plant species constituted the core of the more recent network, and the presence of new ant and plant species increased while their contribution to nestedness remained the same. Generalist species (i.e., those with the most links or interactions) appeared to maintain the stability of the network because the new species incorporated into the communities were linked to this core of generalists. Camponotus planatus was the most extreme generalist ant species (the one with the most links) in both networks, followed by four other ant species; but other species changed either their position along the continuum of generalists relative to specialists or their presence or absence within the network. Even though new species moved into the area during the decade between the surveys, the overall network structure remained unmodified. [ABSTRACT FROM AUTHOR]

Abstract: Discriminating between group members and strangers is a key feature of social life. Nestmate recognition is very effective in social insects and is manifested by aggression and rejection of alien individuals, which are prohibited to enter the nest. Nestmate recognition is based on the quantitative variation in cuticular hydrocarbons, which can include heritable cues from the workers, as well as acquired cues from the environment or queen-derived cues. We tracked the profile of six colonies of the ant Camponotus aethiops for a year under homogeneous laboratory conditions. We performed chemical and behavioral analyses. We show that nestmate recognition was not impaired by constant environment, even though cuticular hydrocarbon profiles changed over time and were slightly converging among colonies. Linear hydrocarbons increased over time, especially in queenless colonies, but appeared to have weak diagnostic power between colonies. The presence of a queen had little influence on nestmate discrimination abilities. Our results suggest that heritable cues of workers are the dominant factor influencing nestmate discrimination in these carpenter ants and highlight the importance of colony kin structure for the evolution of eusociality. [Copyright &y& Elsevier]

In nectar-feeding insects, sugars are an important source of fuel and energy storage. Here, we analyzed the haemolymph sugar levels in foragers of the ant Camponotus rufipes trained to collect nectar from an artificial feeder, and their dependence on the metabolic rate during feeding. The main sugar found was trehalose, followed by glucose and traces of fructose and sucrose. In foragers, trehalose level was independent of their activity and metabolic rate while feeding. Carbohydrate deprivation of the colony had a strong effect on the haemolymph sugar levels of workers, with a significant decrease in trehalose and glucose with increasing starvation. We also found a correlation between haemolymph sugar levels and behavioral states, with immobile workers having higher trehalose and fructose levels than active ones. It is suggested that under food deprivation, inside-nest workers initially stay completely immobile as a strategy to save energy, and only become active and start to search for food when the trehalose levels decrease even more. Based on a conservative estimation, well-fed ants could travel up to 500 m, or spend more than 20 h inactive at 25°C, using only the energy provided by the haemolymph trehalose, before reaching the levels found in starved nest-mates. [ABSTRACT FROM AUTHOR]

Associations between ants of the genera Crematogaster and Camponotus are found in many parts of the world. Associated species use common trails (trail sharing) or even share a common nest (parabiosis). In a tropical lowland forest in Malaysian Borneo, we studied intraspecific and interspecific aggression among the parabiotic species Crematogaster modiglianii and Camponotus rufifemur using both field and laboratory assays. Cr. modiglianii tolerated Ca. rufifemur workers from certain foreign colonies but fiercely attacked those of others. In contrast, Ca. rufifemur was tolerant even towards attacking allocolonial Cr. modiglianii workers but killed other Crematogaster species. By analogy, other Camponotus species usually attacked and killed Cr. modiglianii. Intraspecific confrontations among Ca. rufifemur colonies yielded a gradient from allocolonial tolerance to strong aggression. The aggression patterns coincide with those of Cr. modiglianii towards Ca. rufifemur workers from the same colonies. Our results suggest either that Ca. rufifemur is not able to recognize allocolonial Cr. modiglianii workers as foreign or that they are recognized but tolerated. The unilateral, species-specific but not colony-specific tolerance of Ca. rufifemur towards its partner species contrasts with highly colony-specific tolerance found among neotropical parabioses. [Copyright &y& Elsevier]

Aspects of predator assemblages that alter predator effects on prey have received extensive recent attention. Among other mechanisms, differences in behavior or resource use within predator trophic levels may enhance predator effects on prey, especially if effects of each predator species differ with environmental conditions. We address whether three common ant species (Azteca instabilis F. Smith, Camponotus textor Forel, and Crematogaster spp.) are functionally unique in coffee agroecosystems, asking if each species differs in (1) cooperative foraging behavior, (2) responses to experimentally introduced herbivores, and (3) responses to pest outbreaks. Furthermore, we examined the behaviors and effects of each ant species under different conditions by varying herbivore species, herbivore size, and herbivore density and carrying out observations in different seasons. Ant species significantly differed in foraging behaviors, in effects on individual herbivores, and in responses to pest outbreaks in terms of both type and time of response to herbivores. The behaviors and effects of each ant species differed in the dry and wet seasons and for different herbivore species and sizes. Although A. iastabilis generally removed more larvae and more quickly removed larvae, this was not the case under all conditions. The data presented thus support that common ant species in coffee agroecosystems are behaviorally diverse in their responses to herbivores under different conditions. We discuss the implications of these differences in ant behaviors for enhancement of predatory function in light of both multipredator effects and in terms of the potential importance of predator diversity. [ABSTRACT FROM AUTHOR]

Ants use cuticular hydrocarbons (CHC-profiles) as multicomponent recognition cues to identify colony members (nestmates). Recognition cues (label) are thought to be perceived during ant–ant encounters and compared to a neuronal template that represents the colony label. Over time, the CHC-profile may change, and the template is adjusted accordingly. A phenotype mismatch between label and template, as happens with CHC-profiles of foreign workers (non-nestmates), frequently leads to aggressive behavior. We investigated the template reformation in workers of the carpenter ant Camponotus floridanus by masking their antennae with postpharyngeal gland (PPG) extracts from nestmates or non-nestmates. The behavioral response of manipulated workers encountering unmanipulated workers was measured independently after 2 and after 15 h. After 2 h of incubation, workers treated with either of the two PPG-extracts showed low aggression towards nestmates and high aggression towards non-nestmates. In contrast, after 15 h of incubation, workers treated with non-nestmate PPG-extract showed low aggression towards both nestmates and non-nestmates. The slow (>2 h) adjustment of the template indicates a reformation localized in the central nervous system rather than in chemosensory neurons. In addition, our data show that template adjustment to a new CHC-profile does not impair the assessment of the old CHC-profile as nestmate label. [ABSTRACT FROM AUTHOR]

In ant societies, workers do not usually reproduce but gain indirect fitness benefits from raising related offspring produced by the queen. One of the preconditions of this worker self-restraint is sufficient fertility of the queen. The queen is, therefore, expected to signal her fertility. In Camponotus floridanus, workers can recognize the presence of a highly fertile queen via her eggs, which are marked with the queen's specific hydrocarbon profile. If information on fertility is encoded in the hydrocarbon profile of eggs, we expect workers to be able to differentiate between eggs from highly and weakly fertile queens. We found that workers discriminate between these eggs solely on the basis of their hydrocarbon profiles which differ both qualitatively and quantitatively. This pattern is further supported by the similarity of the egg profiles of workers and weakly fertile queens and the similar treatment of both kinds of eggs. Profiles of queen eggs correspond to the cuticular hydrocarbon profiles of the respective queens. Changes in the cuticular profiles are associated with the size of the colony the queen originates from and her current egg-laying rate. However, partial correlation analysis indicates that only colony size predicts the cuticular profile. Colony size is a buffered indicator of queen fertility as it is a consequence of queen productivity within a certain period of time, whereas daily egg-laying rate varies due to cyclical oviposition. We conclude that surface hydrocarbons of eggs and the cuticular profiles of queens both signal queen fertility, suggesting a major role of fertility signals in the regulation of reproduction in social insects. [ABSTRACT FROM AUTHOR]

We investigated the relative contribution of the queen and workers to colony nestmate recognition cues and on colony insularity in the Carpenter ant Camponotus fellah. Workers were either individually isolated, preventing contact with both queen and workers (colonial deprived, CD), kept in queenless groups, allowing only worker-worker interactions (queen deprived, QD) or in queenright (QR) groups. Two weeks post-separation QD and QR workers were amicable towards each other but both rejected their CD nestmates, which suggests that the queen does not measurably influence the colony recognition cues. By contrast, aggression between QD and QR workers from the same original colony was apparent only after six months of separation. This clearly demonstrates the power of the Gestalt and indicates that the queen is not a dominant contributor to the nestmate recognition cues in this species. Aggression between nestmates was correlated with a greater hydrocarbon (HC) profile divergence for CD than for QD and QR workers, supporting the importance of worker-worker interactions in maintaining the colony Gestalt odour. While the queen does not significantly influence nestmate recognition cues, she does influence colony insularity since within 3 days QD (queenless for six months) workers from different colony origins merged to form a single queenless colony. By contrast, the corresponding QR colonies maintained their territoriality and did not merge. The originally divergent cuticular and postpharyngeal gland HC profiles became congruent following the merger. Therefore, while workers supply and blend the recognition signal, the queen affects worker-worker interaction by reducing social motivation and tolerance of alien conspecifics. [ABSTRACT FROM AUTHOR]

Discusses vibration as a channel of communication for several kinds of animals. Initiation of substrate vibrations during courtship among veiled chameleon; Description of the process of the transmission of vibration signals among carpenter ants; Significance of vibration to termites.

Investigates whether putative isolation-induced cuticular hydrocarbon divergence influences nestmate tolerance in Camponotus fellah worker ants. Chemical analyses of sample ant group's cuticular washes; Behavior and ovarian development; Existence of a Gestalt colony odor in C. fellah.

Deals with a study which investigated potential neurobiological mechanisms that could underlie social bonding in the ant Camponotus fellah through the analysis of trophallaxis. Drug administration; Behavioral effects of octopamine administration; Hydrocarbon transfer between nestmates during dyadic encounters.

Simple Summary: Grooming is a common behavior in animals. It serves the function of removing foreign materials and excessive amounts of self-secreted materials from the body's surface. Social insects, such as honeybees or ants, use various types of pheromones, some of which propagate information about the environment to conspecific individuals, for chemical communication. The individuals that receive such information can respond with suitable behaviors to protect themselves and their society. Hence, grooming is important for the maintenance of the correct performance of their sensory organs on antennae for pheromone perception. Here, we experimentally limited self-grooming of the antennae in workers of the Japanese carpenter ant (Camponotus japonicus) by removing a pair of antennal cleaning apparatuses from the forelegs and investigated their behavioral change in response to exposure to the alarm pheromone or to encounters with nestmates or non-nestmates. Comparisons between self-grooming-nonlimited and self-grooming-limited ants showed that the self-grooming-limited ants gradually exhibited decreased locomotion activity in their fight-or-flight response to the alarm pheromone and experienced increased failure in nestmate and non-nestmate discrimination. Thus, the results of the present study suggest that antennal sensory system maintenance supports social communication, which is indispensable not only to the individual workers but also to the survival of their society. Self-grooming of the antennae is frequently observed in ants. This antennal maintenance behavior is presumed to be essential for effective chemical communication but, to our knowledge, this has not yet been well studied. When we removed the antenna-cleaning apparatuses of the Japanese carpenter ant (C. japonicus) to limit the self-grooming of the antennae, the worker ants demonstrated the self-grooming gesture as usual, but the antennal surface could not be sufficiently cleaned. By using scanning electron microscopy with NanoSuit, we observed the ants' antennae for up to 48 h and found that the antennal surfaces gradually became covered with self-secreted surface material. Concurrently, the self-grooming-limited workers gradually lost their behavioral responsiveness to undecane—the alarm pheromone. Indeed, their locomotive response to the alarm pheromone diminished for up to 24 h after the antenna cleaner removal operation. In addition, the self-grooming-limited workers exhibited less frequent aggressive behavior toward non-nestmate workers, and 36 h after the operation, approximately half of the encountered non-nestmate workers were accepted as nestmates. These results suggest that the antennal sensing system is affected by excess surface material; hence, their proper function is prevented until they are cleaned. [ABSTRACT FROM AUTHOR]

1. The recruitment process of Camponotus pennsylvanicus initiates and regulates foraging activities. Scout ants recruit nestmates to new food sources with alerting motor displays. Workers subsequently leave the nest and follow a recruitment trail that appears to be composed of hindgut material and poison gland secretion (formic acid) to the food. Hindgut material functions as a long-lasting olfactory orientation cue between the food source and the nest, whereas poison gland secretion makes the recruitment trail highly attractive to stimulated ants. Hindgut trails may also have a recruitment effect. 2. Although hindgut material is an important orientation cue during foraging, because ants make repeated foraging runs they may also make use of visual cues. 3. Mass foraging is organized by the behavioral activities of recruiting ants. Starvation intensifies the recruitment displays of scouts, which releases a strong recruitment response in the colony. The behavior of individual recruiters during the organization of foraging facilitates at first a quick mobilization of nestmates to the food; subsequently recruiter behavior changes. These changes the facilitate food transport to the colony. The amount of food brought into the colony along with the decrease in recruitment behaviors may account for the waning and eventual termination of foraging activity. Only ants of a particular age bracket respond to recruitment signals and participate in foraging, and of this group only a small proportion of workers are consistently active in foraging. 4. When compared to other formicine species, the recruitment behavior of Camponotus pennsylvanicus appears to illustrate some features of chemical mass communication while still retaining characteristics of the group recruitment technique. [ABSTRACT FROM AUTHOR]

1. The influence of an artificial drumming signal on the activities of worker ants and on the frequency distribution of activities inside an undisturbed laboratory colony of C. herculeanus L. was investigated by applying the mathematical theory of communication. 2. The measure of uncertainty as to the activities of worker ants at any given time (initial act) is 1.4 bit. After a drumming signal has been applied, the reactions of the ants (second act) cause a decrease to 0.84 bit. The transinformation between first and second acts is 1.07 bit without and 0.48 bit with a drumming signal between the acts. In reference to the proportion of activity groups, the information transferred to the worker ants as a group is 0.043 bit. 3. The information transferred by the signal to the worker ants as individuals was calculated by referring to the proportion of the two-act sequences (uncertainty 1.9 bit) with and without drumming. The result is 0.12 bit, which is 12% of the signal's information content (1 bit). It differs widely between sub-groups as defined by initial activity (0.005-0.61 bit); the signal reduces the uncertainty as to the behavior of the animals by 0.5%-35%. The information transferred by signals of lower acceleration amplitudes is less than that transferred by higher acceleration amplitudes. Sexual animals react similarly to worker ants, but are less sensitive. 4. Besides an increased tendency to changes of activity two typical reactions to the signal occurred" a "freezing" reaction and a reaction characterized by fast, aggressive runs (57% and 6% respectively of the transferred information). The first was interpreted as an unspecific reaction to vibration stimuli, which is adaptive only outside the nests; the second as a specific "alarm" response. 5. The kind of alarm responses to the drumming signal is highly dependent on the situational context. The drumming communication was thus classified as a combined alarm and alarm modulator system. [ABSTRACT FROM AUTHOR]

We report the first record of the rare carpenter ant ( Camponotus microps) from the states of Guanajuato and Querétaro, México. This species was previously known only from the type series from the Chiricahua Mountains of southeastern Arizona, USA. This species is a member of the picipes species complex, and can be easily separated from the similar common Camponotus festinatus, as well as other members of the complex, by the short antennal scapes. [ABSTRACT FROM AUTHOR]

Animals constantly face the challenge of extracting important information out of their environment, and for many animals much of this information is chemical in nature. The ability to discriminate and generalize between chemical stimuli is extremely important and is commonly thought to depend mostly on the structural similarity between the different stimuli. However, we previously provided evidence that in the carpenter antCamponotus aethiops, generalization not only depends on structural similarity, but also on the animal’s previous training experience. When individual ants were conditioned to substance A, they generalized toward a mixture of A and B. However, when trained to substance B, they did not generalize toward this mixture, resulting in asymmetrical generalization. This asymmetry followed an inclusion criterion, where the ants consistently generalized from a molecule with a long carbon chain to molecules with a shorter chain, but not the other way around. Here I will review the evidence for the inclusion criterion, describe possible proximate mechanisms underlying this phenomenon as well as discuss its potential adaptive significance. [ABSTRACT FROM PUBLISHER]

The article discusses a specialized fungal parasite Ophiocordyceps unilateralis which turns the Camponotus leonardi carpenter ant into a zombie. The fungus allows the ant to live until it can manipulate it onto the forest floor to a place where the fungus wishes to be. Topics include the physiological aspects of O. unilateralis infection and research investigating how parasites can control host behavior.