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Simple Summary: Ants are highly adaptable insects that thrive in a variety of climates and habitats worldwide. This study examines how climate and habitat influence the morphological traits of the ant species Camponotus japonicus across 22 sites in mainland China. These sites represent three climate zones and three habitat types. Our analysis shows that both climate and habitat significantly shape the ants' morphological traits. Specifically, ants in mid-temperate farmlands exhibit more constrained morphological traits, while those in sparse woodlands show greater variation. Urban parks present a stable environment with less morphological variation. Temperature, precipitation, humidity, and altitude were found to be closely linked to these morphological traits. This research enhances our understanding of how ants adapt to environmental changes through morphological variation and underscores their critical ecological roles in various ecosystems. Ants are a highly adaptable group of insects that have globally established themselves in diverse climates and habitats. This study investigates the influence of climate and habitat on the morphological traits of Camponotus japonicus across 22 sites in mainland China. These sites span three climate zones (mid-temperate, warm temperate, and subtropical) and three habitat types (urban parks, farmlands, and sparse woodlands). Principal component analysis (PCA) was used to determine the principal axis of morphological variation, while hypervolume analysis and centroid distance calculation were used to verify the environmental filtering hypothesis and the optimal transfer hypothesis. The results support both hypotheses showing that climate and habitat significantly affect the morphological space of C. japonicus workers. In particular, the morphological space is more constrained in mid-temperate farmlands, while workers in sparse woodlands exhibit greater morphological variation. In contrast, urban parks are characterized by higher stability and reduced morphological differences. Additionally, robust regression analysis reveals that environmental factors such as temperature, precipitation, humidity, and altitude are closely linked to the morphological traits of the workers. Understanding how ant morphology responds to external environmental changes enhances our understanding of their adaptability and their essential ecological roles across various ecosystems. [ABSTRACT FROM AUTHOR]

Ants often interact aggressively for resources (e.g. nest sites and food) with members of their own or another species. In these competitive interactions, dominant ant species exert a strong influence on ant species coexistence and plant‐associated arthropod community structure. However, few studies have experimentally manipulated the relative abundance of dominant ant species on plants, preventing a mechanistic understanding of the effects of ant competitive interactions on ant community structure as well as on their interactions with other insects, particularly mutualistic hemipterans. In this study, we performed a field experiment in a tropical dry forest in Brazil to investigate the effects of two dominant ant species (Camponotus crassus and Cephalotes pusillus) on the structure ant communities and the abundance of the ant‐tended hemipteran Enchenopa brasiliensis in Solanum lycocarpum plants. For this, we identified and quantified all ant species foraging on plants and estimated the number of egg masses, nymphs and adults of the mutualistic hemipteran before and after experimentally removing nests of both two dominant ant species. Our results showed that removal of C. pusillus nests significantly changed ant community structure, whereas removal of C. crassus nests did not. We also found that nest removal of both dominant ant species had significant effects on hemipteran abundance. In particular, plants generally hosted more hemipteran eggs, nymphs and adults after (vs before) nest removal of both dominant ant species. Overall, this study demonstrates that dominant ant species can play a pivotal role in structuring ant communities and the interactions between ants and honeydew‐producing hemipteran insects. [ABSTRACT FROM AUTHOR]

The Brazilian cerrado is one of the world's biodiversity hotspots, comprising a mosaic of vegetation physiognomies. The cerrado presents a high ant diversity, and ant genetic variation can be subjected to the influence of landscape features. Here, we investigate how the composition and configuration of a cerrado reserve (4500 ha) in SE Brazil influence dispersal and gene flow (through measures of genetic distance) in two abundant carpenter ants, Camponotus renggeri and C. rufipes. Based on landscape genetics, we evaluated the degree of permeability of different land covers on the dispersal of ant queens, males and workers, employing a genetic optimization algorithm framework. We found little genetic structure in C. renggeri, regardless of caste. By contrast, we observed the formation of clear genetic clusters in C. rufipes, mainly for workers and queens. For workers of both species, we found that genetic distance was not influenced by geographic distance or landscape composition. For queens and males of C. renggeri, geographic distance was the most important factor explaining genetic distance. For C. rufipes queens and males, however, the best model considered the effect of landscape resistance to gene flow (i.e. the cost imposed by land use and cover types), with males dispersing through human-affected areas such as roads, and queens through forested cerrado areas. Our results showed that cerrado landscape can differentially affect ant dispersal, even for closely related species, reinforcing the importance of using different castes and sexes in landscape genetics of social insects. Our study also highlights that preservation of different vegetation physiognomies of cerrado is relevant for ant dispersal performance. [ABSTRACT FROM AUTHOR]

Social insects often share tasks among individuals. In this study, we analyzed the foraging activity of ants (Camponotus japonicus) and recorded the daily passage event counts of individual workers between a nest chamber and a foraging arena in five monodomous colonies. We proposed two hypotheses on the time series of foraging frequency by individual worker ants as follows: (i) for the time series of foraging frequency by individual worker ants, the foraging frequency on a certain day could be expressed by the product of the foraging frequency on the previous day and the exponential of a random number. (ii) The random numbers are correlated between some pairs of worker ants. The results for the five tested ant colonies showed that the probability of total daily passage counts (the sum of an individual's passage count) followed a log-normal distribution. The worker ants behaved differently in terms of active days and foraging frequency. However, for > 54% of the worker ants, the probability of the daily passage count was characterized by a log-normal distribution, and these worker ants performed > 72% of the tasks in each colony. Furthermore, for > 73% of the worker ants, the time development of the passage count was mathematically modeled; the logarithmic first difference between the passage counts on a certain day and those on the previous day was a random normal variable. These results support hypothesis (i). Additionally, the random numbers that were equivalent to the logarithmic first difference were correlated for some pairs of worker ants. These results support hypothesis (ii). [ABSTRACT FROM AUTHOR]

Social isolation negatively affects health, induces detrimental behaviors, and shortens lifespan in social species. Little is known about the mechanisms underpinning these effects because model species are typically short-lived and non-social. Using colonies of the carpenter ant Camponotus fellah, we show that social isolation induces hyperactivity, alters space-use, and reduces lifespan via changes in the expression of genes with key roles in oxidation-reduction and an associated accumulation of reactive oxygen species. These physiological effects are localized to the fat body and oenocytes, which perform liver-like functions in insects. We use pharmacological manipulations to demonstrate that the oxidation-reduction pathway causally underpins the detrimental effects of social isolation on behavior and lifespan. These findings have important implications for our understanding of how social isolation affects behavior and lifespan in general. The mechanisms behind the negative effects of social isolation on social species are unclear. Here, the authors examine colonies of carpenter ants, finding that behavioral, physiological, and lifespan changes may be caused by oxidative stress. [ABSTRACT FROM AUTHOR]

Simple Summary: Florida carpenter ants (Camponotus floridanus) live in colonies comprised of thousands of workers. The smallest workers, known as minors, engage in routine tasks such as nursing and foraging while the largest workers, known as majors, are thought to be soldiers specialized for defending the nest. How ant colonies allocate their workforce to address the dynamic and ever-changing needs of the colonies remains an open question in the field, but current evidence suggests that ant social behavior likely results from a combination of genetic/epigenetic, physiological, and systems-level processes. Here, we extend these studies by investigating the role of olfactory sensitivity in regulating ant behavior. Minor workers exhibited significant shifts in olfactory sensitivity and odor coding as they aged and switched tasks. The olfactory sensitivity of majors, however, remained relatively stable as they aged. From these studies, we also identified a single compound, 3-methylindole, which elicited significantly higher olfactory responses and aversive behavior in nurses compared to foragers, suggesting that this chemical may have a role in brood care. Overall, these studies support the hypothesis that changes in olfactory sensitivity play an important role in regulating social behavior in ants. Age-related changes in behavior and sensory perception have been observed in a wide variety of animal species. In ants and other eusocial insects, workers often progress through an ordered sequence of olfactory-driven behavioral tasks. Notably, these behaviors are plastic, and workers adapt and rapidly switch tasks in response to changing environmental conditions. In the Florida carpenter ant, smaller minors typically perform most of the work needed to maintain the colony, while the larger majors are specialized for nest defense and rarely engage in these routine tasks. Here, we investigate the effects of age and task group on olfactory responses to a series of odorant blends in minor and major worker castes. Consistent with their respective roles within the colony, we observed significant age-associated shifts in the olfactory responses of minors as they transitioned between behavioral states, whereas the responses of majors remained consistently low regardless of age. Furthermore, we have identified a unitary compound, 3-methylindole, which elicited significantly higher responses and behavioral aversion in minor nurses than in similarly aged foragers suggesting that this compound may play an important role in brood care. Taken together, our results suggest that age- and task-associated shifts in olfactory physiology may play a critical role in the social organization of ant colonies. [ABSTRACT FROM AUTHOR]

This study is on the ecology and population dynamics of the membracid Otinotus oneratus Walker on its host plant Tamarindus indica L. The daily activity of O. oneratus when analysed revealed that it was active during 11:00 and 16:00 hr, and on extremely warmer days. Adults preferred woody internodal parts, while the early nymphal stages fed on the axil of the leaves, and the later nymphs fed on the internodal parts along with the adults. The resting posture of the adults were found to be in position with its head directed upwards on its host plant. The mean number of nymphs resting in a posture facing towards and away from node was 79.7 and 17.1 respectively; with adults, for males and females it was 3.0 and 4.6 upwards facing, and for downwards it was 2.4 and 3.6, respectively. The individuals were sluggish, and when disturbed, moved in a spiral manner around the twig, and stopped after moving some distance. Mating occurred for 5 min, followed by a female preoviposition period of 3 days. Eggs were elongate and white and laid in 'V' shaped manner, arranged in two rows with 12-19 eggs in each row. Parental care was exhibited with the females guarding 71.4 to 83.3% of egg masses. The incubation period varied from 8-12 days. Hatching occurred during the morning hours, and the nymphs were slow moving, showing a strong myrmecophilous mutualism, regularly attended by the large black ant Camponotus compressus F. (56.5- 92.9%). Predation by Gonatocerus brevifuniculatus Subba Rao and Mirufens afrangiata Viggiani and Hayat of eggs wqas observed. O. oneratus nymphs mimicked the thorns of the host plant, but they were brightly coloured (in contrast to the twigs). The occurrence of nymphs and adults reached a peak in December and January. The present study also assessed the population dynamics in relation to weather factors. [ABSTRACT FROM AUTHOR]

The physiology and behavior of social organisms correlate with their social environments. However, because social environments are typically confounded by age and physical environments (i.e., spatial location and associated abiotic factors), these correlations are usually difficult to interpret. For example, associations between an individual's social environment and its gene expression patterns may result from both factors being driven by age or behavior. Simultaneous measurement of pertinent variables and quantification of the correlations between these variables can indicate whether relationships are direct (and possibly causal) or indirect. Here, we combine demographic and automated behavioral tracking with a multiomic approach to dissect the correlation structure among the social and physical environment, age, behavior, brain gene expression, and microbiota composition in the carpenter ant Camponotus fellah. Variations in physiology and behavior were most strongly correlated with the social environment. Moreover, seemingly strong correlations between brain gene expression and microbiota composition, physical environment, age, and behavior became weak when controlling for the social environment. Consistent with this, a machine learning analysis revealed that from brain gene expression data, an individual's social environment can be more accurately predicted than any other behavioral metric. These results indicate that social environment is a key regulator of behavior and physiology. This study combines automated behavioral tracking of ants with multi-omics, revealing that individual behavior, brain gene expression, and gut microbiota composition are all more strongly correlated with social network position than they are with one another, indicating that social interactions likely regulate social behavior and underlying physiology. [ABSTRACT FROM AUTHOR]

This study assessed the effects of the Argentine ant (Linepithema humile), an invasive species, on the indigenous ant fauna in Busan, South Korea. Ant communities were sampled using pitfall traps placed along two transects in areas where L. humile was recently discovered (2019) in South Korea. Overall, we identified 14 ant species belonging to 12 genera and four subfamilies. We found that the species richness of the native ant community was significantly lower in areas invaded by L. humile, and most epigeic ants from the study area were not found co-existing with the Argentine ant. Five native epigeic species, namely Nylanderia flavipes, Pristomyrmex punctatus, Tetramorium tsushimae, Formica japonica, and Lasius japonicus, were strongly impacted by the invasion. In contrast, no effects were observed on two epigeic species (Camponotus vitiosus and Monomorium chinense) and one hypogeic species (Brachyponera chinensis). These results indicate that the successful settlement of Argentine ant has had a significant negative impact on native ant diversity in South Korea, confirming that L. humile is a very effective and competitive colonizer, despite its restricted dispersal capability. Management programs need to urgently implement control measures to ensure that L. humile does not spread further in South Korea. [ABSTRACT FROM AUTHOR]

Background: Camponotus floridanus ant colonies are comprised of a single reproductive queen and thousands of sterile female offspring that consist of two morphologically distinct castes: smaller minors and larger majors. Minors perform most of the tasks within the colony, including brood care and food collection, whereas majors have fewer clear roles and have been hypothesized to act as a specialized solider caste associated with colony defense. The allocation of workers to these different tasks depends, in part, on the detection and processing of local information including pheromones and other chemical blends such as cuticular hydrocarbons. However, the role peripheral olfactory sensitivity plays in establishing and maintaining morphologically distinct worker castes and their associated behaviors remains largely unexplored. Results: We examined the electrophysiological responses to general odorants, cuticular extracts, and a trail pheromone in adult minor and major C. floridanus workers, revealing that the repertoire of social behaviors is positively correlated with olfactory sensitivity. Minors in particular display primarily excitatory responses to olfactory stimuli, whereas major workers primarily manifest suppressed, sub-solvent responses. The notable exception to this paradigm is that both minors and majors display robust, dose-dependent excitatory responses to conspecific, non-nestmate cuticular extracts. Moreover, while both minors and majors actively aggress non-nestmate foes, the larger and physiologically distinct majors display significantly enhanced capabilities to rapidly subdue and kill their adversaries. Conclusions: Our studies reveal the behavioral repertoire of minors and majors aligns with profound shifts in peripheral olfactory sensitivity and odor coding. The data reported here support the hypothesis that minors are multipotential workers with broad excitatory sensitivity, and majors are dedicated soldiers with a highly specialized olfactory system for distinguishing non-nestmate foes. Overall, we conclude that C. floridanus majors do indeed represent a physiologically and behaviorally specialized soldier caste in which caste-specific olfactory sensitivity plays an important role in task allocation and the regulation of social behavior in ant colonies. [ABSTRACT FROM AUTHOR]

In animal societies, individuals may take on different roles to fulfil their own needs and the needs of their group. Ant colonies display high levels of organizational complexity, with ants fulfilling different roles at different timescales (what is known as task allocation). Factors affecting task allocation can be at the individual level (e.g. physiology), or at the group level (e.g. the network of interactions). We focus on group level processes by exploring the relationship between interaction networks, task allocation and task switching using a previously published data set (Mersch et al., 2013, Science, 340 (6136), 1090–1093) tracking the behaviour of six Camponotus fellah colonies over 41 days. In our new analyses, our goal was to better explain the noisy process of task switching beyond simple age polyethism. First, we investigated the architecture of interaction networks using node (individual) level network measures and their relation to the individual's task – foraging, cleaning or nursing – and whether or not the ant switched tasks. We then explored how noisy information propagation was among ants, as a function of the colony composition (how many ants carried out which tasks), through the information-theoretic metric of 'effective information'. Our results show that interaction history is tied to task allocation: ants that switched to a task were more likely to have interacted with other ants carrying out that task. The degree to which interactions related to task allocation, as well as the noise in those interactions, depended on which groups of ants were interacting. Overall, we found that colony cohesion was stable even as ant level network measures varied more for ants when they switched functional groups; thus, ant colonies maintained a high level of information flow as determined by network analysis, and ant functional groups played different roles in maintaining colony cohesion through varied information flows. • We analysed the interaction networks of six C. fellah colonies. • We tested how centrality and information flow are tied to task switching. • Node metrics and effective information explained functional group differences. • Interactions were correlated with task switching. • The strength of this correlation, however, differed across functional groups. [ABSTRACT FROM AUTHOR]

European bee-eater (Merops apiaster Linnaeus, 1758; Coraciiformes: Meropidae) is known as a bee-predator, but its food spectrum is variable and depends on the current supply. This is the first study focused on the ants (Hymenoptera: Formicidae) as important prey in the diet of the European bee-eater. In 2017, 9,604 insect prey was obtained from pellets gained from two colonies breeding: (1) underground of a grazed sand dune (Radvaň nad Dunajom) and (2) in the sandy wall (Gabčíkovo) without pasture, both in southern Slovakia. Five ant taxa were identified, the list of ants in the bee-eater's diet was expanded by three taxa Lasius sp., Camponotus vagus (Scopoli, 1763) and Liometopum microcephalum (Panzer, 1798). In summary, ants represent the second most abundant family (12.35 %) of total prey. Compared to adults, nestlings (15.04 %) ate significantly more ants than adults (10.97 %). To study the ants' composition in the diet of bee-eater near to different types of habitats, the pellets of nestlings were chosen because they more accurately reflect the sources of insect during the breeding season. Differences in the feeding of the European bee-eater nestlings between the grazed and the non-grazed locality were confirmed, where Lasius sp. and Tetramorium sp. highly correlated with grazing site. Moreover, nestlings ate significantly more ants in the area, where an open habitat was managed by grazing (6.55 vs. 15.04 %). The presented research indicates the importance of traditional pastures in the country for ants and also for bee-eaters. These ecosystem engineers are likely to find more microhabitats on the pastures, which has also been reflected in the diet of the nestlings breeding on the grazed site. [ABSTRACT FROM AUTHOR]

Much like a single organism, colonies of social insects regulate their collective nutrition towards a specific intake of nutrients. Yet, the mechanisms behind this colony‐level regulation are not fully understood. Although foraging behaviour in social insects has been studied extensively, not much is known on its relation with feeding processes that occur within the nest. In the nest, food is commonly transferred between individuals in numerous oral feeding interactions (trophallaxis). Studies on the properties of these trophallactic networks have so far been limited by: (a) the difficulty to non‐intrusively measure food inside individual ants, let alone its nutritional composition, and (b) the meticulous manual labour involved in detecting trophallactic events.Our dual‐fluorescence imaging set‐up is designed to track two food sources, each labelled with a different fluorophore, as they are disseminated throughout a freely behaving colony of individually tagged ants. Additionally, our image‐based deep learning algorithm for automatic detection of ant trophallaxis events efficiently yields a detailed record of all food‐transfer interactions.Using a series of calibration experiments, we demonstrate the reliability of our measurements. We then exemplify the capabilities of our new method by tracking food dissemination in a colony of Camponotus sanctus ants supplied with two nutritionally distinct food sources. We follow the amount of each food type in the crop of each ant in the colony. Our data reveal the path in nutrient space that the colony took to reach its final nutrient intake, the contributions of the different forager ants to this path and the dynamic nutritional states of all ants in the colony. We further demonstrate the potential applicability of dual‐fluorescence food imaging to other insect species.Our system provides access to data that were previously unavailable and is crucial for a complete description of nutrient regulation by social insects. More broadly, the ability to simultaneously and efficiently track two material flows in a behaving colony provides new opportunities for tackling many open and emerging questions on topics other than nutrition, such as disease spread and social regulation of colony development. [ABSTRACT FROM AUTHOR]

Anthropogenic disturbances, including land use change and exotic species, can alter the diversity and dynamics of ant communities. To examine foraging behavior in an urbanized habitat in northern California, we surveyed the presence of 9 ant species on 876 trees across 4 seasons during both day and night in a 9.5-hectare urbanized oak-exotic woodland. Ants were more likely to be observed on native, evergreen trees, suggesting that native evergreen species may help maintain ant diversity. Species showed clear patterns of temporal partitioning of foraging activity. Ant species varied in their use of native evergreen Quercus agrifolia trees across season and day/night axes. Of the 3 ant species most frequently observed, Camponotus semitestaceus was most active during spring and summer nights, Formica moki was most active during spring and summer days, and Prenolepis imparis was most active during both day and night during fall and winter. Liometopum occidentale was the second most active species during summer day and night, and winter day. Our findings demonstrate that an oak-exotic urban woodland in Northern California was able to maintain a native ant community, and strong temporal partitioning within that community. [ABSTRACT FROM AUTHOR]

Aim: Extrafloral nectar, a carbohydrate‐rich liquid, is the main plant‐based resource offered in exchange for ant protection. The positive results of this protection provided by ants are widely studied and supported; however, studies showing the benefits that ants and their colonies have from the resources offered by plants such as extrafloral nectar are scarce. Here, we evaluated how extrafloral nectar and artificial food resources with different nutrient concentration benefit short‐ and long‐term Camponotus crassus colony fitness (number and weight of individuals) and survival. Methods: We conducted two sets of experiments: (1) in the field we attached artificial ant nests to plants with clogged and unclogged extrafloral nectaries; and (2) in the laboratory we offered artificial food resources with different carbohydrate–protein ratios to ant colonies. With these experiments, we evaluated the number and weight of queens, adult workers, pupae, larvae, and eggs, as well as the survival probability of the colonies. Results: In the first experiment, the short‐term provision of extrafloral nectar resulted in a larger number and weight of individuals with access to this resource. In the second experiment, regardless of time, the supply of more concentrated carbohydrate and nitrogen food increased ant colony fitness and survival. Conclusion: We provided new evidence that extrafloral nectar significantly benefits ant colonies. Our results corroborate the assertion that these relationships are reciprocally beneficial. [ABSTRACT FROM AUTHOR]

First, although these deadwood "follies" are meant for carpenter bees and carpenter ants, the structures will be attractive to a diversity of other insect species in the area. This study creatively adds a whole new layer to the existing landscape design, as the deadwood features will act both as social spaces and as homes for the target insect species, carpenter bees and carpenter ants. [Extracted from the article]

Eusocial insects tend to present low genetic diversity (GD) within colonies, which can increase with the co-occurrence of multiple queens (polygyny) or with multiple mating by a single queen (polyandry). Therefore, it is important to elucidate how these strategies influence GD, which in turn mediate population ecology and how organisms respond to their environment. We studied two carpenter ant species from the Brazilian savanna, Camponotus renggeri and C. rufipes. Using microsatellites, we evaluated the number of breeders, the genetic relatedness and the contribution of polygyny and polyandry to GD within colonies. Both species exhibited facultative polygyny. In C. renggeri , low related queens formed colonies jointly and present low mating frequency. In this species, colony GD increased with the number of queens. Contrastingly, closely related queens of C. rufipes formed polygynous colonies, exhibiting high mating frequency. In C. rufipes , both queens and males contributed to colony GD. Despite the differences, the two species have similar GD at the colony scale. Under low mating frequency, our data support that polygyny has evolutionary importance for increasing GD in ant colonies, a mechanism mainly conferred to polyandry. Although the impact of GD in variable ecological and adaptive contexts remains uncertain, this study highlights how distinct reproductive strategies may generate similar patterns of GD in ants. [ABSTRACT FROM AUTHOR]

Ants are known for their collective intelligence and efficient division of labor. Therefore, observations that seem to contradict these stereotypes are worth reporting. While observing a colony of Camponotus japonicus, we discovered that workers frequently dumped protein-rich food items at a particular spot, while other workers collected the dumped food items and brought them back to the nest. These two counteractive processes were performed simultaneously by the same colony, which indicates possible inefficiency of their collective labor. Discarding a specific type of food to calibrate the nutritional balance of a colony has been previously reported, but we found no reports on re-collecting discarded food. We suspect that this phenomenon might have been an outcome of communication inefficiency within the colony, or that the putative dump site might have served as a temporary deposit of food items before they were redistributed inside the nest. [ABSTRACT FROM AUTHOR]

As soil ecosystem engineers, ants considerably affect soil physical and chemical properties, and further accordingly affect soil erosion. However, few study was made on studying the effects of ant-burrowing activities on soil erosion previously. This study quantified the impacts of ant (Camponotus japonicus)-burrowing activities on runoff and soil erosion rates. Simulated laboratory rainfall experiments were undertaken on six soil tanks filled with clay-loam soil classified as a cumulic anthrosol, three of which introduced with ant colonies for two days and the other three were without ant colonies, under 40, 80, and 120 mm h−1 of rainfall intensities and a slope of 15°. Results showed that ants made mounds with a bulk density of 0.75 g cm−3, which was lower than that of the soil matrix, i.e. 1.34 g cm−3. Soil erosion rates for the tanks with ants were 6.78, 36.90, and 62.00 g m−2 min−1 under three rainfall intensities of 40, 80, and 120 mm h−1, which were much higher than those of 3.94, 23.49, and 44.48 g m−2 min−1 for the tanks without ants. Ant nests reduced the runoff rate by 31%, 20% and 13% compared with those without ants and enhanced the soil water storage within 90 cm depth. Ant nests played a positive role in soil water conservation due to the large nest entrance diameter and the continuous macropore network. However, the ant mounds provided a loose erodible material and changed micro-topography of the slope surface, thereby accelerating the rill formation and exacerbating soil erosion. This study can help understand the effects of burrowing insects on soil erosion, which is an important environmental problem on the Loess Plateau. • Ant nests reduced the runoff rate and increased soil water storage. • Ant mounds changed the micro-topography and accelerated rill generation. • Ant mounds increased soil erosion rate on bare slopes. [ABSTRACT FROM AUTHOR]

Summary: Ants alter soil structure when making their nests and the fresh soil aggregates brought to the surface become available for erosion. However, the effects of burrowing activities of ants on soil hydrological processes are unclear. In this study, the effects of Tetramorium caespitum, Messor aciculatus and Camponotus japonicus nests on the preferential flow and soil surface hydrologic processes at a small scale were assessed on the Loess Plateau. Soil dyeing and rainfall simulation experiments were conducted to quantify the effects of ants' nests on runoff and water infiltration on slopes. The diameters of nest entrances for T. caespitum, M. aciculatus and C. japonicus were 0.19, 0.33 and 0.56 cm, respectively. The nests of M. aciculatus and C. japonicus promoted water infiltration, resulted in large soil water contents and decreased surface runoff. The turret‐like mounds around the nest entrances made by T. caespitum prevented the formation of soil preferential flow. The depths of dyeing in the soil with M. aciculatus and C. japonicus nests were 32.6 and 49.2 cm, respectively, which were significantly (P < 0.05) deeper than those in the soil with T. caespitum nests (10.0 cm) and no nest (10.3 cm). The unstable soil aggregates made by ants on the soil surface break down easily and encourage the loss of soil sediment. The results show that increasing the ant colonies, especially those with larger bodies, could be considered a strategy to increase water infiltration and soil water content in semiarid areas. In the meantime, the sediment loss cannot be neglected. Highlights: This study evaluated the effects of hypogeal ants on soil erosion.The turret‐like mounds of T. caespitum prevent the formation of preferential flow.Ants with larger bodies made bigger nest entrances and resulted in more infiltration.The burrowing activities of ants exacerbate soil erosion. [ABSTRACT FROM AUTHOR]

The ecological and evolutionary success of social insects relies on their ability to efficiently discriminate between group members and aliens. Nestmate recognition occurs by phenotype matching, the comparison of the referent (colony) phenotype to the one of an encountered individual. Based on the level of dissimilarity between the two, the discriminator accepts or rejects the target. The tolerated degree of mismatch is predicted by the acceptance threshold model, which assumes adaptive threshold shifts depending on the costs of discrimination errors. Inherent in the model is that rejection (type I) and acceptance (type II) errors are reciprocally related: if one type decreases, the other increases. We studied whether alarm pheromones modulate the acceptance threshold. We exposed Camponotus aethiops ants to formic acid and subsequently measured aggression toward nestmates and nonnestmates. Formic acid induced both more nonnestmate rejection and more nestmate acceptance than a control treatment, thus uncovering an unexpected effect of an alarm pheromone on responses to nestmates. Nestmate discrimination accuracy was improved via a decrease in both types of errors, a result that cannot be explained by a shift in the acceptance threshold. We propose that formic acid increases the amount of information available to the ants, thus decreasing the perceived phenotypic overlap between nestmate and nonnestmate recognition cues. This mechanism for improved discrimination reveals a novel function of alarm pheromones in recognition processes and may have far-reaching implications in our understanding of the modus operandi of recognition systems in general. [ABSTRACT FROM AUTHOR]

Nutritional regulation by ants emerges from a distributed process: food is collected by a small fraction of workers, stored within the crops of individuals, and spread via local ant-to-ant interactions. The precise individual-level underpinnings of this collective regulation have remained unclear mainly due to difficulties in measuring food within ants' crops. Here we image fluorescent liquid food in individually tagged Camponotus sanctus ants and track the real-time food flow from foragers to their gradually satiating colonies. We show how the feedback between colony satiation level and food inflow is mediated by individual crop loads; specifically, the crop loads of recipient ants control food flow rates, while those of foragers regulate the frequency of foraging-trips. Interestingly, these effects do not rise from pure physical limitations of crop capacity. Our findings suggest that the emergence of food intake regulation does not require individual foragers to assess the global state of the colony. [ABSTRACT FROM AUTHOR]

1. Traits are hypothesised to optimise via natural selection. The schedule of reproduction is an important adaptive trait, but its evolution is difficult to study, as measuring parameters is usually difficult. However, the sufficient amounts of demographic data enable us to estimate these parameters. 2. Here, it is shown that the reproductive schedule of the ant Camponotus (Colobopsis) nipponicus is tuned to maximise the lifetime production of alates. 3. A colony started its reproduction 4 years after the colony founding, at which time they were far smaller than well-developed colonies. This contradicts the prediction of the bang-bang strategy theory. The size distribution of colonies in the study area showed that the mortality of small colonies is much higher than that of large colonies. 4. A simulation analysis suggests that the colonies that are smaller than the threshold can still achieve significant improvement in colny survival to the following year by investing all resources in colony growth instead of reproduction. A sensitivity analysis for the starting year of reproduction showed that the observed schedule maximises lifetime alate production. The demographic data suggest a stable population, which is required for optimisation through this maximisation. 5. The observed reproductive schedule must be optimised, and the breakdown of the bang-bang theory is due to higher mortalities during the incipient stage of colonies. This study demonstrates that having enough demographic data creates a useful tool for studying the evolution of life-history characteristics. [ABSTRACT FROM AUTHOR]

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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]

A higher proportion of polygynous ant species in northern areas suggests that cold climates select for increased queen number per colony. However, the types of social conditions within nests that allow polygynous species to inhabit cold climates are unclear. The Japanese twig-dwelling ant, Camponotus yamaokai Terayama & Satoh, 1990, which has on average two queens per colony, also inhabit colder areas than monogynous related species. C. yamaokai alates remain in natal colonies and always overwinter with workers. A previous study demonstrated that cohabitation by workers facilitates overwintering success of C. yamaokai queens. However, how queen number influences the survival of queens cohabitating with workers and the survival of other castes was not investigated. Here, we compared overwintering survival of queens and workers among experimental groups with different social structures. Wintering experiments revealed that queen survival did not differ between monogynous (one queen) and polygynous (two queens) groups but was correlated positively with worker number. Meanwhile both queen and worker number influenced worker survival, and these factors interacted with worker type (minor or major). Worker survival increased with increasing worker number, but the effect was more pronounced for major workers than for minor workers. With respect to queen number, minor workers survived longer in polygynous groups than in monogynous groups, whereas the opposite pattern was found in major workers. In other words, major worker mortality increased with increasing queen number. These results suggest that cohabitation with workers but not other queens facilitates queen survival, and that queen number increases survival in minor workers but increases mortality in major workers. Possible explanations for this latter pattern are discussed. [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]

Conditions necessary for optimal colony foundation in two carpenter ant species, Camponotus modoc Wheeler and Camponotus vicinus Mayr, were studied. Camponotus modoc and C. vicinus queens were placed in Douglas-fir, Pseudotsuga menziesii (Mirb. Franco) and Styrofoam blocks conditioned in sealed chambers at 70, 80, or 100% RH. Nanitic workers produced after 12 wk were used to assess the effects of substrate and moisture content on colony initiation. Queens of C. vicinus in Douglas-fir and Styrofoam produced worker numbers that did not differ significantly with moisture content; however, the number of colonies initiated by C. modoc differed significantly with moisture content. The results indicate that colony founding in C. vicinus is less sensitive to moisture content than C. modoc for Douglas-fir and Styrofoam. In another test, groups of queens of each species were exposed to 20, 50, 70, and 100% RH and the time until 50% mortality occurred was recorded for each species. C. vicinus lived significantly longer at each of the test humidities than C. modoc, suggesting that the former species is adapted to better survive under xeric conditions. [ABSTRACT FROM AUTHOR]

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]

The objective of this study was to evaluate, in vitro, the colonization and destruction of ants of the genus Camponotus sp. by the ovicidal fungus Pochonia chlamydosporia (VC4 isolate), in the southeast region of Brazil. The insects used in the experiment were worker ants of the genus Camponotus sp., collected periodically in the environment and immediately transported to the laboratory in test tubes. Then, VC4 growth was promoted in 2% chitin agar medium (2% WQ) to obtain a fungal solution containing conidia and/or chlamydospores. Two experimental groups were formed. Treated group consisted of Petri dishes containing 2% agar-water culture medium (2% WA) with nine live insects and 20 µL of fungal solution at the concentration of 15,000 conidia/chlamydospores. Control group consisted of Petri dishes containing 2% WA culture medium and nine live insects. The dishes in the treated and control groups were incubated in BOD at 25 ± 1 °C and 80 ± 10% relative humidity for 4 days. After 4 days, it was observed that the VC4 had grown, colonized, and caused the destruction of the ants. The fungus P. chlamydosporia was efficient at colonizing and destroying the urban ants collected on an experimental basis. Thus, it could open up new ways to reduce the use of chemical compounds in the future, decreasing health and environmental problems. [ABSTRACT FROM AUTHOR]