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Society in eusocial insects is based on the reproductive division of labor, with a small number of reproductive individuals supported by a large number of non-reproductive individuals. Because inclusive fitness of all colony members depends on the survival and fertility of reproductive members, sterile members provide royals with special treatment. Here we show that termite kings and queens each receive special food of a different composition from workers. Sequential analysis of feeding processes demonstrated that workers exhibit discriminative trophallaxis, indicating their decision-making capacity in allocating food to the kings and queens. LC-MS/MS analyses of the stomodeal food and midgut contents revealed king- and queen-specific compounds including diacylglycerols and short-chain peptides. DESI-MSI analyses of ¹³C-labelled termites identified phosphatidylinositol and acetyl-L-carnitine in the royal food. Comparison of the digestive tract structure showed remarkable differences in the volume ratio of the midgut-to-hindgut among castes, indicating that digestive division of labor underlies reproductive division of labor. Our demonstration of king- and queen-specific food in termites provides insight into the nutritional system that underpins the extraordinary reproduction and longevity of royals in eusocial insects.

Bumble bee queens initiate nests solitarily and transition to living socially once they successfully rear their first cohort of offspring. Bumble bees are disproportionately important for early season pollination, and many populations are experiencing dramatic declines. In this system, the onset of the social stage is critical for nest survival, yet the mechanisms that facilitate this transition remain understudied. Further, the majority of conservation efforts target the social stage of the bumble bee life cycle and do not address the solitary founding stage. We experimentally manipulated the timing of worker emergence in young nests of bumble bee (Bombus impatiens) queens to determine whether and how queen fecundity and survival are impacted by the emergence of workers in the nest. We found that queens with workers added to the nest exhibit increased ovary activation, accelerated egg laying, elevated juvenile hormone (JH) titres and also lower mortality relative to solitary queens. We also show that JH is more strongly impacted by the social environment than associated with queen reproductive state, suggesting that this key regulator of insect reproduction has expanded its function in bumble bees to also influence social organization. We further demonstrate that these effects are independent of queen social history, suggesting that this underlying mechanism promoting queen fecundity is reversible and short lived. Synchronization between queen reproductive status and emergence of workers in the nest may ultimately increase the likelihood of early nesting success in social systems with solitary nest founding. Given that bumble bee workers regulate queen physiology as we have demonstrated, the timing of early worker emergence in the nest likely impacts queen fitness, colony developmental trajectories and ultimately nesting success. Collectively, our findings underline the importance of conservation interventions for bumble bees that support the early nesting period a

Agricultural and apicultural practices expose honeybees to a range of pesticides that have the potential to negatively affect their physiology, neurobiology, and behavior. Accumulating evidence suggests that these effects extend to the honeybee gut microbiome, which serves important functions for honeybee health. Here we test the potential effects of the pesticides thiacloprid, acetamiprid, and oxalic acid on the gut microbiota of honeybees, first in direct in vitro inhibition assays and secondly in an in vivo caged bee experiment to test if exposure leads to gut microbiota community changes. We found that thiacloprid did not inhibit the honeybee core gut bacteria in vitro, nor did it affect overall community composition or richness in vivo. Acetamiprid did also not inhibit bacterial growth in vitro, but it did affect community structure within bees. The eight bacterial genera tested showed variable levels of susceptibility to oxalic acid in vitro. In vivo, treatment with this pesticide reduced amplicon sequence variant (ASV) richness and affected gut microbiome composition, with most marked impact on the common crop bacteria Lactobacillus kunkeei and the genus Bombella. We conducted network analyses which captured known associations between bacterial members and illustrated the sensitivity of the microbiome to environmental stressors. Our findings point to risks of honeybee exposure to oxalic acid, which has been deemed safe for use in treatment against Varroa mites in honeybee colonies, and we advocate for more extensive assessment of the long-term effects that it may have on honeybee health.

Agricultural and apicultural practices expose honeybees to a range of pesticides that have the potential to negatively affect their physiology, neurobiology, and behavior. Accumulating evidence suggests that these effects extend to the honeybee gut microbiome, which serves important functions for honeybee health. Here we test the potential effects of the pesticides thiacloprid, acetamiprid, and oxalic acid on the gut microbiota of honeybees, first in direct in vitro inhibition assays and secondly in an in vivo caged bee experiment to test if exposure leads to gut microbiota community changes. We found that thiacloprid did not inhibit the honeybee core gut bacteria in vitro, nor did it affect overall community composition or richness in vivo. Acetamiprid did also not inhibit bacterial growth in vitro, but it did affect community structure within bees. The eight bacterial genera tested showed variable levels of susceptibility to oxalic acid in vitro. In vivo, treatment with this pesticide reduced amplicon sequence variant (ASV) richness and affected gut microbiome composition, with most marked impact on the common crop bacteria Lactobacillus kunkeei and the genus Bombella. We conducted network analyses which captured known associations between bacterial members and illustrated the sensitivity of the microbiome to environmental stressors. Our findings point to risks of honeybee exposure to oxalic acid, which has been deemed safe for use in treatment against Varroa mites in honeybee colonies, and we advocate for more extensive assessment of the long-term effects that it may have on honeybee health.

Social insect genomes exhibit the highest rates of crossing over observed in plants and animals. The evolutionary causes of these extreme rates are unknown. Insight can be gained by comparing recombination rate variation across the genomes of related social and solitary insects. Here, we compare the genomic recombination landscape of the highly social honey bee, Apis mellifera, with the solitary alfalfa leafcutter bee, Megachile rotundata, by analyzing patterns of linkage disequilibrium in population-scale genome sequencing data. We infer that average recombination rates are extremely elevated in A. mellifera compared with M. rotundata. However, our results indicate that similar factors control the distribution of crossovers in the genomes of both species. Recombination rate is significantly reduced in coding regions in both species, with genes inferred to be germline methylated having particularly low rates. Genes with worker-biased patterns of expression in A. mellifera and their orthologs in M. rotundata have higher than average recombination rates in both species, suggesting that selection for higher diversity in genes involved in worker caste functions in social taxa is not the explanation for these elevated rates. Furthermore, we find no evidence that recombination has modulated the efficacy of selection among genes during bee evolution, which does not support the hypothesis that high recombination rates facilitated positive selection for new functions in social insects. Our results indicate that the evolution of sociality in insects likely entailed selection on modifiers that increased recombination rates genome wide, but that the genomic recombination landscape is determined by the same factors.

Social insect colonies possess a range of defences which protect them against highly virulent parasites and colony collapse. The host–parasite interaction between honey bees (Apis mellifera) and the mite Varroa destructor is unusual, as honey bee colonies are relatively poorly defended against this parasite. The interaction has existed since the mid-20th Century, when Varroa switched host to parasitize A. mellifera. The combination of a virulent parasite and relatively naïve host means that, without acaricides, honey bee colonies typically die within 3 years of Varroa infestation. A consequence of acaricide use has been a reduced selective pressure for the evolution of Varroa resistance in honey bee colonies. However, in the past 20 years, several natural-selection-based breeding programmes have resulted in the evolution of Varroa-resistant populations. In these populations, the inhibition of Varroa's reproduction is a common trait. Using a high-density genome-wide association analysis in a Varroa-resistant honey bee population, we identify an ecdysone-induced gene significantly linked to resistance. Ecdysone both initiates metamorphosis in insects and reproduction in Varroa. Previously, using a less dense genetic map and a quantitative trait loci analysis, we have identified Ecdysone-related genes at resistance loci in an independently evolved resistant population. Varroa cannot biosynthesize ecdysone but can acquire it from its diet. Using qPCR, we are able to link the expression of ecdysone-linked resistance genes to Varroa's meals and reproduction. If Varroa co-opts pupal compounds to initiate and time its own reproduction, mutations in the host's ecdysone pathway may represent a key selection tool for honey bee resistance and breeding.

This thesis aimed to use a social insect model to investigate the effect of membrane phospholipid composition on longevity. The two female castes of honeybees are genetically identical yet become either exceptionally long-lived queens (up to 8 years) or short-lived workers (typically 2-6 weeks). This distinction is based on dietary supply during the larval developmental stage where queens are immersed in liquid food (royal jelly) until metamorphosis (pupation) whereas workers get a restricted supply of royal jelly. After emergence, workers begin feeding on honey and pollen (‘bee bread’) with pollen containing a high level of polyunsaturated fatty acids (PUFA), whereas queens feed exclusively on royal jelly with negligible PUFA (assumed to be the same jelly they receive as larvae). PUFA are capable of significant levels of oxidation (i.e. peroxidation) whereas monounsaturated (MUFA) and saturated (SAT) fatty acids are very resistant to peroxidation. Therefore, this thesis investigated the role of dietary lipids (specifically PUFA) and its potential to determine longevity differences in female honeybees. Membrane phospholipids of six different life-history stages, covering all developmental stages from little larva to old adults of the castes of the honey bees (Apis mellifera) were analysed using shotgun mass spectrometry lipidomics. The membrane phospholipids of workers and queens as larvae, pupae, and newly emergent adults all had low PUFA and high MUFA levels. However, queens continued to maintain low PUFA and high MUFA levels throughout their entire lives whereas, by day 4 of adult life, worker bees had increased their PUFA levels 5-fold, with a commensurate decrease in MUFA. This difference in membrane composition appears due to the difference in nutrition after adult emergence. The increase in PUFA in worker membranes occurred in all phospholipid classes but predominantly in phosphatidylcholine (PC) and phosphatidylethanolamine (PE) molecules. The low level of P

Termites are important ecosystem engineers. Yet they are often difficult to identify due to the lack of reliable species-specific morphological traits for many species, which hampers ecological research. Recently, termitologists working with West African termites (West African Termite Taxonomy Initiative) convened for a workshop with the aim of beginning to address this problem. Repeated determination of the same termite samples by the most renowned taxonomists for West African termites identified the huge scale of the problem, as less than 10% of all species could be unambiguously determined to the species level. Intensive discussions and comparisons increased the identification success to around 25% at the end of the workshop. Yet many groups remained problematic and molecular markers and barcoding techniques combined with species delimitation approaches will be needed to help resolve these existing taxonomic problems. Based on the outcome of this workshop, we propose concerted initiatives to address termite taxonomy on a global scale. We are convinced that dedicated workshops on regional taxonomy that follow a similar structured approach, with repeated determination of the same sample, will help overcome the difficulties that termite taxonomy faces. This initiative can also serve as a blueprint for other taxonomical groups that are difficult to identify., SCOPUS: re.j, info:eu-repo/semantics/published

Social insects have evolved enormous capacities to collectively build nests and defend their colonies against both predators and pathogens. The latter is achieved by a combination of individual immune responses and sophisticated collective behavioral and organizational disease defenses, that is, social immunity. We investigated how the presence or absence of these social defense lines affects individual‐level immunity in ant queens after bacterial infection. To this end, we injected queens of the ant Linepithema humile with a mix of gram+ and gram− bacteria or a control solution, reared them either with workers or alone and analyzed their gene expression patterns at 2, 4, 8, and 12 hr post‐injection, using RNA‐seq. This allowed us to test for the effect of bacterial infection, social context, as well as the interaction between the two over the course of infection and raising of an immune response. We found that social isolation per se affected queen gene expression for metabolism genes, but not for immune genes. When infected, queens reared with and without workers up‐regulated similar numbers of innate immune genes revealing activation of Toll and Imd signaling pathways and melanization. Interestingly, however, they mostly regulated different genes along the pathways and showed a different pattern of overall gene up‐regulation or down‐regulation. Hence, we can conclude that the absence of workers does not compromise the onset of an individual immune response by the queens, but that the social environment impacts the route of the individual innate immune responses.

The antagonistic relationship between parasites and their hosts is strongly influenced by genotype-by-genotype interactions. Defense against parasitism is commonly studied in the context of immune system-based mechanisms and, thus, the focus in the search for candidate genes in host-parasite interactions is often on immune genes.In this study, we investigated the association between prevalence of parasite infection and host mitochondrial DNA (mtDNA) haplotypes in two natural populations of bumblebees (Bombus terrestris). The two most common haplotypes of the host populations, termed A and B, differ by a single nonsynonymous nucleotide substitution within the coding region of cytochrome oxidase I, an important player in metabolic pathways. We screened infection by Nosema bombi, a common endoparasite of bumblebees, and the corresponding host mtDNA-haplotype frequencies in over 1400 bumblebees between 2000 and 2010. The island population of Gotland showed lower mtDNA diversity compared to the mainland population in Switzerland. Over time, we observed large fluctuations in infection prevalence, as well as variation in host haplotype frequencies in both populations. Our long-term observation revealed that N. bombi infection of specific host genotypes is transient: We found that withincreasing infection prevalence, proportionally more individuals with haplotype B, but fewer individuals with haplotype A were infected. This suggests that the presence of N. bombi in specific host genotypes relates to infection prevalence. This may be a result of parasite competition, or differential resilience of host types to ward off infections. The findings highlight the important role of host mtDNA haplotypes in the interaction with parasites.

Starvation is one of the most common and severe stressors in nature. Not only does it lead to death if not alleviated, it also forces the starved individual to allocate resources only to the most essential processes. This creates energetic trade-offs which can lead to many secondary challenges for the individual. These energetic trade-offs could be exacerbated in inbred individuals, which have been suggested to have a less efficient metabolism. Here, we studied the effect of inbreeding on starvation resistance in a natural population of Formica exsecta ants, with a focus on survival and tissue-specific expression of stress, metabolism and immunity-related genes. Starvation led to large tissue-specific changes in gene expression, but inbreeding had little effect on most of the genes studied. Our results illustrate the importance of studying stress responses in different tissues instead of entire organisms.

Task allocation among social insect workers is an ideal framework for studying the molecular mechanisms underlying behavioural plasticity because workers of similar genotype adopt different behavioural phenotypes. Elegant laboratory studies have pioneered this effort, but field studies involving the genetic regulation of task allocation are rare. Here, we investigate the expression of the foraging gene in harvester ant workers from five age- and task-related groups in a natural population, and we experimentally test how exposure to light affects foraging expression in brood workers and foragers. Results from our field study show that the regulation of the foraging gene in harvester ants occurs at two time scales: levels of foraging mRNA are associated with ontogenetic changes over weeks in worker age, location and task, and there are significant daily oscillations in foraging expression in foragers. The temporal dissection of foraging expression reveals that gene expression changes in foragers occur across a scale of hours and the level of expression is predicted by activity rhythms: foragers have high levels of foraging mRNA during daylight hours when they are most active outside the nests. In the experimental study, we find complex interactions in foraging expression between task behaviour and light exposure. Oscillations occur in foragers following experimental exposure to 13 L : 11 D (LD) conditions, but not in brood workers under similar conditions. No significant differences were seen in foraging expression over time in either task in 24 h dark (DD) conditions. Interestingly, the expression of foraging in both undisturbed field and experimentally treated foragers is also significantly correlated with the expression of the circadian clock gene, cycle Our results provide evidence that the regulation of this gene is context-dependent and associated with both ontogenetic and daily behavioural plasticity in field colonies of harvester ants. Our results underscore t

"All cold-blooded animals and a large number of warm-blooded ones spend an unexpectedly large proportion of their time doing nothing at all, or at any rate, nothing in particular." (Elton 1927) Many animals are remarkably "lazy", spending >50% of their waking hours "resting" . This is common across all taxa, ecologies, and life histories, including what are commonly considered to be highly industrious animals: the social insects (e.g., Aesop's Fable 'The Grasshopper and the Ant'). This dissertation broadly seeks to explain a phenomenon that has long been observed, but never adequately addressed, by asking: 'why are there 'lazy' ants?' First, I established that inactivity was a real and ecologically relevant phenomenon in the ant Temnothorax rugatulus by testing whether inactivity was a lab artifact. I then showed that inactive workers comprise a behaviorally distinct group of workers that are commonly overlooked in studies looking at colony function, though they typically represent at least half of the individuals within social insect colonies. I then tested a set of mutually non-exclusive hypotheses explaining inactivity in social insects: that (1) inactivity is a form of social "cheating" in which egg-laying workers selfishly invest in their own reproduction rather than contribute to colony fitness, (2) inactive workers comprise a pool of reserve workers used to mitigate the effects of fluctuations in colony workload, (3) inactivity is the result of physiological constraints on worker age such that young and old workers may less active due to inexperience/physical vulnerability, and physiological deterioration respectively, (4) inactive workers are performing an as-yet unidentified function, such as playing a role in communication and acting as food stores, or repletes, and that (5) inactive workers represent the 'slow' end of intra-nest variation in worker 'pace-of-life'. Inactivity is linked to worker age, reproduction, and a potential function as food stores fo

The reproductive division of labour between queen and worker castes in social insects is a defining characteristic of eusociality and a classic example of phenotypic plasticity. Whether social insect larvae develop into queens or workers has long been thought to be determined by environmental cues, i.e. larvae are developmentally totipotent. Contrary to this paradigm, several recent studies have revealed that caste is determined by genotype in some ant species, but whether this is restricted to just a few exceptional species is still unclear. Here, we show that the Mediterranean harvester ant Messor barbarus possesses an unusual reproductive system, in which the female castes are genetically determined. Using both nuclear and mitochondrial data, we show that Iberian populations have two distinct, cryptic lineages. Workers are always inter-lineage hybrids whereas queens are always produced from pure-lineage matings. The results suggest that genetic caste determination may be more widespread in ants than previously thought, and that further investigation in other species is needed to understand the frequency and evolution of this remarkable reproductive system., SCOPUS: ar.j, info:eu-repo/semantics/published

In most social insects, the brood is totipotent and environmental factors determine whether a female egg will develop into a reproductive queen or a functionally sterile worker. However, genetic factors have been shown to affect the female's caste fate in a few ant species. The desert ant Cataglyphis hispanica reproduces by social hybridogenesis. All populations are characterized by the coexistence of two distinct genetic lineages. Queens are almost always found mated with a male of the alternate lineage than their own. Workers develop from hybrid crosses between the genetic lineages, whereas daughter queens are produced asexually via parthenogenesis. Here, we show that the association between genotype and caste in this species is maintained by a 'hard-wired' genetic caste determination system, whereby nonhybrid genomes have lost the ability to develop as workers. Genetic analyses reveal that, in a rare population with multiple-queen colonies, a significant proportion of nestmate queens are mated with males of their own lineage. These queens fail to produce worker offspring; they produce only purebred daughter queens by sexual reproduction. We discuss how the production of reproductive queens through sexual, intralineage crosses may favour the stability of social hybridogenesis in this species. Journal of Evolutionary Biology, SCOPUS: ar.j, FLWIN, info:eu-repo/semantics/published

In most social insects, the brood is totipotent and environmental factors determine whether a female egg will develop into a reproductive queen or a functionally sterile worker. However, genetic factors have been shown to affect the female's caste fate in a few ant species. The desert ant Cataglyphis hispanica reproduces by social hybridogenesis. All populations are characterized by the coexistence of two distinct genetic lineages. Queens are almost always found mated with a male of the alternate lineage than their own. Workers develop from hybrid crosses between the genetic lineages, whereas daughter queens are produced asexually via parthenogenesis. Here, we show that the association between genotype and caste in this species is maintained by a 'hard-wired' genetic caste determination system, whereby nonhybrid genomes have lost the ability to develop as workers. Genetic analyses reveal that, in a rare population with multiple-queen colonies, a significant proportion of nestmate queens are mated with males of their own lineage. These queens fail to produce worker offspring; they produce only purebred daughter queens by sexual reproduction. We discuss how the production of reproductive queens through sexual, intralineage crosses may favour the stability of social hybridogenesis in this species. Journal of Evolutionary Biology, SCOPUS: ar.j, FLWIN, info:eu-repo/semantics/published

The division of labour plays a major role in the success of social insects. For instance, through social prophylaxis, the spread of pathogens within the colony can be reduced if corpse removal is the concern of a specialized group of ants. However, in relatively small colonies, the number of dead individuals and the amount of waste may be too low to justify a specialized group of corpse carriers. We examined the corpse removal habits of the common red ant, Myrmica rubra. Ants acting as corpse carriers were not strictly specialized in corpse management, but split their time between disposing of the dead and foraging. Some corpse-carrying individuals, however, developed a short-term specialization by making several successive corpse transports. Corpse carriers limited cross-contamination by remaining mostly outside the nest and congregating near the nest entrance when resting inside. © 2013 The Association for the Study of Animal Behaviour., SCOPUS: ar.j, info:eu-repo/semantics/published

The division of labour plays a major role in the success of social insects. For instance, through social prophylaxis, the spread of pathogens within the colony can be reduced if corpse removal is the concern of a specialized group of ants. However, in relatively small colonies, the number of dead individuals and the amount of waste may be too low to justify a specialized group of corpse carriers. We examined the corpse removal habits of the common red ant, Myrmica rubra. Ants acting as corpse carriers were not strictly specialized in corpse management, but split their time between disposing of the dead and foraging. Some corpse-carrying individuals, however, developed a short-term specialization by making several successive corpse transports. Corpse carriers limited cross-contamination by remaining mostly outside the nest and congregating near the nest entrance when resting inside. © 2013 The Association for the Study of Animal Behaviour., SCOPUS: ar.j, info:eu-repo/semantics/published

The ant, Formica japonica, is polyphagous and workers hunt other insects as foods. In this study, interspecific aggression was examined in the workers and queens. Behavior experiments demonstrated that interspecific aggressiveness was significantly higher in workers than queens. Workers showed predatory aggressive behavior towards crickets, on the other hand, queens elicited threat behavior but they didn't attack crickets. In order to investigate neuronal mechanisms underlying regulation of aggressive motivation, the role of biogenic amine in the brain in evoking aggressive behavior was examined by measuring biogenic amine using high-performance liquid chromatography (HPLC) with electrochemical detection (ECD). No significant difference in the octopamine (OA) level was found between workers and queens, but the level of N-acetyloctopamine (NacOA) in the brain of queens was significantly higher than that of workers. This study suggests that OAergic system in the brain must involve in controlling aggressive motivation in the ants.

Several genetic and nongenetic hypotheses have been formulated to account for the evolution and maintenance of multiple mating by females (polyandry) in social Hymenoptera. A major hypothesis argues that polyandry allows production of geneti- cally diverse workers varying in their inclination to perform different tasks, thereby enhancing division of labor and colony task efficiency. We tested the relationship between patriline, worker size, and task specialization in the ant Cataglyphis cursor, a spe- cies showing natural variation in queen mating frequency. Our results reveal a significant association between patriline and task preference: workers belonging to different patrilines differ in their propensity to perform a given task (foraging, nest construc- tion, waste management, or food storage). Furthermore, we found that worker size is closely associated with task specialization but not with paternal origin. Overall, these results show that task performance is at least partly genetically influenced in the ant C. cursor, which is a key prerequisite for polyandry to improve division of labor in social insects., SCOPUS: ar.j, info:eu-repo/semantics/published

The ant, Formica japonica, is polyphagous and workers hunt other insects as foods. In this study, interspecific aggression was examined in the workers and queens. Behavior experiments demonstrated that interspecific aggressiveness was significantly higher in workers than queens. Workers showed predatory aggressive behavior towards crickets, on the other hand, queens elicited threat behavior but they didn't attack crickets. In order to investigate neuronal mechanisms underlying regulation of aggressive motivation, the role of biogenic amine in the brain in evoking aggressive behavior was examined by measuring biogenic amine using high-performance liquid chromatography (HPLC) with electrochemical detection (ECD). No significant difference in the octopamine (OA) level was found between workers and queens, but the level of N-acetyloctopamine (NacOA) in the brain of queens was significantly higher than that of workers. This study suggests that OAergic system in the brain must involve in controlling aggressive motivation in the ants.

The ant, Formica japonica, is polyphagous and workers hunt other insects as foods. In this study, interspecific aggression was examined in the workers and queens. Behavior experiments demonstrated that interspecific aggressiveness was significantly higher in workers than queens. Workers showed predatory aggressive behavior towards crickets, on the other hand, queens elicited threat behavior but they didn't attack crickets. In order to investigate neuronal mechanisms underlying regulation of aggressive motivation, the role of biogenic amine in the brain in evoking aggressive behavior was examined by measuring biogenic amine using high-performance liquid chromatography (HPLC) with electrochemical detection (ECD). No significant difference in the octopamine (OA) level was found between workers and queens, but the level of N-acetyloctopamine (NacOA) in the brain of queens was significantly higher than that of workers. This study suggests that OAergic system in the brain must involve in controlling aggressive motivation in the ants.

The ant, Formica japonica, is polyphagous and workers hunt other insects as foods. In this study, interspecific aggression was examined in the workers and queens. Behavior experiments demonstrated that interspecific aggressiveness was significantly higher in workers than queens. Workers showed predatory aggressive behavior towards crickets, on the other hand, queens elicited threat behavior but they didn't attack crickets. In order to investigate neuronal mechanisms underlying regulation of aggressive motivation, the role of biogenic amine in the brain in evoking aggressive behavior was examined by measuring biogenic amine using high-performance liquid chromatography (HPLC) with electrochemical detection (ECD). No significant difference in the octopamine (OA) level was found between workers and queens, but the level of N-acetyloctopamine (NacOA) in the brain of queens was significantly higher than that of workers. This study suggests that OAergic system in the brain must involve in controlling aggressive motivation in the ants.

Several genetic and nongenetic hypotheses have been formulated to account for the evolution and maintenance of multiple mating by females (polyandry) in social Hymenoptera. A major hypothesis argues that polyandry allows production of geneti- cally diverse workers varying in their inclination to perform different tasks, thereby enhancing division of labor and colony task efficiency. We tested the relationship between patriline, worker size, and task specialization in the ant Cataglyphis cursor, a spe- cies showing natural variation in queen mating frequency. Our results reveal a significant association between patriline and task preference: workers belonging to different patrilines differ in their propensity to perform a given task (foraging, nest construc- tion, waste management, or food storage). Furthermore, we found that worker size is closely associated with task specialization but not with paternal origin. Overall, these results show that task performance is at least partly genetically influenced in the ant C. cursor, which is a key prerequisite for polyandry to improve division of labor in social insects., SCOPUS: ar.j, info:eu-repo/semantics/published

The organization of complex societies requires constant information to flow between individuals. Because of their elaborated social structures and principally because of the division of labor, social insects depend on the efficacy of their information web in order to adapt the colony activity to its needs. Although many studies focused on understanding the regulation of the foraging activity, little is known about the intranidal food distribution and stock management regulation. The aim of this thesis is to quantify and describe the dynamics of the food flow and its regulation in an ant colony. A medical imagery technique, scintigraphy, was adapted to follow the propagation of radio-labeled nutrients inside the nest. This technique allowed spatiotemporal dynamics quantification of the food flow and led to the enunciation of simple yet robust regulation rules that are at work during the colony feeding process.The dynamics of the harvest is regulated by the coupling of a positive and negative feedbacks. The harvest acts as both: negative and positive feedbacks. Entering food-loads trigger foragers to exploit the newly discovered food source through the well-known recruitment process. At the same time, the harvest proportionally reduces the entering food flow until the complete stop of the foraging activity when the colony reaches satiety. Surprisingly, the positive feedback (that is the recruitment) is not responsible for a faster entering food flow and is not influenced by the colony needs while the exploring activity is. The spatial dynamics of the food exchange network revealed stable patterns and fine tuning regulation of the feeding process. Spatial analysis of the food distribution showed that sucrose is heterogeneously stored among individuals and also heterogeneously consumed. We observed a regular spatial structure leading to centralization of the stocks: heavy loaded individuals being at the center of the cluster and weakly loaded individuals at its perip, Doctorat en Sciences, info:eu-repo/semantics/nonPublished

The organization of complex societies requires constant information to flow between individuals. Because of their elaborated social structures and principally because of the division of labor, social insects depend on the efficacy of their information web in order to adapt the colony activity to its needs. Although many studies focused on understanding the regulation of the foraging activity, little is known about the intranidal food distribution and stock management regulation. The aim of this thesis is to quantify and describe the dynamics of the food flow and its regulation in an ant colony. A medical imagery technique, scintigraphy, was adapted to follow the propagation of radio-labeled nutrients inside the nest. This technique allowed spatiotemporal dynamics quantification of the food flow and led to the enunciation of simple yet robust regulation rules that are at work during the colony feeding process.The dynamics of the harvest is regulated by the coupling of a positive and negative feedbacks. The harvest acts as both: negative and positive feedbacks. Entering food-loads trigger foragers to exploit the newly discovered food source through the well-known recruitment process. At the same time, the harvest proportionally reduces the entering food flow until the complete stop of the foraging activity when the colony reaches satiety. Surprisingly, the positive feedback (that is the recruitment) is not responsible for a faster entering food flow and is not influenced by the colony needs while the exploring activity is. The spatial dynamics of the food exchange network revealed stable patterns and fine tuning regulation of the feeding process. Spatial analysis of the food distribution showed that sucrose is heterogeneously stored among individuals and also heterogeneously consumed. We observed a regular spatial structure leading to centralization of the stocks: heavy loaded individuals being at the center of the cluster and weakly loaded individuals at its perip, Doctorat en Sciences, info:eu-repo/semantics/nonPublished

Caste polyphenism in social insects provides us with excellent opportunities to examine the plasticity and robustness underlying developmental pathways. Several ant species have evolved unusual castes showing intermediate morphologies between alate queens and wingless workers. In some low-temperature habitats, the ant Myrmecina nipponica produces such intermediate reproductives (i.e. ergatoids), which can mate and store sperm but cannot fly. To gain insight into the developmental and evolutionary aspects associated with ergatoid production, we conducted morphological and histological examinations of the postembryonic development of compound eyes, gonads and wings during the process of caste differentiation. In compound eyes, both the queen-worker and ergatoid-worker differences were already recognized at the third larval instar. In gonads, queen-worker differentiation began at the larval stage, and ergatoid-worker differentiation began between the prepupal and pupal stages. Wing development in ergatoids was generally similar to that in workers throughout postembryonic development. Our results showed that the developmental rate and timing of differentiation in body parts differed among castes and among body parts. These differences suggest that the rearrangement of modular body parts by heterochronic developmental regulation is responsible for the origination of novel castes, which are considered to be adaptations to specific ecological niches.

Caste polyphenism in social insects provides us with excellent opportunities to examine the plasticity and robustness underlying developmental pathways. Several ant species have evolved unusual castes showing intermediate morphologies between alate queens and wingless workers. In some low-temperature habitats, the ant Myrmecina nipponica produces such intermediate reproductives (i.e. ergatoids), which can mate and store sperm but cannot fly. To gain insight into the developmental and evolutionary aspects associated with ergatoid production, we conducted morphological and histological examinations of the postembryonic development of compound eyes, gonads and wings during the process of caste differentiation. In compound eyes, both the queen-worker and ergatoid-worker differences were already recognized at the third larval instar. In gonads, queen-worker differentiation began at the larval stage, and ergatoid-worker differentiation began between the prepupal and pupal stages. Wing development in ergatoids was generally similar to that in workers throughout postembryonic development. Our results showed that the developmental rate and timing of differentiation in body parts differed among castes and among body parts. These differences suggest that the rearrangement of modular body parts by heterochronic developmental regulation is responsible for the origination of novel castes, which are considered to be adaptations to specific ecological niches.

Caste polyphenism in social insects provides us with excellent opportunities to examine the plasticity and robustness underlying developmental pathways. Several ant species have evolved unusual castes showing intermediate morphologies between alate queens and wingless workers. In some low-temperature habitats, the ant Myrmecina nipponica produces such intermediate reproductives (i.e. ergatoids), which can mate and store sperm but cannot fly. To gain insight into the developmental and evolutionary aspects associated with ergatoid production, we conducted morphological and histological examinations of the postembryonic development of compound eyes, gonads and wings during the process of caste differentiation. In compound eyes, both the queen-worker and ergatoid-worker differences were already recognized at the third larval instar. In gonads, queen-worker differentiation began at the larval stage, and ergatoid-worker differentiation began between the prepupal and pupal stages. Wing development in ergatoids was generally similar to that in workers throughout postembryonic development. Our results showed that the developmental rate and timing of differentiation in body parts differed among castes and among body parts. These differences suggest that the rearrangement of modular body parts by heterochronic developmental regulation is responsible for the origination of novel castes, which are considered to be adaptations to specific ecological niches.

1. In haplodiploid social insects where males are haploid and females are diploid, inbreeding depression is expressed as the production of diploid males when homozygosity at the sex-determining locus results in the production of diploid individuals with a male phenotype. Diploid males are often assumed to have reduced fitness compared with their haploid brothers. 2. While studying the reproductive biology of a leaf-cutting ant, Atta sexdens, in Gamboa, Republic of Panama, we detected the presence of a larger male morph. Using microsatellite markers we were able to confirm that the large male morph was diploid in 87% of cases. 3. We infer that the Gamboa population of A. sexdens experiences inbreeding depression because diploid males were found in three out of five mature colonies. However, their frequencies were relatively low because queens were multiply mated and our estimates suggest that many diploid male larvae may not survive to adulthood. 4. We measured two traits potentially linked to male reproductive success: sperm length and sperm number, and showed that diploid males produced fewer but longer sperm. These results provide indirect evidence that diploid male reproductive success would be reduced compared with haploid males if they were able to copulate. 5. We conclude that diploid male production is likely to affect the fitness of A. sexdens queens with a matched mating, as these males are produced at the cost of workers and, if the colony survives to reach mature size, also gynes., 1. In haplodiploid social insects where males are haploid and females are diploid, inbreeding depression is expressed as the production of diploid males when homozygosity at the sex-determining locus results in the production of diploid individuals with a male phenotype. Diploid males are often assumed to have reduced fitness compared with their haploid brothers. 2. While studying the reproductive biology of a leaf-cutting ant, Atta sexdens, in Gamboa, Republic of Panama, we detected the presence of a larger male morph. Using microsatellite markers we were able to confirm that the large male morph was diploid in 87% of cases. 3. We infer that the Gamboa population of A. sexdens experiences inbreeding depression because diploid males were found in three out of five mature colonies. However, their frequencies were relatively low because queens were multiply mated and our estimates suggest that many diploid male larvae may not survive to adulthood. 4. We measured two traits potentially linked to male reproductive success: sperm length and sperm number, and showed that diploid males produced fewer but longer sperm. These results provide indirect evidence that diploid male reproductive success would be reduced compared with haploid males if they were able to copulate. 5. We conclude that diploid male production is likely to affect the fitness of A. sexdens queens with a matched mating, as these males are produced at the cost of workers and, if the colony survives to reach mature size, also gynes.

1. In haplodiploid social insects where males are haploid and females are diploid, inbreeding depression is expressed as the production of diploid males when homozygosity at the sex-determining locus results in the production of diploid individuals with a male phenotype. Diploid males are often assumed to have reduced fitness compared with their haploid brothers. 2. While studying the reproductive biology of a leaf-cutting ant, Atta sexdens, in Gamboa, Republic of Panama, we detected the presence of a larger male morph. Using microsatellite markers we were able to confirm that the large male morph was diploid in 87% of cases. 3. We infer that the Gamboa population of A. sexdens experiences inbreeding depression because diploid males were found in three out of five mature colonies. However, their frequencies were relatively low because queens were multiply mated and our estimates suggest that many diploid male larvae may not survive to adulthood. 4. We measured two traits potentially linked to male reproductive success: sperm length and sperm number, and showed that diploid males produced fewer but longer sperm. These results provide indirect evidence that diploid male reproductive success would be reduced compared with haploid males if they were able to copulate. 5. We conclude that diploid male production is likely to affect the fitness of A. sexdens queens with a matched mating, as these males are produced at the cost of workers and, if the colony survives to reach mature size, also gynes., 1. In haplodiploid social insects where males are haploid and females are diploid, inbreeding depression is expressed as the production of diploid males when homozygosity at the sex-determining locus results in the production of diploid individuals with a male phenotype. Diploid males are often assumed to have reduced fitness compared with their haploid brothers. 2. While studying the reproductive biology of a leaf-cutting ant, Atta sexdens, in Gamboa, Republic of Panama, we detected the presence of a larger male morph. Using microsatellite markers we were able to confirm that the large male morph was diploid in 87% of cases. 3. We infer that the Gamboa population of A. sexdens experiences inbreeding depression because diploid males were found in three out of five mature colonies. However, their frequencies were relatively low because queens were multiply mated and our estimates suggest that many diploid male larvae may not survive to adulthood. 4. We measured two traits potentially linked to male reproductive success: sperm length and sperm number, and showed that diploid males produced fewer but longer sperm. These results provide indirect evidence that diploid male reproductive success would be reduced compared with haploid males if they were able to copulate. 5. We conclude that diploid male production is likely to affect the fitness of A. sexdens queens with a matched mating, as these males are produced at the cost of workers and, if the colony survives to reach mature size, also gynes.

The regulation of protein collection through pollen foraging plays an important role in pollination and in the life of bee colonies that adjust their foraging to natural variation in pollen protein quality and temporal availability. Bumble bees occupy a wide range of habitats from the Nearctic to the Tropics in which they play an important role as pollinators. However, little is known about how a bumble bee colony regulates pollen collection. We manipulated protein quality and colony pollen stores in lab-reared colonies of the native North American bumble bee, Bombus impatiens. We debut evidence that bumble bee colony foraging levels and pollen storage behavior are tuned to the protein quality (range tested: 17-30% protein by dry mass) of pollen collected by foragers and to the amount of stored pollen inside the colony. Pollen foraging levels (number of bees exiting the nest) significantly increased by 55%, and the frequency with which foragers stored pollen in pots significantly increased by 233% for pollen with higher compared to lower protein quality. The number of foragers exiting the nest significantly decreased (by 28%) when we added one pollen load equivalent each 5 min to already high intranidal pollen stores. In addition, pollen odor pumped into the nest is sufficient to increase the number of exiting foragers by 27%. Foragers directly inspected pollen pots at a constant rate over 24 h, presumably to assess pollen levels. Thus, pollen stores can act as an information center regulating colony-level foraging according to pollen protein quality and colony need. © 2008 Springer-Verlag.

Amplification is the main component of many collective phenomena in social and gregarious insects. In a society, individuals face a mixed palette of odours coming from different groups (lines, strains) and individuals present discrimination capabilities. However, often at the collective level, different groups may cooperate and act together. To understand this apparent contradiction, we use a model of food recruitment where each group of foragers have its own blend of pheromone trail that is partly recognized by the others groups. The model shows that a low level of recognition between signals is sufficient to produce a collaborative pattern between groups and that beyond a critical value of recognition, only the aggregation of all the groups around the same food source is observed. The comparison between this model and one describing the site selection by gregarious insects (e.g. cockroach) suggests that such collective response is a generic property of social phenomena governed by amplification processes. © 2005 Elsevier Ltd. All rights reserved., SCOPUS: ar.j, info:eu-repo/semantics/published

Amplification is the main component of many collective phenomena in social and gregarious insects. In a society, individuals face a mixed palette of odours coming from different groups (lines, strains) and individuals present discrimination capabilities. However, often at the collective level, different groups may cooperate and act together. To understand this apparent contradiction, we use a model of food recruitment where each group of foragers have its own blend of pheromone trail that is partly recognized by the others groups. The model shows that a low level of recognition between signals is sufficient to produce a collaborative pattern between groups and that beyond a critical value of recognition, only the aggregation of all the groups around the same food source is observed. The comparison between this model and one describing the site selection by gregarious insects (e.g. cockroach) suggests that such collective response is a generic property of social phenomena governed by amplification processes. © 2005 Elsevier Ltd. All rights reserved., SCOPUS: ar.j, info:eu-repo/semantics/published

Teraformace marsu autonomním robotickým stavebním systémem, inspirovaným sociálním hmyzem. Ideový návrh řešení robotů, dopravy a jejich programu. Návrh struktur stavěných roboty a jejich funkce. Pyramidové struktury protkané spletí ledových tunelů, ohřívají plyn atmosféry Marsu a kumulují teplo ve své hmotě. Tyto struktury jsou postaveny levnými a jednoduchými roboty, napodobujícími chování sociálního hmyzu., Terraforming mars by autonomous robotic building system, inspired by social insect. Idea design of robotic solution, their transportation and software. Design of structures builded by robots and their function. Pyramidal structures interwoven with ice tunnel, heat the atmosphere of Mars and accumulate heat in their mass. These structures are built with cheap and simple robots that mimic the behavior of social insects.

Teraformace marsu autonomním robotickým stavebním systémem, inspirovaným sociálním hmyzem. Ideový návrh řešení robotů, dopravy a jejich programu. Návrh struktur stavěných roboty a jejich funkce. Pyramidové struktury protkané spletí ledových tunelů, ohřívají plyn atmosféry Marsu a kumulují teplo ve své hmotě. Tyto struktury jsou postaveny levnými a jednoduchými roboty, napodobujícími chování sociálního hmyzu., Terraforming mars by autonomous robotic building system, inspired by social insect. Idea design of robotic solution, their transportation and software. Design of structures builded by robots and their function. Pyramidal structures interwoven with ice tunnel, heat the atmosphere of Mars and accumulate heat in their mass. These structures are built with cheap and simple robots that mimic the behavior of social insects.

Teraformace marsu autonomním robotickým stavebním systémem, inspirovaným sociálním hmyzem. Ideový návrh řešení robotů, dopravy a jejich programu. Návrh struktur stavěných roboty a jejich funkce. Pyramidové struktury protkané spletí ledových tunelů, ohřívají plyn atmosféry Marsu a kumulují teplo ve své hmotě. Tyto struktury jsou postaveny levnými a jednoduchými roboty, napodobujícími chování sociálního hmyzu., Terraforming mars by autonomous robotic building system, inspired by social insect. Idea design of robotic solution, their transportation and software. Design of structures builded by robots and their function. Pyramidal structures interwoven with ice tunnel, heat the atmosphere of Mars and accumulate heat in their mass. These structures are built with cheap and simple robots that mimic the behavior of social insects.

Teraformace marsu autonomním robotickým stavebním systémem, inspirovaným sociálním hmyzem. Ideový návrh řešení robotů, dopravy a jejich programu. Návrh struktur stavěných roboty a jejich funkce. Pyramidové struktury protkané spletí ledových tunelů, ohřívají plyn atmosféry Marsu a kumulují teplo ve své hmotě. Tyto struktury jsou postaveny levnými a jednoduchými roboty, napodobujícími chování sociálního hmyzu., Terraforming mars by autonomous robotic building system, inspired by social insect. Idea design of robotic solution, their transportation and software. Design of structures builded by robots and their function. Pyramidal structures interwoven with ice tunnel, heat the atmosphere of Mars and accumulate heat in their mass. These structures are built with cheap and simple robots that mimic the behavior of social insects.

Teraformace marsu autonomním robotickým stavebním systémem, inspirovaným sociálním hmyzem. Ideový návrh řešení robotů, dopravy a jejich programu. Návrh struktur stavěných roboty a jejich funkce. Pyramidové struktury protkané spletí ledových tunelů, ohřívají plyn atmosféry Marsu a kumulují teplo ve své hmotě. Tyto struktury jsou postaveny levnými a jednoduchými roboty, napodobujícími chování sociálního hmyzu., Terraforming mars by autonomous robotic building system, inspired by social insect. Idea design of robotic solution, their transportation and software. Design of structures builded by robots and their function. Pyramidal structures interwoven with ice tunnel, heat the atmosphere of Mars and accumulate heat in their mass. These structures are built with cheap and simple robots that mimic the behavior of social insects.