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At least 19 recordsLinked to original sources

PubMed2004

Communication by electrical means in social insects.

Social insects, belonging to the order Hymenoptera, maintain a fixed, optimal temperature in their nest. Thus, in social wasps and hornets, the optimal nest temperature is 29 degrees C, despite the fact that they are distributed in regions of varying climates both in the northern and southern hemispheres of the globe. Since hornets and bees are relatively small insects, determination of their own body temperature as well as that of their nest and the brood was made via thermometers or by the use of infrared (IR) rays. It has been suggested that thermoregulation in social insect colonies is effected primarily by the adult insects via muscle activation, that is, fluttering of their wings, which can raise both their own and the ambient temperature by many degrees centigrade. However, the larval brood can also contribute to the thermoregulation by acting as heat resources and thereby raising the ambient temperature by 1-2 degrees C. To this end, the adult hornets are endowed with a well-developed musculature and their larvae, too, have muscles that enable them to move about. Not so the hornet pupae which are enclosed in a silk envelope (the cocoon), with a rather thick silk cap spun by the pupating larvae, and have rather undeveloped muscles. In the latter instance, it stands to reason that the pupae benefit from the nest warming achieved primarily by the adult hornets, but how is the information regarding their thermal needs relayed from them to the adults? Previously we showed that the adult hornets are attracted to the pupae by pheromones released by the latter, but such chemical compounds can only convey information of a general nature and we are still left with the question as to how the adult hornet can gauge or ascertain the temperature of a single insulated pupa. The present study provides evidence that the hornet pupa can indeed transmit information regarding its body temperature via electrical means.

Animal Communication↗

PubMed2002

The many selves of social insects.

Social insects show multiple levels of self identity. Most individuals are sterile workers who selflessly labor for their colony, which is often viewed as a superorganism. The superorganism protects itself with colony recognition systems based on learned odors, typically cuticular hydrocarbons. Transfer of these odors within the colony obscures separate clan identities. Residual individual interests do appear to cause conflicts within colonies over sex ratio, male production, caste, and reproductive dominance. However, genomic imprinting theory predicts that the individual's maternal and paternal genes will evolve separate infraorganismal identities, perhaps leaving virtually no coherent individual identity.

Animals↗

PubMed2002

The role of colony organization on pathogen transmission in social insects.

Social organisms are especially vulnerable to pathogens due to the homogeneity of the colony, and the close proximity and extensive interactions among its members. However, the social organization of these groups also offers the potential to provide an effective barrier against the transmission of pathogens within the colony. Social insects with their elaborate colony organizations provide an ideal model system to develop and test this hypothesis. While the different elements of colony organization are generally assumed to be products of ergonomic selection, in this paper we address how the same elements could influence the transmission of pathogens. By developing a simple model, we explore how three parameters of colony organization, division of labor, interaction network and colony demography could influence the transmission of pathogens. We find that heterogeneity among individuals in terms of division of labor alone has little effect on the spread of an infection in the colony and the scenario is indistinguishable from one in which all the individuals are homogeneous. However, division of labor, combined with heterogeneity in the interaction network and demographic schedules reduce the spread of an infection.

Animals↗

PubMed2003

Social insect networks.

Social insect colonies have many of the properties of adaptive networks. The simple rules governing how local interactions among individuals translate into group behaviors are found across social groups, giving social insects the potential to have a profound impact on our understanding of the interplay between network dynamics and social evolution.

Animals↗

PubMed2007

Changing paradigms in insect social evolution: insights from halictine and allodapine bees.

Until the 1980s theories of social insect evolution drew strongly on halictine and allodapine bees. However, that early work suffered from a lack of sound phylogenetic inference and detailed information on social behavior in many critical taxa. Recent studies have changed our understanding of these bee groups in profound ways. It has become apparent that forms of social organization, caste determination, and sex allocation are more labile and complex than previously thought, although the terminologies for describing them are still inadequate. Furthermore, the unexpected complexity means that many key parameters in kin selection and reproductive skew models remain unquantified, and addressing this lack of information will be formidable. At the same time, phylogenetic questions have become more tractable, and DNA sequence-based studies have resolved questions that earlier studies could not resolve, radically changing our understanding of the number of origins and losses of sociality in these bees.

Animals↗

PubMed1997

Molecular advances in understanding social insect population structure.

Social insects present many phenomena seen in all organisms but in more extreme forms and with larger sample sizes than those observable in most natural populations of vertebrates. Microsatellites are proving very much more informative than allozymes for the analysis of population biological problems, and prolifically polymorphic markers are fairly readily developed. In addition, the male-haploid genetic system of many social insects facilitates genetic analysis. The ability to amplify DNA from sperm stored in a female's sperm storage device enables the determination of mating types long after the death of the short-lived males, in addition to information on the degree of mixing of sperm from different males. Mitochondrial (mt) DNA sequences are also proving important, not only in phylogenetic studies but also in molecular population genetics, as a tracer of female movements. Mitochondrial markers have definitively shown the movement of females between colonies, challenging models giving exclusive primacy to kin selection as the explanation for multiqueen colonies, in Australian meat ants, Iridomyrmex purpureus, and the aridzone queenless ant Rhytidoponera sp. 12. Microsatellite and mtDNA variation are being studied in Camponotus consobrinus sugar ants, showing an unexpected diversity of complexity in colony structure, and microsatellites have shown that transfer of ants between nests of the weaver ant Polyrhachis doddi must be slight, despite an apparent lack of hostility.

Animals↗

PubMed2002

Caste totipotency and conflict in a large-colony social insect.

In most social insects with large, complex colonies workers and queens are morphologically quite distinct. This means that caste determination must occur prior to adulthood. However workers and queens in the swarm-founding epiponine wasps are often morphologically indistinguishable, or nearly so, suggesting that caste determination in these wasps could be quite different. To determine the extent of caste lability in the epiponine, Parachartergus colobopterus, we removed all the queens from one colony and all but one from another colony. Worker aggression diminished after queen removal. A week later the colony with no queens had a new, young cohort of mated queens. These must have been either adults or pupae at the time of queen removal, and so could not have been fed any differently from workers. Relatedness patterns confirmed that these new queens would normally have been workers and not queens. A model of inclusive fitness interests shows that workers ought to suppress new queen production, except at low queen numbers, a prediction supported by our empirical results. The patterns of social conflict over queenship resulting from swarm founding in a many-queen society may help to explain the unusually weak caste differentiation in the epiponines.

Animals↗

PubMed2003

Fitness effects of group merging in a social insect.

Animal social groups often consist of non-relatives, a condition that arises in many cases because of group merging. Although indirect fitness contributions are reduced in such groups compared with those in groups composed of close kin, the genetic-heterogeneity hypothesis suggests that these groups may benefit from increased intracolony genetic variation, which may boost group performance through increased task efficiency or parasite resistance. We confirm one prediction of the task-efficiency explanation by demonstrating a genetic basis for task thresholds of socially important behaviours in eastern tent caterpillars. However, we found no evidence that the expanded range of task thresholds in mixed colonies translates into improved individual or colony performance in the field. By contrast, increased group size, a less commonly considered correlate of group mixing, was found to enhance individual fitness through its effects on larval growth. We conclude that fitness benefits offsetting the dilution of relatedness in heterogeneous social groups may often stem from augmented group size rather than increased genotypic diversity.

Animals↗

PubMed2006

Social insects: from selfish genes to self organisation and beyond.

Selfish gene and self-organisation approaches have revolutionised the study of social insects and have provided unparalleled insights into the highly sophisticated nature of insect social evolution. Here, we briefly review the core programs and interfaces with communication and recognition studies that characterise these fields today, and offer an interdisciplinary future perspective for the study of social insect evolutionary biology.

Animals↗

PubMed2005

The evolution of male traits in social insects.

Pair formation in social insects mostly happens early in adult life and away from the social colony context, which precludes promiscuity in the usual sense. Termite males have continuous sperm production, but males of social Hymenoptera have fixed complements of sperm, except for a few species that mate before female dispersal and show male-fighting and lifelong sperm production. We develop an evolutionary framework for testing sexual selection and sperm competition theory across the advanced eusocial insects (ants, wasps, bees, termites) and highlight two areas related to premating sexual selection (sexual dimorphism and male mate number) that have remained understudied and in which considerable progress can be achieved with relatively simple approaches. We also infer that mating plugs may be relatively common, and we review further possibilities for postmating sexual selection, which gradually become less likely in termite evolution, but for which eusocial Hymenoptera provide unusual opportunities because they have clonal ejaculates and store viable sperm for up to several decades.

Animals↗

PubMed2026

Genetic inference in social insects: The continued utility of microsatellites in the sociogenomic era.

Social insects differ from many other biological systems because colonies function as integrated reproductive, ecological, and evolutionary units, often conceptualized as superorganisms. This organization makes genetic inference inherently hierarchical, often requiring genotyping across multiple biological levels: the colony, the population, the individual, and, in some cases, the cellular level. Although whole-genome sequencing and single-nucleotide polymorphism (SNP)-based approaches are now widely used in population genomics, microsatellites or short tandem repeats (STRs) remain a useful approach for cost-effective, low-input, and highly replicated genotyping, particularly in the hierarchical sampling designs common in social insect studies. Here, we review the utility and limitations of microsatellites in social insect research using a three-tiered framework spanning colony-, population-, and individual- or cellular-level analyses. Across these scales, microsatellites are especially valuable for colony delimitation, kinship inference, diagnostic screening of known reproductive systems, and low-input genotyping. By comparing the suitability of microsatellites with that of SNP-based and broader genomic approaches across these applications, this review links marker choice to biological scale, sampling design, and inferential goal in studies of social insects.

Journal Article↗

PubMed2000

Inspiration for optimization from social insect behaviour.

Research in social insect behaviour has provided computer scientists with powerful methods for designing distributed control and optimization algorithms. These techniques are being applied successfully to a variety of scientific and engineering problems. In addition to achieving good performance on a wide spectrum of 'static' problems, such techniques tend to exhibit a high degree of flexibility and robustness in a dynamic environment.

Algorithms↗

PubMed2000

Unrelated helpers in a social insect.

High-resolution genetic markers have revolutionized our understanding of vertebrate mating systems, but have so far yielded few comparable surprises about kinship in social insects. Here we use microsatellite markers to reveal an unexpected and unique social system in what is probably the best-studied social wasp, Polistes dominulus. Social insect colonies are nearly always composed of close relatives; therefore, non-reproductive helping behaviour can be favoured by kin selection, because the helpers aid reproductives who share their genes. In P. dominulus, however, 35% of foundress nestmates are unrelated and gain no such advantage. The P. dominulus system is unlike all other cases of unrelated social insects, because one individual has nearly complete reproductive dominance over subordinates who could have chosen other reproductive options. The only significant advantage that subordinates obtain is a chance at later reproduction, particularly if the queen dies. Thus, P. dominulus societies are functionally unlike other social insects, but similar to certain vertebrate societies, in which the unrelated helpers gain through inheritance of a territory or a mate.

Animals↗

PubMed2004

Conflict over male parentage in social insects.

Mutual policing is an important mechanism that maintains social harmony in group-living organisms by suppressing the selfish behavior of individuals. In social insects, workers police one another (worker-policing) by preventing individual workers from laying eggs that would otherwise develop into males. Within the framework of Hamilton's rule there are two explanations for worker-policing behavior. First, if worker reproduction is cost-free, worker-policing should occur only where workers are more closely related to queen- than to worker-produced male eggs (relatedness hypothesis). Second, if there are substantial costs to unchecked worker reproduction, worker-policing may occur to counteract these costs and increase colony efficiency (efficiency hypothesis). The first explanation predicts that patterns of the parentage of males (male parentage) are associated with relatedness, whereas the latter does not. We have investigated how male parentage varies with colony kin structure and colony size in 50 species of ants, bees, and wasps in a phylogenetically controlled comparative analysis. Our survey revealed that queens produced the majority of males in most of the species and that workers produced more than half of the males in less than 10% of species. Moreover, we show that male parentage does not vary with relatedness as predicted by the relatedness hypothesis. This indicates that intra- and interspecific variation in male parentage cannot be accounted for by the relatedness hypothesis alone and that increased colony efficiency is an important factor responsible for the evolution of worker-policing. Our study reveals greater harmony and more complex regulation of reproduction in social insect colonies than that expected from simple theoretical expectations based on relatedness only.

Aggression↗

PubMed2003

Theory of genomic imprinting conflict in social insects.

BACKGROUND: Genomic imprinting refers to the differential expression of genes inherited from the mother and father (matrigenes and patrigenes). The kinship theory of genomic imprinting treats parent-specific gene expression as products of within-genome conflict. Specifically, matrigenes and patrigenes will be in conflict over treatment of relatives to which they are differently related. Haplodiploid females have many such relatives, and social insects have many contexts in which they affect relatives, so haplodiploid social insects are prime candidates for tests of the kinship theory of imprinting. RESULTS: Matrigenic and patrigenic relatednesses are derived for individuals affected in a variety of contexts, including queen competition, sex ratio, worker laying of male eggs and policing, colony fission, and adoption of new queens. Numerous predictions emerge for what contexts should elicit imprinting, which individuals and tissues will show it, and the direction of imprinting effects. The predictions often vary for different genetic structures (varying queen and mate number) and often contrast with predictions for diploids. CONCLUSION: Because the contexts differ from the normal imprinting case, and because nothing is currently known about imprinting in social insects, these predictions can serve as a strong a priori test of the kinship theory of imprinting. If the predictions are correct, then social insects, which have long served as exemplars of cooperation between individuals, will also be shown to be extraordinary examples of competition within individual genomes.

Animals↗

PubMed2001

Demographic mechanisms for the evolution of long life in social insects.

One of the most remarkable life history traits of many species of eusocial insects is the extraordinary longevity of their queens, with the recorded life span of some individuals exceeding 30 years. Surprisingly, little research has been conducted on either the proximate or ultimate questions concerning what factors favor the evolution of the long life spans in social insects. The broad objective of this paper is to address four sets of questions: (1) What are the similarities and differences in the longevity patterns among species in the four main groups of social insects - bees, wasps, ants and termites? (2) What is the evolutionary association of longevity and sociality in insects? (3) Are there biodemographic principles that can be derived from studies on longevity in social insects? and (4) What are the general implications for longevity in vertebrates, including humans?

Animals↗

PubMed2005

Influence of caste polyethism on longevity of workers in social insect colonies.

Different patterns of division of labor can affect the expected longevity of social insects workers. It has been earlier suggested that when tasks performed inside and outside colony are equally risky then the expected longevity of workers in colonies with caste polyethism is greater than that in colonies without polyethism. To verify these predictions I used a model assuming two sets of tasks, associated with different mortality rates. In the colony without polyethism the workers preformed safe and risky tasks in turn, while in the colony with caste polyethism the workers specialized in only one set of tasks. The outcomes suggest that the expected longevity of workers in colonies with caste polyethism cannot be greater than that in colonies without polyethism. Only if there is no aging and under some special and rare conditions are there no differences in expected longevity between colonies with and without caste polyethism. If aging is independent of activity, caste polyethism does not shorten longevity when all tasks in the colony are equally risky. The results can explain why caste polyethism is not as widespread among social insects as age polyethism.

Animals↗

PubMed2003

The formation of spatial patterns in social insects: from simple behaviours to complex structures.

Many of the collective activities performed by social insects result in the formation of complex spatio-temporal patterns. Without centralized control, workers are able to work together and collectively tackle tasks far beyond the abilities of any one individual. The resulting patterns produced by a colony are not explicitly coded at the individual level, but rather emerge from nonlinear interactions between individuals or between individuals and their environment. We present a few selected examples to illustrate some of the basic mechanisms used by social insects, such as templates, stigmergy and self-organization. These mechanisms can be used in combination to organize pattern formation at the colony level.

Adaptation, Physiological↗