The invasive bumblebee Bombus terrestris (Linnaeus, 1758) disrupts the adaptive function of heteranthery by indiscriminately visiting the pollinating and feeding anthers of Senna arnottiana flowers.

Heteranthery, the presence of different types of anthers on the same flower, is a floral adaptation that aims to balance the need for pollinators to collect pollen as a food resource while ensuring sufficient pollen for pollination. We investigate the role of heteranthery in the pollination of Senna arnottiana flowers and how it is affected by the behaviour of visiting bee species, with a particular focus on the impact of the invasive bumblebee Bombus terrestris. In three populations of S. arnottiana we measured the size of three sets of anthers and style, stigma-anther separation, pollen quantity and fruit set, and contrasted it with the body size, behaviour, and pollination effectiveness of all floral visitors. Different bee species visited S. arnottiana flowers, and their foraging behaviour varied. Large-bodied native bees, including Centris cineraria, Caupolicana sp. and Cadeguala occidentalis, preferentially visited short anthers, whereas B. terrestris, an exotic bumblebee, foraged from both short and long anthers without distinction. In addition, B. terrestris contacted the stigma at a lower rate than large-bodied native bees. Instead of concentrating its pollen-gathering efforts on the feeding anthers, as predicted by the "division of labor" hypothesis, B. terrestris indiscriminately visited both types of anthers similarly. This behaviour of B. terrestris may disrupt the adaptive significance of heteranthery by mixing the roles of pollination and feeding anthers of S. arnottiana. Therefore, our results highlight the potential disruption of this relationship by exotic pollinators and the need to consider it in conservation efforts.

Resource adaptation drives the size-complexity rule in termites.

The size-complexity rule posits that the evolution of larger cooperative groups should favour more division of labour. Examples include more cell types in larger multicellular organisms, and more polymorphic castes in larger eusocial colonies. However, a correlation between division of labour and group size may reflect a shared response of both traits to resource availability and/or profitability. Here, this possibility was addressed by investigating the evolution of sterile caste number (worker and soldier morphotypes) in termites, a major clade of eusocial insects in which the drivers of caste polymorphism are poorly understood. A novel dataset on 90 termite species was compiled from the published literature. The analysis showed that sterile caste number did increase markedly with colony size. However, after controlling for resource adaptations and phylogeny, there was no evidence for this relationship. Rather, sterile caste number increased with increasing nest-food separation and decreased with soil-feeding, through changes in worker (but not soldier) morphotype number. Further, colony size increased with nest-food separation, thus driving the false correlation between sterile caste number and colony size. These findings support adaptation to higher energy acquisition as key to the rise of complex insect societies, with larger size being a by-product.

El cuidado como cuestión de tiempo: una perspectiva feminista sobre el tiempo cotidiano de cuidadoras de personas adultas con discapacidad / Caregiving as a matter of time: A feminist perspective of the daily time of women caregivers of adults with disabilities / O cuidado como questão de tempo: uma perspectiva feminista sobre o tempo cotidiano de mulheres cuidadoras de pessoas adultas com deficiência

El artículo aborda el carácter histórico y político del tiempo, por considerarle un articulador de la existencia humana, a partir de una lectura crítica de la vida cotidiana. La reproducción de la temporalidad está mediada por el trabajo, el que, analizado desde una perspectiva feminista-marxista, permite reconocer desigualdades en la experiencia del tiempo de hombres y mujeres, basadas en la división sexual del trabajo. Para profundizar en este fenómeno se presentan resultados derivados de una investigación cualitativa que buscó analizar la experiencia del tiempo cotidiano de mujeres que realizan el trabajo de cuidados de personas adultas con discapacidad en Santiago de Chile. Se realizaron entrevistas semiestructuradas y observaciones participantes en los contextos cotidianos de ocho mujeres, reconociendo que su experiencia del tiempo depende de otras personas, que está densificada por la continua realización simultánea de trabajos no remunerados y que no distingue tiempos libres, de ocio ni por fuera del cuidado. Se concluye reconociendo que las desigualdades de género también producen desigualdades en la experiencia del tiempo, lo que insta a avanzar en políticas sociales que reconozcan el cuidado como un derecho social para que las mujeres puedan construir experiencias de sentido, azar, demora y libertad.

The article addresses time's historical and political character, considering it an articulator of human existence from a critical reading of everyday life. The reproduction of temporality is mediated by work, which, analyzed from a feminist-Marxist perspective, allows the recognition of inequalities in the experience of time for men and women based on the sexual division of labor. To delve into this phenomenon, the article presents the results from qualitative research that sought to analyze the daily experience of women who are caregivers of adults with disabilities in Santiago de Chile. Methodologically, semi-structured interviews and participant observations were made in the everyday contexts of eight women, recognizing that their experience of time depends on other people, that it is densified by the continuous and simultaneous performance of unpaid work, and that it does not distinguish free time, leisure, or time outside care. It concludes by recognizing that gender inequalities also produce inequalities in the experience of time, which urges progress in social policies recognizing care as a social right so that women can build experiences of meaning, chance, delay, and freedom.

O artigo aborda a natureza histórica e política do tempo, considerando-o um articulador da existência humana, a partir de uma leitura crítica da vida cotidiana. A reprodução da temporalidade é mediada pelo trabalho, que, analisado a partir de uma perspectiva feminista-marxista, permite reconhecer desigualdades na experiência do tempo de homens e mulheres, a partir da divisão sexual do trabalho. Para aprofundar este fenômeno, são apresentados os resultados derivados de uma pesquisa qualitativa, que buscou analisar a experiência do tempo cotidiano de mulheres que realizam o trabalho de cuidar de adultos com deficiência em Santiago do Chile. Foram realizadas entrevistas semiestruturadas e observações participantes nos contextos cotidianos de oito mulheres, reconhecendo que sua experiência do tempo depende de outras pessoas, que está intensificada pelo desempenho contínuo e simultâneo de trabalhos não remunerados, e que não distingue os tempos livres, de lazer nem externo ao cuidado. Conclui-se reconhecendo que as desigualdades de gênero também produzem desigualdades na experiência do tempo, o que urge avançar em políticas sociais que reconheçam o cuidado como um direito social, para que as mulheres possam construir experiências de sentido, casualidade, lentidão e liberdade.

Heteromorphic stamens are differentially attractive in Swartzia (Fabaceae).

The division of labour hypothesis between stamens has explained the evolution of divergent functions between dimorphic stamens in the same flower. However, little is known about whether the distinct type of stamens differs in attractiveness to pollinators. Therefore, we investigate whether the two types of stamens commonly found in Swartzia have different visual and olfactory attractants. We performed observations of anthesis dynamics, registration and collection of floral visitors, measurements of reflectance of floral parts and chemical analysis of the volatile organic compounds of the floral parts of two species, S. flaemingii and S. simplex. Both species have two distinct sets of stamens: one with smaller and abundant stamens in the centre of the flower and the other with fewer but larger abaxial stamens. The sets differ in UV reflectance (only S. simplex) and exhibit a distinct chromatic contrast. Concerning olfactory attractiveness, aliphatic compounds make up most of the odour of the two species, both whole flowers and most of their floral organs. On the other hand, only S. simplex presented apocarotenoids (as ionones) and benzenoids. Furthermore, there are differences in the proportion of volatiles emitted by the stamen in both cases, as the high proportion of sesquiterpenes among the smaller stamens compared to the larger ones. In conclusion, the two types of stamens found in S. flaemingii and S. simplex show a distinct attractiveness. In addition, our data have demonstrated diverse ways of differential attractiveness both between distinct stamens set per flower and between the two species from the same pollen flowers genus.

Mandibular morphology, task specialization and bite mechanics in Pheidole ants (Hymenoptera: Formicidae).

Ants show remarkable ecological and evolutionary success due to their social life history and division of labour among colony members. In some lineages, the worker force became subdivided into morphologically distinct individuals (i.e. minor versus major workers), allowing for the differential performance of particular roles in the colony. However, the functional and ecological significance of these morphological differences are not well understood. Here, we applied finite element analysis (FEA) to explore the biomechanical differences between major and minor ant worker mandibles. Analyses were carried out on mandibles of two Pheidole species, a dimorphic ant genus. We tested whether major mandibles evolved to minimize stress when compared to minors using combinations of the apical tooth and masticatory margin bites under strike and pressure conditions. Majors performed better in pressure conditions yet, contrary to our expectations, minors performed better in strike bite scenarios. Moreover, we demonstrated that even small morphological differences in ant mandibles might lead to substantial differences in biomechanical responses to bite loading. These results also underscore the potential of FEA to uncover biomechanical consequences of morphological differences within and between ant workers.

Correlation between octopaminergic signalling and foraging task specialisation in honeybees.

Regulation of pollen and nectar foraging in honeybees is linked to differences in the sensitivity to the reward. Octopamine (OA) participates in the processing of reward-related information in the bee brain, being a candidate to mediate and modulate the division of labour among pollen and nectar foragers. Here we tested the hypothesis that OA affects the resource preferences of foragers. We first investigated whether oral administration of OA is involved in the transition from nectar to pollen foraging. We quantified the percentage of OA-treated bees that switched from a sucrose solution to a pollen feeder when the sugar concentration was decreased experimentally. We also evaluated if feeding the colonies sucrose solution containing OA increases the rate of bees collecting pollen. Finally, we quantified OA and tyramine (TYR) receptor genes expression of pollen and nectar foragers in different parts of the brain, as a putative mechanism that affects the decision-making process regarding the resource type collected. Adding OA in the food modified the probability that foragers switch from nectar to pollen collection. The proportion of pollen foragers also increased after feeding colonies with OA-containing food. Furthermore, the expression level of the AmoctαR1 was upregulated in foragers arriving at pollen sources compared with those arriving at sugar-water feeders. Using age-matched pollen and nectar foragers that returned to the hive, we detected an upregulated expression of a TYR receptor gene in the suboesophageal ganglia. These findings support our prediction that OA signalling affects the decision in honeybee foragers to collect pollen or nectar.

Pollen reinforces learning in honey bee pollen foragers but not in nectar foragers.

Searching for reward motivates and drives behaviour. In honey bees Apis mellifera, specialized pollen foragers are attracted to and learn odours with pollen. However, the role of pollen as a reward remains poorly understood. Unlike nectar, pollen is not ingested during collection. We hypothesized that pollen (but not nectar) foragers could learn pollen by sole antennal or tarsal stimulation. Then, we tested how pairing of pollen (either hand- or bee-collected) and a neutral odour during a pre-conditioning affects performance of both pollen and nectar foragers during the classical conditioning of the proboscis extension response. Secondly, we tested whether nectar and pollen foragers perceive the simultaneous presentation of pollen (on the tarsi) and sugar (on the antennae) as a better reinforcement than sucrose alone. Finally, we searched for differences in learning of the pollen and nectar foragers when they were prevented from ingesting the reward during the conditioning. Differences in pollen-reinforced learning correlate with division of labour between pollen and nectar foragers. Results show that pollen foragers performed better than nectar foragers during the conditioning phase after being pre-conditioned with pollen. Pollen foragers also performed better than nectar foragers in both the acquisition and extinction phases of the conditioning, when reinforced with the dual reward. Consistently, pollen foragers showed improved abilities to learn cues reinforced without sugar ingestion. We discussed that differences in how pollen and nectar foragers respond to a cue associated with pollen greatly contribute to the physiological mechanism that underlies foraging specialization in the honeybee.

Structure and development of anthers and connective glands in two species of Stigmaphyllon (Malpighiaceae): are heteromorphic anthers related to division of labour?

Heteranthery has been largely associated with a division of labour between anthers. Most species of Stigmaphyllon (Malpighiaceae) present heteromorphic anthers and glandular connectives of different development; yet, the functional meaning of this condition has never been explored in the genus. The aims of this study were to provide a comparative description of the structure and development of anthers and their connective glands in S. bonariense and S. jatrophifolium and to assess the existence of division of functions. Natural populations were selected to collect flowers at different stages. Anthers were subjected to morpho-anatomical, histochemical and pollen viability studies. For both species, abundance of pollen grains and size of anther and their connective glands were estimated. Three types of stamens are recognized: stamen with small, intermediate and large anthers. Anthers of both species exhibit a similar glandular tissue in the connective, and the histochemical analysis revealed that it produce a mucilagous secretion. The pattern of anther wall development, stainability and release of pollen grains was identical among anther types. For both species, we observed a positive relationship between anther size and abundance of pollen grains, but an inverse relationship between area of anthers and size (area and thickness) of connective glands in small anthers vs. intermediate and large ones. Our results evidence a specialization of anthers related to division of labour between heteromorphic stamens in two species of Stigmaphyllon. Thus, one set of anthers produces large amount of pollen grains for pollination and another sets large quantities of mucilage, which would improve pollen transport (better adherence to pollinator body and dampness maintenance). Nevertheless, heteranthery in both Stigmaphyllon species would represent a transitional state towards the division of labour rather than a stable state.

Caste-Specific Expression of Na+/K+-ATPase in the Asian Weaver Ant, Oecophylla smaragdina (Fabricius, 1775).

Social insect colonies adopt different levels of survival strategies and exhibit well-defined reproductive division of labour. Oecophylla smaragdina (Fabricius, 1775) has physiological and behavioral adaptations that enable them to forage at extreme environmental conditions and are lethal to most other insects. Ion homeostasis is the key process in an organism's survival mechanism. Among ion pumps, the ATP-dependent sodium-potassium ion pump is essential for maintaining the Na+ and K+ ionic balance and is well known as the primary consumer of energy. Oecophylla smaragdina plays pivotal role as a model among social insects for understanding ion homeostasis at the organization level of the castes. We have evaluated the expression and activity of Na+/K+-ATPase among various castes of O. smaragdina (worker subcastes, queen and male). Real-time PCR and immunoblotting analyses revealed the differential expression of Na+/K+-ATPase in the castes. Significantly higher expression of Na+/K+-ATPase mRNA and protein were observed in the minor workers, queen, major workers and males respectively. These results suggest that in the weaver ant colony, the castes might have variously adapted and evolved with a well-developed ion transport mechanism which allows them to perform allocated tasks within the nest and could be a key to their adaptive benefits towards division of labour.

Heteranthery as a solution to the demand for pollen as food and for pollination - Legitimate flower visitors reject flowers without feeding anthers.

Heteranthery, the presence of feeding and pollinating anthers in the same flower, seems to mediate the evolutionary dilemma for plants to protect their gametes and yet provide food for pollinators. This study aims to elucidate the role of heteranthery in the buzz-pollinated Senna reniformis. The fecundity of pollen from long-, medium- and short-sized anthers was determined by hand cross-pollination experiments, and the quantity, size, ornamentation and viability of pollen of different anthers were compared. Rates of flower rejection by bees were measured in anther removal experiments to assess the preferences of flower visitors for feeding or pollinating anthers. Large bees, which were the effective pollinators of self-incompatible S. reniformis, avoided flowers without short feeding anthers, but not those without medium or long anthers. Illegitimate small and medium-sized bees were unresponsive to anther exclusion experiments. Long anthers deposited pollen on the back and short anthers on the venter of large bees. Pollen from long anthers had higher in vitro viability and higher fruit and seed set after cross-pollination than pollen from other sized anthers. Short anthers produce feeding pollen to effective pollinators and long anthers are related to pollination of S. reniformis. Bee behaviour and size was found to directly influence the role of anthers in the 'division of labour'. Only large bee pollinators that carry the pollinating pollen from long anthers in 'safe sites' associated short anthers with the presence of food. In the absence of these larger bee pollinators, the role of heteranthery in S. reniformis would be strongly compromised and its function would be lost.

Sexual castes of Trachymyrmex fuscus (Formicidae: Attini) performing worker tasks / Castas sexuadas de Trachymyrmex fuscus (Formicidae: Attini) executando tarefas de operárias

ABSTRACT: The main of this research was to report an atypical foraging behavior in a colony of Trachymyrmex fuscus, situated in "Cerrado" (savanna ecoregion of Goiás, Brazil). The colony foraging activity was performed only by sexual caste. Comparison of the foraging rhythm of this colony with another of the same specie where foraging was performed only by worker caste, showed that working time hours were very similar. After observations on the foraging behavior, both colonies were excavated in order to characterize them (nest size, population composition and estimating of the symbiotic fungus volume). Besides the foraging activity performed only by sexual females, other important observations were highlighted in that colony: low number of workers, presence of worker larvae and pupae (45 and 43 respectively) and apparently normal growth of the symbiotic fungus. Our hypothesis is that sexual females were in charge of the entire colony maintenance. This could be a strategy of colony survival when the worker caste is reduced.

RESUMO: Este trabalho objetivou registrar um comportamento atípico de forrageamento em uma colônia de Trachymyrmex fuscus, localizada em área de cerrado, em Ipameri, Goiás, Brasil. Nessa colônia, a atividade de forrageamento era executada somente por castas sexuadas. A comparação do ritmo diário de forrageamento dessa colônia com o de outra, da mesma espécie, em que tal atividade era executada por castas operárias, mostrou ritmos das jornadas de trabalho relativamente similares. Essas colônias foram escavadas para sua própria caracterização. Além da atividade forrageadora, executada somente por fêmeas, outras observações relevantes mereceram destaque na referida colônia: inexpressivo número de operárias (5), presença de larvas e pupas de operárias (45 e 43, respectivamente) e crescimento aparentemente normal de fungo simbionte. Nossa hipótese é a de que as fêmeas sexuadas faziam a manutenção de toda a colônia. Essa pode ser uma estratégia para a sobrevivência da colônia em um momento em que a casta operária encontra-se reduzida.

El concepto de situs ocupacional: por qué esta propuesta no es plausible: una explicación sociológica / The concept of occupational situs: why this notion is not plausible: a sociological explanation

Seis años atrás apareció en este mismo medio una propuesta desde el interior de la enfermería académica, que sugería el desarrollo -y aun la preexistencia- de un situs ocupacional de enfermería. Siguiendo este concepto, la enfermería podría tomar distancia de la dominación médica e instalar un situs propio de enfermería, con las enfermeras en la cúspide de la estructura y otras ocupaciones asociadas en posiciones subalternas. Esta proposición, aunque muy prometedora, no logró despertar mayor discusión en las revistas del rubro. En parte, esta omisión puede ser resultado de que al tratarse de un concepto de limitado interés empírico, aun para la sociología de las profesiones (desde donde proviene), el situs ocupacional se ha enmohecido en el olvido. En el presente artículo tendré como objetivo el argumentar por qué los conceptos de situs y situs ocupacional, además de tener poca utilidad hoy en día, no son aplicables en la conformación de un 'situs de enfermería' La estratificación de categorías ocupacionales es un fenómeno mucho más complejo que meramente disponer lo que un grupo de profesiones 'debería' incluir o dejar fuera, por lo que sugiero su inoperatividad en la recomposición de estructuras profesionales. Representaciones contemporáneas sobre la estratificación social en el trabajo son mejor descritas a través del análisis del funcionamiento de credenciales académicas y, sobre todo, de las relaciones sistémicas a través de las cuales las profesiones tienen influencias mutuas, tanto en sus campos de práctica como en la construcción de narrativas profesionales.

Six years ago, there appeared in this same journal a proposal from the field of academic nursing, suggesting the development or even the pre-existence of an occupational situs of nursing. By using this concept, nursing could take distance from medical dominance and establish its own occupational situs, meaning that nurses would be on top of the structure and subordinate occupations on lower levels. Although promising, this proposal did not persuade other researchers into developing a debate in related journals. This omission may be partly due to the fact that, given its empirical limitations even for the sociology of professions (where the concept originates), the concept of occupational situs has fallen into oblivion. In this article I discuss why concepts such as situs and occupational situs, besides their limited usefulness today, are no longer applicable to the conformation of a 'nursing situs.' The stratification of occupational categories is much more complex than merely deciding what a group of professions should include or not include; I thus suggest the ineffectiveness of the concept in setting up professional structures. Contemporary representations of social stratification in different occupations are best described by analysing the role of academic credentials and, especially, the systemic relations through which professions develop mutual influence both in their practical fields and in the construction of professional narratives.

Skills, division of labour and economies of scale among Amazonian hunters and South Indian honey collectors.

In foraging and other productive activities, individuals make choices regarding whether and with whom to cooperate, and in what capacities. The size and composition of cooperative groups can be understood as a self-organized outcome of these choices, which are made under local ecological and social constraints. This article describes a theoretical framework for explaining the size and composition of foraging groups based on three principles: (i) the sexual division of labour; (ii) the intergenerational division of labour; and (iii) economies of scale in production. We test predictions from the theory with data from two field contexts: Tsimane' game hunters of lowland Bolivia, and Jenu Kuruba honey collectors of South India. In each case, we estimate the impacts of group size and individual group members' effort on group success. We characterize differences in the skill requirements of different foraging activities and show that individuals participate more frequently in activities in which they are more efficient. We evaluate returns to scale across different resource types and observe higher returns at larger group sizes in foraging activities (such as hunting large game) that benefit from coordinated and complementary roles. These results inform us that the foraging group size and composition are guided by the motivated choice of individuals on the basis of relative efficiency, benefits of cooperation, opportunity costs and other social considerations.

Specialization and group size: brain and behavioural correlates of colony size in ants lacking morphological castes.

Group size in both multicellular organisms and animal societies can correlate with the degree of division of labour. For ants, the task specialization hypothesis (TSH) proposes that increased behavioural specialization enabled by larger group size corresponds to anatomical specialization of worker brains. Alternatively, the social brain hypothesis proposes that increased levels of social stimuli in larger colonies lead to enlarged brain regions in all workers, regardless of their task specialization. We tested these hypotheses in acacia ants (Pseudomyrmex spinicola), which exhibit behavioural but not morphological task specialization. In wild colonies, we marked, followed and tested ant workers involved in foraging tasks on the leaves (leaf-ants) and in defensive tasks on the host tree trunk (trunk-ants). Task specialization increased with colony size, especially in defensive tasks. The relationship between colony size and brain region volume was task-dependent, supporting the TSH. Specifically, as colony size increased, the relative size of regions within the mushroom bodies of the brain decreased in trunk-ants but increased in leaf-ants; those regions play important roles in learning and memory. Our findings suggest that workers specialized in defence may have reduced learning abilities relative to leaf-ants; these inferences remain to be tested. In societies with monomorphic workers, brain polymorphism enhanced by group size could be a mechanism by which division of labour is achieved.

Dolor, trabajo y su diagnóstico psicosocial de género: un ejemplo / Pain, work and gender psychosocial diagnosis: an example

El objetivo de este artículo es describir y comprender el fenómeno del dolor crónico sin causa orgánica (más conocido como fibromialgia), desde una perspectiva feminista y crítica, mediante la creación de una herramienta que diagnostique este malestar según sus dimensiones biopsicosociales: el diagnóstico psicosocial de género. Esta herramienta, que aquí se presenta, toma en consideración la dimensión laboral (tanto profesional como familiar) de las personas afectadas en el contexto cultural catalán (Estado Español) de las últimas cinco décadas, ambivalente en términos de igualdad de género. La producción de datos que se usan en este artículo se obtuvo a través de entrevistas en profundidad, realizadas en el área metropolitana de Barcelona (Catalunya, España), que se analizaron mediante análisis de contenido y análisis crítico del discurso.

The aim of this paper is to describe and understand the phenomena of chronic pain without organic cause (better known as fibromyalgia) from a feminist and critical perspective through made of a tool by which to diagnose this pain as bio-psycho-social dimensions: gender psycho-social diagnosis. This tool, presented here, taking into account the labour dimension (both professional and family) of the affected people in the cultural context Catalan (Spanish State) of the last 5 decades, ambivalent in terms of gender equality. The production data we use in this paper it's obtained through in-depth interviews (conducted in the metropolitan area of Barcelona, Catalunya, Spain) and analyzed by content analysis and critical discourse analysis.

A divisão sexual do trabalho no sistema de integração agroindustrial / The sexual division of labor in the agribusiness system of integration

Neste texto mostramos algumas das transformações nas relações de trabalho no setor da agroindústria, ocorridas nas pequenas propriedades familiares rurais, localizadas no oeste catarinense e que são vinculadas ao sistema de integração da Sadia. Analisa particularmente a manutenção da desigual divisão sexual do trabalho na pequena unidade produtiva familiar avícola. Destacamos ainda alguns elementos presentes na divisão sociossexual nesse setor e concluímos indicando alguns desafios para o Serviço Social.

In this text we show some of the tranformatios in the labour relations in the agroindustry sector that ocurred in the small rural family properties, located in the west of Santa Catarina's State and that are vinculated to Sadia's sistem of integration. Analise in particular the maintenance of the unequal sexual division of labour in the small poultry familiar productive unity. We underline yet some elements in the social‑sexual division of labour in this sector and indicate some challenges for the social service.

The Natural History of Nest Defence in a Stingless Bee, Tetragonisca angustula (Latreille) (Hymenoptera: Apidae), with Two Distinct Types of Entrance Guards

The stingless bee Tetragonsica angustula (Latreille) is the only social bee known that has two different types of nest entrance guards. As in other stingless bees and the honey bee one type stands on, in or near the nest entrance. The second type, so far only known in T. angustula, hovers near the nest entrance. In order to gain further understanding of this unique situation we studied guarding behaviour in both types of guards. Using marked bees, we found that individual worker bees guarded for a long time, up to 20 days, relative to their short, average c. 21 day, lifespan. Relatively few, 33 percent, individually marked guards were seen performing both types of guarding. The others only acted as standing guards. The bees that did perform both types did so over similar periods of their life. Hovering bouts were 57 min long, interrupted by breaks inside the hive of a few minutes (3.3 ± 1.5 min). Standing bouts were slightly longer (74 min) and also interrupted by short breaks (7.82 ± 6.45 min). Human breath, mimicking a vertebrate intruder, caused the guards to retreat into the nest rather than to attack the intruder. Some colonies protected themselves against intruders by closing the entrance during the night (32 percent and 56 percent of colonies during two nights). In summary, our results indicate that nest entrance guarding in T. angustula involves division of labour between the two types, in which most guarding individuals only act as standing guards.