Search

Orchid bees are the only corbiculate bee lineage that is not obligately eusocial. However, multiple species of orchid bee show facultative sociality, with reproductive division of labor and a social hierarchy effectively enforced by oophagy. Orchid bee species differ in the degree of reproductive skew in social groups, as well as the rigidity of social roles. In the orchid bee Euglossa dilemma, previous observation of social groups of two or three individuals found that reproductive skew was complete, with one clear dominant individual that ate and replaced each subordinate laid egg. Here, we compare patterns of egg laying and egg-replacement between typical social nests of 2–3 individuals and larger social nests of 4–5 individuals. We find a striking difference in the reproductive behavior of colonies of varying group size; larger nests exhibit more reproductive inefficiency and conflict over the dominant social position, characterized by repeated oophagy and slower egg replacement. Our findings are consistent with the hypothesis that group size in E. dilemma may be limited by the ability of dominant bees to keep up with egg replacement. We discuss the possible causes and consequences of observed behavioral variation and its implications for understanding social behavior in orchid bees. [ABSTRACT FROM AUTHOR]

This commentary paper addresses the outdated and misleading terminology used to categorize termites into "higher" and "lower". These terms perpetuate a linear progression view of evolution, which is both inaccurate and detrimental to our understanding of the diversity of life. We trace the historical origins of these terms and highlight their flawed interpretation of evolutionary relationships. We advocate for the adoption of Termitidae (or termitid), rather than "higher termites". As for the paraphyletic group of "lower termites", we recommend refraining from grouping them together, unless specifically referring to their symbionts. In such cases, we propose "protist-dependent termites" or "non-Termitidae termites". [ABSTRACT FROM AUTHOR]

An incipient termite colony initially functions as a biparental family unit. The emergence of the first workers initiates the transition from biparental to alloparental care within a colony. During this transition, the number of protozoa harbored by Reticulitermes speratus (Kolbe) kings and queens is dynamic. In Coptotermes gestroi (Wasmann), the transition to alloparental care is completed by 150 days after colony foundation. In the present study, we quantified the protozoan abundance of C. gestroi and Coptotermes formosanus Shiraki kings and queens at ten time points during the transition from biparental to alloparental care (0–400 days post colony foundation). The protozoan abundance of C. gestroi and C. formosanus kings and queens peaked on either day 35 or 60 during the biparental care period, and then progressively decreased during the remainder of the study. By day 400 the protozoan abundance of kings and queens was either similar to or less than the abundance observed within unmated dealates. Both C. gestroi and C. formosanus kings and queens still harbored protozoa at day 150 even though the transition to alloparental care was completed by this time. On days 250 and 400 for C. formosanus, and on day 400 for C. gestroi, the protozoan abundance of kings was greater than the abundance of queens. These results indicate that alloparental care can become set within a colony prior to the loss of protozoa within the royal pair, and that queens lose their protozoa earlier than kings during incipient colony development. [ABSTRACT FROM AUTHOR]

Termites feed on a carbon-rich but nitrogen-poor diet and evolved efficient nitrogen conservation strategies. It was previously suggested that during time of low access to resources (i.e., starvation), subterranean termites (Rhinotermitidae) colonies would adopt an energy conservation strategy by cannibalizing soldiers, a dependent caste. However, such hypothesis was tested with relatively small groups of foragers, which may not have reflected how resources are reallocated in whole colonies when food (carbon) is scarce. The current study subjected 2-year-old colonies (≈ 3000 termites with all castes and instars) to starvation, in order to reexamine if cannibalism is part of an active energy conservation strategy. Within 12 days of starvation, eggs and larvae were all cannibalized, followed by young workers. Soldiers then died marginally faster than old workers. By 22 days, cannibalism was no longer observed, and the king and queen were among the last individuals to die. Termites that engaged in the process of ecdysis with no energetic resources, failed to molt, died in the process, and the subsequent cannibalism was a passive mortality-driven process. Therefore, cannibalism was primarily the result of the inherent termite behavior for recycling nitrogen resources. The hemimetabolous developmental pathway, the difference of timing in the molting cycle of termite instars and the relatively rapid exhaustion of soldiers, indirectly determined the sequence of starvation-induced mortality and subsequent cannibalism. Although termites have evolved efficient nitrogen conservation strategies, they have not evolved an efficient carbon conservation strategy, which is essentially limited to keeping the primary reproductives alive as long as possible. [ABSTRACT FROM AUTHOR]

In termites, primary reproductives proceed through dispersal flight with finite metabolic reserves. During colony foundation, the mated pair requires just enough resources to produce the first few workers, through biparental care. When alloparental care is established, the primary reproductives are fully supported by their own offspring. It was, therefore, argued that the pressure to accumulate large quantities of metabolic reserves in termite imagoes was relaxed over evolutionary time, which resulted in a progressive reduction in alate size compared to ancestral wood roaches. However, such directional reduction in size may partially be countered if mated pairs with relatively large internal metabolic resources are more successful than mated pairs with relatively low internal resources. This hypothesis was tested with Coptotermes gestroi by establishing incipient termite colonies with a wide range of combinations of female and male initial weights in laboratory conditions. Both females and males depleted most of their internal resources within 9 months, and the combined initial weight of female and male explained 27% of the variation in incipient colony growth. Mature colonies that can invest into high-quality alates may have a slight fitness advantage; however, this advantage may be secondary to other environmental factors, as during large Coptotermes dispersal flights, a vast majority of alates die within the first few days, which would increase the fitness of colonies that invested in quantity over quality. Within a given termite species, the relative size of imagoes may, therefore, reflect a reproductive strategy trade-off emerging from the life history of the species. [ABSTRACT FROM AUTHOR]

In the subterranean termite Coptotermes gestroi (Wasmann), soldiers developing in incipient colonies display strong fluctuating asymmetry when compared with soldiers developing in mature colonies. This strong asymmetry may arise from two different types of stress factors on individuals. First, the accelerated development of nanitic (small) soldiers may impose a direct physiological stress as Coptotermes soldiers produced in incipient colonies have two less molting events than soldiers produced in mature colonies. Second, the environmental conditions in incipient colonies present a major constraint with limited access to resources and small numbers of workers to care for the developing brood. In this study, 459 soldiers from 73 incipient colonies (6-month-old) displaying only nanitic soldiers were investigated in a range of nurturing capacity scenarios. Nanitic soldiers developing in incipient colonies with high nurturing capacity displayed more symmetrical traits than the ones developing in colonies with low nurturing capacity. In addition, the first soldiers to emerge in the colony were the most asymmetrical individuals, showing that as the conditions improve rapidly with the growth of the colony, newly produced nanitic soldiers manifest the lessening of stress in normalization of their morphology. However, the nurturing capacity of the colony only partially explained the developmental instability variability, implying that the accelerated development of nanitic soldiers remains an important stress factor in incipient colonies, in comparison with soldiers developing in mature colonies with two additional molts and homeostatic environmental conditions. [ABSTRACT FROM AUTHOR]

This study investigated age polyethism and the frequencies of behaviors in relation to the distance from the egg cluster in nests of Coptotermes formosanus Shiraki, a lower termite. Juvenile colonies of C. formosanus were introduced in planar arenas and termite activity was recorded with camcorders. The results showed that there were differences in distribution of caste/instar between the royal chamber and the secondary feeding site. There was a gradient of termite distribution within the vicinity of the royal chamber, with the egg cluster as the center. A negative correlation between the number of behavioral events per individual and distance of the behavioral event from the egg cluster was found for many behaviors. However, some behaviors were positively correlated with the distance from the egg clusters in the royal chamber, implying that not all behavior frequencies were termite density dependent. Finally, most motionless termites were found near the royal chamber, presumably about to molt or recently molted. Our study confirmed the occurrence of age polyethism in C. formosanus and there was heterogeneous distribution of caste/instar and behaviors away from the egg clusters. Task division was not only instar dependent but also location dependent, although behavioral compartmentalization was not as distinct as found in higher termites. This observation suggests that the complexity of age polyethism in Coptotermes is intermediate between lower termites and higher termites, as a case of evolutionary step. [ABSTRACT FROM AUTHOR]

Juvenile colonies of Coptotermes formosanus Shiraki were investigated to determine the social interactions among all individuals near the central nest of a colony. The behavioral repertoire of whole colonies of subterranean termites has yet to be identified because of their cryptic nests. Colonies were placed in planar arenas, and their behavioral repertoire and activities were recorded with video cameras. All castes and larval instars were determined and behavioral interactions were monitored and described, including feeding behaviors, grooming, nest maintenance, and inactivity. When two termites interacted, it was also determined which one was the donor or the recipient of the act. An ethogram was constructed by calculating relative frequency of each behavior for first instar larvae, second instar larvae, first instar workers, second instar workers or older, queen, king, soldiers and presoldiers. Larval instars, primary reproductives and soldiers were mostly passive during interactions. Workers performed most of the tasks; however, there was a difference of task divisions among worker instars. Young workers ( W ) performed most of the grooming of individuals in the central nest, while older workers ( W ) provided nest maintenance and sanitation, by collecting fecal matter from most nest mates. In addition, older workers were mostly in charge of caring for the primary reproductives and the maintenance of the royal chamber. This study identified instar-specific activities and provides a first insight into caste and age polyethism in C. formosanus. [ABSTRACT FROM AUTHOR]

In a termite colony, the incipient phase is the most critical part of the life of the colony. The quality of the investment in the first offspring by the primary reproductives may determine the rate of success of the colony to survive the first year and its growth rate in the following years. However, termite colonies possess a physiological constraint, forcing the group to maintain a relatively fixed caste proportion. During the development of the incipient colony, there is therefore a conflict for the group on the developmental pathways of larvae into workers or soldiers. On the one hand, the more workers produced, the more work forces would be available to provide for the primary reproductives, the brood and the nest maintenance (overall nurturing capacity). On the other hand, some larvae must develop into soldiers to maintain the caste proportion, reducing the potential number of workers. Using incipient colonies of Coptotermes gestroi (Wasmann), we investigated the cost of maintaining the soldier proportion over the growth of the colony within the first year. Our results showed that an incipient colony maintains a stable soldier proportion regardless of the stress imposed. The resources redirected into the replacement of soldiers not only reduced the total number of workers, but it also reduced the overall growth of the colony by delaying the development of the remaining eggs. Our observations suggest that in termite incipient colonies, because of physiological constraints, the maintenance of the soldier proportion overrides the development of the colony. [ABSTRACT FROM AUTHOR]

The caste developmental pathway for the production of soldiers and nymphs in termite colonies is variable among species and limited numbers of studies have properly categorized such pathways. In this study, the developmental pathway for the production of soldiers and nymphs in Coptotermes formosanus Shiraki has been re-analyzed using the data from previous studies in light of new observations. Five distinct colony life stages were determined based on the caste developmental pathway used by the colony at each stage, which we here redefined as: incipient colony, immature colony, juvenile colony, mature colony, and senescent colony. We determined that in incipient colonies, the first soldier (nanitic) emerges from a second instar larva. We suggest that the production of a nanitic soldier is cost-effective as it allows the colony to focus on the production of workers from the first cohort of individuals. However, in an immature colony, the origin for the production of soldiers shifts to first and second instar workers. In juvenile colonies, soldiers are essentially produced from second instar workers. In mature colonies (>5 years), soldiers are mostly produced from second instar workers, occasionally from third instar workers, and we suggest that nymphs are primarily produced from second instar larvae. Finally, in senescent colonies, the absence of brood leads to the accumulation of old individuals. We concluded that descriptions from previous studies may have overlooked the group dynamics within a colony and that the caste developmental pathway in C. formosanus is dependent on the age of the colony. [ABSTRACT FROM AUTHOR]

In order to maintain healthy colonies, termite workers dispose of the cadavers of dead nest mates by cannibalism, burial, or necrophoresis. However, when multiple reproductives found a new colony by pleometrosis, there are no worker castes at the early stages of the foundation to eliminate or isolate the corpses. In this study, we showed that in young pleometrotic colonies, reproductives of Pseudacanthotermes spiniger had the ability to perform this task. Because of the claustral conditions, and the potential inability of the dealates to feed on their own, their behaviour was restricted to the burial of the cadaver within the initial chamber. This burial behaviour, previously not reported in the reproductive caste of termites, appeared to be induced by chemical signals released by the corpses during decomposition, among which various fatty acids, indole and phenol were the most active. The burial finally resulted in the physical isolation of corpses, thus reducing the chances for opportunistic pathogens to spread among the rest of the individuals. [ABSTRACT FROM AUTHOR]