Orphaned Colonies Research Articles

Types and Fecundity of Neotenic Reproductives Produced in 5-Year-Old Orphaned Colonies of the Drywood Termite, Cryptotermes domesticus (Blattodea: Kalotermitidae)

Orphaned colonies of Cryptotermes domesticus readily produce replacement reproductives and continue propagation. In this study, we aimed to investigate the production and fecundity of neotenic reproductives in 5-year-old colonies of C. domesticus after orphaning. All 15 experimental colonies were successfully re-established by the neotenic reproductive pair. Three types of neotenic reproductives with various wing-bud lengths were observed: type I with micro wing buds, type II with short wing buds, and type III with long wing buds. Four patterns of pairs made up of these neotenics, namely, type I + type II, type I + type III, type II + type II, and type II + type III, exhibited reproductive capacities similar to those of the primary reproductive pair. We speculated that these neotenic reproductives were derived from various nymphal instars. The 5-year-old colonies had three instars of nymphs, with the majority being in the second instar, followed by the first. Thus, the combination of neotenic reproductives with short wing buds and micro wing buds was the dominant differentiation pathway of the orphaned colonies. After the removal of the original primary reproductive pair, the nymphs matured into neotenic reproductives and took over reproduction in the colony in 107.40 ± 15.18 days. This study highlights the importance of quarantine and routine inspection of wood, as well as the significance of early prevention and control of C. domesticus infestation in wood. Moreover, this study confirms the high differentiation and reproductive capacities of C. domesticus.

Comparison of Feature Extraction Methods for Sound-Based Classification of Honey Bee Activity

Honey bees are one of the most important insects on the planet since they play a key role in the pollination services of both cultivated and spontaneous flora. Recent years have seen an increase in bee mortality which points out the necessity of intensive beehive monitoring in order to better understand this phenomenon and try to help these important insects. In this scenario, this work presents an algorithm for sound-based classification of honey bee activity reporting a preliminary comparison between various extracted features used separately as input to a convolutional neural network classifier. In particular, the orphaned colony situation has been considered using a dataset acquired in a real situation. Different experiments with different setups have been carried out in order to test the performance of the proposed system, and the results have confirmed its potentiality.

Queen execution in a monogynous ant.

Workers in many species of social insects are capable of laying unfertilized eggs, which can develop into haploid males. This causes a conflict about male parentage between queens and workers. In a few species, this may result in matricide, that is, workers kill the colony's queen. Queen killing has so far been observed mainly in multi‐queen colonies or in annual species, when the queen's fecundity declines at the end of the reproductive period. Here, we report queen expulsion and matricide in a monogynous, monandrous ant with perennial societies. Workers were seen to aggressively expel both related and unrelated queens from their nest shortly after the end of hibernation. Queen expulsion and matricide led to a significant decrease in the number of workers and brood, but eventually increased the direct fitness of workers through significant male production. Long‐term observations revealed a short lifespan of queens, while workers in orphaned colonies survived and produced male offspring over several years.

Worker thelytoky allows requeening of orphaned colonies but increases susceptibility to reproductive cheating in an ant

In some social insects, workers can produce females asexually through thelytokous parthenogenesis. This allows them to produce replacement queens (i.e. requeening) if the queen has died, but also to compete with the queen to produce females (i.e. reproductive cheating). For the first time, we experimentally tested the role of worker thelytoky under quasinatural conditions in the ant Cataglyphis cursor, where the queen uses both sexual and thelytokous reproduction. We reared pairs of orphaned and queenright colonies in enclosures for almost 3 months, during which they competed for resources. Orphaned colonies lost more workers than queenright colonies over the course of the experiment, presumably because of the costs of reproductive conflicts between workers. Nevertheless, they produced new queens through worker thelytoky and new colonies through colony fission. This is the first unambiguous demonstration that worker thelytoky allows requeening under natural conditions in this species. We further showed that worker thelytoky results in reproductive cheating in the form of a few workers reproducing in the presence of the queen (in queenright colonies) and a few worker lineages producing more new queens than other lineages (in orphaned colonies). In addition, it also results in rare instances of social parasitism, that is, workers entering and reproducing in foreign colonies. These benefits to workers seem too occasional and too low to drive the evolution of thelytoky in this species. We argue that thelytoky probably evolved in the queen caste, where it allows the production of young queens and confers frequent and large benefits by increasing gene transmission, but is also expressed in workers because of genetic correlations between the two castes.

Auxiliary brood cell construction in nests of the stingless bee Plebeia lucii (Apidae: Meliponini)

Queen production in stingless bees with fusion of neighboring brood cells occurs by the perforation of the adjacent brood cell or construction of an auxiliary one. This study describes the auxiliary brood cell building behavior in queenless colonies of Plebeia lucii. Queenright and queenless (orphan) colonies were monitored, and auxiliary cell construction was video-recorded in orphan colonies. Brood cells with auxiliary cells added were analyzed with X-rays to identify the amount of food and the larval behavior into the brood cells. Plebeia lucii had specific behavioral sequence in auxiliary cell building. The addition of auxiliary cells is the main strategy to produce queens in P. lucii, mainly for the production of emergency queens in orphan colonies because queen absence triggered a high production of auxiliary cells. X-ray analyses showed that auxiliary cell addition occurred when the food in the larval brood cells had been completely eaten and showed changes in dorsoventral position of the larvae. Larvae of males did not perforate auxiliary cells, indicating that sex-related factors affect this behavior. The wax handling by workers and the fused thin and concave-shaped wall between the auxiliary and larval brood cells seems to facilitate wall perforation by the larvae.

Worker reproduction of the invasive yellow crazy ant Anoplolepis gracilipes

BackgroundReproductive division of labor is one of the key features of social insects. Queens are adapted for reproduction while workers are adapted for foraging and colony maintenance. In many species, however, workers retain functional ovaries and can lay unfertilized male eggs or trophic eggs. Here we report for the first time on the occurrence of physogastric workers and apparent worker reproduction in the invasive yellow crazy ant Anoplolepis gracilipes (Fr. Smith). We further examined the reproductive potential and nutritional role of physogastric workers through multidisciplinary approaches including morphological characterization, laboratory manipulation, genetic analysis and behavioral observation.ResultsEgg production with two types of eggs, namely reproductive and trophic eggs, by physogastric workers was found. The reproductive egg was confirmed to be haploid and male-destined, suggesting that the workers produced males via arrhenotokous parthenogenesis as no spermatheca was discovered. Detailed observations suggested that larvae were mainly fed with trophic eggs. Along with consumption of trophic eggs by queens and other castes as part of their diet, the vital role of physogastric workers as “trophic specialist” is confirmed.ConclusionWe propose that adaptive advantages derived from worker reproduction for A. gracilipes may include 1) trophic eggs provisioned by physogastric workers likely assist colonies of A. gracilipes in overcoming unfavorable conditions such as paucity of food during critical founding stage; 2) worker-produced males are fertile and thus might offer an inclusive fitness advantage for the doomed orphaned colony.

Orphaning does not affect the colony productivity of the primitive eusocial wasp Polistes snelleni

In colonies of primitively eusocial wasps, some dominant workers become successive queens and inherit queenship after the death of the foundress queens. Although workers in many species do not mate, workers of Polistes snelleni are capable of mating and female production. In this study, we removed foundress queens from colonies of P. snelleni to evaluate the effects of queen loss on the dominant–subordinate relationships among the remaining workers and the productivity of colonies in the species. The foundress queens were the sole egg layers in almost all of the queenright colonies. The frequency of dominance behaviour among the wasps in the queenright colonies was significantly less than in the orphan colonies. The frequency of dominance behaviour in the successive queens after queen removal was significantly more than in the foundress queens. Multiple workers had developed ovaries, including the successive queens in 66.7 % (10/15) of the orphan colonies after queen removal. The orphan colonies produced significantly more cells and eggs than the queenright colonies. Our results suggest that the reproductive potential of the successive queens in the orphan colonies is not lower than that of the foundress queens, and that the productivity of the orphan colonies is maintained rather than causing potential conflict over direct reproduction among workers.

Multiple male and female reproductive strategies and the presence of a polyandric mating system in the termite Reticulitermes labralis (Isoptera:Rhinotermitidae)

Reproductive systems of termite colonies may involve the number of individuals in the reproductive caste and the copulatory selectivity of reproductive individuals (i.e., polyandry or polygamy), both of which directly impact the fertility and genetic diversity of the colony. Polygamy is widespread in the lower termites, whereas polyandry appears to be mostly absent in termites. In this paper, the differentiation of male and female neotenics were observed in orphaned experimental colonies of the subterranean termite Reticulitermes labralis. The artificial orphaned colonies began to produce neotenics a week after colony establishing, with more neotenics appearing in the same group over time. Finally, each experimental group reserved multi-neotenics that consisted of male and female neotenic individuals. Our results demonstrated that these neotenic individuals retained in the colony participated in reproduction. A genetic analysis at four microsatellite loci showed that in addition to the conspicuous morphologically male reproductives, there were inconspicuous males or workers that had copulated with the females in the orphaned colony. Multiple male and female reproductive individuals existed together in a single colony, and one female neotenic could mate with several male reproductives in a short time. Thus, multiple male and female reproductive systems and a polyandric mating system are present in R. labralis.

Duration of development of males in colonies of Polistes dominula (Christ) (Hymenoptera, Vespidae: Polistinae) in the south of Ukraine

The relation between the duration of ontogenesis of Polistes dominula males and the social structure of their colonies was studied in July–August 2012. Males developing in successful colonies with a foundress passed through the later-instar larval and pupal stages more quickly than those in orphaned colonies. Successful colonies more often produced males with weakly melanized mesopleura as compared with orphaned ones. Males from the two categories of colonies did not differ in the head and wing size. The influence of mechanical stress and nutrition during larval development and the specific signaling behavior of the foundresses on the male phenotypic diversity in P. dominula is discussed.

Colony take-over and brood survival in temporary social parasites of the ant genus Formica

Parasites reduce host fitness, and so instigate counter adaptations by their hosts. In temporary social parasitism, usurpers must not only enter the colony unharmed, but also have their eggs reared by the host workers. We introduced parasitic Formica lugubris and Formica aquilonia queens into queen right and orphaned fragments of three host species, Formica cinerea, Formica picea and Formica fusca, and show that workers of all three host species kill over 40 % of the introduced queens within 10 days, regardless of the presence/absence of a resident queen, and parasite species. More parasite queens died in F. cinerea than in F. picea and F. fusca. There were no major differences in survival between the parasite species (except that F. lugubris survived longer than F. aquilonia in F. fusca colonies compared to F. picea colonies), but parasite queens survived longer in orphaned than in queen right fragments of F. fusca. Experimental introduction of parasite (F. aquilonia) eggs into orphaned colonies of F. fusca showed that none of the parasite eggs were reared until pupation; whereas on average, 12 % of the con-specific hetero-colonial eggs introduced in the same manner were reared until pupation. In all colonies that received parasite brood, all offspring consisted of worker-laid males, whereas the corresponding value was 50 % for colonies that received con-specific hetero-colonial brood. Thus, when the risks of entering host colonies and brood failure are combined, the rate of successful colony take-over is very low. Moreover, the host workers can to some extent alleviate the costs of parasitism by producing a final batch of own offspring.

Variation in patriline reproductive success during queen production in orphaned colonies of the thelytokous antCataglyphis cursor

In genetically diverse insect societies (polygynous or polyandrous queens), the production of new queens can set the ground for competition among lineages. This competition can be very intense when workers can reproduce using thelytoky as worker lineages that manage to produce new queens gain a huge benefit. Selection at the individual level might then lead to the evolution of cheating genotypes, i.e. genotypes that reproduce more than their fair share. We studied the variation in reproductive success among worker patrilines in the thelytokous and highly polyandrous ant Cataglyphis cursor. Workers produce new queens by thelytoky in orphaned colonies. The reproductive success of each patriline was assessed in 13 orphaned colonies using genetic analysis of 433 workers and 326 worker-produced queens. Our results show that patrilines contributed unequally to queen production in half of the colonies, and the success of patrilines was function of their frequencies in workers. However, over all colonies, we observed a significant difference in the distribution of patrilines between workers and worker-produced queens, and this difference was significant in three of 13 colonies. In addition, six colonies contained a low percentage of foreign workers (drifters), and in one colony, they produced a disproportionably high number of queens. Hence, we found some evidence for the occurrence of rare cheating genotypes. Nevertheless, cheating appears to be less pronounced than in the Cape Honey bee, a species with a similar reproductive system. We argue that worker reproduction by parthenogenesis might not be common in natural populations of C. cursor.

Inconspicuous matured males of worker form are produced in orphaned colonies of Reticulitermes speratus (Isoptera: Rhinotermitidae) and participate in reproduction

Differentiation of neotenics is easily induced by orphaning the worker termites of Reticulitermes speratus (Kolbe). Although it has previously been reported that the sex ratio of neotenics is female-biased, the background of this phenomenon and the gonad developmental process of workers in artificially orphaned colonies are unknown. Although both male and female conspicuous neotenics can emerge as a response to the orphaning of the colony, we observed that majority of the reproductive males that are formed do not molt into the neotenic morph and are therefore inconspicuous in the population. Participation of the inconspicuous reproductive males in sexual reproduction was confirmed by genetic analysis. Slight pigmentation of the abdominal sternites is the only characteristic of the inconspicuous reproductive males that enables them to be distinguished from normal male workers. The presence of the female ergatoid (one type of female neotenic) did not induce the production of inconspicuous reproductive males during the 12-week experiment time.

Worker reproductive parasitism in naturally orphaned colonies of the Asian red dwarf honey bee, Apis florea

The truce between honey bee (Apis spp.) workers over reproduction is broken in the absence of their queen. Queenright workers generally abstain from personal reproduction, raising only the queen’s offspring. Queenless workers activate their ovaries, produce eggs, and reduce the rate at which they destroy worker-laid eggs, so that some eggs are reared to maturity. Reduced policing of worker-laid eggs renders queenless nests vulnerable to worker reproductive parasitism (WRP), and may result in the colony raising eggs of unrelated (non-natal) workers that parasitize it. Queenless colonies of A. florea are heavily parasitized with the eggs of non-natal workers. However, queenless colonies often abscond upon disturbance and build a small comb in which to rear their own male offspring. We investigated three naturally occurring orphaned colonies to determine if they are also parasitized. We show that WRP is present in orphaned colonies, and non-natal workers have significantly higher rates of ovary activation than natal workers. In contrast to experimentally manipulated colonies, in our samples, natal and non-natal workers had statistically equal reproductive success, but this may have been due to the small number of non-natals present.

Worker dominance and policing in the ant Temnothorax unifasciatus

In many species of eusocial Hymenoptera, conflict about the production of males is resolved through “policing.” Recent studies in wasps and the ant Temnothorax unifasciatus suggest that in these species policing workers are dominant themselves and selfishly increase their own chances of later becoming fertile. Policing may therefore to some extent be associated with dominance and selfishness, and dominance and policing behaviour are indeed difficult to distinguish and often not mutually exclusive. Moreover, selfish policing requires that workers form rank orders already in the presence of the queen. Here, we try to allocate aggressiveness by workers towards policing and/or dominance behaviour and investigate whether hierarchies based on subtle, non-aggressive interactions exist in queenright colonies of the ant T. unifasciatus. We either split colonies into a queenright and queenless halve or temporarily removed the queen from complete colonies, which in both cases allows a few dominant workers to lay eggs in the queenless colony. Reunification of colony halves and return of the queen to orphaned colonies led to aggression against those workers that had become fertile during the absence of the queen. Dominant workers in reunited, split colonies were more severely attacked than those in orphaned colonies after return of the queen. Furthermore, we observed that workers, which later became dominant egg layers under queenless conditions, have more contact with the queen than other workers. Both results corroborate the existence of rank relationships among workers in queenright colonies and show that results from policing experiments may be affected by the disturbance of pre-existing hierarchies through colony splitting.

Hierarchy length in orphaned colonies of the ant Temnothorax nylanderi

Workers of the ant Temnothorax nylanderi form dominance orders in orphaned colonies in which only one or a few top-ranking workers begin to produce males from unfertilized eggs. Between one and 11 individuals initiated 80% of all aggression in 14 queenless colonies. As predicted from inclusive fitness models (Molet M, van Baalen M, Monnin T, Insectes Soc 52:247-256, 2005), hierarchy length was found to first increase with colony size and then to level off at larger worker numbers. The frequency and skew of aggression decreased with increasing size, indicating that rank orders are less pronounced in larger colonies.

The orphaned colony

This article examines British encounters with Indian, Andamanese, white and African orphans in colonial India in the second half of the nineteenth century. It argues that orphans provided colonial administrators with opportunities to articulate increasingly scientific constructions of race, which might undergird contemporary imperialism, and simultaneously to explore the limits of colonial authority. The absence of parents was doubly helpful to these discoveries. At one level, the removal of the parent isolated the child from the contamination of culture. This left it available to experts, who wished to study the nature of the biological material or to leave their own impressions. At another level, it eliminated a source of political interference in the relationship between the child and the unrelated adult, which could now be interpreted largely in terms of scientific, bureaucratic or political necessity, including the language of savage-repression that constitutes a part of the prose of counter-insurgency. Orphaning was not only a metaphor for governance, it was also a problem of governance, and in some situations, a technique for the management of colonised populations.

Aggressions and size-related fecundity of queenless workers in the ant Cataglyphis cursor

In social hymenoptera, the reproductive division of labor is often linked to differences in individual body size with the reproductive caste (the queen) being larger than the workers. Likewise, the reproductive potential may vary with size within the worker caste and could affect the evolution of worker size in social insects. Here, we tested the relationship between worker size and reproductive potential in the facultative parthenogenetic ant Cataglyphis cursor. Colonies are headed by a multiply mated queen, but workers can produce gynes (virgin queens) and workers by thelytokous parthenogenesis after the queen's death. We observed the behaviour of workers (n = 357) until the production of gynes (212 h over 3 months) in an orphaned colony (mated queen not present). The size of workers was measured, and their paternal lineage determined using six microsatellite markers, to control for an effect of patriline. Larger workers were more likely to reproduce and lay more eggs indicating that individual level selection could take place. However, paternal lineage had no effect on the reproductive potential and worker size. From the behavioural and genetic data, we also show for the first time in this species, evidence of aggressive interactions among workers and a potential for nepotism to occur in orphaned colonies, as the five gynes produced belonged to a single paternal lineage.

Not only cuticular lipids: First evidence of differences between foundresses and their daughters in polar substances in the paper wasp Polistes dominulus

Several studies have shown that differences in the relative abundance of cuticular hydrocarbons occur between reproductives and non-reproductives in many social insects. These differences also exist between Polistes dominulus foundresses and their first emerged daughters (usually indicated as workers), but they gradually disappear when workers from orphaned colonies develop their ovaries and assume a reproductive role in the colony. However, hydrocarbons are not the exclusive components of cuticular layer of wasps. Mass-spectrometry analysis of cuticular methanol extracts from Polistes paper wasps showed a complex pattern of polar substances, partly or totally proteinaceous in nature. We found that these compounds, ranging from 918 to 2679 Da, showed a clear caste differentiation between foundresses and their first emerged daughters (usually indicated as “workers”), both in queen-right and in orphaned colonies. Conversely to hydrocarbons, workers from orphaned colonies maintain a significant difference from foundresses in the pattern of the medium molecular weight (MW) polar compounds obtained by MALDI-TOF. On the basis of such results we hypothesize that a reliable cue to identify foundresses from daughters, and not only their reproductive status, may exist in Polistes wasps. Although the great majority of previous work on social insect communication has focused on cuticular hydrocarbons, our findings suggest that the medium MW component of cuticular substances may be involved in recognition.

Are workers of Atta leafcutter ants capable of reproduction?

Workers of most eusocial Hymenoptera can produce sons after queen loss, which (posthumously) benefits the queen and increases worker inclusive fitness. However, the evolutionary loss of worker ovaries has occurred in several lineages, while workers in other taxa may be infertile despite having ovaries. Workers of Atta leafcutter ants only lay trophic eggs in queenright colonies. Although Atta colonies are commonly kept at universities, museums, and zoos, no reports of worker sons in orphaned colonies exist, suggesting that Atta workers are infertile. To explicitly test this, we created eleven orphaned laboratory nests of Atta cephalotes, A. sexdens, and A. colombica, and maintained them for 3–6 months after queen loss. Eight colonies did not produce any brood, but three nests produced 1–4 worker-derived male larvae and pupae. Microsatellite genotyping indicated that these were worker sons. However, all males were tiny (3.5–9 mm long) compared to normal queen sons (16 mm long), and would almost certainly be unable to mate. We also found reproductive eggs, but most of these had no yolk and were thus inviable. We conclude that Atta workers are not completely infertile, but that worker fertility is low compared to the sister genus Acromyrmex, where workers routinely produce normally-size males after queen loss in the laboratory. We hypothesize that worker reproduction in orphaned Atta field colonies is almost never successful because the last workers die before their sons can be raised to adulthood, but that the importance of worker-laid trophic eggs for queen feeding has precluded the evolutionary loss of worker ovaries.

F queen in a temperate paper wasp Polistes snelleni Saussure (Hymenoptera Vespidae)

Colonies of a temperate paper wasp Polistes snelleni were artificially orphaned in the laboratory to examine whether workers mated before orphaning can become inseminated egg-layers (replacement queens). Of 23 worker reproductives (with developed ovaries) in 14 colonies, 4 from 4 colonies were inseminated and became egg-layers. Since they did not contact males after orphaning, they were inseminated in the presence of foundress queens and became fertilized reproductives in orphan colonies without mating after orphaning. In addition to worker reproductives, 2 non-reproductive workers from 2 other colonies were also inseminated before orphaning. These results indicate that some workers of P. snelleni mate before orphaning and subsequently become inseminated egglayers after orphaning, showing the behavioural plasticity of temperate Polistes.