Showing papers in "Insectes Sociaux in 1986"
TL;DR: Evidence is presented that extranidal Ortstreue is based on long-lasting individual memory of spatially organized visual cues, and that olfactory cues, probably identical with scent markings of the home range, are a cause of idiosyncratic OrtStreue during the dark period.
Abstract: Route fidelity and site allegiance (Ortstreue) ofFormica rufa group ants are analysed with repect to orienting cues and preservation through periods of isolation or winter dormancy. Colour-marked workers showed certain site allegiance to different parts of a moundnest, but the phenomenon was too weak to explain the retention of extranidal Ortstreue measurad in nature. The same applies to kinesthetic and other cues based on intranest architecture. Evidence is presented that extranidal Ortstreue is based on long-lasting individual memory of spatially organized visual cues. The engram stored through several months of winter dormancy can be indirectly identified with a representation of landmark/canopy patterns. The experiments carried out in large openair arenas show, however, that olfactory cues, probably identical with scent markings of the home range, are a cause of idiosyncratic Ortstreue during the dark period. The latter orienting cues, which in the main are switched off in the presence of visual cues, may also be stored in the memory, but preservation through winter dormancy could not be confirmed. The possibility that the ants may use geomagnetic cues was tested, but the result was negative. The ecological implications of the findings are discussed.
122 citations
TL;DR: The ontogeny of the social structure in relation to the reproductive success of its members in four colonies of the bumblebee is investigated and a characteristic behavioural pattern, in which egg laying by the elite workers occurs in the last period of colony development is confirmed.
Abstract: We investigated the ontogeny of the social structure in relation to the reproductive success of its members in four colonies of the bumblebeeBombus terrestris L. In all four colonies, the time of colony development was divided into four periods. Only in the last period did worker-oviposition occur.
121 citations
TL;DR: The life cycle and aspects of the social organization of Exoneura bicolor are described for the first time, and it is suggested that terms such as ‘eussocial’ and ‘semisocial’ are inappropriate to describe even ontogenetic stages in allodapine colony development.
Abstract: The life cycle and aspects of the social organization ofExoneura bicolor are described for the first time The population studied was univoltine, with egg production occuring from late winter through to early summer Throughout the year most nests are occupied by more than one female, and most new nests are initiated by groups of up to 6 cofoundresses Reproductive differentiation between nestmates is very pronounced during winter, with only one or two egg-layers in each nest These females appear to be largely responsible for maintaining their adult nestmates in Autumn In spring, additional females are inseminated and begin to lay eggs, though some remain unmated and do not show ovarian enlargement New nests are founded during late spring, and most foundresses are mated and have enlarged ovaries Relatedness between nestmates was estimated using a polymorphic enzyme regression technique, and was found to be similar for both overwintered and co-founded nests, suggesting that co-foundresses originate from the same natal nests The consequences of persistant multi-female nests and reproductive differentiation are discussed, and it is suggested that terms such as ‘eusocial’ and ‘semisocial’ are inappropriate to describe even ontogenetic stages in allodapine colony development
71 citations
TL;DR: Two polycalic systems of the Neo-Guinean polygynus revealed the presence of functional reproductives in more than one calie, thus suggesting a process of colony reproduction by budding, and observations on swarming and postflight behaviour of N. costalis do not support the possibility that polygynous associations result from foundation in common after swarming.
Abstract: The nests of the Neo-GuineanNasutitermes polygynus Roisin and Pasteels and the NeotropicalN. costalis (Holmgren) are polycalic. Seventy percent of theN. polygynus nests and half theN. costalis nests were found to be devoid of royal nodule and reproductives. Two polycalic systems ofN. polygynus revealed the presence of functional reproductives in more than one calie, thus suggesting a process of colony reproduction by budding. Multiple imaginal queens are extremely frequent in both species: inN. costalis, all the 14 nests with reproductives were polygynous, whereas inN. polygynus, only one nest of 14 was monogynous. The proportion of polygynous societies is much higher in these species than in any other termite so far studied. Multiple kings are usually associated with polygyny. The numbers of functional sexuals encountered in the two species are also exceptional: up to 105 queens inN. polygynus, 97 inN. costalis. The coexistence of queens of different generations, recognizable by their sclerite pigmentation, occurred in fourN. polygynus and twoN. costalis nests. The younger queens are usually more numerous and smaller than the older ones. In both species, the average size of the queens is negatively correlated with their number. Average egg production rates were recorded inN. polygynus. They are in good correlation with the queens' average fresh weight. A colony ofN. polygynus orphaned by removal of the five constituting calies recovered and rebuilt two new nests, in both of which hundreds of young adultoid replacement reproductives were found. Observations on swarming and postflight behaviour ofN. costalis do not support the possibility that polygynous associations result from foundation in common after swarming. The ecological significance of polycalism, the relationships between queen age, number and physogastry, and the methods of formation of polygynous associations are discussed.
47 citations
TL;DR: A single large brood of reproductives was produced each year, which took about seven months from egg-laying to maturity, and sometimes remained in the nest for several more months before flighting was complete.
Abstract: Mature nests ofMacrotermes michaelseni were sampled at approximately monthly intervals over two years A single large brood of reproductives was produced each year, which took about seven months from egg-laying to maturity, and sometimes remained in the nest for several more months before flighting was complete The sterile population of the nest was remarkably constant through the year, showing no response to the seasonal rainfall pattern or to the presence of the developing reproductive brood in the nest Some changes were observed in the course of a severe drought, resulting in a gradual reduction in the sterile populations of nests, and in the overall termite population of the area
45 citations
TL;DR: Nest architecture ofHalictus ligatus was studied at Victoria, southern Ontario; over 130 nests were excavated in 1984 and found cells near the surface may suffer from waterlogging after heavy rains and nests situated in denser vegetation suffered less mortality from mould.
Abstract: Nest architecture ofHalictus ligatus was studied at Victoria, southern Ontario; over 130 nests were excavated in 1984. The most important findings are as follows. Nest failure was lower in vegetated areas than in bare ground. Nests with entrances hidden under leaves may suffer less mortality from parasites than those out in the open. Loops around cells are dug in response to moist soil conditions and appear to be an intermediate step towards cavity formation. Brood mortality due to mould seemed to result from cell waterlogging which the excavation of loops may help to prevent. Cells near the surface may suffer from waterlogging after heavy rains. Nests situated in denser vegetation suffered less mortality from mould. Gyne-producing cells are larger than male or worker-producing ones. Mandibular wear is an accurate measure of the amount of excavation performed by an individual female.
45 citations
TL;DR: There was an excess of males among the workers of colonies that had begun to form nymphs and alates, and among the soldiers of all colonies, and the unusual chromosomal mechanism of sex determination was discussed.
Abstract: Seventy field-collected colonies of the termiteIncisitermes schwarzi Banks were analyzed in terms of caste- and sex-ratios. The main findings were: (1) approximately equal numbers of males and females were found among the workers in colonies that had not yet begun nymphal and imaginal molts; (2) there was an excess of males among the workers of colonies that had begun to form nymphs and alates, and among the soldiers of all colonies; this is believed to be a secondary effect of the fact that (3) female workers develop into nymphs and alates before males do, and female alates leave the colony, on average, earlier than males; (4) comparison of colonies at a stage before the nymphal molts have begun, with colonies containing nymphs, suggests a loss of about 10 percent of the females during the transition to nymphal stages; (5) one period of alate production occurs per year, lasting about 2 months, with 20 to 50 percent of the workers turning into alates; (6) 26 percent of the colonies had one or both primary reproductives replaced by secondary reproductives, leading to a certain amount of inbreeding; (7) except for greater maturity, there was no apparent difference in composition between colonies headed by primary reproductives and those headed by secondary reproductives; (8) soldiers made up about 7 percent of the average colony, numerically, with small soldiers 3 times as numerous as large soldiers; (9) colonies produce small soldiers first, later adding large soldiers; soldier production is lower when nymphs and alates are forming. The findings are discussed in relation to the reproductive cycle and life cycle of the colony, the amount of inbreeding in the population, and the unusual chromosomal mechanism of sex determination.
32 citations
TL;DR: A unique “wall-papering” behavior was also discovered: the workers line the pupal chambers with fragments of discarded pupal cocoons, rendering these spaces drier and hence presumably more suitable for pupal occupation.
Abstract: We report here the first detailed account of a member ofPrionopelta, a pantropical genus possessing the smallest workers in the primitive ant tribe Amblyoponini.
1.
Colonies ofP. amabilis were found nesting in small rotting logs and tree branches on the floor of primary rain forest in Costa Rica. Two that were more carefully excavated possessed a single dealate queen and a worker population unusually large for Amblyoponini. One of the latter colonies, which was in the process of eclosing alate queens (during late March), contained over 700 workers.
2.
P. amabilis workers prey preferentially on campodeid diplurans, although they also accept (less readily) a limited variety of other small arthropods. The prey are given directly to the larger larvae. The queen is fed trophic eggs which we infer to have been laid by the workers.
3.
A moderately well-marked temporal division of labor occurs, thus distinguishingP. amabilis fromAmblyopone pallipes, the only other amblyoponine hitherto studied in this regard. Younger workers attend the brood and queen, forming a retinue around the latter individual. Older workers are more active in foraging. As expected, the ovaries are better developed in workers associated with the queen than in foragers.
4.
Emigration to nest sites is conducted individually, with the workers carrying brood but not other adult nestmates. A foot-dragging behavior, possibly associated with trail-laying, is described. Alarm pheromones are apparently absent.
5.
A unique “wall-papering” behavior was also discovered: the workers line the pupal chambers with fragments of discarded pupal cocoons, rendering these spaces drier and hence presumably more suitable for pupal occupation.
29 citations
TL;DR: Individual worker bees (Apis mellifera L.) of known age (donor bees) were artificially fed with sugar syrup containing Methylene blue as a tracer dye, which fed significantly less sugar syrup to recipient workers than bees of other ages.
Abstract: Individual worker bees (Apis mellifera L.) of known age (donor bees) were artificially fed with sugar syrup containing Methylene blue as a tracer dye. The donor bee was placed into a group of 30 recipient workers and the amount of transferred food was quantified. Donor bees, at the age of 5–8 days and older than 30 days, fed significantly less sugar syrup to recipient workers than bees of other ages. This was found for both the number of fed recipients, and for the amount of food received per recipient bee.
28 citations
TL;DR: It is hypothesize that the trigger hairs characteristic of M. barbouri and other species of the subgenusMyrmoteras could represent an adaptation to collembolan prey.
Abstract: Field and laboratory studies on a colony ofMyrmoteras toro collected in Central Sulawesi and aM. barbouri colony from Singapore have provided the first ecological and behavioral information on this enigmatic formicine genus. Both species capture prey singly by the trap-jaw method, much as do many dacetine and odontomachine ants. Before striking the ants open their jaws 280°, the greatest degree yet recorded in the ants. Also, the nest area is defended from encroachment by other invertebrates by slapping intruders repeatedly with the mandibles.
26 citations
TL;DR: It can be now claimed that inN.
Abstract: The influence of the reproductives on soldier production was studied in two species of higher termites,Nasutitermes lujae (Nasutitermitinae) andCubitermes fungifaber (Termitinae). In both species, the royal pair has a stimulatory influence on soldier production. The soldier molts are two to three times more numerous when workers are reared with the reproductives. InN. lujae, the king and the queen have an apparently equal stimulatory influence. The reproductives act on both induction and orientation of the molts toward the soldier type. It can be now claimed that inN. lujae, in which the existence of an inhibitory soldier pheromone was recently evidenced, the proportion of soldiers results from the balance between the stimulatory influences of the reproductives and the inhibitory influences of the soldiers. The hypothetical nature of the royal stimulatory influence is discussed.
TL;DR: P. canadensis (Brazil) exhibited the greatest average angle of cell divergence and was the only wasp investigated that regularly built its nest a several small combs in close proximity, and in many species the comb angle with respect to the petiole changed during construction.
Abstract: Measurements were taken from the nests of 12 species ofPolistes wasps and qualitative differences described. The combs of theFuscopolistes spp.,P. Palisotius major andP. Epicnemius pacificus were horizontal and either oval or round with a central petiole, while those of theP. Aphanilopterus spp. were tear-shaped with eccentric or lateral petioles. For all species the angle of the petiole to the substrate was close to 90°. The fourFuscopolistes species usually built the first cell vertically, regardless of the substrate angle, and thus reduced the angle of the nest. In contrast, the angle of the first cell increased the nest angle of the 6Aphanilopterus species studied. A regression of average cell diameter on headwith was significant. All species stopped lengthening cells after larvae pupated in them.P. (A.) canadensis (Brazil) exhibited the greatest average angle of cell divergence and was also the only wasp investigated that regularly built its nest a several small combs in close proximity. In many species the comb angle with respect to the petiole changed during construction. Temperate species tended do add more pulp to the petiole of the nest than did tropical species, built secondary petioles, and added pulp to the substrate. Whether or not pulp is added to pupal caps and comb back, paper strength and color, and the shape of cell backs were also variable among species.
TL;DR: Minor workers ofPheidole cephalica respond to small quantities of water placed in the nest entrance by making alarm runs through the nest, often ending at alternate entrances, which proved significant in both the “liberal” test, in which all species were counted equally, and the ‘conservative’ test, which sets of closely related species were treated as single taxonomic units.
Abstract: Minor workers ofPheidole cephalica respond to small quantities of water placed in the nest entrance by making alarm runs through the nest, often ending at alternate entrances (fig. 1). They use odor trails to lead nestmates into the entrance galleries and sometimes away from the nest altogether. With this procedure one or two workers are able to mobilize a large fraction of the colony in 30 secs or less.
TL;DR: The weaver ant,Polyrhachis simplex, inhabits areas characterized by high ambient temperatures, year round open water and Homoptera-hosting plants and its main food source is “honeydew” excreted by four homoptera species.
Abstract: The weaver ant,Polyrhachis simplex, inhabits areas characterized by high ambient temperatures, year round open water and Homoptera-hosting plants. Its main food source is “honeydew” excreted by four homoptera species. We estimated the daily energy expenditure ofP. simplex and measured its energy intake of honeydew when it attended the aphidChaitophorous populialbae. Daily energy expenditure was estimated as 1.85 to 2.58 J/day and energy intake was calculated as 8.18 to 24.54 J/day, i.e. 4.4 to 9.4 times its energy requirements.
TL;DR: Basiceros manni has a behavioral repertory comparable in complexity but not in detail to that ofEurhopalothrix heliscata, the only other basicerotine species studied to date.
Abstract: We report here the first detailed observations of a member of the Neotropical genusBasiceros (B. manni), which possesses the largest and anatomically most primitive workers and queens within the ant tribe Basicerotini.
1.
Colonies ofBasiceros manni were found nesting in small rotting logs and a leguminous seed pod on the floor of Costa Rican rain forest. The mature colony composition is a single dealate queen and approximately 50 workers. New queens and males eclosed during late March, in the dry season.
2.
B. manni workers and queens are cryptically colored to an extreme degree, a condition enhanced by the accumulation of soil and litter particles on the body surface with the aid of a double layer of plumose hairs (fig. 1–3). They are also among the slowest-moving of all ants and “freeze” into immobility for minutes at a time when disturbed.
3.
The workers capture a wide diversity of insects, including beetle larvae and (in the laboratory) centipedes, termites, andDrosophila adults. The prey are fed directly to the larvae. So far as known the workers forage singly and do not recruit.
4.
Emigration is facilitated by a communication behavior apparently preliminary to adult transport: workers that have encountered suitable nest sites tug at the appendages of nestmates, causing them to search on their own. Workers also carry nestmates to the new sites, but less commonly.
5.
The repertory size is unusually small for myrmicine ants. A relatively simple temporal division of labor occurs, with young workers functioning more as nurses and older ones as foragers (fig. 4, tables I, II). The ovaries are maximally developed in the youngest workers, evidently in association with the laying of trophic eggs. Conversely, the poison gland reservoir reaches its greatest size in older workers, in association with increased predatory activity.
6.
Overall,B. manni has a behavioral repertory comparable in complexity but not in detail to that ofEurhopalothrix heliscata, the only other basicerotine species studied to date.
TL;DR: The analysis of the possibilities of localization of prey by foraging workers shows that the maximal distance is 3 mm, which establishes that antennation is more emphasized when the prey is immobilized or is anaesthetized with CO2.
Abstract: L'analyse des possibilites de localisation des proies par les ouvrieres pourvoyeuses montre que la distance maximale est de 3 mm. La sequence comportementale la plus riche, lors de la capture de la proie, comprend les phases suivantes: detection, localisation, approche, palpation antennaire, attaque avec fermeture brusque des mandibules, soulevement, piqure et transport. Une analyse sequentielle montre que la palpation est la plus intense quand la proie s'immobilise ou est anesthesiee au CO2. Dans ce dernier cas, la proie est saisie a la suite d'une fermeture lente des mandibules suivie aussitot du transport vers le nid.
TL;DR: The experiments suggest that the area is chemically modified by the ants' activity, but the possibility of a specific marking behaviour was not further investigated, and the society size appears to be less important in determining the general level of activity for recently-settled societies.
Abstract: Leptothorax unifasciatus workers differentiate new areas from those previously explored. Indeed, a “coming and going” behaviour appears more frequent on a virgin paper than on a familiar one. The decrease of activity on a new paper after some hours indicates that this species rapidly gets to known such an area in the experimental device used here. The experiments suggest that the area is chemically modified by the ants' activity, but the possibility of a specific marking behaviour was not further investigated.
TL;DR: The most distinctive properties include the occurence of defensive retinues around the queen which intensify when the colony is exposed, the use of trunk trails during foraging, predation on arthropod eggs, and the absence of adult transport during colony emigration.
Abstract: Erebomyrma, a Neotropical genus of pheidologetine ants with caste dimorphism convergent to that ofPheidole, also resemblesPheidole in its pattern of division of labor. The major workers ofE. nevermanni, the species examined during this study, assist in subduing larger prey, defend the nest, and serve as semi-repletes in liquid food storage. Their repertory is limited and specialized when minor workers are present but expands to include foraging and brood care when the minor workers are removed. The expansion is accompanied by a 10X or more increase in general activity rate. Other details of the natural history and social behavior ofE. nevermanni are given. The most distinctive properties include the occurence of defensive retinues around the queen which intensify when the colony is exposed, the use of trunk trails during foraging, predation on arthropod eggs, and the absence of adult transport during colony emigration.
TL;DR: The twoPseudomyrmex species studied have the following communication systems: P. triplarinus informs its nestmates about the presence of food, but not about its location, and P. termitarius does neither.
Abstract: The twoPseudomyrmex species studied have the following communication systems:
a)
P. triplarinus informs its nestmates about the presence of food, but not about its location.P. termitarius does neither.
b)
Both species recognize their territory and/or area around the nest entrance through odours on the substrate.P. triplarinus marks its territory with a pheromone from the thorax, probably from the metapleural gland. This territorial mark lasts less than 1 h, and probably advertises at least part of the home range of the colony. The territorial odour used byP. termitarius, probably works as a nest entrance orientation mark, and lasts over 5 h, but less than 24 h. The origin of the odour is not clear.
c)
P. triplarinus uses a cephalic pheromone as the main signal for nestmate recognition.P. termitarius uses non-identified odours, present on all body parts of the insect, as a nestmate recognition signal.
d)
Both species produce alarm pheromones from the head and the gaster.
TL;DR: Evidence of the frequent occurrence of such relocations of a humus-feeding termite from the forest of the Ivory Coast frequently migrates some distance away, by a subterranean route, and builds a new nest is presented.
Abstract: Cubitermes fungifaber, a humus-feeding termite from the forest of the Ivory Coast, builds an earthen nest by successive additions. When the nest is experimentally damaged, the surviving colony frequently migrates some distance away, by a subterranean route, and builds a new nest. This relocation sometimes occurs without any noticeable previous disturbance. We present evidence of the frequent occurrence of such relocations, which could be normal events during the development of the society.
TL;DR: Ultrastructural examination reveals a well-developed smooth endoplasmic reticulum along with numerous mitochondria as the major cytoplasmic constituents in the pygidial, Dufour's and Pavan's gland.
Abstract: Ants of the subfamily Dolichoderinae possess four major abdominal glands. The lack of a functional sting probably explains the rather moderate development of the sting associated poison and Dufour's glands. The extremely large pygidial gland has become the main source of the dolichoderine defensive secretions, while the Pavan's gland, when present, produces the trail substances. The large tergal gland between tergites 6 and 7, formerly called the anal gland, due to its anatomical position and general morphological characteristics, is homologous to the pygidial gland, which is found inaall other ant subfamilies. Pavan's gland, on the other hand, is apparently a peculiarity to the Dolichoderinae and Aneuretinae. The sac-like appearence of the Pavan's gland only represents the resevoir part, while the real secretory component of the gland is to be located in the thickened epithelium of the seventh abdominal sternite. Ultrastructural examination reveals a well-developed smooth endoplasmic reticulum along with numerous mitochondria as the major cytoplasmic constituents in the pygidial, Dufour's and Pavan's gland. Both characters can be related to the lipophilic secretion of these glands, while the moderately developed granular endoplasmic reticulum of the poison gland secretory cells may point to some protein synthesis. Both the pygidial and poison gland are comprised of individual secretory units with a glandular cell and its own duct cell, while the Dufour's and Pavan's gland correspond to the glandular epithelium type.
TL;DR: Morphological evidence indicates the Southeast Asian genusProatta is phylogenetically close to the Attini, with polygynous colonies, and the worker repertoire, temporal division of labor, and emigration behavior are discussed.
Abstract: 1
Morphological evidence indicates the Southeast Asian genusProatta is phylogenetically close to the Attini The gyne ofProatta is described for the first time
2
Colonies ofProtta butteli are polygynous, with numerous queens present There is no evidence for aggression between queens or differential treatment of queens by workers Also, there is no sign of intraspecific aggression: the ants readily accepted workers transplanted from distant sites
3
Workers search for food solitarity, foraging only a short distance (invariably less than a meter) from each nest entrance Within the limited foraging area worker density tends to be high, and clumps of as many as 50 foragers are sometimes present This foraging pattern allows for rapid exploitation of discovered food Recruitment occurs along odor trails formed from a pheromone originating in the poison gland
4
In addition to small prey and scavenged arthropod corpses, the ants capture prey larger than themselves Such prey are taken by an inchoate form of group predation The first worker to encounter the prey attempts to restrain it Because of the high forager density, additional workers soon arrive seemingly by chance and aid in pinning the prey in place Unlike attine ants,Proatta butteli does not feed on fungi
5
The worker repertoire, temporal division of labor, and emigration behavior are discussed Although workers vary little in head width (051 to 070 mm) they show a modest division of labor by size, with smaller individuals being relatively numerous in the brood area
TL;DR: A relationship was found to exist between the date of orphanship, the percentage of “short-lived” females and the sex ratio of the offspring and the duration of life-span of these various categories of wasp.
Abstract: In a previous paper we described a study under laboratory conditions of the pattern of development of the various categories of descendants during the life of a colony; the present study is particularly concerned with the duration of life-span of these various categories. The life-spans of females showed a bimodal distribution and short-lived and long-lived wasps were distinguished. Considerable overlap was observed between the periods during which these two categories of wasp emerged. A relationship was found to exist between the date of orphanship, the percentage of “short-lived” females and the sex ratio of the offspring. Colonies which lost their queen as early as June showed an increase in the number of descendants produced, but these descendants were predominantly male and, among the females, the majority were “short-lived”.
TL;DR: The form of normal groups of Myrmica rubra has been studied in artificial nests consisting of a single tier of cells, with a cortex composed only of workers that functions as a defensive zone and a zone in which prey are prepared for ingestion.
Abstract: 1.
The form of normal groups ofMyrmica rubra has been studied in artificial nests consisting of a single tier of cells. An envelope of workers spreads out and covers the queens and brood leaving a cortex composed only of workers that functions as a defensive zone and a zone in which prey are prepared for ingestion. The cortex is especially well developed near the entrance. As the egg cluster grows, it breaks up, often with worker help and releases larvae; when these are ready to pupate the workers take them back into the central core of non-feeding brood and queens.
2.
The sociability of queens varies from those that are often alone, to those that are rarely alone and spend most of their time with other queens. Sociable queens may be very specific in the individuals they associate with or very indifferent to their companions. All the queens lay eggs in variable numbers but the quantity is not related to their sociability.
TL;DR: The ability of the speciesMessor barbarus to adapt to new trail system conditions, with particular reference to the extreme changes in the environment caused by fire, is studied.
Abstract: This paper studies the ability of the speciesMessor barbarus to adapt to new trail system conditions, with particular reference to the extreme changes in the environment caused by fire. It was observed that trails established after the fire differed significantly from those used by the colony previously. Not all nest established new trails after the fire, since some re-used former trails. Similarly, a close relationship was observed between average trail width and density of vegetation, together with an increase in linearity and length of trails after the fire.
TL;DR: The data indicate that the sexes are distributed randomly within the termite colony, both within castes and between castes, and do not support the idea that the close genetic relatedness of same-sex siblings and preferential sex-biased altruistic behavior underly the evolution of eusociality in termites.
Abstract: Nine colonies of the lower termiteIncisitermes schwarzi, inhabiting tall, narrow dead mangrove tree trunks, were sectioned in the field; the sections were taken back to the laboratory and the termites in each section were classified by sex and caste. In a separate series of observations, portions of colonies were introduced into a narrow tunnel, and later the position, sex, and caste of each individual were recorded. The data from both kinds of study indicate that the sexes are distributed randomly within the termite colony, both within castes and between castes. The only exception was a slight tendency for soldiers of one sex to be associated with non-soldiers of the opposite sex. The observations do not support the idea that the close genetic relatedness of same-sex siblings (due to multiple sex chromosomes) and preferential sex-biased altruistic behavior underly the evolution of eusociality in termites.
TL;DR: The chromosome number and karyotype of two wasp species of the genusPolistes were determined by a technique involving colchicine and sodium citrate pre-treatment, which permitted a more precise chromosome identification.
Abstract: The chromosome number and karyotype of two wasp species of the genusPolistes were determined by a technique involving colchicine and sodium citrate pre-treatment, which permitted a more precise chromosome identification The speciesPolistes (Aphanilopterus) simillimus, with n=28, 2n=56 chromosomes, andPolistes (Aphanilopterus) versicolor versicolor, with n=31, 2n=62 chromosomes, showed sharply characteristic individual karyotypes
TL;DR: Large and medium-size larvae are placed by the workers upon large-size preys, on which they feed unaided, whereas small larvae are fed with pieces of prey as among many other ants.
Abstract: Les Fourmis du genreAphaenogaster (A. senilis etA. subterranea) ont une facon particuliere de nourrir leurs larves, en fonction de leur taille et de celle de la proie offerte. Les larves grosses et moyennes sont disposees par les ouvrieres sur les grandes proies, et se nourrissent elles-memes, tandis que les petites recoivent des morceaux de proies comme chez les autres fourmis. Ce comportement specifique disparait, chezA. subterranea, en l'absence de la reine. D'autre part, chezA. senilis, en l'absence de grosses larves, les petites sont traitees comme l'etaient les grosses.
TL;DR: Two new species of Anochetus in theemarginatus group (A elegans andA vallensis) are described from the Andes of western Colombia as discussed by the authors, A elegans is the largest species in the genus
Abstract: Two new species ofAnochetus in theemarginatus group (A elegans andA vallensis) are described from the Andes of western ColombiaA elegans is the largest species in the genus