Social parasitism of <Emphasis Type="Italic">Polistes dominulus</Emphasis> by <Emphasis Type="Italic">Polistes nimphus</Emphasis> (Hymenoptera,Vespidae)

Summary Interspecific facultative social parasitism is well known in ants and in bumble-bees, but it is rarer in wasps. This form of parasitism is traditionally considered to be an intermediate stage in the evolution of obligate interspecific parasitism, where the parasites are no longer able to nest alone. We report field and experimental observations of a newly discovered facultative parasitic relationship between two closely related free-living Polistes species: P. nimphus and P. dominulus. P. nimphus foundresses sometimes usurp the nests of the larger P. dominulus before worker emergence. The invading queen takes over the nest with abundant abdomen stroking on the nest surface and is accepted by workers if they emerge 6 or more days after usurpation. Morphometric comparisons show that the usurper species, though smaller than its victims, has morphological adaptations consisting of larger heads, mandibles and front femora relative to their body size that may give it an advantage during nest invasion. This strategy is likely to be taken only after the foundress loses her original nest because invading P. nimphus queens have lower reproductive success than they would have had on their own nest. Overall, we found that P. nimphus usurpers use strategies of invasion similar to those of two obligate parasites, suggesting that this may be an example of one of the pathways by which social parasitism evolved.Received 4 April 2003; revised 8 August 2003; accepted 14 September 2003.     

The social organization of forest hanuman langurs(Presbytis entellus)

The social organization of hanuman langurs (Presbytis entellus;Colobinae) was studied in Kanha Tiger Reserve, Central Indian Highlands, for 2300 hr (1980–1985), in a mosaic of moist deciduous forest and anthropogenic meadow. The langur population density was 46.15/km ² and the mean troop and band sizes were 21.7 and 14.0, respectively. Of 14 troops, 13 were one-male and 1 was trimale. The population adult sex ratio was 1:2.5. The majority of female sexual solicitations was directed toward the harem male. The birth season was December to May, with an estimated gestation of 171–224 days. A review of langur reproductive seasonality suggests that breeding throughout the year is confined to those populations able to exploit human food sources. Mortality during the first year of life was 40%, including infanticide. A significant positive correlation was found between the age of an infant at death or disappearance and the mother’s subsequent interbirth interval. Five cases of social change are described, including female transfer, one-male to multimale change, troop formation, and gradual and rapid replacement of troop males. Takeover-associated infant killing by band males, in an undisturbed moderate-density population, supported the sexual-selection/infanticide hypothesis but not the social-pathology hypothesis. However, it could not be directly confirmed that an invading infanticidal male gains a reproductive advantage. The male tenure of harems was estimated to be 45 months.     

Tutoring in Wild Golden Lion Tamarins

Among most nonhuman primates, juveniles must acquire most of their solid food independently. Information gleaned from adults results from efforts initiated by the juveniles. Donation of food or foraging information by adults to immatures is rare among apes and virtually unknown among monkeys. We report 3 observations in which wild adult golden lion tamarins appear to have directed their immature offspring to a location where a hidden prey item was located. According to the definition of Caro and Hauser (1992), the tamarins were tutoring their young.     

Grooming behavior of spider monkeys (Ateles geoffroyi) on barro colorado Island,Panama

Quantitative grooming data are presented for free-ranging black-handed spider monkeys (Ateles geoffroyi) on Barro Colorado Island, Republic of Panama. A total of 126 grooming sessions was recorded, with an average session length of 2.0 min (range, 0.1 to 10.0 min). Grooming was an infrequent behavior; on average, individuals allocated only 2.5% of their daily activity to grooming. Two daily peaks of grooming activity were observed, one near midday and another in the late aftermoon between 1600 and 1700. Adult females groomed most frequently, followed by males and then juveniles. Juveniles were the most frequent recipients of grooming, followed by females and then males. Individual preferences were observed primarily between mother-offspring, male-male, and juvenile-male grooming partners in this male-bonded fission-fusion, species. Grooming interactions reflect many of the social characteristics of spider monkey societies: intraclass grouping preferences, long period of juvenile dependence, male philopatry, and female dispersal.     

Social boundaries in a Malagasy Prosimian,the Sifaka (Propithecus verreauxi)

Using focal animal samples, the social organization of sifakas was studied in two forests for 2500 hr spread over 18 months. Data were also obtained on the size and composition of groups at two other sites. The size and adult sex ratio of groups varied widely within populations, although population-wide sex ratios approached unity. During the brief annual mating season, some males mated with females belonging to other groups. The response of both male and female group members to the approach of a nongroup male appeared to depend on his identity. It is argued that while group size may be constrained by the availability of resources, group composition reflects the effects of small-sample demographic variations rather than the outcome of reproductive competition among or between males and females. Spatial boundaries of groups do not coincide with social or reproductive boundaries even within a single breeding season; further study is needed of the processes whereby relationships are established and maintained between individuals from different groups.     

Social behavior and brood decline in reproductive-phase colonies ofBelonogaster petiolata (Degeer) (Hymenoptera: Vespidae)

Colonies ofBelonogaster petiolata in Gauteng (South Africa) produced reproductive offspring (gynes and males) in late January and early February of each nesting season; their appearance was associated with a decline in worker and brood numbers. Brood decline could commence in the presence of a dominant, reproductively active queen, and loss or removal of the queen was not followed directly by cessation of nest growth and brood care. An older worker usually took over the α-position in queenless colonies. Several factors appear to contribute to brood decline and, ultimately, termination of the colony cycle in this species. These include (1) cessation of the supply of solid food to colonies (and particularly their larvae) during the reproductive phase, (2) a decrease in the worker/larva ratio during the latter phase due to the progressive loss of workers, (3) increasing number of gynes and males, and (4) an adult priority over food reception from foragers.     

Demography of the striped mouse (Rhabdomys pumilio) in the succulent karoo

The striped mouse (Rhabdomys pumilio) is widely distributed in southern Africa, inhabiting a wide range of habitats. We describe the demography of the striped mouse in the arid succulent karoo of South Africa, and compare our findings with those of published results for the same species from the moist grasslands of South Africa. In both habitats, breeding starts in spring, but the breeding season in the succulent karoo is only half as long as in the grasslands, which can be explained by different patterns and levels of rainfall; the succulent karoo receives mainly winter rain and rainfall is much less (about 160 mm year⁻¹) than in the grasslands (>1000 mm year⁻¹) which experience summer rain. Population density increased from 37 (start of breeding season) to 171 (end of breeding season) mice per hectare. A high yearly survival rate of 27% during our study from summer to the next breeding season resulted in a population density that was 10 times higher in the succulent karoo than in grasslands. The comparatively high population density may result in habitat saturation and thus forced philopatry, promoting group living in the succulent karoo, which contrasts with the solitary life-style exhibited by populations in moist grasslands.

Zusammenfassung

Demographie der Striemengrasmaus (Rhabdomys pumilio) in der SukkulentenkarooDie Striemengrasmaus (Rhabdomys pumilio) ist im südlichen Afrika weit verbreitet und kommt in unterschiedlichen Habitaten vor. In dieser Studie beschreiben wir die Demographie der Striemengrasmaus in der ariden Sukkulentenkaroo Südafrikas, und vergleichen unsere Ergebnisse mit den Ergebnissen früherer Studien, welche dieselbe Art in den feuchten Grasländern Südafrikas untersucht haben. Die Fortpflanzungssaison beginnt in beiden Habitaten im Frühling, aber sie ist in der Sukkulentenkaroo nur halb so lange wie in den Grasländern. Der Grund dafür wird im unterschiedlichen Niederschlagsmuster vermutet: In der Sukkulentenkaroo regnet es wenig im Winter (ca. 160 mm), während es in den Grasländern viel im Sommer regnet (>1000 mm). Die Überlebensrate in der Sukkulentenkaroo war vom Sommer zur nächsten Fortpflanzungssaison im Frühjahr mit 27% außerordentlich hoch, während die Populationsdichte zehnmal so groß war wie in den Grasländern. Am Anfang der Fortpflanzungssaison betrug die Populationsdichte 37 Mäuse ha⁻¹, am Ende der Fortpflanzungssaison 171 Mäuse ha⁻¹. Die außergewöhnlich hohe Populationsdichte führt womöglich zu Habitatsättigung und einem Fehlen freier Territorien, was mit erklären könnte, warum die Striemengrasmaus in der Sukkulentenkaroo gruppenlebend ist, in den Grasländern hingegen solitär.     

Agonistic and grooming behavior of captive crowned lemurs (Lemur coronatus) during the breeding season

Captive breeding of rare and endangered prosimians may be enhanced by an increased understanding of all aspects of their seasonal mating behavior. In this study, the agonistic and grooming behaior of captiveL. coronatus were studied during their annual breeding season. Between October and March, selected aspects of agonistic and grooming behavior of four male-female groups were recorded. Males initiated significantly more allogrooming than females. The frequency of this behavior pattern increased significantly in the weeks of estrus. Females performed significantly more agonistic behavior patterns than males. The mean frequency of agonistic interactions decreased significantly during the breeding season. In successfully reproducing groups males showed much less agonism towards females, than they did in unsuccessful groups. Inter-specific comparisons demonstrated that the patterns of agonistic interactions during the breeding season are very different among closely related species of lemurids. The conclusions drawn from this study are that captive breeding of crowned lemurs may be enhanced by keeping permanent multi-male, multi-female groups.     

Colony Membership, Division of Labor, and Genetic Relatedness Among Females of Colonies of Eustenogaster fraterna (Hymenoptera, Vespidae, Stenogastrinae)

To compare the social structure of primitively social wasps with that of communal breeding vertebrates, we used a new technique based on micro videocameras applied to the nest envelope to study the organization of behavior in Malaysian colonies of the stenogastrine wasp Eustenogaster fraterna. The reproductive division of labor in this species appears to be different from that reported so far in other species of Stenogastrinae: it is at a very primitive stage because the helpers work less hard and take fewer risks than the egg-layers. Nevertheless, the very low-risk tasks performed by the helpers (nest guarding and supply of abdominal secretion to the young larvae) are important for the colonies. Behavioral characters and ovarian development of the helpers suggest that females are only temporary helpers and that they wait to start their own production of offspring in the hope of inheriting the nest. Females of the same colony can be highly related, but in some colonies we found low-related individuals. The social organization of these wasps resembles that of vertebrate groups with helpers at the den, i.e., in the small number of individuals, the division of labor with limited reproductive inhibition, and the prolonged external work of the reproductive individuals. However, the main drive to sociality in these insects appears to be different, being based mainly on problems connected with short adult life and long immature brood development.     

Usurpations and late associations in the solitary founding social wasp,Polistes biglumis bimaculatus (Hymenoptera: Vespidae)

One hundred twenty-five colonies of a population of the montane, haplometrotic, paper waspPolistes biglumis bimaculatus were marked for identification and then periodically surveyed during an entire summer period. This made it possible to record intraspecific nest usurpations (both single and multiple) and to observe associations between two females, defined here as late associations. Both usurpation and late association occurred primarily in the latter half of the preemergence period. Some evidence suggests that a foundress usurps a conspecific nest as a consequence of her own nest failure. After nest failure, usurpation and late association are the only available options for achieving reproductive success because, in the mountain habitat, the short summer does not allow for successful renesting. Late associations generally occurred earlier than usurpation. However, our evidence suggests that nest usurpation and late association may be the same phenomenon.     

Life history characteristics and behaviour of the bamboo aphid,Pseudoregma bambucicola (Hemiptera: Pemphigidae), having sterile soldiers

Summary Life history and behavioural characteristics of the bamboo aphid,Pseudoregma bambucicola (Takahashi), which has sterile soldiers, were studied in the laboratory. The stadium of normal (fertile) first instar larvae was two times longer than that of second instar larvae, and the stadium of soldier-type (sterile) first instar larvae was much longer (max. 116 days) than the stadium of normal first instar, suggesting that soldiers are able to take nutrition from bamboo. Stimulation of larvae with breath, vibration of bamboo shoots or disturbing the larvae with the tip of a fine brush induced significantly more defensive acts by soldiers than those by normal larvae — the latter usually fled. Soldiers did not attack non-kin conspecific intruders or even aphids of different species, suggesting that, in this species, kin-recognition ability is low.     

Species and Colony Components in the Recognition Odor of Young Social Wasps: Their Expression and Learning (Polistes biglumis and P. atrimandibularis; Hymenoptera: Vespidae)

In Polistes, nestmate recognition relies on the learning of recognition cues from the nest. When wasps recognize nestmates, they match the template learned with the odor of the encountered wasp. The social wasp Polistes biglumis use the homogeneous odor of their colony to recognize nestmates. When these colonies become host colonies of the social parasite P. atrimandibularis, colony odor is no longer homogeneous, as the parasite offspring have an odor that differs from that of their hosts. In trying to understand how the mechanism of nestmate recognition works in parasitized colonies and why parasite offspring are accepted by hosts, we tested the responses of resident Polistes biglumis wasps from parasitized and unparasitized colonies to newly emerged parasites and to nestmate and non-nestmate conspecifics. The experiments indicate that immediately upon eclosion both young parasites and young hosts lack a colony odor and that colony odor can be soon acquired from the accepting colony. In addition, while residents of nonparasitized colonies recognize only the odor of their species, resident hosts of parasitized colonies have learned a template that fits the odors of two species.     

The social contingency model and olive baboons

A theoretical and illustrative analysis of sequences of actions between pairs of olive baboons (Papio cynocephals anubis) is carried out using the social contingency model originally suggested by Jones and Gerard (1967) in social psychology. The model provides the basis for a step-by-step analysis and a typology. Signals from body postures, facial expressions, and vocalizations are subject to close study by using the model, in a similar fashion to its use in social skills analysis (Argyle, 1988). Sequences are categorized according to individual and joint strategies. Examples are given of three categories of contingency, reactive, mutual, and asymmetrical, which are adapted from their social psychological usage. The model is extended by a new category for competitive relationships between baboons: a conflictive category. The contingencies, as they are shown graphically, have a superficial resemblance to Tinbergen's (1951) zigzag diagrams, but their purpose is distinct in focusing on the detail of both infrequent and repeated interactions. The overall aim of the contingencies is to improve the analysis of social behavior at the proximate level and the model is potentially applicable to observation records at a level of detail that is often not utilized in reporting field studies.     

Nesting biology of the arboreal fungus-growing ant <Emphasis Type="Italic">Cyphomyrmex cornutus</Emphasis> and behavioral interactions with the social-parasitic ant <Emphasis Type="Italic">Megalomyrmex mondabora</Emphasis>

We describe the extraordinary nesting habits of the fungus-growing ant Cyphomyrmex cornutus (Formicidae, Myrmicinae, Attini) and the natural history of Megalomyrmex mondabora (Formicidae, Myrmicinae, Solenopsidini), a social parasite that inhabits nests of C. cornutus and other small attine ants. The study was carried out at two sites on the Atlantic slope of Costa Rica. The C. cornutus nest is an oblong mass of accreted soil, attached to or suspended from low vegetation in wet forest understory. Less than a fourth of the nest volume has chambers and is inhabited by C. cornutus; the remainder is a semi-solid mass of accreted soil often housing a variety of arthropods, including other unspecialized commensal ant species. Five C. cornutus colonies examined were parasitized by M. mondabora. Colonies of M. mondabora inhabited chambers very near those of the host. In laboratory observations, M. mondabora and C. cornutus workers interacted with little aggression despite the consumption of C. cornutus larvae and fungi by M. mondabora. During most interactions, C. cornutus workers responded submissively, whereas M. mondabora appeared indifferent or nonresponsive. Megalomyrmex mondabora parasitizes several other attine species (Cyphomyrmex costatus, Cyphomyrmex salvini, and Apterostigma goniodes), and it appears therefore a relatively unspecialized social parasite with broad attine hostassociation. The size of M. mondabora workers vary with host species, suggesting M. mondabora sensu lato comprises either cryptic species or the host environment affects worker size. Received 14 September 2006; revised 1 February 2007; accepted 6 February 2007.