Effects of social conditions on Juvenile Hormone mediated reproductive development in Bombus terrestris workers

Abstract. During the annual life cycle of the bumble bee Bombus terrestris (L.) colony, there is a stage characterized by worker reproduction in the presence of the queen. It has been proposed that this is a result of a decrease in queen inhibition. This hypothesis was examined by studying the effects of queens taken from colonies at different stages of development on several aspects of worker physiology and behaviour: rates of Juvenile Hormone (JH) release in vitro , ovary development, and behaviour associated with reproduction. After optimizing and validating the radiochemical assay for JH release for bumble bee workers, we found that queenless workers had significantly more developed ovaries and higher rates of release of JH than did queenright workers, confirming and extending previous findings that suggest that bumblebee ovarian development is under JH control. Mated queens, separated from their colony and brood, can have the same inhibitory effect on the reproductive development of callow workers. In contrast, workers confined with virgin queens or in queenless groups demonstrated a significantly higher rate of release of JH, overt aggression and threatening behaviours. However, there were no differences in rates of release of JH between workers confined in groups in the laboratory with queens taken from colonies either before or after the onset of worker reproduction. Furthermore, overt aggression and threatening behaviours were similar and low in both types of groups. These results gave no support to the hypothesis that a decrease in queen inhibition is associated with the onset of worker reproduction. We also show that young workers reared in colonies either before or after worker reproduction occurs, or in queenless colonies, all demonstrated similar, low rates of release of JH. These results suggest that older workers may inhibit the corpora allata of younger workers in queenless colonies.     

Fatal attack on an infant by an adult female tonkean macaque

We describe a fatal attack on a 10-month-old female infant by an adult female Tonkean macaque (Macaca tonkeana)in a semi-free-ranging group. During an intense conflict involving many group members, an adult female, the second most dominant in the group, attacked the infant of a lower-ranking female. The attacker remained near the victim for approximately 20 min, grabbing and biting it repeatedly, until the mother retrieved the infant. She died 2 days later. An autopsy revealed no lethal injury;the main cause of death was starvation or dehydration or both. We discuss social conditions under which a fatal attack by an adult female might occur.     

Host-seeking behaviour of tracheal mites (Acari: Tarsonemidae) on honey bees (Hymenoptera: Apidae)

The behaviour of the endoparasitic tracheal mite, Acarapis woodi (Rennie) on honey bees (Apis mellifera L.) is a challenge to observe because of its small size. Through a microscope, we videotaped this mite's movement on young bees, dead bees and bees exposed to vegetable oil. Previous studies have shown that solid vegetable oil decreases mite infestations in a bee colony. We hypothesized that the oil alters mite behaviour to the detriment of the parasite, thus helping to safeguard the host. Habitat-seeking behaviour, identified as necessary for mites to locate a new host environment, was disrupted on both dead and oil-treated bees. Questing behaviour, which is associated with transfer between hosts, increased significantly on the dead and oily bees. The behaviours of mites were significantly different between all three treatments (x ²=494.96, p<0.001 on dead bees and x ²=851.11, p<0.001 on oily bees). Both questing and seeking behaviours were significantly different on each of the thoracic treatments (F _2,66=7.88, p<0.001 and F _2,66=21.28, p<0.001) and mite questing behaviour was not altered between males and females on live or oily bees (F _1,22=0.25, p<0.62), but habitat seeking was (F _1,22=7.42, p<0.012). The male questing and habitat-seeking behaviours were observed. We conclude that oil-treated bees gained protection from habitat-seeking mites because the normal behaviour of the mites seeking an oviposition site is interrupted.     

Plant–pollinator interactions in the understory of a lowland mixed dipterocarp forest in Sarawak

Pollination biology of 41 plants species of 21 families blooming in the forest understory was investigated in a lowland mixed diplerocarp forest in Lambir Hills National Park, Sarawak. Among these species, 29 species (71%) were pollinated by bees, four (10%) by nectariniid birds, three by small dipterans, and others by moths, butterflies, syrphid flies, wasps, and beetles. The 29 bee-pollinated species consisted of five distinct pollination guilds: ten species pollinated by medium traplining bees (two Amegilla species), nine by small traplining bees (three halictid and a xylocopine species), two by stingless bees and beetles, seven by stingless bees, and one by megachilid bees. The bees constituting the first two guilds were shade-loving, swiftly flying, long-tongued trapliners. Proboscis lengths of these pollinators correlated with flower depth of the host plant. Pollination systems in the forest understory were distinguished from that in the canopy by the prevalence of specific interactions, the number of traplining solitary bees, and lack of pollination systems by mass-recruiting eusocial bees, large Xylocopa bees, thrips, bats, and wind. These characteristics are largely similar between the Palaeotropics and the Neotropics through convergence of nectarivorous birds (spiderhunters vs. hummingbirds) and traplining bees (Amegilla vs. euglossine bees).     

Behavioural specialization in pre-reproductive colonies of the allodapine beeExoneura bicolor (Hymenoptera: Anthophoridae)

Summary Exoneura bicolor is a univoltine allodapine bee common in montane forests of southern Australia, where it exhibits a semisocial/quasisocial colony organization. Within-nest behaviour in postemergence autumn nests ofExoneura bicolor was recorded with the aim of studying behavioural specialization in pre-reproductive colonies. Ten complete colonies were transferred to purpose-built observation nests shortly before brood eclosion in late summer. Behaviour within observation nests was recorded for periods of up to 44 days after establishment, covering a period when colonies are preparing for overwintering. Dispersal of females and brood rearing do not occur at this time, although some females may become inseminated. Analyses of data using multivariate techniques indicated four distinguishable behavioural castes, designated here as Guards, Nest Absenters, Nest Modifiers and Non-recruits. This represents a higher degree of behavioural specialization than recorded to date for other allodapines. Behaviours performed by Guards and Nest Absenters are likely to involve considerable risks, but benefit the colony as a whole, so that some nestmates in prereproductive colonies exhibit altruism that frequently aids adult siblings or cousins. The males in our study were fed by females via trophallaxis and two of the males participated in nest maintenance tasks. Our results suggest that autumn colonies ofE. bicolor form well-integrated behavioural units even though brood rearing does not commence until the following spring.     

Dominance hierarchies in male lizards: Implications for zoo management programs

Depending on spatial requirements and the distribution of key resources in the environment, social behavior among lizards varies from defense of exclusive territories to the establishment of dominance hierarchies. In captivity or under conditions where dispersal is not possible, dominance hierarchies often emerge in species that are otherwise territorial. This review explores some of the morphological, behavioral, and hormonal determinants of social status in male lizards and how these may lead to differential reproductive function in dominant and subordinate individuals. Emphasis is placed on the importance of population density, local resource dispersion, and the composition and stability of social groups in promoting hierarchical behavior. Results of these studies have ramifications for several aspects of zoo management, including exhibit design, choice of animals to be housed together, provision of resources in space and time, and orientation of enclosures within captive breeding facilities. © 1994 Wiley-Liss, Inc.     

Social problems in geriatric dentistry: an overview

Many studies have reported on the dental status of elderly patients. The results demonstrate consistent differences between normative and perceived needs in addition to varying levels of awareness of dental education among carers. This review article attempts to integrate a range of social factors which must be considered if holistic and comprehensive care is to be delivered to elderly patients.     

Effects of recent experience on foraging decisions by bumble bees

The temporal and spatial scales employed by foraging bees in sampling their environment and making foraging decisions should depend both on the limits of bumble bee memory and on the spatial and temporal pattern of rewards in the habitat. We analyzed data from previous experiments to determine how recent foraging experience by bumble bees affects their flight distances to subsequent flowers. A single visit to a flower as sufficient to affect the flight distance to the next flower. However, longer sequences of two or three visits had an additional effect on the subsequent flight distance of individual foragers. This suggests that bumble bees can integrate information from at least three flowers for making a subsequent foraging decision. The existence of memory for floral characteristics at least at this scale may have significance for floral selection in natural environments.     

Demography and social structure of one group of muriquis (Brachyteles arachnoides)

We monitored one group of muriquis, or woolly spider monkeys (Brachyteles arachnoides), over a 9-year period at Fazenda Montes Claros, Minas Gerais, Brazil. The group grew from 22 to 42 individuals due to the births of 21 surviving infants. Eight immigrations involving immature females were offset by emigrations and disappearances. The home range of the group expanded as the group size increased. The group traveled as a cohesive unit during the first 6 years of the study, but recently it has begun to show greater tendencies to fission temporarily into smaller subgroups. Six adult males from the other muriqui group at this site have simultaneously increased their associations with the main study group. These observations indicate that the group is in a state of transition which may lead, ultimately, either to its division into two smaller units or to a more fluid social structure.     

The natural history of de Brazza's monkey in Kenya

Polygynous groups of de Brazzas monkeys (Cercopithecus neglectus) were observed in the Kisere Forest Reserve between December 1987 and March 1989. Total number of contact hours was 528. Three troops numbered 11, 13, and 16 monkeys. Three solitary adult males were seen. All troops had a single adult male, at least three adult females, and juveniles. Five births occurred in the course of the study. Home range varied from 4.1 to 6 ha, and flooded areas of the forest were heavily used. This species was only found near rivers and spent more than 50% of the time below 5 m. Daily path length ranged from 330 to 1001 m. The de Brazza's monkeys were mainly frugivorous, but leave and invertebrates also formed a substantial part of the diet. Other guenons avoided de Brazza's, which did not join polyspecific interactions.