Characterization of cuticular hydrocarbons of diploid and haploid males, workers and queens of the stingless bee Melipona quadrifasciata

Males, queens and workers of stingless bees show differences in external morphology, behaviour and roles within a colony. In addition, each individual has a cuticular chemical signature responsible for mutual communication that is essential for maintaining the integrity of the colony. In this paper we characterize the cuticular hydrocarbon composition of newly emerged diploid and haploid males, workers and virgin queens of Melipona quadrifasciata by gas chromatography-mass spectrometry (GC/MS) analysis. This is the first time that the cuticular profile of diploid males in a species of stingless bee has been characterized. We found differences in the cuticular hydrocarbon composition among males, workers and virgin queens, recording both qualitative and quantitative differences among individuals of different phenotypes. However, no compound was found exclusively in diploid males. The cuticular chemical profiles of haploid and diploid males were very similar to those of workers. Moreover, the cuticular lipids of males and workers were significantly different from those of queens. Tricosane, pentacosene-2 and 7-methyl-heptacosane were the compounds responsible for this significant separation. This result correlates with the behavioural and morphological differences among these phenotypes.     

Comparative study of the cuticular hydrocarbon in queens, workers and males of Ectatomma vizottoi (Hymenoptera, Formicidae) by Fourier transform-infrared photoacoustic spectroscopy

Fourier transform-infrared photoacoustic spectroscopy was applied for the first time, to our knowledge, to distinguish different castes of an ant species. The method was applied directly to the abdomen of queens, workers and males of Ectatomma vizottoi ants, without any special sample preparation. The absorption bands of secondary amide and hydrocarbons were identified; using these as variables in a canonical discriminant analysis we found significant differences between the castes. Queens have a greater hydrocarbon content than do workers and males, which is related to their function in the colony. This technique can be used to analyze and distinguish small chemical differences in biological systems, even in opaque samples.     

Reproductive responses to photoperiod and temperature by artificially hibernated bumblebee (Bombus terrestris) queens

Post‐hibernated bumblebee (Bombus terrestris) queens were kept for 1 week under photoperiodic conditions of 8 h light : 16 h dark, and at four different temperatures (24, 28, 32 and 36°C). The reproductive performance of the queens was then observed. It was found that exposure temperature and hibernation duration did not affect the oviposition rate. The pre‐oviposition period was found to be shortest (3.8 ± 0.7 days) for queens that had hibernated for 4.0 months and had been activated at 28°C. Timing of the initiation of the switch‐point was not affected by exposure temperature and hibernation duration. Significantly higher numbers of workers (268.0 ± 31.4) and sexual queens (119.3 ± 16.8) were produced by the queens that had hibernated for 3.0 months and had been activated at 28 and 36°C, respectively. The queens that had hibernated for 4.0 months and had been activated at 36°C produced the highest number of males (296.2 ± 32.3).     

Sex ratio determination by queens and workers in the ant Pheidole desertorum

Because workers in colonies of eusocial Hymenoptera are more closely related to sisters than to brothers, theory predicts workers should bias investment in reproductive broods to favour reproductive females over males. However, conflict between queens and workers is predicted. Queens are equally related to daughters and sons, and should act to prevent workers from biasing investment. Previous study of the ant Pheidole desertorum showed that workers are nearly three times more closely related to reproductive females than males; however, the investment sex ratio is very near equal, consistent with substantial queen control of workers. Near-equal investment is produced by an equal frequency of colonies whose reproductive broods consist of only females (female specialists) and colonies whose reproductive broods consist of only males or whose sex ratios are extremely male biased (male specialists). Because natural selection should act on P. desertorum workers to bias investment in favour of reproductive females, why do workers in male-specialist colonies rear only (or mostly) males? We tested the hypothesis that queens prevent workers from rearing reproductive females by experimentally providing workers with immature reproductive broods of both sexes. Workers reared available reproductive females, while failing to rear available males. Worker preference for rearing reproductive females is consistent with queens preventing their occurrence in colonies of male specialists. These results provide evidence that queens and workers will act in opposition to determine the sex ratio, a fundamental prediction of queen-worker conflict theory. Copyright 2000 The Association for the Study of Animal Behaviour.     

Respiration in bumblebee queens: effect of life phase on the discontinuous ventilation cycle

Evidence for discontinuous ventilation cycles (DVC) has been obtained for many insects under various experimental conditions. Here, we show that DVC's exist for queens of the bumblebee Bombus terrestris in different phases of their life cycle: before entering diapause (pre-diapause queens) and when a colony has been established (post-diapause queens). Pre- and post-diapause queens experience distinct environmental conditions (ambient O₂ and CO₂ concentrations) which is reflected in their DVC: both ventilation frequency and amount of carbon dioxide emitted change with differences in ambient CO₂ concentration.     

Distribution of acid phosphatases in the hypopharyngeal glands from workers,queens and males of a Brazilian stingless bee Scaptotrigona postica Latreille: an ultrastructural cytochemical study

The present study reports the localization of acid phosphatase in the hypopharyngeal gland cells from workers (newly-emerged, nurse and forager), queens (newly-emerged and laying) and males (newly-emerged and mature for mating) of the Brazilian stingless bee, Scaptotrigona postica. The phosphatase activity varied in intensity and localization depending on the individual class, physiological age and the substrate used. In newly-emerged workers, the phosphatase-positive sites suggest the involvement of the enzyme with cellular differentiation that occurs in the presecretory phase, in nurse workers with protein synthesis and in forager workers with changes in cellular activity or glandular regression. In males mature for mating and laying queens, the positive sites are related to secretory activity, showing that the gland maintains some activity in spite of the regressive aspect. Of the substrates used, beta-glycerophosphate gave the least specific localization.     

Absence of nepotism in the harassment of duelling queens by honeybee workers

Nepotism shapes interactions among the members of almost every animal society. However, clear evidence of nepotism within highly cooperative insect societies, such as ant, wasp and honeybee colonies, is rare. Recent empirical findings suggest that nepotism occurs within honeybee colonies where kin-selection theory most strongly predicts its existence: during the lethal queen-queen duels that determine which of several young queens will become the colony's next queen. In this study, I test whether worker bees act nepotistically by hindering duelling queens that are distantly related to themselves. I accomplished this by observing labelled workers harassing duelling queen bees in observation hives and subsequently by determining worker-queen relatedness using DNA microsatellites. I show that the workers that harassed duelling queens were neither more-closely nor more-distantly related to them than were workers selected randomly from the colony. Thus, workers did not behave nepotistically by hindering half-sister queens more than full-sister queens. These results demonstrate that under certain conditions, natural selection limits the evolution of nepotism within animal societies despite strong theoretical predictions for its existence.     

Male production by non-natal workers in the bumblebee, Bombus deuteronymus (Hymenoptera: Apidae)

Social insect societies are considered to be composed of many extremely cooperative individuals. While workers are traditionally believed to behave altruistically, recent studies have revealed behaviors that are more selfish. One such example is intraspecific social parasitism, where workers invade conspecific colonies and produce male offspring that are reared by unrelated host workers. Such intraspecific parasitism has been reported in honeybees (Apis cerana, and A. florea) and “semi-wild” bumblebee colonies of Bombus terrestris. Here we report on intraspecific social parasitism by workers in “wild” colonies of the bumblebee B. deuteronymus. Three of the 11 B. deuteronymus colonies studied were invaded by non-natal workers, of which 75% became reproductive and produced 19% of the adult males. The invading non-natal workers produced significantly more males than resident natal workers and the non-natal brood was not discriminated against by the natal workers.     

Glycogen in honeybee queens,workers and drones (Apis mellifera carnica Pollm.)

Honey bees (Apis mellifera carnica Pollm.) have low glycogen reserves in summer. Upon emergence drones have significantly larger amounts per unit weight when emerging, than workers; perhaps as adaption to the risk of not being fed as intensely as young workers. Maximum content was 0.23mg for workers (28d), and 0.59mg for drones (after emergence). Workers have relatively constant glycogen contents during their life, and very young drones have more glycogen than older ones. Young queens are similar to workers. In workers and queens in summer the greatest amounts of glycogen are found in the thorax. When the bees start flying (6th-8th day of life), drones have the highest amounts in the head (probably to supply their eyes), and upon maturity, drones have the least glycogen in the abdomen.Workers in winter show different glycogen values depending on whether they are active bees from the core area (0.23mg) or inactive ones from the outer surface of the winter cluster (0.37mg). They use glycogen from the thorax and the abdomen for their ongoing energy need.     

Exocrine gland secretions of virgin queens of five bumblebee species (Hymenoptera: Apidae, Bombini)

Secretions of three different glands (mandibular gland, labial gland, and Dufour's gland) of virgin queens of five bumblebee species (Bombus lucorum, B. lapidarius, B. hypnorum, B. pascuorum, and B. terrestris) were analysed. Around 200 compounds were identified in the secretions. The compositions of the secretions of labial and mandibular glands were species-specific. Dufour's gland of all species produced mainly hydrocarbons, both saturated and unsaturated, the proportions of which differed quantitatively between the species studied.     

Relative availability and utilization of algae in two subarctic rivers

The ash free dry weight of algae in the plankton, epilithon and gut of predominant herbivores was determined between June 1975 and July 1976 in 2 subarctic Canadian rivers (Baker Creek, Yellowknife River). Algae usually represented < 1% of suspended solids in both rivers and up to 8o% of material attached to rocks. While they were never found in the gut of rotifers and copepod nauplii in Baker Creek, they accounted for 0.5% of the contents of the planktonic conchostracon Lynceus brachyurus. Due to the inpalatable colonial structure of most attached algal species, the zoobenthos (mainly mayfly nymphs) contained only a few cells. Size selection against large fragments of detritus resulted in increased consumption of algae (5–13%) by Simulium venustum, S. decorum and S. arcticum. In the Yellowknife River, Diaptomus ashlandi (CIII–CVI stages) and Holopedium gibberum contained only a few (30–50) algal cells during summer. Because of size selection, large algae were not ingested by these species. The inpalatability of colonial algae greatly reduced consumption in the predominant zoobenthic species, Ephemerella coxalis and E. margarita. While all species digested diatoms, the Chlorophyta usually passed through the gut unharmed. It is concluded that algae are not an important energy source for invertebrates in either stream.     

微生态制剂EM原露对熊蜂蜂王产卵前期卵巢发育及卵子发生的影响

用60%蔗糖,60%蔗糖加EM原露,60%蔗糖加花粉,60%蔗糖加花粉加EM原露4种食料饲喂复苏熊蜂Bombus terrestris L.蜂王,研究EM原露对复苏蜂王产卵前期卵巢发育及卵子发生的影响。结果表明,EM原露对熊蜂蜂王产卵前期卵巢发育及卵子发生表现出一定抑制性,但影响不显著。虽然于第2天,EM原露对其开始发生显著抑制性影响(P=0.047),且EM原露与花粉的交互作用对其发育促进影响亦显著(P=0.014),但从第5天始,EM原露对其影响下降为不显著,而花粉开始表现出显著性促进熊蜂蜂王卵巢发育(P=0.000)。EM原露对熊蜂蜂王卵子发生并无促进或抑制作用,然而花粉的缺失促使熊蜂蜂王卵子发生停滞。     

Resource partitioning between pelagic coregonids in a subarctic watercourse following a biological invasion

If a pelagic ecosystem is invaded by an efficient planktivorous fish, competition theory predicts that habitat and/or diet segregation should occur if the invader and native planktivores are to co-exist. We compared the diet and pelagic habitat use between invading vendace (Coregonus albula) and two native morphs of whitefish (Coregonus lavaretus) in three subarctic lakes located within the same watercourse. No clear vertical habitat segregation was found as vendace prevailed throughout the entire depth range. Zooplankton generally dominated the diet of all three coregonids. No obvious resource partitioning was found in two of the lakes, while in the third lake the diets of whitefish and vendace differed significantly from each other. Here, the predominant pelagic whitefish morph fed extensively on water mites whereas vendace mainly consumed surface insects and to some extent small fish, apparently as a result of highly depleted zooplankton resources. The results suggest that various levels of resource depletion following the vendace invasion caused the observed differences between the lakes, indicating that different levels of resource partitioning were associated with dissimilar competition intensities. At present, coexistence of these congeneric species seems to be possible, although the vendace invasion has apparently resulted in a challenging and unstable situation for the planktivorous whitefish.     

Ergatoid queens and intercastes in ants: Two distinct adult forms which look morphologically intermediate between workers and winged queens

Summary The term ergatogyne is used in ants to describe permanently-wingless female adults which are morphologically intermediate between workers and winged queens. This definition is ambiguous because there are two distinct categories of ergatogynes: ergatoid queens and intercastes. Both have an external appearance (ocelli and alitrunk structure) which combines traditional queen and worker characters, and thus can be confused if they both function as reproductives — however intercastes in most species cannot reproduce.Ergatoid queens have replaced winged queens in a substantial number of species. They are sometimes externally similar to conspecific workers, especially in various ponerine species which exhibit limited size dimorphism between castes. Ergatoid queens retain the specialized attributes of a reproductive caste, including larger ovaries, and they are always the functional egg-layers in a colony. In contrast, conspecific intercastes represent various graded stages in a series connecting workers and winged queens, and they occur together with the queens. These hybrid phenotypes result from deviations from the normal pattern of caste differentiation during larval development. Intercastes generally lack a spermatheca and have no reproductive function; however they can mate in a few leptothoracine ants, and then reproduce instead of winged queens in a proportion of colonies.