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1.
The ability of social insects to discriminate against non-nestmates is vital for maintaining colony integrity, and in most
social insect species, individuals act aggressively towards non-nestmates that intrude into their nest. Our experimental field
data revealed that intra-colony aggression in the primitive bulldog ant Myrmecia nigriceps is negligible; our series of bioassays revealed no significant difference in the occurrence of aggression in trials involving
workers from the same, a close (less than 300 m) or a far (more than 1.5 km) nest. Further, non-nestmate intruders were able
to enter the nest in 60% of our trials; a similar level was observed in trials involving nestmates. These results suggest
that workers of M. nigriceps are either unable to recognize alien conspecifics or that the costs of ignoring workers from foreign colonies are sufficiently
low to favor low levels of inter-colony aggression in this species. 相似文献
2.
In ants, winged queens that are specialized for independent colony foundation can be replaced by wingless reproductives better
adapted for colony fission. We studied this shift in reproductive strategy by comparing two Mystrium species from Madagascar using morphometry, allometry and dissections. Mystrium rogeri has a single dealate queen in each colony with a larger thorax than workers and similar mandibles that allow these queens
to hunt during non-claustral foundation. In contrast, Mystrium ‘red’ lacks winged queens and half of the female adults belong to a wingless ‘intermorph’ caste smaller and allometrically distinct
from the workers. Intermorphs have functional ovaries and spermatheca while those of workers are degenerate. Intermorphs care
for brood and a few mate and reproduce making them an all-purpose caste that takes charge of both work and reproduction. However,
their mandibles are reduced and inappropriate for hunting centipedes, unlike the workers’ mandibles. This together with their
small thorax disallow them to perform independent colony foundation, and colonies reproduce by fission. M. rogeri workers have mandibles polymorphic in size and shape, which allow for all tasks from brood care to hunting. In M. ‘red’, colonial investment in reproduction has shifted from producing expensive winged queens to more numerous helpers. M. ‘red’ intermorphs are the first case of reproductives smaller than workers in ants and illustrate their potential to diversify
their caste system for better colonial economy. 相似文献
3.
We investigated nest odor dynamics in the common yellow jacket, Vespula vulgaris. In six isolated colonies, we tested the aggression rates toward dead nestmates that had been stored for 10 min, 10 and 19 days
outside their colonies at –76 °C. The aggression rate increased from about 12% toward recently killed nestmates up to 30%
toward nestmates killed 19 days before the experiment. Obviously, the conserved nest odor profile of the nestmates frozen
for several days did not match with that of their colony anymore. This indicates a change of the nest odor within the colony.
In a second experiment, we kept two colonies each in one nest box with a complete separation of both neighbor nests by a solid
wall inside the box for 28 days. In confrontation experiments, the colony members treated dead foragers from the neighbor
nest as aggressively as dead foreign, non-neighbor workers (about 39% each) whereas only about 14% reacted aggressively toward
dead nestmates. Seventeen days after the replacement of the solid wall by a metallic grid, which allowed no physical contact
but air exchange between the two neighbor colonies, the aggression rates toward foreign workers and nestmates remained relatively
unaffected whereas it decreased significantly toward dead neighbors to about 11%. These results suggest a nest odor dynamic
caused by volatiles transferred between two adjacent colonies, resulting in an equalization of the former colony specific
nest odors. A change of nest odor dynamics influenced by volatiles was so far described only for one ant species at all. 相似文献
4.
Despite its evolutionary significance, behavioural flexibility of social response has rarely been investigated in insects. We studied a host–social parasite system: the slave-making ant Polyergus rufescens and its host Formica rufibarbis. Free-living host workers from parasitized and from unparasitized areas were compared in their level of aggression against the parasite and alien conspecifics. We expected that a seasonal change would occur in the acceptance threshold of F. rufibarbis workers from a parasitized area towards the parasite, whereas F. rufibarbis workers from an unparasitized area would not show substantial changes connected with the parasites peak in activity (raiding and colony-founding season). The results showed a significant adaptive behavioural flexibility of host species workers and are consistent with the acceptance threshold models (Reeve 1989) prediction that recognition systems are not fixed but context-dependent. In particular, host workers from the unparasitized area were highly aggressive towards the parasite regardless of the season, whereas host workers from the parasitized area significantly increased their aggression towards the parasite during its raiding and colony-founding season. Being able to detect and possibly kill a Polyergus scout searching for host nests can be an effective strategy for a Formica colony to avoid being raided or usurped by a parasite queen. 相似文献
5.
In many social taxa, reproductively dominant individuals sometimes use aggression to secure and maintain reproductive status.
In the social insects, queen aggression towards subordinate individuals or workers has been documented and is predicted to
occur only in species with a small colony size and a low level of queen–worker dimorphism. We report queen aggression towards
reproductive workers in the ant species Aphaenogaster cockerelli, a species with a relatively large colony size and a high level of reproductive dimorphism. Through analysis of cuticular
hydrocarbon profiles, we show that queens are aggressive only to reproductively active workers. Non-reproductive workers treated
with a hydrocarbon typical for reproductives are attacked by workers but not by queens, which suggests different ways of recognition.
We provide possible explanations of why queen aggression is observed in this species. 相似文献
6.
Social interactions may shape brain development. In primitively eusocial insects, the mushroom body (MB), an area of the brain associated with sensory integration and learning, is larger in queens than in workers. This may reflect a strategy of neural investment in queens or it may be a plastic response to social interactions in the nest. Here, we show that nest foundresses—the reproductive females who will become queens but are solitary until their first workers are born—have larger MBs than workers in the primitively eusocial sweat bee Augochlorella aurata. Whole brain size and optic lobe size do not differ between the two groups, but foundresses also have larger antennal lobes than workers. This shows that increased neural investment in MBs precedes social group formation. Larger MBs among foundresses may reflect the increased larval nutrition provisioned to future queens and the lack of social aggression from a dominant queen upon adult emergence. 相似文献
7.
Global pollinator declines have been attributed to habitat destruction, pesticide use, and climate change or some combination
of these factors, and managed honey bees, Apis mellifera, are part of worldwide pollinator declines. Here we exposed honey bee colonies during three brood generations to sub-lethal
doses of a widely used pesticide, imidacloprid, and then subsequently challenged newly emerged bees with the gut parasite,
Nosema spp. The pesticide dosages used were below levels demonstrated to cause effects on longevity or foraging in adult honey bees.
Nosema infections increased significantly in the bees from pesticide-treated hives when compared to bees from control hives demonstrating
an indirect effect of pesticides on pathogen growth in honey bees. We clearly demonstrate an increase in pathogen growth within
individual bees reared in colonies exposed to one of the most widely used pesticides worldwide, imidacloprid, at below levels
considered harmful to bees. The finding that individual bees with undetectable levels of the target pesticide, after being
reared in a sub-lethal pesticide environment within the colony, had higher Nosema is significant. Interactions between pesticides and pathogens could be a major contributor to increased mortality of honey
bee colonies, including colony collapse disorder, and other pollinator declines worldwide. 相似文献
8.
A quantitative protocol for the rapid analysis of Microcystis cells and colonies in lake sediment was developed using a modified flow cytometer, the CytoSense. For cell enumeration, diluted sediment samples containing Microcystis were processed with sonication to disintegrate colonies into single cells. An optimized procedure suggested that 5 mg dw (dry weight)/mL dilution combined with 200 W × 2 min sonication yielded the highest counting efficiency. Under the optimized determination conditions, the quantification limit of this protocol was 3.3×10 4 cells/g dw. For colony analysis, Microcystis were isolated from the sediment by filtration. Colony lengths measured by flow cytometry were similar to those measured by microscopy for the size range of one single cell to almost 400 μupm in length. Moreover, the relationship between colony size and cell number was determined for three Microcystis species, including Microcystis flos-aquae, M. aeruginosa and M. wessenbergii. Regression formulas were used to calculate the cell numbers in different-sized colonies. The developed protocol was applied to field sediment samples from Lake Taihu. The results indicated the potential and applicability of flow cytometry as a tool for the rapid analysis of benthic Microcystis. This study provided a new capability for the high frequency monitoring of benthic overwintering and population dynamics of this bloom-forming cyanobacterium. 相似文献
9.
The development of animals depends on both genetic and environmental effects to a varying extent. Their relative influences can be evaluated in the social insects by raising the intracolonial diversity to an extreme in nests consisting of workers from more than one species. In this study, we studied the effects of mixed honeybee colonies of Apis mellifera and Apis cerana on the rearing of grafted queen larvae of A. cerana. A. mellifera sealed worker brood was introduced into A. cerana colonies and on emergence, the adults were accepted. Then, A. cerana larvae were grafted for queen rearing into two of these mixed-species colonies. Similarly, A. cerana larvae and A. mellifera larvae were also grafted conspecifically as controls. The success rate of A. cerana queen rearing in the test colonies was 64.5%, surpassing all previous attempts at interspecific queen rearing. After emergence, all virgin queens obtained from the three groups ( N=90) were measured morphometrically. The A. cerana queens from the mixed-species colonies differed significantly in size and pigmentation from the A. cerana control queens and closely approximated the A. mellifera queens. It is inferred that these changes in the A. cerana queens reared in the mixed-species colonies can be attributed to feeding by heterospecific nurse bees and/or chemical differences in royal jelly. Our data show a strong impact of environment on the development of queens. The results further suggest that in honeybees the cues for brood recognition can be learned by heterospecific workers after eclosion, thereby providing a novel analogy to slave making in ants. 相似文献
11.
Madagascar provides some of the rare examples where two or more primate species of the same genus and with seemingly identical
niche requirements occur in sympatry. If congeneric primate species co-occur in other parts of the world, they differ in size
in a way that is consistent with Hutchinson’s rule for coexisting species, or they occupy different ecological niches. In
some areas of Madagascar, mouse lemurs do not follow these “rules” and thus seem to violate one of the principles of community
ecology. In order to understand the mechanisms that allow coexistence of sympatric congeneric species without obvious niche
differentiation, we studied food composition of two identical sized omnivorous mouse lemur species, Microcebus griseorufus and M. murinus with the help of stable isotope analyses ( δ
15N and δ
13C). The two species are closely related sister species. During the rich season, when food seems abundant, the two species
do not differ in their nitrogen isotope composition, indicating that the two species occupy the same trophic level. But they
differ in their δ
13C values, indicating that M. griseorufus feeds more on C 4 and CAM (Crassulacean-acid-metabolism) plants than M. murinus. During the lean season, M. murinus has lower δ
15N values, indicating that the two species feed at different trophic levels during times of food shortage. Hybrids between
the two species showed intermediate food composition. The results reflect subtle differences in foraging or metabolic adaptations
that are difficult to quantify by traditional observations but that represent possibilities to allow coexistence of species. 相似文献
12.
Queens of some species of social insects form dominance hierarchies in which only the top-ranking individual reproduces. Such unequal partitioning of reproduction can be stable when subordinate queens increase their inclusive fitness indirectly by helping to rear a related dominant queen's offspring. We investigated whether subordinate queens of the ant, Leptothorax gredleri, affect the reproductive success of the dominant queen. In laboratory colonies with two queens, first eggs were laid approximately 20 days later than in colonies with a single queen, presumably due to aggressive competition among nestmate queens. Nevertheless, two-queen colonies produced on average more brood than one-queen colonies, although egg laying was completely or almost completely monopolized by one single queen. The presence of a subordinate queen therefore appears to increase the productivity of the dominant. 相似文献
13.
The vespine wasps, Vespa velutina, specialise in hawking honeybee foragers returning to their nests. We studied their behaviour in China using native Apis cerana and introduced A. mellifera colonies. When the wasps are hawking, A. cerana recruits threefold more guard bees to stave off predation than A. mellifera. The former also utilises wing shimmering as a visual pattern disruption mechanism, which is not shown by A. mellifera. A. cerana foragers halve the time of normal flight needed to dart into the nest entrance, while A. mellifera actually slows down in sashaying flight manoeuvres. V. velutina preferentially hawks A. mellifera foragers when both A. mellifera and A. cerana occur in the same apiary. The pace of wasp-hawking was highest in mid-summer but the frequency of hawking wasps was three
times higher at A. mellifera colonies than at the A. cerana colonies. The wasps were taking A. mellifera foragers at a frequency eightfold greater than A. cerana foragers. The final hawking success rates of the wasps were about three times higher for A. mellifera foragers than for A. cerana. The relative success of native A. cerana over European A. mellifera in thwarting predation by the wasp V. velutina is interpreted as the result of co-evolution between the Asian wasp and honeybee, respectively. 相似文献
14.
In theory, larger colonies of social insects should have greater colony organisation. While inter-specific comparative studies provide support for this idea, there is little direct intra-specific evidence. We investigated differences in task specialisation between large (>450 workers) and small (<80 workers) colonies of the ponerine ant Rhytidoponera metallica. Observations of individually marked young or old workers revealed greater task specialisation in large colonies. Age polyethism was detected in large but not small colonies. In large colonies, old workers spent significantly more time foraging than young workers did, while young workers spent more time caring for brood. In small colonies, young and old workers spent a similar amount of time foraging and caring for brood. This difference in task allocation patterns in large and small colonies was associated with a difference in contact rates between workers. Workers in small colonies have a lower contact rate between nestmates and a greater variability in time between contacts than workers from large colonies. 相似文献
15.
The intertidal midge Clunio, which reproduces on exposed rocky seashores, becomes enclosed in an irregularly shaped air bubble during short submersion
by incoming waves. This water-repellent property of Clunio’s cuticle is caused by a complete cover of hydrophobic microtrichia offering an effective surf tolerance. These microtrichia
not only trap a thin air layer above the cuticle but also maintain a larger air bubble between the insect’s ventral side and
legs. The effectiveness of the water repellence was quantitatively characterised on the basis of a known model (Crisp and
Thorpe, Discuss Faraday Soc 3:210–220, 1948). The parameters of the model are the contact angle θ (>90°) at the contact line of air/water/microtrichia and the distance between individual microtrichia and their radius. When
the microtrichia are 1.1 μm apart and have a radius of 0.1 μm and an estimated contact angle θ of 140°, the air layer is stable against hydrostatic pressures of up to 3 m water column. As shown by a modified version
of the model, considerably larger air bubbles can be trapped by the microtrichia cover of the legs up to distances of 0.5 mm
from the body. The widely spaced (about 8 μm apart) and longer setae of Clunio are not involved in the formation of air layers and air bubble. 相似文献
16.
Diversification of sperm morphology has been investigated in the context of sperm competition, but the adaptive significance
of sperm bundles is still unclear. In analyzing 10 taxa of the genus Carabus subgenus Ohomopterus and one related Carabus ground beetles, we found that dimorphic sperm bundles occurred in most species with varied degrees of bimodality, whereas
sperm were generally monomorphic. Comparative analyses with phylogenetically independent contrasts revealed that the sizes
of large and small sperm bundles evolved more rapidly than, and were not correlated with, the length of sperm, suggesting
more intense selection on sperm bundle sizes and their independent responses to different evolutionary forces. The size of
large sperm bundles was positively correlated with male genital morphology (pertinent to displacement of rival spermatophores)
and postcopulatory guarding duration as well as male body length, suggesting that larger sperm bundles have been favored when
the risk of spermatophore displacement is high. Larger sperm bundles may be advantageous because of their ability to migrate
more rapidly into the spermatheca. In contrast, no clear association was detected between the small sperm bundle size and
mating traits despite its rapid diversification. The present study provides the first record of heteromorphic sperm bundles,
the diversity of which may be promoted by sperm competition. 相似文献
17.
Ferganodon
narynensis gen. et sp. nov. is represented by a lower molariform tooth from the Middle Jurassic (Callovian) Balabansai Svita in Kyrgyzstan.
The new genus is allied with Klamelia zhaopengi Chow and Rich 1984 from the Middle Jurassic Shishugou Formation in Xinjiang, northwest China to the new family Klameliidae based on parallelogram-shaped
lower molariforms, imbricating rather than interlocking of cusps e- d- f, by a peculiar distolabial cingulid cusp, and by vertical folding of the enamel on the labial crown side. The new family
Klameliidae fam. nov. is most similar to Gobiconodontidae by the structure of the molariform teeth and represents a previously
unrecognized radiation of eutriconodontan mammals possibly endemic to Central Asia. 相似文献
18.
Kratochvil et al. (Naturwissenschaften 95:209–215, 2008) reported recently that in the leopard gecko ( Eublepharis macularius) of the family Eublepharidae with temperature-dependent sex determination (TSD), clutches in which eggs were incubated at
the same temperature produce only same-sex siblings. Interpreting this result in light of studies of sex steroid hormone involvement
in sex determination, they suggested that maternally derived yolk steroid hormones could constrain sex-determining mechanisms
in TSD reptiles. We have worked extensively with this species and have routinely incubated clutches at constant temperatures.
To test the consistency of high frequency same-sex clutches across different incubation temperatures, we examined our records
of clutches at the University of Texas at Austin from 1992 to 2001. We observed that clutches in which eggs were incubated
at the same incubation temperature produced mixed-sex clutches as well as same-sex clutches. Furthermore, cases in which eggs
within a clutch were separated and incubated at different temperatures produced the expected number of mixed-sex clutches.
These results suggest that maternal influences on sex determination are secondary relative to incubation temperature effects. 相似文献
19.
High genetic diversity is important for the functioning of large insect societies. Across the social Hymenoptera (ants, bees, and wasps), species with the largest colonies tend to have a high colony-level genetic diversity resulting from multiple queens (polygyny) or queens that mate with multiple males (polyandry). Here we studied the genetic structure of Trigona spinipes, a stingless bee species with colonies an order of magnitude larger than those of polyandrous honeybees. Genotypes of adult workers and pupae from 43 nests distributed across three Brazilian biomes showed that T. spinipes colonies are usually headed by one singly mated queen. Apart from revealing a notable exception from the general incidence of high genetic diversity in large insect societies, our results reinforce previous findings suggesting the absence of polyandry in stingless bees and provide evidence against the sperm limitation hypothesis for the evolution of polyandry. Stingless bee species with large colonies, such as T. spinipes, thus seem promising study models to unravel alternative mechanisms to increase genetic diversity within colonies or understand the adaptive value of low genetic diversity in large insect societies. 相似文献
20.
The giant Asian honeybee ( Apis dorsata), like all other members of the genus Apis, has a complex mating system in which the queens and males (drones) mate at spatially defined drone congregation areas (DCAs).
Here, we studied the temporal genetic structure of a DCA of A. dorsata over an 8-day time window by the genotyping of sampled drones with microsatellite markers. Analysis of the genotypic data
revealed a significant genetic differentiation between 3 sampling days and indicated that the DCA was used by at least two
subpopulations at all days in varying proportions. The estimation of the number of colonies which used the DCA ranged between
20 and 40 colonies per subpopulation, depending on the estimation procedure and population. The overall effective population
size was estimated as high as N
e=140. The DCA seems to counteract known tendencies of A. dorsata for inbreeding within colony aggregations by facilitating gene flow among subpopulations and increasing the effective population
size. 相似文献
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