Discrimination of nestmate workers and drones in honeybees

Summary Discrimination of nestmates from non-nestmates has mainly been investigated in female social insects. Little is known about discrimination of males. Here we show that under natural conditions at the nest entrance, honeybee workers can discriminate nestmate drones from non-nestmate drones as effectively as they can discriminate nestmate workers from non-nestmate workers.     

Brain tyramine and reproductive states of workers in honeybees

To explore the role of tyramine in the transformation of reproductive states of honeybee workers, brain levels of tyramine and N-acetyltyramine were measured in both normal and queenless workers. Queenless workers had higher tyramine levels and lower N-acetyltyramine levels than normal workers did. Intermediate reproductive workers that were transferred into a normal colony from a queenless colony had intermediate levels of tyramine and N-acetyltyramine. Elevation of tyramine in the queenless workers occurred at an earlier adult stage than elevation of dopamine. Tyramine levels in intermediate reproductive workers returned to the levels seen in normal workers, but dopamine levels in intermediate reproductive workers remained elevated at the same level as in queenless workers. Thus, brain tyramine may be regulated by the colony condition with or without a queen. Injection of an amine uptake inhibitor, reserpine, depleted tyramine and elevated N-acetyltyramine. Distributions of tyramine and dopamine within the brain were distinctively different, whereas distributions of N-acetyltyramine and N-acetyldopamine were similar, suggesting that each functional amine is stored in specific neurosecretory cells and released to the relevant receptor sites but that metabolism into each N-acetylmetabolite is determined by diffusion.     

Swarming motility

Swarming involves differentiation of vegetative cells into hyperflagellated swarm cells that undergo rapid and coordinated population migration across solid surfaces. Cell density, surface contact, and physiological signals all provide critical stimuli, and close cell alignment and the production of secreted migration factors facilitate mass translocation. Flagella biogenesis is central to swarming, and the flhDC flagellar master operon is the focal point of a regulatory network governing differentiation and migration.     

Distribution and levels of dopamine and its metabolites in brains of reproductive workers in honeybees

To explore the role of dopamine and its metabolites for change of reproductive states of workers in honeybees (Apis mellifera), brain levels of dopamine relative substances were measured and localized in both normal workers and queenless workers. Dopamine and two possible metabolites of dopamine, N-acetyldopamine (NADA) and norepinephrine were detected in brain extracts. The brain levels of dopamine, NADA and norepinephrine were positively correlated with ovary development. Individuals with high dopamine levels had high levels of NADA or norepinephrine, suggesting that these metabolites might be involved in the change of reproductive sates of workers. Dopamine was distributed mainly in the protocerebrum, whereas NADA was in both the optic lobes and the protocerebrum. Dopamine levels in each distinct brain regions were higher in queenless workers than in normal workers, whereas there was a higher NADA level in the optic lobes in queenless workers than in normal workers. These results suggest that dopamine might be stored and/or released around the protocerebrum and the deutocerebrum, and also diffuse to the optic lobes where dopamine secretory cells are absent, resulting in high NADA levels in the optic lobes. The different manner of level changes of dopamine and its metabolites in each brain region might cause compound behavioural modulations in reproductive workers.     

Swarming of mosquitoes

Experiments have been made on the swarming of a number of mosquitoes, especially Culex fatigans, under laboratory conditions and the influence of light intensity, temperature, different color swarm markers; and time factors, both in regard to duration of the change of light and the time lapse between experiments, have been studied.

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Résumé Des expériences sur l'essaimage des moustiques mâles (surtout Culex fatigans) ont été faites au laboratoire. La cage dans laquelle se formaient les essaims était placée dans une chambre dont l'éclairage, la température et l'humidité pouvaient être réglés.Les essaims qui comprenaient le plus grand nombre d'individus et qui duraient le plus longtemps, étaient obtenus quand le changement d'éclairement (crépuscule artificiel) durait plus de 20 minutes et quand la température était de 24–25° après une durée de plus de cinq heures depuis le dernier changement.Dans ces conditions artificielles les moustiques faisaient des essaims tous les matins et tous les soirs. Le commencement de l'essaimage le soir, et sa fin le matin avaient lieu à un même éclairement (1,6 log lux). Si l'éclairement était tenu inférieur à 1,6 log lux, les essaims duraient toute la nuit jusqu'à ce que la lumière soit relevée.Quelques observations sur Culex nigripalpus et Anopheles quadrimaculatus indiquent que les déliminations de l'éclairement permettent l'essaimage. Chez. C. nigripalpus ils étaient presque les mêmes que celles de Culex fatigans. Psorophora howardii et Aëdes taeniorhynchus ne font pas d'essaimage dans la petite cage mais la dernière espèce fait un essaim dans une cage plus grande après un éclairement subit.

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Contribution No. 113, Florida State Board of Health, Entomological Research Center, Vero Beach, Florida. This investigation was supported by Public Health Research Grant E-1492, from the National Institute of Allergy and Infectious Diseases, Public Health Service.     

Swarming behavior in plant roots

Interactions between individuals that are guided by simple rules can generate swarming behavior. Swarming behavior has been observed in many groups of organisms, including humans, and recent research has revealed that plants also demonstrate social behavior based on mutual interaction with other individuals. However, this behavior has not previously been analyzed in the context of swarming. Here, we show that roots can be influenced by their neighbors to induce a tendency to align the directions of their growth. In the apparently noisy patterns formed by growing roots, episodic alignments are observed as the roots grow close to each other. These events are incompatible with the statistics of purely random growth. We present experimental results and a theoretical model that describes the growth of maize roots in terms of swarming.     

Dynamics of Bacterial Swarming

When vegetative bacteria that can swim are grown in a rich medium on an agar surface, they become multinucleate, elongate, synthesize large numbers of flagella, produce wetting agents, and move across the surface in coordinated packs: they swarm. We examined the motion of swarming Escherichia coli, comparing the motion of individual cells to their motion during swimming. Swarming cells' speeds are comparable to bulk swimming speeds, but very broadly distributed. Their speeds and orientations are correlated over a short distance (several cell lengths), but this correlation is not isotropic. We observe the swirling that is conspicuous in many swarming systems, probably due to increasingly long-lived correlations among cells that associate into groups. The normal run-tumble behavior seen in swimming chemotaxis is largely suppressed, instead, cells are continually reoriented by random jostling by their neighbors, randomizing their directions in a few tenths of a second. At the edge of the swarm, cells often pause, then swim back toward the center of the swarm or along its edge. Local alignment among cells, a necessary condition of many flocking theories, is accomplished by cell body collisions and/or short-range hydrodynamic interactions.     

双翅目昆虫的婚飞

婚飞是昆虫的一个基本行为,促成远缘繁殖,对双翅目昆虫的繁殖和交配均有非常重要的意义。文中对双翅目昆虫中具有婚飞行为的类群、婚飞标志物、环境因子对婚飞的影响进行了概括总结,并特别讨论了舞虻科昆虫的婚飞行为。     

Swarming motility in undomesticated Bacillus subtilis

Swarming motility was identified and characterized in an undomesticated strain of Bacillus subtilis. Rapid surface migration was preceded by a cell density-dependent lag period, which could be eliminated if actively swarming cells were used as the inoculum. The leading edge of the swarm was characterized by multicellular rafts of highly flagellated cells. Flagellum biosynthesis and surfactant production were required for swarming. Swarming was not found in any of several standard laboratory strains. Laboratory strains are characteristically unable to produce surfactant, but such a strain remained unable to swarm even when surfactant was provided by extracellular complementation. We conclude that robust swarming is a feature of undomesticated B. subtilis and that this behaviour has been lost or attenuated in laboratory strains through the accumulation of multiple genetic defects.     

Periodic Reversals in Paenibacillus dendritiformis Swarming

Bacterial swarming is a type of motility characterized by a rapid and collective migration of bacteria on surfaces. Most swarming species form densely packed dynamic clusters in the form of whirls and jets, in which hundreds of rod-shaped rigid cells move in circular and straight patterns, respectively. Recent studies have suggested that short-range steric interactions may dominate hydrodynamic interactions and that geometrical factors, such as a cell''s aspect ratio, play an important role in bacterial swarming. Typically, the aspect ratio for most swarming species is only up to 5, and a detailed understanding of the role of much larger aspect ratios remains an open challenge. Here we study the dynamics of Paenibacillus dendritiformis C morphotype, a very long, hyperflagellated, straight (rigid), rod-shaped bacterium with an aspect ratio of ∼20. We find that instead of swarming in whirls and jets as observed in most species, including the shorter T morphotype of P. dendritiformis, the C morphotype moves in densely packed straight but thin long lines. Within these lines, all bacteria show periodic reversals, with a typical reversal time of 20 s, which is independent of their neighbors, the initial nutrient level, agar rigidity, surfactant addition, humidity level, temperature, nutrient chemotaxis, oxygen level, illumination intensity or gradient, and cell length. The evolutionary advantage of this unique back-and-forth surface translocation remains unclear.     

Potential effects of tyramine on the transition to reproductive workers in honeybees (Apis mellifera L.)

Abstract.  To explore the role of brain tyramine in reproductive worker honeybees, its effects after injection and oral treatment on brain dopamine levels and ovarian development in queenless worker honeybees are determined. Both tyramine injection and oral treatment in 10-day-old queenless bees leads to tyramine transportation into the brain and significantly elevates brain dopamine levels as a function of the tyramine concentration. Ovarian diameters are significantly larger in 10-day-old queenless bees treated with tyramine compared with queenless bees of the same age without tyramine treatment. Results on yolk formation in the ovary support the finding of increased ovarian diameter, suggesting that oral tyramine treatment accelerates ovarian development through dopamine effects and/or direct effects of tyramine on the ovary in queenless bees. Thus, tyramine has potential effects on the enhancement of brain dopamine levels and the acceleration of ovarian development for the transition of normal workers to reproductive worker honeybees.     

Swarming strategies for cooperative species

In this paper, we propose a model to investigate the relative efficiency of simple swarming strategies based on the interplay between spontaneous and recruitment-based emigration. We conduct a dynamical study of the model which combines inverse density dependence, saturation effects and induced vs. diffusion-like population transfer. The influence of the most relevant parameters is explored on a systematic basis, and transition values for which qualitative changes occur in the system's behaviour are given. The model is then used to study colonization of a multiple sites environment, as well as confrontation between species featuring different swarming strategies. Simulation results indicate that cooperative organisms should have an interest in evolving recruitment-based emigration. The corresponding population transfer patterns prove more efficient in invading new territories, eliminating competitors in the process. We suggest that this advantage could have promoted a simple form of coordinated swarming in species featuring a primitive type of cooperation.     

Modeling Vortex Swarming In Daphnia

Based on experimental observations in Daphnia, we introduce an agent-based model for the motion of single and swarms of animals. Each agent is described by a stochastic equation that also considers the conditions for active biological motion. An environmental potential further reflects local conditions for Daphnia, such as attraction to light sources. This model is sufficient to describe the observed cycling behavior of single Daphnia. To simulate vortex swarming of many Daphnia, i.e. the collective rotation of the swarm in one direction, we extend the model by considering avoidance of collisions. Two different ansatzes to model such a behavior are developed and compared. By means of computer simulations of a multi-agent system we show that local avoidance—as a special form of asymmetric repulsion between animals—leads to the emergence of a vortex swarm. The transition from uncorrelated rotation of single agents to the vortex swarming as a function of the swarm size is investigated. Eventually, some evidence of avoidance behavior in Daphnia is provided by comparing experimental and simulation results for two animals.     

蝗虫为什么能暴发成灾?

"蝗虫"因其种类多-全世界已知蝗虫超过10000种,我国已知蝗虫近900种:蝗害范围大-全球除南极洲,欧亚大陆北纬55°以北地区外均有蝗虫分布,真可谓是"虫"中之"皇"!全世界各大洲都有它们各自代表性的蝗虫,如亚洲的印度黄脊蝗、黑翅竹蝗、稻蝗等;欧洲的意大利蝗、摩洛哥蝗、小翅曲背蝗等;非洲是沙漠蝗、红蝗、塞内加尔小车蝗等等。飞蝗是一种世界分布的蝗虫。不同属种的蝗虫由于它们长期生活栖居在不同的大陆以及不同的生境场所,就具有适应各种生态条件与环境的本领,并有着不同的形态和生态学特征。     

Genetic Determinants of Swarming in Rhizobium etli

Swarming motility is considered to be a social phenomenon that enables groups of bacteria to move coordinately atop solid surfaces. The differentiated swarmer cell population is embedded in an extracellular slime layer, and the phenomenon has previously been linked with biofilm formation and virulence. The gram-negative nitrogen-fixing soil bacterium Rhizobium etli CNPAF512 was previously shown to display swarming behavior on soft agar plates. In a search for novel genetic determinants of swarming, a detailed analysis of the swarming behavior of 700 miniTn5 mutants of R. etli was performed. Twenty-four mutants defective in swarming or displaying abnormal swarming patterns were identified and could be divided into three groups based on their swarming pattern. Fourteen mutants were completely swarming deficient, five mutants showed an atypical swarming pattern with no completely smooth edge and local extrusions, and five mutants displayed an intermediate swarming phenotype. Sequence analysis of the targeted genes indicated that the mutants were likely affected in quorum-sensing, polysaccharide composition or export, motility, and amino acid and polyamines metabolism. Several of the identified mutants displayed a reduced symbiotic nitrogen fixation activity.     

蜜蜂无政府主义蜂群的研究进展

西方蜜蜂Apis mellifera作为典型的社会性昆虫, 最重要的特征是生殖劳动分工。蜂王垄断蜂群的生殖权利, 工蜂生殖功能受到抑制, 从事除产卵和交配以外的所有职能。而在无政府主义蜂群中, 即使蜂王存在, 也有较多工蜂的卵巢激活并产卵, 蜂群中大多数雄蜂是工蜂的后代。这些特殊蜂群为正常蜂群工蜂不育机制研究提供了绝佳的反例材料。本文对无政府主义蜂群的行为特征、 产生条件、 遗传基础等研究进行了综述。无政府主义蜂群中有较多的工蜂产卵, 且工蜂所产卵能够逃避工蜂监督, 这种行为的产生受环境、 遗传组成、 基因表达等多种因素的影响, 并且遗传结构体系复杂, 参与调控的基因数量多。无政府主义蜂群行为机制的研究为工蜂不育机制的揭示及其他社会性昆虫工职不育基因的筛选和功能研究提供借鉴。     

Large scale homing in honeybees

Honeybee foragers frequently fly several kilometres to and from vital resources, and communicate those locations to their nest mates by a symbolic dance language. Research has shown that they achieve this feat by memorizing landmarks and the skyline panorama, using the sun and polarized skylight as compasses and by integrating their outbound flight paths. In order to investigate the capacity of the honeybees' homing abilities, we artificially displaced foragers to novel release spots at various distances up to 13 km in the four cardinal directions. Returning bees were individually registered by a radio frequency identification (RFID) system at the hive entrance. We found that homing rate, homing speed and the maximum homing distance depend on the release direction. Bees released in the east were more likely to find their way back home, and returned faster than bees released in any other direction, due to the familiarity of global landmarks seen from the hive. Our findings suggest that such large scale homing is facilitated by global landmarks acting as beacons, and possibly the entire skyline panorama.     

Nonelemental visual learning in honeybees

Free-flying honeybees, Apis mellifera, learn visual stimuli in the appetitive context of food search. Visual compound stimuli are relevant in nautre as bees learn flower images that consist of many visual elements. We studied whether elemental associations between each visual element and the reinforcement (elemental approach) are enough to explain the solving of visual discrimination problems that raise ambiguity at the elemental level. We asked whether bees could solve three different visual discriminations: (1) positive patterning (A−, B−, AB+); (2) negative patterning (A+, B+, AB−); and (3) biconditional discrimination (AB+, CD+, AC−, BD−). In experiments 1 and 2 bees had to discriminate a yellow-violet chequerboard from the yellow or the violet squares alone. In experiment 3, four different gratings combining one colour (yellow or violet) with one orientation (vertical or horizontal) had to be discriminated. In all three problems binary compounds were trained in such a way that each element appeared equally often as rewarded and nonrewarded. Bees could solve the three discrimination problems. They always chose the reinforced stimulus despite ambiguity at the level of the elements. For solving positive patterning, elemental processing could be used. For negative patterning and biconditional discrimination, nonelemental processing strategies (unique-cue or configural approach) are necessary to account for these results. Although we cannot decide between a configural and a unique-cue interpretation, we can clearly reject purely elemental processing in these cases. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.