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cellulose degradation by leucocoprinus gongylophorus, the fungus cultured by the leaf-cutting ant atta sexdens rubropilosa.leucocoprinus gongylophorus, the fungus cultured by the leaf-cutting ant atta sexdens rubropilosa, is able to degrade efficiently cellulose, microcrystaline cellulose, carboximethylcellulose, and cellobiose. analysis of the degradation products indicate that the fungus produce extracellular beta-glucosidase, exo- and endo-glucanase. the importance of cellulose degradation to the association of fungus and ant is discussed.19957574556
yeasts associated with nests of the leaf-cutting ant atta sexdens rubropilosa forel, 1908.a total of 137 yeasts associated with the leaf-cutting ant atta sexdens rubropilosa forel, 1908 were characterized, being selected 93 for analysis. twenty four species belonging to seven genera (candida, cryptococcus, rhodotorula, sporobolomyces, tremella, trichosporon, pichia) were isolated from the different analysed material. the genus candida was widely distributed, with c. homilentoma, c. colliculosa-like, c. famata and c. colliculosa being the most prevalent. a few isolates did not fit the ...19979111918
metabolism of plant polysaccharides by leucoagaricus gongylophorus, the symbiotic fungus of the leaf-cutting ant atta sexdens latta sexdens l. ants feed on the fungus they cultivate on cut leaves inside their nests. the fungus, leucoagaricus gongylophorus, metabolizes plant polysaccharides, such as xylan, starch, pectin, and cellulose, mediating assimilation of these compounds by the ants. this metabolic integration may be an important part of the ant-fungus symbiosis, and it involves primarily xylan and starch, both of which support rapid fungal growth. cellulose seems to be less important for symbiont nutrition, since ...19989835568
comparative study of temporal summation and response form in hymenopteran photoreceptors.1. temporal summation was measured in green-sensitive photoreceptors of seven hymenopteran species with various life styles: three bees, melipona quadrifasciata quadrifasciata, trigona spinnipes and bombus morio; one wasp, polistes canadensis; and three ants, pseudomyrmex phyllophilus, camponotus rufipes, and atta sexdens rubropilosa. in all species approximate agreement with bloch's law was confirmed. 2. critical durations (tc), which varied from 10 ms (pseudomyrmex) to 46 ms (atta), are discus ...19892746551
morphological changes in the ommatidia of an ant in the day and night states.morphological changes in dioptric structures, in the position of screening pigments and in the microvillar arrangement of the rhabdom were observed in atta sexdens ant ommatidia exposed to different light/dark schedules. during the day there was a funneling of the crystalline cone and the pigments were close to the rhabdom. at night the crystalline cone became thicker and shorter than in the day state and the pigments moved away from the rhabdom. endogenous control for these changes was demonstr ...19892636013
occurrence of killer yeasts in leaf-cutting ant nests.killer activity was screened in 99 yeast strains isolated from the nests of the leaf-cutting ant atta sexdens against 6 standard sensitive strains, as well as against each other. among this yeast community killer activity was widespread since 77 strains (78%) were able to kill or inhibit the growth of at least one standard strain or nest strain. toxin production was observed in representatives of all the studied genera including aureobasidium, rhodotorula, tremella and trichosporon, whose killer ...200212099266
survival of atta sexdens workers on different food sources.leaf-cutting ants belonging to the tribe attini are major herbivores and important agriculture pests in the neotropics, these ants being thought to feed on the sap which exudes from the plant material which they cut and also on the mycelium of a symbiotic fungus that grows on plant material inside their nests in what is called "the fungus garden". however, we have found that the survival of atta sexdens worker ants on leaves, on mycelium of the ants' symbiotic fungus, leucoagaricus gongylophorus ...200312769984
fluid intake rates in ants correlate with their feeding habits.this study investigates the techniques of nectar feeding in 11 different ant species, and quantitatively compares fluid intake rates over a wide range of nectar concentrations in four species that largely differ in their feeding habits. ants were observed to employ two different techniques for liquid food intake, in which the glossa works either as a passive duct-like structure (sucking), or as an up- and downwards moving shovel (licking). the technique employed for collecting fluids at ad libit ...200312769988
electron microscopic study of light muscle degeneration in queens of atta sexdens (hymenoptera: formicidae.the reabsorption of the flight muscles of a. sexdens queens was studied just after the autotomy of the wings, and 1,10,15,25 and 45 days thereafter. the muscle cells degenerate slowly, the first alterations taking place in the mitochondria and sarcoplasm. signs of degeneration appear in the myofibrils after only 10 days and alterations increase with time. after 45 days the myofibrils have completely disintegrated.1979533651
toxicity of synthetic piperonyl compounds to leaf-cutting ants and their symbiotic fungus.the development of leucoagaricus gongylophorus, the fungus cultured by the leaf-cutting ant atta sexdens was inhibited in vitro by synthetic compounds containing the piperonyl group. in addition, worker ants that were fed daily on an artificial diet to which these compounds were added had a higher mortality rate than the controls. the inhibition of the fungal growth increased with the size of the carbon side chain ranging from c1 through c8 and decreasing thereafter. 1-(3,4-methylenedioxybenzylo ...200111464791
forager size of the leaf-cutting ant atta sexdens (hymenoptera: formicidae) in a mature eucalyptus forest in brazil.we determined the size characteristics of foragers of the leaf-cutting ant atta sexdens in a mature eucalyptus forest in campos dos goytacazes, rio de janeiro state, brazil, at daytime (7:30 to 10:00 hr) and nighttime (19:00 to 23:00 hr). there were no significant differences between daytime and nighttime ant mass (ma), but leaf fragment mass (ml) and burden (b = [ma + ml]/ma), which indicates relative load capacity, were significantly greater at daytime. there was a positive linear relationship ...200011487943
cryptococcus haglerorum, sp. nov., an anamorphic basidiomycetous yeast isolated from nests of the leaf-cutting ant atta sexdens.a yeast strain (cbs 8902) was isolated from the nest of a leaf-cutting ant and was shown to be related to cryptococcus humicola. sequencing of the d1/d2 region of the 26s ribosomal dna and physiological characterization revealed a separate taxonomic position. a novel species named cryptococcus haglerorum is proposed to accommodate strain cbs 8902 that assimilates n-hexadecane and several benzene compounds. physiological characteristics distinguishing the novel species from some other members of ...200312785310
ocurrence of the antibiotic producing bacterium burkholderia sp. in colonies of the leaf-cutting ant atta sexdens rubropilosa.fungus garden material from recently established atta sexdens rubropilosa colonies (6-12 months old) was sampled to detect antibiotic producing microorganisms that inhibited the growth of pathogens of insects and of the fungus gardens but did not affect their mutualistic fungus. a bacterium with activity against the entomopathogenic fungus beauveria bassiana was isolated from 56% of the gardens tested (n=57) and identified from its biochemical profile and from 16s and 23s ribosomal dna sequences ...200415476982
activity of ricinus communis (euphorbiaceae) and ricinine against the leaf-cutting ant atta sexdens rubropilosa (hymenoptera: formicidae) and the symbiotic fungus leucoagaricus gongylophorus.the focus of this study was the identification of compounds from plant extracts for use in crop protection. this paper reports on the toxic activity of fractions of leaf extracts of ricinus communis l (euphorbiaceae) and isolated active compounds in the leaf-cutting ant atta sexdens rubropilosa forel and its symbiotic fungus leucoagaricus gongylophorus (singer) möller. the main compounds responsible for activity against the fungus and ant in leaf extracts of r communis were found to be fatty aci ...200415382509
sympodiomyces attinorum sp. nov., a yeast species associated with nests of the leaf-cutting ant atta sexdens.four strains of a novel yeast species were isolated from laboratory nests of the leaf-cutting ant atta sexdens in brazil. three strains were found in older sponges and one was in a waste deposit in the ant nests. sequencing of the d1/d2 region of the large-subunit rrna gene showed that the novel species, named sympodiomyces attinorum sp. nov., is phylogenetically related to sympodiomyces parvus. unlike sympodiomyces parvus, sympodiomyces attinorum can ferment glucose, assimilate methyl alpha-d-g ...200415388759
the intramandibular gland of leaf-cutting ants (atta sexdens rubropilosa forel 1908).the eusociality developed in hymenoptera and isoptera is driven by an efficient interaction between exocrine glands and jointed appendages, both in close interaction with the environment. in this context, the mandible of ants plays an important role, since, in addition to being the main jointed appendage, it possess glandular functions. as an example we might name the two glands associated with the mandible: the mandibular and the intramandibular glands. the intramandibular gland is found inside ...200616198116
colony behavior of atta sexdens rubropilosa (hymenoptera: formicidae) in the absence of the queen under laboratory conditions.a colony of atta sexdens rubropilosa was studied in the presence and absence of the queen. the frequency of 23 previously defined behaviors was quantified in terms of average frequencies of act occurrence. colony behavioral activities such as foraging, fungal care, and refuse manipulation were not directly influenced by the queen's presence up to 30 days after the queen's death. the queen, which also seems to maintain colony cohesion aside from reproduction, indirectly affected brood care.200312914995
ultrastructural studies of the mandibular glands of the minima, media and soldier ants of atta sexdens rubropilosa (forel 1908) (hymenoptera: formicidae).the mandibular glands of hymenoptera are structures associated with the mandibles and constitute part of the salivary glands system. histological studies in workers of atta sexdens rubropilosa revealed that this gland contains two portions: a secretory and a storage portion or reservoir. both portions are connected by means of canaliculi. the object of the present work was the study of the ultratructure of the mandibular glands of minima, media and soldier ant of a. s. rubropilosa by tem techniq ...200515935305
the mandibular gland secretions of the leaf-cutting ants atta sexdens sexdens and atta opaciceps exhibit intercaste and intercolony variations.the mandibular gland secretions of worker castes from wild colonies of the leaf-cutting ants atta sexdens sexdens and atta opaciceps were analyzed quantitatively by gas chromatography-mass spectrometry. the secretions comprised a complex mixture of volatile, mainly oxygenated compounds, and their profiles exhibited considerable qualitative and quantitative variations among species and castes. the known alarm pheromone 4-methyl-3-heptanone was common to both species. the elevated relative proport ...200616683202
production of polysaccharidases in different carbon sources by leucoagaricus gongylophorus möller (singer), the symbiotic fungus of the leaf-cutting ant atta sexdens linnaeus.leucoagaricus gongylophorus, the fungus cultured by the leaf-cutting ant atta sexdens, produces polysaccharidases that degrade leaf components by generating nutrients believed to be essential for ant nutrition. we evaluated pectinase, amylase, xylanase, and cellulase production by l. gongylophorus in laboratory cultures and found that polysaccharidases are produced during fungal growth on pectin, starch, cellulose, xylan, or glucose but not cellulase, whose production is inhibited during fungal ...200616775790
queen influence on workers behavior of the leaf-cutting ant atta sexdens rubropilosa (forel, 1908).in an ant colony, the queen is the single reproducer and can interact with her workers via pheromones and cuticular compounds. however, in most species queen importance is not restricted to reproduction: in the initial development of the colony, her presence might play a more important role. in this work, we studied the effects of queen absence on workers behavior displayed in the foraging arena. ants mortality and refuse accumulation was also measured daily. the results showed that queen absenc ...200616862305
selection of entomopathogenic fungi for use in combination with sub-lethal doses of imidacloprid: perspectives for the control of the leaf-cutting ant atta sexdens rubropilosa forel (hymenoptera: formicidae).in the first part of this study, four isolates of the fungus beauveria bassiana (bals.) vuillemin (lpp1, lpp2, cg05 and cg24) and one isolate of metarhizium anisopliae (metsch.) sorokin (cg46) were tested against adult foragers of atta sexdens rubropilosa. ants were allowed to walk on filter paper discs, inside petri dishes, previously impregnated with 1 ml of a conidia suspension (2 x 10(7) conidia ml(-1)), maintained at 80% rh and 26 degrees c for 24 h and subsequently, transferred to sterile ...200717404893
starch metabolism in leucoagaricus gongylophorus, the symbiotic fungus of leaf-cutting ants.leucoagaricus gongylophorus, the symbiotic fungus of the leaf-cutting ants, degrades starch, this degradation being supposed to occur in the plant material which leafcutters forage to the nests, generating most of the glucose which the ants utilize for food. in the present investigation, we show that laboratory cultures of l. gongylophorus produce extracellular alpha-amylase and maltase which degrade starch to glucose, reinforcing that the ants can obtain glucose from starch through the symbioti ...200616380244
ultrastructure and physiology of the co2 sensitive sensillum ampullaceum in the leaf-cutting ant atta sexdens.the sensilla ampullacea on the apical antennomere of the leaf-cutting ant atta sexdens were investigated regarding both their responses to co2 and their ultrastructure. by staining the sensillum during recording, we confirmed that the sensilla ampullacea are responsible for co2 perception. we showed that the sensory neurons of the sensilla ampullacea are continuously active without adaptation during stimulation with co2 (test duration: 1 h). this feature should enable ants to assess the absolute ...200018088913
a macroglomerulus in the antennal lobe of leaf-cutting ant workers and its possible functional significance.ants have a well-developed olfactory system, and pheromone communication is essential for regulating social life within their colonies. we compared the organization of primary olfactory centers (antennal lobes, als) in the brain of two closely related species of leaf-cutting ants (atta vollenweideri, atta sexdens). both species express a striking size polymorphism associated with polyethism. we discovered that the als of large workers contain a substantially enlarged glomerulus (macroglomerulus, ...200515843501
isolation of xanthyletin, an inhibitor of ants' symbiotic fungus, by high-speed counter-current chromatography.xanthyletin, an inhibitor of symbiotic fungus (leucoagaricus gongylophorus) of leaf-cutting ant (atta sexdens rubropilosa), as well as suberosin, seselin and xanthoxyletin were isolated from citrus sinensis grafted on citrus limonia. a two-phase solvent system composed of hexane/ethanol/acetonitrile/water (10:8:1:1, v/v) was used for the high-speed counter-current chromatographic isolation of xanthyletin with high yield and over 99% purity as determined by liquid and gas chromatography with mass ...200919296958
fungus-growing ants.fungus-growing ants (attini) are in reality unique fungus-culturing insects.there are several hundred species in some dozen genera, of which acromyrmex and atta are the conspicuous leaf-cutters. the center of their activities is the fungus garden, which is also the site of the queen and brood. the garden, in most species, is made from fresh green leaves or other vegetal material. the ants forage for this, forming distinct trails to the vegetation that is being harvested. the cut leaves or other ...196617757227
survey of neodohrniphora spp. (diptera: phoridae) at colonies of atta sexdens rubropilosa (forel) and specificity of attack behaviour in relation to their hosts.atta sexdens rubropilosa is a leaf-cutting ant that is a significant agricultural and forestry pest in the neotropical region. this ant is parasitized by flies from the genera neodohrniphora spp., apocephalus spp. and myrmosicarius spp. this study was carried out to determine which species of neodohrniphora spp. are found near foraging trails of atta sexdens rubropilosa and to evaluate the specificity of attack behaviour of these parasitoids. from may 2002 to april 2004, we sampled neodohrniphor ...200818257954
mortality of atta sexdens rubropilosa (hymenoptera: formicidae) workers in contact with colony waste from different plant sources.the objective of this work was to study the effect of colony waste on the mortality of workers of atta sexdens rubropilosa forel colonies fed with different plant substrates. eight nests were used; two colonies each were fed with acalypha wilkesiana müller.arg, ligustrum japonicum thunb, eucalyptus urophylla s.t. blake or a mixture of the three substrates in equal proportions. irrespective of diet, being kept with waste led to higher mortality. however, workers that were kept in contact with was ...201019366474
ethnopharmacological survey among migrants living in the southeast atlantic forest of diadema, são paulo, brazil.understanding how people of diverse cultural backgrounds have traditionally used plants and animals as medicinal substances during displacements is one of the most important objectives of ethnopharmacological studies. an ethnopharmacological survey conducted among migrants living in the southeast atlantic forest remnants (diadema, são paulo, brazil) is presented herein.201021034478
simple and rapid ce-uv method for the assessment of trail pheromone compounds of leaf-cutting ants' venom glands.leaf-cutting ants cause large losses in several crops around the world. in the ant species atta sexdens, each colony comprises up to 5 million individuals. in order to keep a close connection among such a large number of individuals, an efficient chemical communication system is necessary. among other different substances, these animals use alkylpyrazines to mark their trails and to guide ant workers from the nest to their sources of food. in this study, ce-uv was used to apply a method for qual ...201121462224
salivary system in leaf-cutting ants (atta sexdens rubropilosa forel, 1908) castes: a confocal study.the salivary system in ants is not only limited to digestory functions, but also has important role in the communication. the glands which compose the salivary complex are: the post-pharyngeal, hypopharyngeal, mandibular, and thoracic salivary gland, showing peculiar features which may vary according to the castes the individuals belong to and according to the functions they develop. the present study compared the morphological differences among the glands of atta sexdens rubropilosa workers, ma ...200818554918
identification and expression of capa gene in the fire ant, solenopsis invicta.recent genome analyses suggested the absence of a number of neuropeptide genes in ants. one of the apparently missing genes was the capa gene. capa gene expression in insects is typically associated with the neuroendocrine system of abdominal ganglia; mature capa peptides are known to regulate diuresis and visceral muscle contraction. the apparent absence of the capa gene raised questions about possible compensation of these functions. in this study, we re-examined this controversial issue and s ...201424718032
considerations for assessing maximum critical temperatures in small ectothermic animals: insights from leaf-cutting ants.the thermal limits of individual animals were originally proposed as a link between animal physiology and thermal ecology. although this link is valid in theory, the evaluation of physiological tolerances involves some problems that are the focus of this study. one rationale was that heating rates shall influence upper critical limits, so that ecological thermal limits need to consider experimental heating rates. in addition, if thermal limits are not surpassed in experiments, subsequent tests o ...201222384147
cerebral extraocular photoreceptors in ants.clusters of dark pigmented cells, called putative cerebral extraocular photoreceptors (ceps), are described in the optic lobes of four ant species: atta sexdens, camponotus rufipes, camponotus crassus, and pseudomyrmex adustus. electron-micrographs of ceps show a central rhabdom-like structure formed by tightly interleaved cells containing shielding pigments, with axons projecting toward the outer optic chiasm. the presence of a great number of mitochondria, nucleolus, and multivesciular bodies ...199618621321
variability of non-mutualistic filamentous fungi associated with atta sexdens rubropilosa nests.a survey of the filamentous fungi other than the symbiotic one found in association with atta sexdens rubropilosa colonies was carried out. different fungal species (27 taxa) were isolated a few days after treating the workers with toxic baits (sulfluramid; mirex-s), from 40 laboratory and 20 field nests. syncephalastrum racemosum (54%) and escovopsis weberi (21%), trichoderma harzianum (38%) and fusarium oxysporum (23%) were the prevalent species in laboratory and field nests, respectively. acr ...200516475502
yeasts found on an ephemeral reproductive caste of the leaf-cutting ant atta sexdens rubropilosa.winged males of leaf-cutting ants are considered an ephemeral reproductive caste only produced before the mating flight season. although much is known about the yeast diversity found in fungus gardens of attine ants, no study has focused on the yeasts associated with males of leaf-cutting ants. here, we surveyed the yeasts on the integuments of males of atta sexdens rubropilosa and assessed their potential role in the attine ant-microbe symbiosis. using culture-dependent techniques, we found yea ...201425012689
a metabolic pathway assembled by enzyme selection may support herbivory of leaf-cutter ants on plant starch.mutualistic associations shape the evolution in different organism groups. the association between the leaf-cutter ant atta sexdens and the basidiomycete fungus leucoagaricus gongylophorus has enabled them to degrade starch from plant material generating glucose, which is a major food source for both mutualists. starch degradation is promoted by enzymes contained in the fecal fluid that ants deposit on the fungus culture in cut leaves inside the nests. to understand the dynamics of starch degrad ...201323500892
ants can learn to forage on one-way trails.the trails formed by many ant species between nest and food source are two-way roads on which outgoing and returning workers meet and touch each other all along. the way to get back home, after grasping a food load, is to take the same route on which they have arrived from the nest. in many species such trails are chemically marked by pheromones providing orientation cues for the ants to find their way. other species rely on their vision and use landmarks as cues. we have developed a method to s ...200919337369
seed dispersal and predation of buchenavia tomentosa eichler (combretaceae) in a cerrado sensu stricto, midwest brazil.the ecology of seed dispersal is critical to understand the patterns of distribution and abundance of plant species. we investigated seed dispersal aspects associated with the high abundance of buchenavia tomentosa in the serra azul state park (pesa). we estimated fruit production and conducted fruit removal experiments. we carried out diurnal and nocturnal observations on frugivory as well as germination tests. fruiting occurred in the dry season and totaled 1,365,015 ± 762,670 fruits.ha-1. b. ...201526602355
chemistry of metapleural gland secretions of three attine ants,atta sexdens rubropilosa, atta cephalotes, andacromyrmex octospinosus (hymenoptera: formicidae).the chemical composition of the secretions of the metapleural glands of workers and soldiers of twoatta species,atta sexdens rubropilosa anda. cephalotes, and workers ofacromyrmex octospinosus, has been studied. as indicated by infrared spectrometry and confirmed by the ninhydrin test, the secretions contain chiefly proteins. of the volatile acidic portion, which is present as ionized salts, phenylacetic acid is the major component in workers and soldiers ofa. s. rubropilosa anda. cephalotes. bo ...199624227619
the postpharyngeal gland: specialized organ for lipid nutrition in leaf-cutting ants.there are several hypotheses about the possible functions of the postpharyngeal gland (ppg) in ants. the proposed functions include roles as cephalic or gastric caeca and diverticulum of the digestive tract, mixing of hydrocarbons, nestmate recognition, feeding larvae, and the accumulation of lipids inside this gland, whose origin is contradictory. the current study aimed to investigate the functions of these glands by examining the protein expression profile of the ppgs of atta sexdens rubropil ...201627149618
does diatomaceous earth control leaf-cutter ants (hymenoptera: formicidae) in the eucalyptus plantations?genus atta includes some of the most important formicidae leaf cutter ants which cause extensive damage to the eucalyptus plantations. atta sexdens rubropilosa forel, one of the chief pests in brazilian reforestation, can restrict and reduce forest productivity by its intense and constant leaf-cutting activities on plants at all stages. therefore, the demand for new products to control a. sexdens rubropilosa indicates the study of the utilization of the dry powder formulation of diatomaceous ear ...201526470237
foliar substrate affects cuticular hydrocarbon profiles and intraspecific aggression in the leafcutter ant atta sexdens.cuticular hydrocarbons (chcs) are traditionally considered to be one of the most important chemical cues used in the nestmate recognition process of social hymenopterans. however, it has been suggested that in the leafcutter ant genus atta, it is not the chcs, but the alarm pheromone that is involved in the nestmate recognition process. in this study we used a laboratory population of atta sexdens to explore the association between their chc profile variation and intraspecific aggression. in the ...201526463072
comparative morpho-physiology of the metapleural glands of two atta leaf-cutting ant queens nesting in clayish and organic soils.queens of leaf-cutting ants found their nests singly, each consisting of a vertical tunnel and a final horizontal chamber. because of the claustral mode of nest founding, the queen and/or her initial fungus garden are exposed to threats imposed by several soil pathogens, and the antibiotic secretions produced by their metapleural glands are considered a main adaptation to deal with them. nests of two atta leaf-cutting ant species, atta vollenweideri and atta sexdens rubropilosa, occur in differe ...201526145506
sublethal doses of fipronil intensify synapsin immunostaining in atta sexdens rubropilosa (hymenoptera: formicidae) brains.although ants are common insects in agricultural ecosystems, few studies have considered how xenobiotics might induce physiological and morphological alterations in these insects. this study aimed to verify the neurotoxic action of sublethal doses of fipronil on the mushroom bodies of brains from the leaf-cutting ant atta sexdens rubropilosa through immunocytochemistry analysis for the protein synapsin.201626097143
reactions by army ant workers to nestmates having had contact with sympatric ant species.it was recently shown that pheidole megacephala colonies (an invasive species originating from africa) counterattack when raided by the army ant, eciton burchellii. the subsequent contact permits pheidole cuticular compounds (that constitute the "colony odour") to be transferred onto the raiding eciton, which are then not recognised by their colony-mates and killed. using a simple method for transferring cuticular compounds, we tested if this phenomenon occurs for neotropical ants. eciton worker ...201425444708
mitochondrial and peroxisomal population in post-pharyngeal glands of leaf-cutting ants after lipid supplementation.the post-pharyngeal gland (ppg) occurs in ants and some sphecidae wasps. among its several roles is the storage of lipids from food. in order to investigate the effect of lipids on the cell, especially on mitochondria and peroxisomes, the present study was aimed at examining the peroxisomal and mitochondrial population in the ppg of atta sexdens rubropilosa after lipid supplementation by confocal laser scanning microscopy and transmission electron microscopy. soybean oil provided as lipid supple ...201525203360
are ant assemblages of brazilian veredas characterised by location or habitat type?wetland areas in the brazilian cerrado, known as "veredas", represent ecosystems formed on sandy soils with high concentrations of peat, and are responsible for the recharge of aquiferous reservoirs. they are currently under threat by various human activities, most notably the clearing of vegetation for eucalyptus plantations. despite their ecological importance and high conservation value, little is known about the actual effects of human disturbance on the animal community. to assess how habit ...201425055090
foraging leaf-cutting ants learn to reject vitis vinifera ssp. vinifera plants that emit herbivore-induced volatiles.leaf-cutting ants (lcas) are dominant herbivores of the neotropics, as well as economically important pests. their foraging ecology and patterns/mechanisms of food selection have received considerable attention. recently, it has been documented that lcas exhibit a delayed rejection of previously accepted food plants following treatment with a fungicide that makes the plants unsuitable as substrate for their symbiotic fungus. here, we investigated whether lcas similarly reject plants with induced ...201424929941
seasonal activity and foraging preferences of the leaf-cutting ant atta sexdens piriventris (santschi) (hymenoptera: formicidae).leaf-cutting ants are known for their habit of foraging. these habits can be influenced by several factors, including variations in topography, soil, and climate among others. the objective of this research was to study the seasonal activity and foraging preferences of the leaf-cutting ant atta sexdens piriventris (santschi). the study was carried out from january to october of 2007 in grasslands of the state of santa catarina, brazil. nests of a. sexdens piriventris were randomly selected and t ...201327193272
spatial distribution and fruiting phenology of protium heptaphyllum (burseraceae) determine the design of the underground foraging system of atta sexdens l. (hymenoptera: formicidae).leaf-cutting ants have long been recognized to forage via complex trail systems but the nature and the ecological drivers of the different foraging strategies adopted remain a key topic. here, we described the spatiotemporal use of belowground foraging galleries by atta sexdens l. in the brazilian atlantic forest, and examined the adaptive advantages of this foraging strategy. protium heptaphyllum adult trees (dbh > 10 cm), seed/seedling clumps and ant gallery entrances were mapped across two 1- ...201223950059
ricinus communis and jatropha curcas (euphorbiaceae) seed oil toxicity against atta sexdens rubropilosa (hymenoptera: formicidae).leaf-cutting ants are the main herbivores in the new world tropics. although the toxicity of seed oils against these ants has been poorly investigated, previous results revealed that seed oils exert considerable toxic activity against these insects. this paper analyzes the toxic action and deterrent properties of castor oil, ricinus communis l., and physic nut oil, jatropha curcas l., against workers of the leaf-cutting ant atta sexdens rubropilosa reared in laboratory. toxic effect was analyzed ...201323786062
fungal communities in the garden chamber soils of leaf-cutting ants.leaf-cutting ants modify the properties of the soil adjacent to their nests. here, we examined whether such an ant-altered environment impacts the belowground fungal communities. fungal diversity and community structure of soil from the fungus garden chambers of atta sexdens rubropilosa and atta bisphaerica, two widespread leaf-cutting ants in brazil, were determined and compared with non-nest soils. culture-dependent methods revealed similar species richness but different community compositions ...201423681670
dealing with water deficit in atta ant colonies: large ants scout for water while small ants transport it.leafcutter ants (atta sexdens rubropilosa) (forel 1908) have an elaborate social organization, complete with caste divisions. activities carried out by specialist groups contribute to the overall success and survival of the colony when it is confronted with environmental challenges such as dehydration. ants detect variations in humidity inside the nest and react by activating several types of behavior that enhance water uptake and decrease water loss, but it is not clear whether or not a single ...201223213476
toxicological and histopathological effects of hydramethylnon on atta sexdens rubropilosa (hymenoptera: formicidae) workers.the leaf-cut ants are important agricultural pest, because they can cause intense defoliation in plants and destroy large areas cultivated. although there are several works for the control of these insects by examining the toxicity of natural chemical compounds on various species of ants, few are focused on analyses of morphological changes caused in the affected organs. the aim of this study was to evaluate the effects of hydramethylnon on atta sexdens rubropilosa workers through toxicological ...201323148883
molecular characterization of a mariner-like element in the atta sexdens rubropilosa genome.mobile elements are widely present in eukaryotic genomes. they are repeated dna segments that are able to move from one locus to another within the genome. they are divided into two main categories, depending on their mechanism of transposition, involving rna (class i) or dna (class ii) molecules. the mariner-like elements are class ii transposons. they encode their own transposase, which is necessary and sufficient for transposition in the absence of host factors. they are flanked by a short in ...201222653597
increasing attractiveness of baits with venom gland extract for atta sexdens rubropilosa (forel) (hymenoptera: formicidae).the effect of larval cuticle extract (larval pheromone) and venom gland extract (trail pheromone) on transport of formulated baits by atta sexdens rubropilosa (forel) was studied in the field and under laboratory conditions. in the laboratory, we observed the transport to the nest of baits impregnated with 10 μl of venom gland extract (0.01 gland/bait) or 10 μl of larval cuticle extract (0.05 larva/bait). the most transported impregnated bait was then tested in the field placing rubber septa imp ...201223950048
on the morphology of the worker immatures of the leafcutter ant atta sexdens linnaeus (hymenoptera: formicidae).leafcutter ants of the genus atta fabricius are serious agricultural pests. morphological studies of immature stages within this group are few, and the data provided for species of considerable importance are usually incomplete. in this study, the immatures of atta sexdens linnaeus are described and compared using light and scanning electron microscopy. only specimens from founding stage colonies (i.e., lacking adult workers) were used. the existence of four larval instars was estimated by a fre ...201222419653
influence of caffeine on the survival of leaf-cutting ants atta sexdens rubropilosa and in vitro growth of their mutualistic fungus.leaf-cutting ants collect plant fresh material for the cultivation of their mutualistic fungus. atta sexdens rubropilosa forel (hymenoptera: formicidae) cause great economic losses through their foraging activity, mainly in agriculture. the main control method is the application of granulated toxic baits incorporated with an active ingredient (ai). the present goal is to evaluate the effect of caffeine on in vitro growth of the mutualistic fungus and on the survival of the leaf-cutting ants, aim ...201222323386
comparison of radial growth rate of the mutualistic fungus of atta sexdens rubropilosa forel in two culture media.in vitro culture of the mutualistic fungus of leaf-cutting ants is troublesome due to its low growth rate, which leads to storage problems and contaminants accumulation. this paper aims at comparing the radial growth rate of the mutualistic fungus of atta sexdens rubropilosa forel in two different culture media (pagnocca b and mea lp). although total mea lp radial growth was greater all along the bioassay, no significant difference was detected between growth efficiencies of the two media. previ ...201024031524
high-speed counter-current chromatographic isolation of ricinine, an insecticide from ricinus communis.the alkaloid ricinine, an insecticide for leaf-cutting ant (atta sexdens rubropilosa), was obtained from ricinus communis. a two-phase solvent system composed of ch(2)cl(2)/etoh/h(2)o (93:35:72, v/v/v) was used for high-speed counter-current chromatographic (hsccc) isolation of ricinine in high yield and with over 96% purity, as determined by liquid and gas chromatography-mass spectrometry (lc-ms and gc-ms). identification of ricinine was performed by comparison of (1)h nmr, (13)c nmr and lc-ms/ ...200919249053
leaf-cutting ant faecal fluid and mandibular gland secretion: effects on microfungi spore germination.the mandibular gland secretion (mgs) and the faecal fluid (ff) of the leaf-cutting ant atta sexdens rubropilosa forel affected the spore germination of selected microfungi isolated from nests of this insect. mgs was more effective than the ff, completely inhibiting the spore germination of four out of six microfungi species.200824031181
electrophysiological responses of atta sexdens rubropilosa workers to essential oils of eucalyptus and its chemical composition.the leaf-cutting ant atta sexdens rubropilosa forel, 1908 is the most harmful of the eucalyptus pests, causing severe losses in wood production through defoliation. various strategies have been tried and effort spent on the development of methods to control this pest, however no practical and environmentally acceptable one currently exists. in this work the chemical composition of the essential oil of seven eucalyptus species was identified and the selectivity and sensitivity of antennal recepto ...200917137124
interference of beta-eudesmol in nestmate recognition in atta sexdens rubropilosa (hymenoptera: formicidae).leaf-cutter ant species (atta spp.) are key pests of cultivated crops in the neotropics, and recent studies have demonstrated that workers of atta spp., particularly of atta sexdens rubropilosa, exhibit aggressive behavior among nestmates when in contact with the sesquiterpene beta-eudesmol, found in leaves of eucalyptus maculata. however, the underlying mechanism sparking this behavior pattern has yet to be investigated. this work aimed to elucidate the mechanism by which this substance elicits ...200818439338
toxicological and histopathological effects of boric acid on atta sexdens rubropilosa (hymenoptera: formicidae) workers.the current study compared the toxicity of different concentrations of boric acid in adult workers of atta sexdens rubropilosa forel (hymenoptera: formicidae), with toxicological bioassays, and examining the dose-dependent and time-dependent histopathological changes, of the midgut, malpighian tubules, and postpharyngeal glands. our results revealed the importance of conducting toxicological bioassays combined with morphological analyses of the organs of ants chronically exposed to insecticides ...201020568613
atta sexdens (l.) (hymenoptera: formicidae) demography in the colombian amazon: an evaluation of the palatable forage hypothesis.this study tested expectations of the palatable forage hypothesis for atta sexdens (l.). literature records on atta and acromyrmex nest density in the neotropics were analyzed and a. sexdens demographical aspects were studied in six transects located along the colombian amazon river. literature research results did not show that atta and acromyrmex nest densities are consistently higher in disturbed habitats. in transects, 56 active and 182 inactive nests were found in 2008. higher active nest n ...201122251676
behavioral changes in workers of the leaf-cutting ant atta sexdens rubropilosa induced by chemical components of eucalyptus maculata leaves.the response of atta sexdens rubropilosa forel workers to essential oils, epicuticular wax and hexane, dichloromethane, ethyl acetate, and methanol extracts of eucalyptus maculata was evaluated. hexane extracts of e. maculata interfered with the recognition mechanism among workers. the main active compounds identified from this plant were the sesquiterpenes elemol and beta-eudesmol. these compounds may be responsible for the resistance of this species to ant attack.200415586673
cuticular metals: quantification and mapping by complementary techniques.metal-replete cuticle was characterised by back-scattered electron imaging, secondary ion mass spectrometry, proton induced x-ray emission and sem-x-ray microanalysis. each technique was found to have singular advantages and limitations for localising and quantifying metal content. manganese and zinc were found coincident at the mandibular cutting edge of the leaf-cutting ant atta sexdens; these two metals were found in different zones within jaws of the ragworm, nereis virens; while only mangan ...19979778383
essential oil of aristolochia trilobata: synthesis, routes of exposure, acute toxicity, binary mixtures and behavioral effects on leaf-cutting ants.plants of the genus aristolochia have been frequently reported as important medicinal plants. despite their high bioactive potential, to date, there are no reports of their effects on leaf-cutting ants. therefore, the present study aimed to evaluate the insecticidal activity of the essential oil of aristolochia trilobata and its major components on atta sexdens and acromyrmex balzani, two species of leaf-cutting ants. the bioassays were performed regarding routes of exposure, acute toxicity, bin ...201728245600
reproductive ecology of phorid parasitoids in relation to the head size of leaf-cutting ants atta sexdens forel.the leaf-cutting ant atta sexdens forel (hymenoptera: formicidae) is one of the most damaging agricultural pests in the neotropics. management strategies predominantly rely on the use of general insecticides. what is needed are more species-specific and environmentally friendly options. parasitioids such as phorid flies (diptera: phoridae) may be one such option, but a greater understanding of the ecology of the flies and their ant hosts is essential to devise biological control strategies. here ...201627903323
pathogenic nature of syncephalastrum in atta sexdens rubropilosa fungus gardens.leaf-cutter ants are considered to be a major herbivore and agricultural pest in the neotropics. they are often controlled by environmentally persistent insecticides. biological control using pathogenic fungi is regarded as an alternative for the management of these insects. here, we assess whether the filamentous fungus syncephalastrum sp. is a pathogenic microorganism responsible for a characteristic disease in fungus gardens. we also characterise the damage caused by this fungus by evaluating ...201727539810
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