RESUMO
The objective of this study was to describe the histology and histochemistry of the integument covering the back and stinger of the freshwater stingray Potamotrygon rex, endemic to the Middle Upper Tocantins River. The species has a dark back and yellowish circular spots that extend to the tail, which has one to two stings located in the median portion of the tail. Through histological study it was observed that the epithelia of the back and stinger are composed of non-keratinized stratified pavement epithelial tissue, and are organized in three layers: basal, intermediate and superficial. The differences between the tissues are related to the cell types that compose them. The back is organized with epithelial cells, mucus cells, granulocyte cells and chromatophores. The mucus cells are distributed in different layers along the animal's back, influencing the thickness of the tissue. The tissue that covers the stinger is composed of epithelial cells, chromatophores and specialized cells in protein synthesis. In the histochemistry, the stinger epithelial cells were stained with Bromophenol Blue, especially those of the intermediate layer, which were called specialized cells. In the back the epithelial cells were stained with Bromophenol Blue, Alcian Blue and PAS, and the mucous cells with PAS. In both tissues the presence of protein reserves was detected, areas so called because they are stained strongly with Bromophenol Blue. The results show that the stinger presents activity directed to the production of proteins, and that the back is organized to produce different components, which constitute the cuticle that covers the animal's body.
O objetivo deste estudo foi descrever a histologia e histoquímica do tegumento que reveste o dorso e o ferrão da arraia de água doce Potamotrygon rex, endêmica do Médio Alto Tocantins. A espécie possui o dorso escuro e manchas circulares amareladas que se estendem até a cauda, que possui de um a dois ferrões localizados na porção mediana da cauda. Através do estudo histológico observou-se que os epitélios do dorso e do ferrão são compostos por tecido epitelial pavimentoso estratificado não queratinizado, e estão organizados em três camadas: basal, intermediária e superficial. As diferenças entre os tecidos estão relacionadas aos tipos de células que os compõem. O dorso é organizado com células epiteliais, células mucosas, células de granulócitos e cromatóforos. As células mucosas estão distribuídas em diferentes camadas ao longo do dorso do animal, influenciando na espessura do tecido. O tecido que reveste o ferrão é composto por células epiteliais, cromatóforos e células proteicas. Na histoquímica, as células epiteliais do ferrão foram coradas com Azul de Bromofenol, principalmente as da camada intermediária, que foram denominadas células proteicas. No dorso as células epiteliais foram coradas com Azul de Bromofenol, Azul Alcian e PAS, e as células mucosas com PAS. Em ambos os tecidos também foi detectada a presença de reservatórios de proteínas, áreas assim denominadas por estarem fortemente coradas com Azul de Bromofenol. Os resultados mostram que o ferrão apresenta atividade direcionada à produção de proteínas, e que o dorso se organiza para produzir diferentes componentes que constituem a cutícula que reveste o corpo do animal.
Assuntos
Rajidae/fisiologia , Tegumento Comum/fisiologiaRESUMO
In social species, the presence of several reproductive individuals can generate conflict. In social insects, as queen number increases, individual oviposition rate may decrease because of direct and indirect behavioural and/or chemical interactions. Understanding the factors that mediate differences in queen fecundity should provide insight into the regulation and maintenance of highly polygynous insect societies, such as those of the invasive Argentine ant (Linepithema humile). In this study, we investigated (1) whether differences in the oviposition rates of Argentine ant queens exposed to polygynous conditions could result from interactions among them; (2) whether such differences in fecundity stemmed from differences in worker attention; and (3) whether polygynous conditions affected the cuticular hydrocarbon profiles of queens (CHCs). We found that differences in queen fecundity and CHC profiles observed under polygynous conditions disappeared when queens were exposed to monogynous conditions, suggesting some form of reproductive inhibition may exist when queens cohabit. These differences did not seem to arise from variation in worker attention because more fecund queens were not more attractive to workers. Levels of some CHCs were higher in more fecund queens. These CHCs are associated with greater queen productivity and survival. Our findings indicate that such compounds could be multifunctional queen pheromones.
Assuntos
Formigas/fisiologia , Comportamento de Nidação/fisiologia , Animais , Análise Discriminante , Feminino , Fertilidade/fisiologia , Hierarquia Social , Hidrocarbonetos/metabolismo , Tegumento Comum/fisiologia , Ovário/fisiologia , Óvulo/fisiologia , Reprodução/fisiologiaRESUMO
Phosphine resistance is a worldwide issue threatening the grain industry. The cuticles of insects are covered with a layer of lipids, which protect insect bodies from the harmful effects of pesticides. The main components of the cuticular lipids are hydrocarbon compounds. In this research, phosphine-resistant and -susceptible strains of two main stored-grain insects, T. castaneum and R. dominica, were tested to determine the possible role of their cuticular hydrocarbons in phosphine resistance. Direct immersion solid-phase microextraction followed by gas chromatography-mass spectrometry (GC-MS) was applied to extract and analyze the cuticular hydrocarbons. The results showed significant differences between the resistant and susceptible strains regarding the cuticular hydrocarbons that were investigated. The resistant insects of both species contained higher amounts than the susceptible insects for the majority of the hydrocarbons, sixteen from cuticular extraction and nineteen from the homogenized body extraction for T. castaneum and eighteen from cuticular extraction and twenty-one from the homogenized body extraction for R. dominica. 3-methylnonacosane and 2-methylheptacosane had the highest significant difference between the susceptible and resistant strains of T. castaneum from the cuticle and the homogenized body, respectively. Unknown5 from the cuticle and 3-methylhentriacontane from the homogenized body recorded the highest significant differences in R. dominica. The higher hydrocarbon content is a key factor in eliminating phosphine from entering resistant insect bodies, acting as a barrier between insects and the surrounding phosphine environment.
Assuntos
Alcanos/isolamento & purificação , Besouros/efeitos dos fármacos , Resistência a Inseticidas/fisiologia , Inseticidas/farmacologia , Fosfinas/farmacologia , Tribolium/efeitos dos fármacos , Alcanos/química , Alcanos/classificação , Animais , Besouros/química , Besouros/fisiologia , Misturas Complexas/química , Grão Comestível/parasitologia , Cromatografia Gasosa-Espectrometria de Massas , Tegumento Comum/fisiologia , Microextração em Fase Sólida , Tribolium/química , Tribolium/fisiologia , Triticum/parasitologiaRESUMO
Fatty acid synthase is a multifunctional enzyme involved in the formation of fatty acids. Despite the role of fatty acids in cell signalling and energy metabolism, and as precursors to pheromones and hydrocarbons that waterproof the cuticle, the insect fatty acid synthases have been scarcely studied. Here we perform the molecular characterization of three fatty acid synthase genes (fatty acid synthase RPRC000123, RPRC000269 and RPRC002909) in the Chagas disease vector, Rhodnius prolixus. Gene expression screening by reverse transcription quantitative PCR showed that RPRC000123 and RPRC002909 are expressed almost exclusively in the integument tissue whilst RPRC000269 is mostly expressed in the fat body and also in several body organs. Phylogenetic analysis, together with gene expression results, showed that RPRC000269, RPRC002909 and RPRC000123 are orthologues of Drosophila melanogaster fatty acid synthase 1 (FASN1), FASN2 and FASN3 genes, respectively. After RNA interference-mediated knockdown of RPRC000123, insects died immediately after moulting to the next developmental stage. However, mortality was prevented by placing the insects under saturated humidity conditions, suggesting that dehydration might play a role in the insects' death. Lipid analyses in RPRC000123-silenced insects showed reduced amounts of integument fatty acids and methyl-branched hydrocarbons, compared to controls. These data support an important role for FASN3 in the biosynthesis of the precursors to hydrocarbons that waterproof the insect cuticle.
Assuntos
Ácido Graxo Sintases/genética , Proteínas de Insetos/genética , Água/metabolismo , Animais , Ácido Graxo Sintases/metabolismo , Proteínas de Insetos/metabolismo , Tegumento Comum/fisiologia , Ninfa/crescimento & desenvolvimento , Ninfa/fisiologia , Filogenia , Rhodnius , Perda Insensível de ÁguaRESUMO
Differences in the timing of exoskeleton melanization and sclerotization are evident when comparing eusocial and solitary bees. This cuticular maturation heterochrony may be associated with life style, considering that eusocial bees remain protected inside the nest for many days after emergence, while the solitary bees immediately start outside activities. To address this issue, we characterized gene expression using large-scale RNA sequencing (RNA-seq), and quantified cuticular hydrocarbon (CHC) through gas chromatography-mass spectrometry in comparative studies of the integument (cuticle plus its underlying epidermis) of two eusocial and a solitary bee species. In addition, we used transmission electron microscopy (TEM) for studying the developing cuticle of these and other three bee species also differing in life style. We found 13,200, 55,209 and 30,161 transcript types in the integument of the eusocial Apis mellifera and Frieseomelitta varia, and the solitary Centris analis, respectively. In general, structural cuticle proteins and chitin-related genes were upregulated in pharate-adults and newly-emerged bees whereas transcripts for odorant binding proteins, cytochrome P450 and antioxidant proteins were overrepresented in foragers. Consistent with our hypothesis, a distance correlation analysis based on the differentially expressed genes suggested delayed cuticle maturation in A. mellifera in comparison to the solitary bee. However, this was not confirmed in the comparison with F. varia. The expression profiles of 27 of 119 genes displaying functional attributes related to cuticle formation/differentiation were positively correlated between A. mellifera and F. varia, and negatively or non-correlated with C. analis, suggesting roles in cuticular maturation heterochrony. However, we also found transcript profiles positively correlated between each one of the eusocial species and C. analis. Gene co-expression networks greatly differed between the bee species, but we identified common gene interactions exclusively between the eusocial species. Except for F. varia, the TEM analysis is consistent with cuticle development timing adapted to the social or solitary life style. In support to our hypothesis, the absolute quantities of n-alkanes and unsaturated CHCs were significantly higher in foragers than in the earlier developmental phases of the eusocial bees, but did not discriminate newly-emerged from foragers in C. analis. By highlighting differences in integument gene expression, cuticle ultrastructure, and CHC profiles between eusocial and solitary bees, our data provided insights into the process of heterochronic cuticle maturation associated to the way of life.
Assuntos
Abelhas/genética , Epiderme/metabolismo , Epiderme/ultraestrutura , Hidrocarbonetos/análise , Proteínas de Insetos/genética , Tegumento Comum/fisiologia , Transcriptoma , Animais , Abelhas/crescimento & desenvolvimento , Feminino , Metamorfose BiológicaRESUMO
Facultative air-breathing fish can exchange respiratory gases using an air-breathing organ (ABO), such as the oral cavity of the integument, during environmental hypoxia. The goby Gobionellus oceanicus inhabits areas subject to environmental hypoxia; however, its ABO is unknown. To investigate the respiratory potential of G. oceanicus, the gill and integument surface area, diffusion capacity, and their diffusion barrier thickness were measured. Our results show that although gill surface area is smaller than observed in other facultative air-breathing fish, but it has all features necessary to perform aquatic gas exchange. Additionally the integument of the palate has a short diffusion barrier thickness and a large calculated O2 -diffusion capacity suggesting that it functions as the ABO.
Assuntos
Tegumento Comum/anatomia & histologia , Tegumento Comum/fisiologia , Perciformes/anatomia & histologia , Perciformes/fisiologia , Respiração , Nadadeiras de Animais/anatomia & histologia , Animais , Brânquias/anatomia & histologia , Brânquias/fisiologia , HipóxiaRESUMO
In this study cuticular hydrocarbons (CHCs) were characterized from wings of individual unmated males of different Anastrepha ludens (Loew) mass-reared strains of different ages (3 and 19-day-old): (a) a standard mass-reared colony (control), (b) a genetic sexing strain, (c) a selected strain, (d) a hybrid strain, and (e) wild males. We found that the hydrocarbon profiles in all males included two n-alkanes, five monomethyl alkanes, and two alkenes. CHCs ranged from C26 to C31 . The most prominent peaks were 2-methyloctacosane (2-Me-C28), n-nonacosene (C29:1), 2-methyltriacontane (2-Me-C30), and n-hentriacontene (C31:1). Significant variations in the CHC amounts of the mass-reared strains were observed from Day 9 and thereafter. Comparison of CHCs using multivariate and canonical analyses across ages and among mass-reared strains and wild males revealed qualitative and quantitative differences. The relative amounts of C29:1 and 2-Me-C30 were significantly higher across age groups in the mass-reared strains than those in the wild males. In contrast, amounts of n-nonacosane (C29) significantly increased in wild males as they aged. Through statistical analyses, we inferred that CHC amounts vary with age. Wild males differed significantly from the mass-reared strains in the amount of C29, and the genetic sexing strain Tap-7 had significantly higher values for 2-methylhexacosane (2-Me-C26). In contrast the selected and control strain differed from the other strains in amounts of C29:1 and 2-Me-C30. We suggest that differential profiles in hydrocarbon composition among the strains may be mainly due to environmental pressures.
Assuntos
Envelhecimento/fisiologia , Hidrocarbonetos/metabolismo , Tegumento Comum/fisiologia , Tephritidae/fisiologia , Animais , Hidrocarbonetos/química , Masculino , Tephritidae/classificação , Tephritidae/crescimento & desenvolvimentoRESUMO
Insect resistance to chemical insecticides is attributed to a combination of different mechanisms, such as metabolic resistance, knockdown resistance, and the cuticular resistance or penetration factor. The insect integument offers an efficient barrier against contact insecticides and its role as penetration factor has been previously reported; however, there is no information about its potential function in the metabolic resistance. Cytochrome P450 genes (CYP) are highly expressed in the fat body of several insects and thus play a key role in their metabolic resistance. Here, we describe new members that belong to the highly genome-wide expanded CYP3093A and CYP4EM subfamilies in the Chagas disease vectors Rhodnius prolixus and Triatoma infestans. We modeled the docking of deltamethrin in their active site and detected differences in some amino acids between both species that are critical for a correct interaction with the substrate. We also knocked down the two constitutively most expressed genes in the integument of resistant T. infestans nymphs (CYP3093A11 and CYP4EM10) in order to find clues on their participation in deltamethrin resistance. This is the first report on the role of the insect integument in detoxification events; although these two CYP genes do not fully explain the resistance observed in T. infestans.
Assuntos
Sistema Enzimático do Citocromo P-450/genética , Proteínas de Insetos/genética , Insetos Vetores/genética , Inseticidas/farmacocinética , Tegumento Comum/fisiologia , Nitrilas/farmacocinética , Piretrinas/farmacocinética , Triatoma/genética , Animais , Doença de Chagas/patologia , Doença de Chagas/prevenção & controle , Doença de Chagas/transmissão , Sistema Enzimático do Citocromo P-450/metabolismo , Genes de Insetos/genética , Inativação Metabólica/genética , Proteínas de Insetos/metabolismo , Insetos Vetores/metabolismo , Insetos Vetores/parasitologia , Resistência a Inseticidas/genética , Inseticidas/química , Simulação de Acoplamento Molecular , Nitrilas/química , Ninfa , Filogenia , Piretrinas/química , Rhodnius/genética , Rhodnius/metabolismo , Rhodnius/parasitologia , Triatoma/metabolismo , Triatoma/parasitologia , Trypanosoma cruzi/patogenicidadeRESUMO
The larvae of the two distantly related nonsocial bees Ericrocis lata (Apidae) and Hesperapis (Carinapis) rhodocerata (Melittidae), which develop mostly under arid desert areas of North America, and that differ in that they either spin (E. lata) or do not spin (H. rhodocerata) protective cocoons before entering diapause, produce transparent films that cover the larval integument. To understand the nature of these films, their responses to topochemical tests and their characteristics when examined with fluorescence and high-performance polarization microscopy and microspectroscopy were studied. A positive staining by Sudan black B, birefringence of negative sign, and a Fourier transform-infrared (FT-IR) spectrum typical of lipids were detected for the integument covering of both species. The FT-IR signature, particularly, suggests a wax chemical composition for these lipid coverings, resembling the waxes that are used as construction materials in the honey cells produced by social bees. Considering the arid environmental conditions under which these larvae develop, we hypothesize that their covering films may have evolved as protection against water depletion. This hypothesis seems especially appropriate for H. rhodocerata larvae, which are capable of undergoing a long diapause period in the absence of a protective cocoon.
Assuntos
Abelhas/fisiologia , Diapausa/fisiologia , Tegumento Comum/fisiologia , Microscopia de Polarização/métodos , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , AnimaisRESUMO
Several studies searching for methods to control Rhipicephalus sanguineus s.l., (dog tick) infestations have been developed aiming to minimize the damages caused by these ectoparasites to the hosts and the environment, which is harmed by the indiscriminate use of toxic acaricide products. In this scenario, neem oil has been used as a natural alternative against ticks, once this chemical has repellent properties and interferes in the growth regulation of these ectoparasites, inhibiting ecdysis. The present study evaluated the effects of azadirachtin-enriched neem oil on the integument of semi-engorged R.sanguineus s.l., females through morphohistological techniques. The results showed the occurrence of significant morphological and histochemical alterations, mainly in the females exposed to higher concentrations, which demonstrates the dose-dependent action of the chemical. A decrease in the cuticle thickness was observed, as well as a modification in the distribution of the epithelial cells, which displayed pyknotic and fragmented nuclei, and intensely vacuolated cytoplasm, indicating that these cells would be undergoing death processes. These morphological alterations observed in the integument of the females exposed to the azadirachtin-enriched neem oil encourage the use of this chemical as a strategy to control these ectoparasites.
Assuntos
Acaricidas/farmacologia , Azadirachta/química , Glicerídeos/farmacologia , Limoninas/farmacologia , Rhipicephalus sanguineus/efeitos dos fármacos , Terpenos/farmacologia , Acaricidas/análise , Animais , Feminino , Glicerídeos/análise , Tegumento Comum/fisiologia , Limoninas/análise , Rhipicephalus sanguineus/fisiologia , Terpenos/análiseRESUMO
The integument of insects and other arthropods is composed of an inner basal lamina coated by the epidermis, which secretes the bulk of the outer integument layer, the cuticle. The genome sequencing of several insect species has allowed predicting classes of proteins integrating the cuticle. However, only a small proportion of them, as well as other proteins in the integumentary system, have been validated. Using two-dimensional gel electrophoresis coupled with mass spectrometry, we identified 45 different proteins in a total of 112 selected gel spots derived from thoracic integument samples of developing honeybee workers, including 14 cuticular proteins (AmelCPR 3, AmelCPR 12, AmelCPR 16, AmelCPR 27, apidermin 2, apidermin 3, endocuticle structural glycoprotein SgAbd-8-like, LOC100577363, LOC408365, LOC413679, LOC725454, LOC100576916, LOC725838, and peritrophin 3-C analogous). Gene ontology functional analysis revealed that the higher proportions of the identified proteins have molecular functions related to catalytic and structural molecule activities, are involved in metabolic biological processes, and pertain to the protein class of structural or cytoskeletal proteins and hydrolases. It is noteworthy that 26.7% of the identified proteins, including five cuticular proteins, were revealed as protein species resulting from allelic isoforms or derived from posttranslational modifications. Also, 66.7% of the identified cuticular proteins were expressed in more than one developmental phase, thus indicating that they are part of the larval, pupal, and adult cuticle. Our data provide experimental support for predicted honeybee gene products and new information on proteins expressed in the developing integument.
Assuntos
Abelhas/genética , Expressão Gênica , Proteínas de Insetos/genética , Animais , Abelhas/crescimento & desenvolvimento , Abelhas/metabolismo , Eletroforese em Gel Bidimensional , Proteínas de Insetos/metabolismo , Tegumento Comum/fisiologia , Larva/genética , Larva/crescimento & desenvolvimento , Larva/metabolismo , Pupa/genética , Pupa/crescimento & desenvolvimento , Pupa/metabolismo , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por MatrizRESUMO
The presence of denticles in the external surface, oral cavity, fins, and clasper of Elasmobranchii has been widely reported. These structures, called body denticles, may be observed on the body surface of sharks. Dermal and oral denticles are made up by a basal plate that is embedded in the dermis, forming a peduncle that grows from the base to the crown. These denticles may protect the skin against abrasion, and improve hydrodynamics and gill arches function. Rhizoprionodon lalandii is a widely distributed and very common species in Brazilian coastal areas. The aims of this study was to compare the morphology of oral and body denticles of R. lalandii to understand the implications of these structures in the behavior of these animals. Morphological analysis showed that there are differences between dermal and oral denticles, which are related to their role in different body regions. Body denticles have three cusps, and well-defined crests and ridges, and literature data suggest that suggest that hydrodynamics is their main function. Most of the oral denticles have only one cusp, and their morphology and distribution showed that their main functions are preparing food to be swallowed and protecting the oral cavity against abrasion.
Assuntos
Tegumento Comum/fisiologia , Tubarões/anatomia & histologia , Tubarões/fisiologia , Animais , Brasil , Tegumento Comum/anatomia & histologia , MicroscopiaRESUMO
The cuticular chemical composition plays a significant role in the recognition of nest mates in social insects, thus functioning as a chemical signature of the colony. The structure of cuticular chemicals is subject to interference from genetic and exogenous factors, including diet. In this study, various colonies of the Ectatomma brunneum ant were removed from their natural environment and housed in a laboratory to monitor the response of the cuticular chemical composition to dietary changes. Analyses were performed using gas chromatography and Fourier transform infrared photoacoustic spectroscopy, which has not been previously used for this type of analysis. The results indicate that this method is useful for analyzing biological and natural systems. We observed changes in the chemical signature with food traces in the first 30 days under feed control. Therefore, genetic information may not be the only criterion that can be used to describe the chemical signature of a species; environmental variations also influence recognition signals. Furthermore, these results reinforce the reliability of the Fourier transform infrared photoacoustic spectroscopy method.
Assuntos
Formigas/química , Dieta , Tegumento Comum/fisiologia , Técnicas Fotoacústicas , Animais , Cromatografia Gasosa , Análise Discriminante , Ionização de Chama , Hidrocarbonetos/análise , Espectroscopia de Infravermelho com Transformada de Fourier , VibraçãoRESUMO
Larvae of tortoise beetles are postulated to have fecal shields as the main defensive strategy against predators. Such a device protects beetles both physically and chemically. In order to examine how larvae Chelymorpha reimoseri are protected against predatory ants, which frequently visit extrafloral nectaries in their host plant, the morning glory Ipomoea carnea, we conducted anti-predation bioassays with live 5th instars. In the field, larvae in contact with ants had survival between 40 and 73 %, independently of shield presence. In the laboratory, when exposed to Camponotus crassus, larvae with shields had significantly higher survival (85 %) than those without shields (64 %). In both scenarios, larval survival was significantly higher when compared with palatable Spodoptera frugiperda larvae, as the latter were all consumed. We also observed that when C. reimoseri larvae showed no movement, the ants walked on them without attacking. We hypothesized that if the larval integument has a pattern of cuticular compounds (CCs) similar to that of its host plant, larvae would be rendered chemically camouflaged. In the field and laboratory, the freeze-dried palatable larvae of S. frugiperda treated with CCs of 5th instar C. reimoseri and left on I. carnea leaves were significantly less removed by ants than controls without these compounds. We also found a similarity of approximately 50 % between the CCs in C. reimoseri larvae and I. carnea host leaves. Both findings provide evidence in support of the hypothesis that chemical camouflage plays an important role in larval defense, which is reported for the first time in an ectophagous leaf beetle larva.
Assuntos
Formigas/fisiologia , Besouros/fisiologia , Cadeia Alimentar , Comportamento Predatório , Animais , Brasil , Galinhas/fisiologia , Besouros/química , Besouros/crescimento & desenvolvimento , Fezes/química , Cromatografia Gasosa-Espectrometria de Massas , Tegumento Comum/fisiologia , Ipomoea/química , Larva/química , Larva/fisiologia , Folhas de Planta/química , Spodoptera/fisiologiaRESUMO
During evolution, the cuticle surface of insects acquired functions in communication, such as inter- and intra-specific recognition, identification of gender, physiological state, and fertility. In eusocial bees, the information in the cuticular surface is important not only to discriminate nestmates from non-nestmates but also to identify an individual's class, life phase or task. A comparative study of the cuticular surface chemical profile of workers of Scaptotrigona postica in different phases of life, i.e., newly emerged workers (NE), brood comb area workers (CA), and forager workers (FO) was undertaken by gas chromatography linked to mass spectrometry. Multivariate statistical analysis was performed to verify how workers are grouped according to their chemical profile and to determine which compounds are responsible for separating them into groups. The cuticle surface of workers contains mainly hydrocarbons and a small amount of oxygenated compounds. Multivariate statistical analysis showed qualitative and quantitative variation in relation to the life phases/tasks performed, and all groups were distinct. The most abundant compound found in NE and CA was n-heptacosane, while in FO, it was (Z)-9-heptacosene. The compounds that differentiate NE from other groups are n-tricosane and n-hexacosane. A (Z)-X-octacosene and n-nonacosane are the chemicals that distinguish CA from NE and FO, while 11- and 13-methylpentacosane, (Z)-X-hexacosene, and (Z)-9-heptacosene characterize FO as distinct from NE and CA. The probable function of alkenes is nestmate recognition, mainly in FO. The results show that the cuticle surfaces of workers are characteristic of the phase of life/task performed by workers, allowing intra-colonial recognition.
Assuntos
Abelhas/fisiologia , Sinais (Psicologia) , Hidrocarbonetos/metabolismo , Comportamento de Nidação , Animais , Brasil , Cromatografia Gasosa-Espectrometria de Massas , Tegumento Comum/fisiologia , Reconhecimento Psicológico , Ceras/químicaRESUMO
Triatoma infestans Klug (Hemiptera: Reduviidae) populations were sampled in various localities throughout most of the species' geographic range of distribution in Argentina, Bolivia, Paraguay and Peru. In order to contribute to understanding of the diversity and population structure of this major vector of Chagas' disease, cuticular hydrocarbon (CHC) profiles were analysed by capillary gas chromatography and variations evaluated by statistical methods of classification and ordination. High levels of intrapopulation variation were detected, along with low levels of variability among populations. Based on relative amounts of the major odd-numbered straight-chain hydrocarbons n-C27 to n-C33, two hydrocarbon phenotypes were evident, unequally distributed along the species' geographic range. Analysis of CHC patterns showed that T. infestans populations segregate into two major groups consisting of an Andean group, which comprises specimens from Peru and most parts of Bolivia, and a non-Andean group, which includes all specimens from Argentina and Paraguay, together with those from Tarija (Bolivia). Pyrethroid-resistant and -susceptible specimens were differentiated based on relative amounts of some straight and monomethyl-branched hydrocarbon components.
Assuntos
Hidrocarbonetos/metabolismo , Insetos Vetores/classificação , Insetos Vetores/fisiologia , Triatoma/classificação , Triatoma/fisiologia , Animais , Doença de Chagas/transmissão , Doença de Chagas/veterinária , Cromatografia Gasosa , Análise Discriminante , Feminino , Humanos , Insetos Vetores/genética , Resistência a Inseticidas , Tegumento Comum/fisiologia , Masculino , Filogenia , Dinâmica Populacional , Análise de Componente Principal , Piretrinas/farmacologia , América do Sul , Triatoma/genéticaRESUMO
The most conspicuous ants in all of tropical America are those that belong to the tribe Attini which cultivate fungus. The objective of the present study is to verify the alterations that occur in the cuticle of the worker larvae from Myrmicocrypta, Mycetarotes and Trachymyrmex with the purpose of trying to establish the degree of this association. Attine ants from the Atta genus were used as a control group. The analysis of histological sections showed results about the distribution of the cells and tissues on the epidermis of A. sexdens rubropilosa ant larvae and Mycetarotes parallelus, Trachymyrmex fuscus and Myrmicocrypta sp. A cuticle covering the ants was observed in the larvae of all the species, and this is formed by a simple cubic epithelium, whose cells possibly change its shape to prismatic, depending on their secretory activity. Just under this epithelium large adipose cells with reserve granules in their cytoplasm were found. The presence of a space filled by granulose and acellular material was also observed, indicating that the larvae were in a molt period. The presence of fungal hyphae is observed both on the external side of the basal attine larvae as well as emitting projections to the interior of the cuticle reaching the epithelium and the adipocyte cells. Data obtained in the present study demonstrated that the fungus deposited on the surface of immature ants from attine basal species maintain a close relationship with them, once the fungus hyphae have the ability to disorganize the cuticle lamellas, penetrating the interior of the insect cells through the emission of prolongations transporting the cuticle and epithelium barriers and making substances exchanges between larvae and fungus.
Assuntos
Fungos/fisiologia , Himenópteros/microbiologia , Himenópteros/fisiologia , Simbiose , Animais , Epitélio/microbiologia , Epitélio/fisiologia , Hifas/fisiologia , Tegumento Comum/microbiologia , Tegumento Comum/fisiologia , Larva/microbiologia , Larva/fisiologiaRESUMO
Triatoma dimidiata Latreille is a major vector of Chagas disease with an extensive geographic distribution from Central Mexico, through Central America, to northern South America. As a result of its variability in phenetic and genetic characters, disagreement concerning its taxonomic status has been raised. In this study, the cuticular hydrocarbon pattern of T. dimidiata populations from Mexico, Belize, Guatemala, Honduras, Costa Rica, and Colombia was analyzed by capillary gas chromatography coupled to mass spectrometry; linear discriminant analysis was used to help elucidate population structure. Vector populations segregated into five distinct groups; specimens from Yucatan Peninsula, together with those from Central Mexico, Central America, and Colombia corresponded to different T. dimidiata subspecies, a putative different species comprising insects from Belize, together with an isolated population collected at bat caves in Guatemala. The analysis revalidates the earlier division of T dimidiata into three subspecies, T. d. maculipennis, T. d. dimidiata, and T. d. capitata; and an additional subspecies and a distinct species are proposed.
Assuntos
Hidrocarbonetos/metabolismo , Tegumento Comum/fisiologia , Triatoma/classificação , Triatoma/fisiologia , Animais , Feminino , Hidrocarbonetos/química , Masculino , Filogenia , Especificidade da Espécie , Triatoma/genéticaRESUMO
We studied the effect of the entomopathogenic fungus Beauveria bassiana strain GHA on a) colony development of the beetles Tribolium castaneum (Herbst) and Ulomoides dermestoides (Fairmaire) (Coleoptera: Tenebrionidae) under laboratory conditions; and 2) the volatile blend released by both beetles, containing defensive pheromones, by using the solid phase microextraction technique. Colony development of both species was strongly altered 3 mo after treatment with B. bassiana, showing a significant reduction in progeny of 37.5% for T. castaneum and 50.0% for U. dermestoides. We also showed that the volatiles released by T. castaneum diminished close to 20% compared with those of healthy beetles, whereas in U. dermestoides secretions dramatically dropped to 5%, 7 d after immersion in 1 x 10(9) conidia per ml. These results suggest that after infection events take place, fungus-induced diminished secretion of the defensive pheromones may be a physiologic clue for behavioral changes in infected beetles.
Assuntos
Beauveria/fisiologia , Besouros/microbiologia , Animais , Comportamento Animal , Tegumento Comum/fisiologia , Especificidade da EspécieRESUMO
Triatominae bugs experience changes in the mechanical properties of their cuticle prior to feeding. This process-plasticization-allows a rapid stretching of the unsclerotized abdominal cuticle of triatominae larvae and it is evoked by sensory inputs related to feeding. We tested: (a) whether the cuticle recovers its original mechanical properties after plasticization, (b) whether repeated stimulation would be able to evoke recurrent plasticization along the same larval instar, (c) the temporal course of recovering cuticular stiffness. We injected Ringer solution into the body cavity of the bugs at constant pressure, using the injection rate (ml/min) as a measure of the cuticle extensibility. To trigger plasticization, individuals were allowed to feed on blood from an artificial feeder at 32+/-2 degrees C. After plasticization occurred, the abdominal cuticle gradually recovered its original mechanical properties. Bugs were capable of plasticizing for a second time when repeatedly stimulated. The effects of plasticization vanished between 1 and 2 h after stimulation. Although one full meal could suffice to accomplish moult in other Triatomine species, Triatoma infestans is able to feed repeatedly during a single larval instar. Accordingly to this, their cuticle recovers stiffness in some hours and becomes able to respond repeatedly to sensory inputs associated with feeding.