RESUMO
We investigated by scanning electron microscopy the morphology, distribution, and abundance of antennal sensilla of females Phlebotomus duboscqi sand fly, an important vector of zoonotic cutaneous leishmaniasis at Afrotropical region. Thirteen well-differentiated sensilla were identified, among six types of cuticular sensilla. The probable function of these sensillary types is discussed in relation to their external structure and distribution. Five sensillary types were classified as olfactory sensilla, as they have specific morphological characters of sensilla with this function. Number and distribution of sensilla significantly differed between antennal segments. The results of the present work, besides corroborating in the expansion of the morphological and ultrastructural knowledge of P. duboscqi, can foment future electrophysiological studies for the development of volatile semiochemicals, to be used as attractants in traps for monitoring and selective vector control of this sand fly.
Assuntos
Phlebotomus/ultraestrutura , Sensilas/ultraestrutura , Animais , Feminino , Phlebotomus/fisiologia , Sensilas/fisiologiaRESUMO
Theraphosid tarantulas are large spiders that bear dense hairy adhesive pads on the distal parts of their legs: scopula and claw tufts. These structures allow them to climb on vertical smooth surfaces and contribute to prey capture. While adult females and juveniles remain most of the time in their burrows, adult males actively walk searching for females during the reproductive period. Adhesion and locomotion thus play important roles in the ecology and reproduction of these animals. In this paper, we review the current state of the knowledge on adhesion and locomotion in tarantulas, focusing on functional and evolutionary morphology.
Assuntos
Extremidades/fisiologia , Locomoção/fisiologia , Sensilas/fisiologia , Aranhas/fisiologia , Animais , Extremidades/anatomia & histologia , Feminino , Masculino , Sensilas/anatomia & histologia , Aranhas/anatomia & histologiaRESUMO
The fourth instar larva and pupa of Dasyhelea flavifrons Guérin-Méneville are redescribed, illustrated, and photomicrographed using binocular, phase-contrast, and scanning electron microscopy. Comparisons with the American species of the grisea group were made. The immatures were collected by using a siphon bottle in tree-holes and from water collected in dead snail shells in Salta Province, Argentina, transported to the laboratory and there bred to the emergence of the adults. Details on larval habitats are given. These are the first records from Argentina and in gastrotelmata.
Assuntos
Ceratopogonidae/anatomia & histologia , Ceratopogonidae/fisiologia , Ecossistema , Larva/anatomia & histologia , Larva/fisiologia , Pupa/anatomia & histologia , Pupa/fisiologia , Animais , Argentina , Feminino , Masculino , Microscopia Eletrônica de Varredura , Sensilas/anatomia & histologia , Sensilas/fisiologia , Especificidade da EspécieRESUMO
Surazomus saturninoae sp. nov. is described from eastern Amazon. The male has a pentagonal flagellum, similar to those of three other species in the genus. These four species are herein gathered as the arboreus-group of Surazomus. We present a brief synopsis of chaetotaxy description in hubbardiines and several homology proposals for the flagellum of the species in the arboreus-group: the posterior lobes may be homologous to the lateral lobes of hubbardiine species with trilobed flagella; the setal brush with 4-5 setae on the posterior lobe may be composed of one Dl2 seta and enlarged lobular microsetae; the single, median posterior coupling pocket may be homologous to the pair of posterior pockets seen in other hubbardiines; the single, median anterior coupling pocket may be homologous to the pair of pockets on the anterior border of the flagellum seen in other hubbardiines. Based on the morphology of these pockets and the chelicerae within Surazomus, we discuss the anchoring mechanism during the mating march.
Assuntos
Aracnídeos/classificação , Aracnídeos/fisiologia , Flagelos/fisiologia , Reprodução , Sensilas/fisiologia , Distribuição Animal , Estruturas Animais/anatomia & histologia , Estruturas Animais/crescimento & desenvolvimento , Animais , Aracnídeos/anatomia & histologia , Feminino , Masculino , Sensilas/anatomia & histologiaRESUMO
The gustatory system of animals is involved in food quality assessment and controls the feeding decision of an individual confronted with a potential alimentary source. Triatomines are haematophagous insects that feed on vertebrate blood. Once they reach a potential host, they walk over the host skin searching for an adequate site to pierce. Then, they insert their stylets and take a first sampling gorge to decide whether food is acceptable. Our work reveals that the presence of bitter compounds inhibits the feeding behavior of these bugs. Firstly, triatomines decreased their feeding behavior if substrates spread with quinine or caffeine were detected by external receptors localized exclusively in the antennae. Morphological inspections along with electrophysiological recordings revealed the existence of four gustatory sensilla located in the tip of the antenna that respond to both bitter tastants. The absence of these bitter detectors by antennal ablation reversed the observed feeding inhibition evoked by bitter compounds. Secondly, once triatomines pumped the first volume of food with bitter compounds (quinine, caffeine, berberine, salicin), a decrease in their feeding behavior was observed. Morphological inspections revealed the existence of eight gustatory sensilla located in the pharynx that might be responsible for the internal bitter detection. Finally, we found that a brief pre-exposure to bitter compounds negatively modulates the motivation of bugs to feed on an appetitive solution. Results presented here highlight the relevance of bitter taste perception in the modulation of the feeding behavior of a blood-sucking insect.
Assuntos
Rhodnius/fisiologia , Sensilas/fisiologia , Paladar/fisiologia , Alcaloides , Animais , Antenas de Artrópodes/fisiologia , Comportamento Animal/efeitos dos fármacos , Comportamento Animal/fisiologia , Álcoois Benzílicos , Ingestão de Alimentos/efeitos dos fármacos , Fenômenos Eletrofisiológicos , Comportamento Alimentar/fisiologia , Glucosídeos , Inibição Psicológica , Larva/efeitos dos fármacos , Larva/fisiologia , Larva/ultraestrutura , Parasitos , Rhodnius/efeitos dos fármacos , Rhodnius/ultraestrutura , Sensilas/ultraestrutura , Paladar/efeitos dos fármacosRESUMO
The aim of this study, therefore, was to investigate the ultrastructure of gyrodactylid sensilla and to ascertain how these may be employed in the colonisation of new hosts using the Gyrodactylus gasterostei Gläser, 1974--Gasterosteus aculeatus L. model. As Gyrodactylus has no specific transmission stage in its life-cycle, movement between hosts must be achieved by strategies employed by the adult. This study suggests that certain sensilla, presented for the first time in Gyrodactylus gasterostei, may serve as chemoreceptors and mechanoreceptors and possible photoreceptors. The results of this study provide photographic data using scanning electron microscope (SEM) and transmission electron microscopy (TEM) concerning the sensory structures that are found on the tegument and in the sub-tegumental zone of G. gasterostei that infect 3-spine sticklebacks (Gasterosteus aculeatus L.). For this reason, it is vital to understand the factors underlying transmission to a new host, and a detailed, ultrastructural examination of the sensory structures that are used may improve current understanding of the receptors that Gyrodactylus species employ to interpret both their host and ambient environments. Such information may assist in the interpretation of transmission behaviors, particularly their responses to chemical or physical cues which gyrodactylids employ in host location during the transmission process.
Assuntos
Infecções por Cestoides/veterinária , Doenças dos Peixes/parasitologia , Platelmintos/ultraestrutura , Sensilas/ultraestrutura , Smegmamorpha/parasitologia , Animais , Infecções por Cestoides/parasitologia , Feminino , Masculino , Platelmintos/fisiologia , Sensilas/fisiologiaRESUMO
Several blood-feeding (hematophagous) insects are vectors of a number of diseases including dengue, Chagas disease and leishmaniasis which persistently affect public health throughout Latin America. The vectors of those diseases include mosquitoes, triatomine bugs and sandflies. As vector control is an efficient way to prevent these illnesses it is important to understand the sensory biology of those harmful insects. We study the physiology of the olfactory system of those insects and apply that knowledge on the development of methods to manipulate their behavior. Here we review some of the latest information on insect olfaction with emphasis on hematophagous insects. The insect olfactory sensory neurons are housed inside hair-like organs called sensilla which are mainly distributed on the antenna and mouthparts. The identity of many of the odor compounds that those neurons detect are already known in hematophagous insects. They include several constituents of host (vertebrate) odor, sex, aggregation and alarm pheromones, and compounds related to egg-deposition behavior. Recent work has contributed significant knowledge on how odor information is processed in the insect first odor-processing center in the brain, the antennal lobe. The quality, quantity, and temporal features of the odor stimuli are encoded by the neural networks of the antennal lobe. Information regarding odor mixtures is also encoded. While natural mixtures evoke strong responses, synthetic mixtures that deviate from their natural counterparts in terms of key constituents or proportions of those constituents evoke weaker responses. The processing of olfactory information is largely unexplored in hematophagous insects. However, many aspects of their olfactory behavior are known. As in other insects, responses to relevant single odor compounds are weak while natural mixtures evoke strong responses. Future challenges include studying how information about odor mixtures is processed in their brain. This could help develop highly attractive synthetic odor blends to lure them into traps.
Assuntos
Insetos/fisiologia , Condutos Olfatórios/anatomia & histologia , Condutos Olfatórios/fisiologia , Olfato/fisiologia , Animais , Antenas de Artrópodes/fisiologia , Sangue , Comportamento Alimentar , Odorantes , Sensilas/fisiologiaRESUMO
The sensilla of insects are integumental units that play a role as sensory structures and are crucial for the perception of stimuli and for communication. In this study, we compared the antennal sensilla of females (workers and queens), males (haploid (n) and diploid (2n)), and queen-like males (QLMs, resulting from 2n males after juvenile hormone (JH) treatment) in the stingless bee Melipona quadrifasciata. Images of the dorsal antenna surfaces were acquired using a scanning electron microscope. As reported for other hymenopterans, this species exhibits a heterogeneous sensillar distribution along the antennae. Thirteen different types of sensilla were found in the antennae of M. quadrifasciata: trichodea (subtypes I to VI), chaetica (subtypes I and II), placodea, basiconica, ampullacea, coeloconica, and coelocapitula. Sensilla trichodea I were the most abundant, followed by sensilla placodea, which might function in olfactory perception. Sensilla basiconica, sensilla chaetica I, sensilla coeloconica, and sensilla ampullacea were found exclusively in females. In terms of the composition and size of the sensilla, the antennae of QLMs most closely resemble those of the 2n male, although QLMs exhibit a queen phenotype. This study represents the first comparative analysis of the antennal sensilla of M. quadrifasciata. The differences found in the type and amount of sensilla between the castes and sexes are discussed based on the presumed sensillary functions.
Assuntos
Himenópteros , Sensilas/anatomia & histologia , Animais , Feminino , Masculino , Sensilas/fisiologia , OlfatoRESUMO
Phagostimulants are chemical compounds that stimulate feeding. Some tick species are known to have pores in their inner cheliceral digits, called pit sensillum (ps), which are involved in taste perception. This study investigated the existence of ps in chelicerae of Rhipicephalus sanguineus ticks by scanning electron microscopy (SEM) and their involvement in the perception of phagostimulatory substances, such as the salts potassium chloride and sodium chloride (KCl and NaCl), sugars (glucose, sucrose and fructose), purines (guanine and hypoxanthine), the nucleotide adenosine triphosphate (ATP) and the tripeptide reduced glutathione (GSH), as well as their combinations at different concentrations. By means of scanning electron microscopy, a ps was observed at the expected location. Using a single-sensillum recording technique, strong activity by R. sanguineus cheliceral sensilla in response to glucose, ATP, GSH and high concentrations of salts was recorded. The responses to ATP and to KCl at 1M were multicellular, while the responses to the other stimulant compounds were monocellular. Glucose and GSH stimulated different neurons. The taste response of R. sanguineus chelicerae seemed to be selective, given that substances that were not expected to participate in this tick's biology were not perceived.
Assuntos
Rhipicephalus sanguineus/fisiologia , Rhipicephalus sanguineus/ultraestrutura , Sensilas/fisiologia , Sensilas/ultraestrutura , Animais , Fenômenos Eletrofisiológicos , Feminino , Masculino , Microscopia Eletrônica de Varredura , Percepção GustatóriaRESUMO
Triatomines undergo morphological changes as an adaptive response to different habitats (wild, peridomestic, domestic, laboratory). The characterization of the antennal phenotype provides information on intraspecific variation caused by geographical origin and/or habitat. Triatoma patagonica Del Ponte, 1929 is known to occur in peridomiciles of rural areas in Argentina, where it also invades non-colonized dwellings. Here we describe and compare the antennal phenotype of T. patagonica in populations of different geographic origin, and explore possible modifications induced by laboratory rearing with the aim of investigating the range of phenotypic variation of the species for the first time. Sixty antennas of adult males and females of T. patagonica belonging to two peridomiciliary populations of different geographical origin were analyzed. Four types of sensilla were observed in three antennal segments, showing sexual dimorphism in the species. The multivariate analysis separated the populations of similar habitat (peridomicile) but different geographical origin, without showing differences between the peridomiciliary and laboratory populations of the same geographical origin. These results suggest phenotypic plasticity in T. patagonica, which would allow the species to adapt to a wide range of habitats without having a close association with a given host and its environment. The range of antennal phenotypic variation of T. patagonica would also be an indicator of its current stage of adaptation to the human environment.