RESUMO
The detection of magnetic fields by animals is known as magnetoreception. The ferromagnetic hypothesis explains magnetoreception assuming that magnetic nanoparticles are used as magnetic field transducers. Magnetite nanoparticles in the abdomen of Apis mellifera honeybees have been proposed in the literature as the magnetic field transducer. However, studies with ants and stingless bees have shown that the whole body of the insect contain magnetic material, and that the largest magnetization is in the antennae. The aim of the present study is to investigate the magnetization of all the body parts of honeybees as has been done with ants and stingless bees. To do that, the head without antennae, antennae, thorax, and abdomen obtained from Apis mellifera honeybees were analyzed using magnetometry and Ferromagnetic Resonance (FMR) techniques. The magnetometry and FMR measurements show the presence of magnetic material in all honeybee body parts. Our results present evidence of the presence of biomineralized magnetite nanoparticles in the honeybee abdomen and, for the first time, magnetite in the antennae. FMR measurements permit to identify the magnetite in the abdomen as biomineralized. As behavioral experiments reported in the literature have shown that the abdomen is involved in magnetoreception, new experimental approaches must be done to confirm or discard the involvement of the antennae in magnetoreception.
Assuntos
Abdome , Antenas de Artrópodes , Animais , Abelhas/fisiologia , Antenas de Artrópodes/fisiologia , Óxido Ferroso-Férrico/química , Óxido Ferroso-Férrico/metabolismo , Campos MagnéticosRESUMO
Chemoreception through odorant receptors (ORs), ionotropic receptors (IRs) and gustatory receptors (GRs) represents the functions of key proteins in the chemical ecology of insects. Recent studies have identified chemoreceptors in coleopterans, facilitating the evolutionary analysis of not only ORs but also IRs and GRs. Thus, Cerambycidae, Tenebrionidae and Curculionidae have received increased attention. However, knowledge of the chemoreceptors from Scarabaeidae is still limited, particularly for those that are sympatric. Considering the roles of chemoreceptors, this analysis could shed light on evolutionary processes in the context of sympatry. Therefore, the aim of this study was to identify and compare the repertoires of ORs, GRs and IRs between two sympatric scarab beetles, Hylamorpha elegans and Brachysternus prasinus. Here, construction of the antennal transcriptomes of both scarab beetle species and analyses of their phylogeny, molecular evolution and relative expression were performed. Thus, 119 new candidate chemoreceptors were identified for the first time, including 17 transcripts for B. prasinus (1 GR, 3 IRs and 13 ORs) and 102 for H. elegans (22 GRs, 14 IRs and 66 ORs). Orthologs between the two scarab beetle species were found, revealing specific expansions as well as absence in some clades. Purifying selection appears to have occurred on H. elegans and B. prasinus ORs. Further efforts will be focused on target identification to characterize kairomone and/or pheromone receptors.
Assuntos
Besouros , Receptores Odorantes , Gorgulhos , Animais , Transcriptoma , Simpatria , Perfilação da Expressão Gênica , Besouros/genética , Besouros/metabolismo , Gorgulhos/genética , Filogenia , Receptores Odorantes/genética , Receptores Odorantes/metabolismo , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Antenas de Artrópodes/metabolismoRESUMO
We describe here a new species in the genus Disersus Sharp, 1882 from the Otongachi Reserve in Ecuador. Disersus otongachi sp.nov. is externally similar to other representatives of the genus, however, this species can be clearly distinguished for significantly longer antennae and the unique shape of the male genitalia.
Assuntos
Besouros , Animais , Antenas de Artrópodes/anatomia & histologia , Besouros/anatomia & histologia , Besouros/classificação , Equador , Genitália Masculina/anatomia & histologia , Masculino , Especificidade da EspécieRESUMO
The study of insect semiochemicals, especially pheromones, is of fundamental importance for the development of strategies for controlling agricultural pests. In this study, volatile compounds involved in the communication between males and females of the fruit fly, Anastrepha obliqua (Diptera: Tephritidae), for mating purposes were characterized to develop attractant formulations for females of this species. Extracts containing volatile compounds released by males of A. obliqua were obtained by the dynamic headspace technique and analyzed by gas chromatography coupled with an electroantennographic detector (GC-EAD) and gas chromatography coupled with mass spectrometry (GC-MS). Twenty-one volatile compounds were identified in the aeration extracts of males. Five of them caused EAD responses from the antennae of females: 1-heptanol, linalool, (Z)-3-nonen-1-ol, (E,Z)-3,6-nonadien-1-ol, and (Z,E)-α-farnesene. Six synthetic mixtures of these compounds, including the five-component blend and all possible four-component blends, were formulated in a biopolymer and used in behavioral bioassays conducted in the laboratory arena with conspecific virgin females. One blend of 1-heptanol, linalool, (Z)-3-nonen-1-ol, and (Z,E)-α-farnesene attracted more females than the collection of volatiles from virgin males used as control. The other mixtures were as attractive to A. obliqua females as the control treatment. This study indicates potential for use of these compounds in monitoring and control strategies for this pest.
Assuntos
Monoterpenos Acíclicos/isolamento & purificação , Heptanol/isolamento & purificação , Sesquiterpenos/isolamento & purificação , Atrativos Sexuais/fisiologia , Tephritidae/fisiologia , Animais , Antenas de Artrópodes/fisiologia , Feminino , Cromatografia Gasosa-Espectrometria de Massas , Masculino , Atrativos Sexuais/química , Tephritidae/químicaRESUMO
Body and head lice are known to be exclusive ectoparasites of human hosts. Current genomic and transcriptomic data suggest that both louse types represent ecotypes of the same species. They exhibit morphological and physiological differences that probably arose from living in different biotopes. Sensory traits represent suitable candidates to be affected by environmental heterogeneity. Therefore, through scanning electron microscope studies, this study analysed and compared the sensory structures of both ecotypes' antennae. Seven types of sensory structures were identified in both ecotypes: bristles, tuft organs, pore organs, single pore and three morphotypes of sensilla basiconica. Notably, the single pore and the morphotypes of sensilla basiconica were described for the first time in the body louse antenna. This study's comparative analysis mainly revealed size differences across the sensory structures of the ecotypes. Bristles of the flagellomere 2 of the body louse antenna were longer than the head louse bristles. In addition, the pore organs of the head louse antenna presented a higher diameter than those of the body louse. The possible relevance of size differences regarding the biotopes exploited by the body louse and the head louse is discussed. Yet, physiological studies may help to fully understand the phenotypical differences of both ecotypes.
Assuntos
Antenas de Artrópodes/ultraestrutura , Ecótipo , Pediculus , Animais , Humanos , Microscopia Eletrônica de Varredura , Pediculus/anatomia & histologia , Pediculus/fisiologia , Pediculus/ultraestrutura , Sensilas/ultraestruturaRESUMO
The round-headed pine beetle Dendroctonus adjunctus, whose dispersion and colonization behaviors are linked to a communication system mediated by semiochemicals, is one of the five most critical primary pests in forest ecosystems in Mexico. This study provides the first head transcriptome analysis of D. adjunctus and the identification of the nonreceptor olfactory genes involved in the perception of odors. De novo assembly yielded 44,420 unigenes, and GO annotations were similar to those of antennal transcriptomes of other beetle species, which reflect metabolic processes related to smell and signal transduction. A total of 36 new transcripts of nonreceptor olfactory genes were identified, of which 27 encode OBPs, 7 encode CSPs, and 2 encode SNMP candidates, which were subsequently compared to homologous proteins from other bark beetles and Coleoptera species by searching for sequence motifs and performing phylogenetic analyses. Our study provides information on genes encoding nonreceptor proteins in D. adjunctus and broadens the knowledge of olfactory genes in Coleoptera and bark beetle species, and will help to understand colonization and aggregation behaviors for the development of tools that complement management strategies.
Assuntos
Besouros/genética , Receptores Odorantes/genética , Transcriptoma/genética , Gorgulhos/genética , Animais , Antenas de Artrópodes/metabolismo , Ecossistema , Perfilação da Expressão Gênica/métodos , Proteínas de Insetos/genética , Odorantes , Filogenia , Pinus , Transdução de Sinais/genética , Olfato/genéticaRESUMO
The yellow fever mosquito Aedes aegypti is a prolific vector of arboviral and filarial diseases that largely relies on its sense of smell to find humans. To facilitate in-depth analysis of the neural circuitry underlying Ae. aegypti olfactory-driven behaviors, we generated an updated in vitro atlas for the antennal lobe olfactory brain region of this disease vector using two independent neuronal staining methods. We performed morphological reconstructions with replicate fixed, dissected and stained brain samples from adult male and female Ae. aegypti of the LVPib12 genome reference strain and determined that the antennal lobe in both sexes is comprised of approximately 80 discrete glomeruli. Guided by landmark features in the antennal lobe, we found 63 of these glomeruli are stereotypically located in spatially invariant positions within these in vitro preparations. A posteriorly positioned, mediodorsal glomerulus denoted MD1 was identified as the largest spatially invariant glomerulus in the antennal lobe. Spatial organization of glomeruli in a recently field-derived strain of Ae. aegypti from Puerto Rico was conserved, despite differences in antennal lobe shape relative to the inbred LVPib12 strain. This model in vitro atlas will serve as a useful community resource to improve antennal lobe annotation and anatomically map projection patterns of neurons expressing target genes in this olfactory center. It will also facilitate the development of chemotopic maps of odor representation in the mosquito antennal lobe to decode the molecular and cellular basis of Ae. aegypti attraction to human scent and other chemosensory cues.
Assuntos
Antenas de Artrópodes/fisiologia , Rede Nervosa/fisiologia , Condutos Olfatórios/fisiologia , Neurônios Receptores Olfatórios/fisiologia , Olfato/fisiologia , Aedes/anatomia & histologia , Animais , Feminino , Masculino , Mosquitos Vetores/anatomia & histologia , Porto Rico , Transdução de SinaisRESUMO
Diverse mechanosensory neurons detect different mechanical forces that can impact animal behavior. Yet our understanding of the anatomical and physiological diversity of these neurons and the behaviors that they influence is limited. We previously discovered that grooming of the Drosophila melanogaster antennae is elicited by an antennal mechanosensory chordotonal organ, the Johnston's organ (JO) (Hampel et al., 2015). Here, we describe anatomically and physiologically distinct JO mechanosensory neuron subpopulations that each elicit antennal grooming. We show that the subpopulations project to different, discrete zones in the brain and differ in their responses to mechanical stimulation of the antennae. Although activation of each subpopulation elicits antennal grooming, distinct subpopulations also elicit the additional behaviors of wing flapping or backward locomotion. Our results provide a comprehensive description of the diversity of mechanosensory neurons in the JO, and reveal that distinct JO subpopulations can elicit both common and distinct behavioral responses.
Assuntos
Antenas de Artrópodes/fisiologia , Drosophila melanogaster/fisiologia , Asseio Animal/fisiologia , Mecanorreceptores/fisiologia , Neurônios/fisiologia , Órgãos dos Sentidos/fisiologia , Animais , Drosophila melanogaster/anatomia & histologia , Feminino , Masculino , Órgãos dos Sentidos/citologia , Órgãos dos Sentidos/inervaçãoRESUMO
Larvae of the burrowing water beetle family Noteridae are distributed worldwide and are often abundant in a broad range of aquatic habitats, playing an important role in structuring freshwater communities, yet they have remained among the most poorly studied groups of aquatic beetles. Studies on sensillar equipment of aquatic insect larvae are largely lacking, despite their potential use in phylogeny and biometric identification methods. In this article, the external morphology and distribution of sensilla on the head appendages of first instar larvae of selected genera of Noteridae were examined using scanning electron microscopy. Seven main types were distinguished based on their morphological structure: basiconica (3 subtypes), campaniformia (2 subtypes), chaetica (7 subtypes), coeloconica (6 subtypes), coniform complex (2 subtypes), placodea, and styloconica (3 subtypes). The apex of the labial palpus was found to be the most variable and informative region in regard to the number, relative position, and topology of sensilla. Fingerprint models were, therefore, generated for this region in each of the studied genera, allowing their identification.
Assuntos
Biometria , Besouros/anatomia & histologia , Besouros/classificação , Sensilas/anatomia & histologia , Animais , Antenas de Artrópodes/ultraestrutura , Besouros/ultraestrutura , Feminino , Cabeça , Larva/anatomia & histologia , Larva/ultraestrutura , Masculino , Filogenia , Sensilas/ultraestruturaRESUMO
The antennal sensilla and the antenna of females Nyssomyia intermedia, one of the main vectors of American cutaneous leishmaniasis, were studied by scanning electron microscopy. The main goal was to characterize the quantity, typology, and topography of the sensilla with particular attention to the olfactory types. The insects were captured in the city of Corte de Pedra, State of Bahia, Brazil, by CDC-type light traps and raised in a laboratory as a new colony. Fourteen well-differentiated sensilla were identified, among six cuticular types: trichoidea, campaniformia, squamiformia, basiconica, chaetica, and coeloconica. Of these, six sensilla were classified as olfactory sensilla due to their specific morphological features. Smaller noninnervated pilosities of microtrichiae type were also evidenced by covering all antennal segments. The antennal segments differ in shapes and sizes, and the amount and distribution of types and subtypes of sensilla. This study may foment future taxonomic and phylogenetic analysis for a better evolutionary understanding of the sand flies. Besides, it may assist the targeting of future electrophysiological studies by Single Sensillum Recording, and aim to develop alternative measures of monitoring and control of this vector.
Assuntos
Antenas de Artrópodes/ultraestrutura , Insetos Vetores/ultraestrutura , Psychodidae/ultraestrutura , Animais , Brasil , Feminino , Leishmaniose Cutânea , Microscopia Eletrônica de Varredura , Sensilas/ultraestruturaRESUMO
Sleep plays an essential role in both neural and energetic homeostasis of animals. Honey bees (Apis mellifera) manifest the sleep state as a reduction in muscle tone and antennal movements, which is susceptible to physical or chemical disturbances. This social insect is one of the most important pollinators in agricultural ecosystems, being exposed to a great variety of agrochemicals, which might affect its sleep behaviour. The intake of glyphosate (GLY), the herbicide most widely used worldwide, impairs learning, gustatory responsiveness and navigation in honey bees. In general, these cognitive abilities are linked with the amount and quality of sleep. Furthermore, it has been reported that animals exposed to sleep disturbances show impairments in both metabolism and memory consolidation. Consequently, we assessed the sleep pattern of bees fed with a sugar solution containing GLY (0, 25, 50 and 100 ng) by quantifying their antennal activity during the scotophase. We found that the ingestion of 50 ng of GLY decreased both antennal activity and sleep bout frequency. This sleep deepening after GLY intake could be explained as a consequence of the regenerative function of sleep and the metabolic stress induced by the herbicide.
Assuntos
Glicina/análogos & derivados , Herbicidas/administração & dosagem , Sono/efeitos dos fármacos , Administração Oral , Animais , Antenas de Artrópodes/efeitos dos fármacos , Abelhas , Glicina/administração & dosagem , GlifosatoRESUMO
The giant sugarcane borer Telchin licus (Drury, 1773) (Lepidoptera: Castniidae) is a day-flying moth pest of sugarcane, pineapples and bananas. To better understand the chemical communication in this species, we examined the morphology of its olfactory system and the chemical composition of its body parts. The ventral surface of the clubbed antennae of T. licus has six morphological types of sensilla: sensilla trichodea, basiconica, chaetica, squamiforma, coeloconica, and auricillica. The telescopic ovipositor shows no evidence of a sexual gland, or female-specific compounds. On the other hand, the midleg basitarsus of males releases (E,Z)-2,13-octadecadienol and (Z,E)-2,13-octadecadienol, which are electroantennographically active in both sexes. These compounds are known female sex pheromones in the Sesiidae family and are male-specific compounds in another castniid moth, although further investigations are necessary to elucidate their ecological role in the Castniidae family.
Assuntos
Mariposas/anatomia & histologia , Mariposas/fisiologia , Animais , Antenas de Artrópodes/anatomia & histologia , Antenas de Artrópodes/química , Antenas de Artrópodes/fisiologia , Antenas de Artrópodes/ultraestrutura , Feminino , Masculino , Mariposas/química , Mariposas/ultraestrutura , Oviposição , Saccharum/parasitologia , Atrativos Sexuais/análise , Atrativos Sexuais/metabolismoRESUMO
BACKGROUND: Rhodnius prolixus has become a model for revealing the molecular bases of insect sensory biology due to the publication of its genome and its well-characterized behavioural repertoire. Gene expression modulation underlies behaviour-triggering processes at peripheral and central levels. Still, the regulation of sensory-related gene transcription in sensory organs is poorly understood. Here we study the genetic bases of plasticity in antennal sensory function, using R. prolixus as an insect model. RESULTS: Antennal expression of neuromodulatory genes such as those coding for neuropeptides, neurohormones and their receptors was characterized in fifth instar larvae and female and male adults by means of RNA-Sequencing (RNA-Seq). New nuclear receptor and takeout gene sequences were identified for this species, as well as those of enzymes involved in the biosynthesis and processing of neuropeptides and biogenic amines. CONCLUSIONS: We report a broad repertoire of neuromodulatory and neuroendocrine-related genes expressed in the antennae of R. prolixus and suggest that they may serve as the local basis for modulation of sensory neuron physiology. Diverse neuropeptide precursor genes showed consistent expression in the antennae of all stages studied. Future studies should characterize the role of these modulatory components acting over antennal sensory processes to assess the relative contribution of peripheral and central regulatory systems on the plastic expression of insect behaviour.
Assuntos
Perfilação da Expressão Gênica/veterinária , Proteínas de Insetos/genética , Rhodnius/crescimento & desenvolvimento , Animais , Antenas de Artrópodes/química , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Larva , Masculino , Neuropeptídeos/genética , Neurotransmissores/genética , Filogenia , Receptores de Neuropeptídeos/genética , Receptores de Neurotransmissores/genética , Rhodnius/genética , Análise de Sequência de RNA/veterináriaRESUMO
Pyrethroids are synthetic insecticides that have a repellent action. This effect has been associated with an increase in the locomotor activity, which causes the avoidance of the insecticide-treated area (excito-repellency). In this work, we studied with behavior and electrophysiological recordings the occurrence of olfactory-mediated repellency caused by pyrethroids of different volatility in the German cockroach Blattella germanica (Linnaeus, 1767). Male cockroaches were spatially repelled when they were exposed to D-allethrin vapors and vapothrin vapors in a dose-dependent manner. No repellency was observed when insects were exposed to permethrin, a non-volatile pyrethroid. To confirm the role of olfaction in this phenomenon, we measured the electrical activity of the cockroaches' antennae in response to these insecticides. There was a significant increase in the electrical activity in response to D-allethrin and vapothrin, but no increase was observed in insects exposed to permethrin. Locomotor activity of cockroaches exposed to pyrethroids was measured in order to discard excito-repellency. No changes in locomotor activity were observed for any of the insecticides. Finally, we found that volatile pyrethroids in the vapor phase cause spatial repellency in cockroaches, being the first report of an olfactory-mediated repellency phenomenon caused by pyrethroids in cockroaches.
Assuntos
Baratas/fisiologia , Repelentes de Insetos , Piretrinas , Olfato , Animais , Antenas de Artrópodes/fisiologia , Fenômenos Eletrofisiológicos , Locomoção , Masculino , Compostos Orgânicos VoláteisRESUMO
After an insect herbivore has reached its host plant, contact cues from the leaf surface often determine host acceptance. We studied contact cues during oviposition behavior of a willow pest, the sawfly Nematus oligospilus (Hymenoptera: Tenthredinidae), a specialist feeder on Salix (Salicaceae) trees, and how it determines oviposition preference in lab and field conditions. We described the sequence of behaviors that lead to egg laying on the most and least preferred willow species. Then we studied the morphology of chemosensory structures present on the female antenna, cerci and ovipositor. Since phenolic glycosides (PGs) are the main secondary metabolites present in Salicaceae species, we investigated their role in host acceptance. We quantified these compounds in different willow species and correlated PG content with oviposition preference under lab and natural field conditions. We demonstrated a major role for contact cues in triggering N. oligospilus egg laying on the leaf surface of preferred willow genotypes. Firstly cues are sensed by antennae, determining to leave or stay on the leaf. After that, sensing is performed by abdominal cerci, which finally triggers egg laying. The lack of PGs in non-preferred species and the significant correlation observed between PGs, natural damage and oviposition preference suggest a role for these compounds in host selection. Our study suggests that in specialist feeders, secondary compounds normally acting as defenses can actually act as a susceptibility factor by triggering specific insect behavior for oviposition. These defensive compounds could be selected against to increase resistance.
Assuntos
Sinais (Psicologia) , Herbivoria , Himenópteros/fisiologia , Folhas de Planta/química , Salix/parasitologia , Animais , Antenas de Artrópodes/fisiologia , Antenas de Artrópodes/ultraestrutura , Células Quimiorreceptoras/fisiologia , Feminino , Florestas , Himenópteros/citologia , Microscopia Eletrônica de Varredura , Oviposição/fisiologia , Salix/química , Propriedades de SuperfícieRESUMO
This study aimed to identify ORs (odorant receptors) and Orco (odorant receptor coreceptor) genes in Sitophilus zeamais Motschulsky (Coleoptera: Curculionoidea), to explore the relative expression levels of these genes in different adult tissues and obtain information on highly expressed receptor proteins. Putative OR and Orco genes were identified from transcriptomic data previously obtained for S. zeamais using bioinformatics methods. Quantitative real-time PCR was used to compare the differences in expression in seven adult tissues (male antennae, female antennae, heads, thoraxes, abdomens, wings, and legs). The candidate OR and Orco gene sequences were analyzed, and the protein physicochemical properties were predicted. We identified 64 OR genes including the Orco gene. Forty-seven OR genes, including Orco, were over expressed in male or female antennae. Seventeen OR genes appeared to be expressed at elevated levels in male antennae. Twenty-nine genes were expressed at significantly elevated levels in female antennae. In total, 11 OR genes were selected for further sequence analysis. The selected proteins were structurally characterized, and bioinformatics analysis was performed. Overall, in this study, candidate ORs of S. zeamais have been identified for the first time, and these ORs could be molecular targets for interference in the insect olfactory system.
Assuntos
Besouros/genética , Proteínas de Insetos/genética , Receptores Odorantes/genética , Animais , Antenas de Artrópodes , Feminino , Masculino , Estrutura Terciária de Proteína , Reação em Cadeia da Polimerase em Tempo Real , TranscriptomaRESUMO
In the sensory system of insects, olfactory sensilla constitute important functional elements for discriminating odors. Therefore, we used light microscopy and scanning electron microscopy to investigate the morphology and distribution of sensilla in the antennae of Lobesia botrana (Denis & Schiffermüller). In addition, we studied the expression of the gene encoding for pheromone-binding protein 1 (LbotPBP1) by in situ hybridization. Lobesia botrana antennae are filiform and are subdivided into three segments: scape, pedicel, and flagellum. The number of flagellum and their overall length were significantly higher and longer in males than in females. Six morphological types of sensilla (trichodea, chaetica, coeloconica, auricillica, basiconica, and styloconica) were identified on the antennae of both sexes. Trichodea sensilla were the most abundant on the antennae of L. botrana, and three subtypes, discerned by their lengths, were observed. However, sensilla trichodea subtype III was only present in male antennae. Moreover, LbotPBP1 expression was restricted to this type of sensilla, thus confirming its olfactory role, specifically under the context of sexual pheromone perception.
Assuntos
Antenas de Artrópodes/anatomia & histologia , Proteínas de Transporte/metabolismo , Proteínas de Insetos/metabolismo , Mariposas , Feromônios/metabolismo , Sensilas/ultraestrutura , Animais , Antenas de Artrópodes/ultraestrutura , Feminino , Masculino , Microscopia Eletrônica de Varredura , OlfatoRESUMO
We analyze an ant navigation model based on Weber's law, where the ants move across a pheromone landscape sensing the area using two antennae. The key parameter of the model is the angle [Formula: see text] representing the span of the ant's sensing area. We show that when [Formula: see text] ants are able to follow (straight) pheromone trails proving that for initial conditions close to the trail, there exists a Lyapunov function that ensures ant trajectories converge on and follow the pheromone trail, with these solutions being locally asymptotically stable. Furthermore, we indicate that the features of the ant trajectories such as convergence speed or oscillation wave length are controlled by the angle [Formula: see text]. For [Formula: see text], we present numerical evidence that indicates that ants are unable to follow pheromone trails. We also assess our model by comparing it to previous experimental results, showing that the solutions' behavior falls into biologically meaningful ranges. Our work provides solid mathematical support for experimental studies where it was found that ant perception follows a Weber's law, by proving that such models lead to the desired robust and stable trail following.
Assuntos
Formigas/fisiologia , Modelos Biológicos , Animais , Antenas de Artrópodes/fisiologia , Comportamento Animal/fisiologia , Biologia Computacional , Comportamento Alimentar/fisiologia , Modelos Lineares , Locomoção/fisiologia , Conceitos Matemáticos , Feromônios/fisiologiaRESUMO
Floral scents attract pollinators to plant rewards; in nectarless flowers, pollen grains are the only reward. Thus, pollen not only fertilizes ovules, but also feeds pollinators. This dilemma is resolved by specialization of anthers (i.e., heteranthery): feeding anthers that feed pollinators and pollinating anthers for fertilization. We hypothesized that the chemical composition of floral volatiles differs between the two types of anther and influences pollination preference for feeding anthers. We used Solanum rostratum as a study model because its heterantherous flowers produce a floral scent that suggests a close association with their pollinators. The main aim of this study was to determine the chemical composition of the two types of anther and to investigate how they influence foraging behaviour of pollinators. To characterize this composition, we used solid phase microextraction and hexane extraction followed by gas chromatography-mass spectrometry. We registered 12 volatile compounds in S. rostratum floral extracts, mainly aromatic and sesquiterpene compounds. The proportion of these compounds differed between feeding and pollinating anthers. Some of these compounds were probably emitted by osmophores located in both anther types. Also, we used electroantennography to investigate Melipona solani antennal response to floral volatiles. The M. solani antennae are receptive to the highest floral extract dose tested. Finally, we conducted two behavioural bioassays to test bee attraction for each type of floral extract: a) multiple-choice in a feeding arena using M. solani and b) Y-olfactometer bioassay using Bombus impatiens. Both bee species preferred feeding anthers in bioassays. In conclusion, heteranthery involves chemical differentiation (i.e., proportion of volatiles compounds) in anther specialization that influences bee preference for feeding anthers over pollinating anthers.
Assuntos
Pólen/química , Solanum/química , Compostos Orgânicos Voláteis/análise , Animais , Antenas de Artrópodes/efeitos dos fármacos , Antenas de Artrópodes/fisiologia , Abelhas/fisiologia , Comportamento Animal/efeitos dos fármacos , Flores/química , Flores/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Pólen/metabolismo , Solanum/metabolismo , Microextração em Fase Sólida , Compostos Orgânicos Voláteis/isolamento & purificação , Compostos Orgânicos Voláteis/farmacologiaRESUMO
Lutzomyia migonei is incriminated as a vector of Leishmania braziliensis, the main causative agent of cutaneous leishmaniasis in Brazil. Recently, this phlebotomine sand fly species has been suggested as a vector for Leishmania infantum, which causes zoonotic visceral leishmaniasis. Considering the widespread distribution of Lu. migonei in South America, the existence of isolated populations has been hypothesized. Three Lu. migonei populations, two from north-eastern Brazil (Machados, Pernambuco State, and Baturité, Ceará State) and other from the south-eastern region (Niterói, Rio de Janeiro State) were analysed both morphologically and genetically. Though no significant morphological differences were found amongst the sand fly specimens analysed, discriminant analysis based on specific morphometric characters (i.e., length of wing, antennal segment 3 and coxite for males, and length of wing and antennal segment 3 for females), showed that specimens from Machados were closer to Baturité than to Niterói. The molecular analysis of cytochrome c oxidase subunit I gene sequences also supported this observation by the distinct separation of two monophyletic clades, grouping specimens from Machados and Baturité separately from those of Niterói. Our results suggest the existence of different populations within the distribution range of Lu. migonei. Whether these populations are reproductively isolated and/or present differences in terms of vector competence/capacity for L. braziliensis and L. infantum needs to be further investigated.