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1.
Ecotoxicol Environ Saf ; 208: 111622, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33396142

RESUMO

The continuous growth in global population since the beginning of the 20th century result in the necessity of food and energy provision favoring the intensive use of agricultural products such as pesticides. Although pesticides are important to prevent losses in the conventional chemically based agriculture, they frequently present side effects, which goes against agricultural production. The use of pesticides cause direct and indirect effects to soil organisms unbalancing essential soil processes (e.g. primary production, organic matter decomposition, nutrient cycling). Under tropical conditions, very little is known regarding the effects of pesticides to terrestrial organisms. Hence, the aim of the present study was to assess the ecotoxicological effects of the herbicide DMA® 806 BR (active ingredient: 2,4-D) and the insecticide Regent® 800 WG (active ingredient: fipronil), on terrestrial plant species (the dicot Raphanus sativus var. acanthioformis and the monocot Allium cepa), and soil invertebrates (the collembolan Folsomia candida and the enchytraeid Enchytraeus crypticus), using natural (NS) and artificial soils (TAS). For both pesticides, negative effects on non-target species were observed at concentrations lower than the doses recommended to prevent pests in sugarcane fields. For both soils, the dicot species was the most affected by the herbicide (R. sativus > A. cepa > F. candida > E. crypticus) and the collembolan species was the most affected by the insecticide (F. candida > E. crypticus = R. sativus = A. cepa). Although the order of the organisms' sensitivity for both pesticides was the same in both soils, results showed that the extent of the effects was soil dependent. Considering the ecologically relevant concentrations tested, and their severe effects to non-target organisms, it may be concluded that the use of fipronil and 2,4-D under recommended conditions may pose a risk to the terrestrial environment.


Assuntos
Ácido 2,4-Diclorofenoxiacético/toxicidade , Praguicidas/toxicidade , Pirazóis/toxicidade , Saccharum/fisiologia , Poluentes do Solo/análise , Agricultura , Animais , Artrópodes/efeitos dos fármacos , Artrópodes/fisiologia , Ecotoxicologia , Inseticidas/toxicidade , Oligoquetos/efeitos dos fármacos , Oligoquetos/fisiologia , Solo/química
2.
Toxicon ; 188: 11-15, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33039367

RESUMO

Vipers include approximately 300 species and usually feed on vertebrates, but over 30 species of them occasionally eat centipedes. Centipedes have been also known to occur in stomach contents of a Japanese pit viper, mamushi, Gloydius blomhoffii. Toxicity of the venom of mamushi to small mammals has been well studied, but there is no information concerning its toxicity to arthropods. Here, we studied the toxicity of the raw venom to the red-headed centipede, Scolopendra subspinipes mutilans, by comparing with the toxicity to two other common prey animals, a house mouse, Mus musclus, and a pond frog, Pelophylax nigromaculatus. The lethal doses for mice weighing around 21.5 g and frogs weighing around 3.78 g were less than 5 µl (equivalent to ca. 0.23 and 1.32 µl/g, respectively), which presumably corresponds to an approximate dose of mamushi's one envenomation. On the other hand, centipedes weighing around 1.86 g needed 10-36 µl of venom to die (16.0 µl/g on average). This result suggests that the centipedes are much more resistant to the venom than other prey animals, and it is difficult for mamushi to kill or incapacitate centipedes by the venom of a single envenomation.


Assuntos
Agkistrodon , Venenos de Crotalídeos/toxicidade , Sequência de Aminoácidos , Animais , Artrópodes/fisiologia , Crotalinae , Transcriptoma
3.
PLoS One ; 15(5): e0232835, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32384101

RESUMO

Many plant species harbor communities of symbionts that release nutrients used by their host plants. However, the importance of these nutrients to plant growth and reproductive effort is not well understood. Here, we evaluate the relationship between the communities that colonize pitcher plant phytotelmata and the pitcher plants' vegetative growth and flower production to better understand the symbiotic role played by phytotelma communities. We focus on the mountain variety purple pitcher plant (Sarracenia purpurea var. montana), which occurs in small and isolated populations in Western North Carolina. We found that greater symbiont community diversity is associated with higher flower production the following season. We then examined geographic variation in communities and found that smaller plant populations supported less diverse symbiont communities. We relate our observations to patterns of community diversity predicted by community ecology theory.


Assuntos
Artrópodes/fisiologia , Biota/fisiologia , Sarraceniaceae/crescimento & desenvolvimento , Simbiose/fisiologia , Animais , Biodiversidade , Chironomidae/crescimento & desenvolvimento , Chironomidae/metabolismo , Copépodes/metabolismo , Culicidae/metabolismo , Flores/crescimento & desenvolvimento , Larva , Ácaros/metabolismo , Ciclo do Nitrogênio , Dispersão Vegetal , Folhas de Planta/crescimento & desenvolvimento , Reprodução , Sarraceniaceae/metabolismo
4.
Proc Natl Acad Sci U S A ; 117(22): 11865-11874, 2020 06 02.
Artigo em Inglês | MEDLINE | ID: mdl-32444484

RESUMO

Striated muscle contraction involves sliding of actin thin filaments along myosin thick filaments, controlled by calcium through thin filament activation. In relaxed muscle, the two heads of myosin interact with each other on the filament surface to form the interacting-heads motif (IHM). A key question is how both heads are released from the surface to approach actin and produce force. We used time-resolved synchrotron X-ray diffraction to study tarantula muscle before and after tetani. The patterns showed that the IHM is present in live relaxed muscle. Tetanic contraction produced only a very small backbone elongation, implying that mechanosensing-proposed in vertebrate muscle-is not of primary importance in tarantula. Rather, thick filament activation results from increases in myosin phosphorylation that release a fraction of heads to produce force, with the remainder staying in the ordered IHM configuration. After the tetanus, the released heads slowly recover toward the resting, helically ordered state. During this time the released heads remain close to actin and can quickly rebind, enhancing the force produced by posttetanic twitches, structurally explaining posttetanic potentiation. Taken together, these results suggest that, in addition to stretch activation in insects, two other mechanisms for thick filament activation have evolved to disrupt the interactions that establish the relaxed helices of IHMs: one in invertebrates, by either regulatory light-chain phosphorylation (as in arthropods) or Ca2+-binding (in mollusks, lacking phosphorylation), and another in vertebrates, by mechanosensing.


Assuntos
Músculo Estriado/fisiologia , Miosinas/metabolismo , Fosforilação/fisiologia , Citoesqueleto de Actina/química , Citoesqueleto de Actina/metabolismo , Animais , Artrópodes/fisiologia , Evolução Molecular , Invertebrados/fisiologia , Modelos Moleculares , Contração Muscular , Relaxamento Muscular , Miosinas/química , Estrutura Secundária de Proteína , Aranhas/fisiologia , Vertebrados/fisiologia
5.
PLoS One ; 15(4): e0231471, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32348341

RESUMO

Multivariate geometric designs for mixture experiments and response surface methodology (RSM) were tested as a means of optimizing plant mixtures to support generalist predatory arthropods. The mixture design included 14 treatment groups, each comprised of six planters and having a proportion of 0.00, 0.17, 0.33, 0.66, or 1.00 of each plant species. The response variable was the frequency of predators trapped on sticky card traps placed in each group and replaced 2 times per week. The following plant species were used: Spring 2017: Euphorbia milii, E. heterophylla, and Phaseolus lunatus; Summer 2017: E. milii, Fagopyrum esculentum, and Chamaecrista fasciculata; and, Summer 2018: E. milii, F. esculentum, and Portulaca umbraticola. Predator occurrence was influenced by: 1) Linear mixture effects, which indicated that predator occurrence was driven by the amount of a single plant species in the mixture; or, 2) Nonlinear blending effects, which indicated that the plant mixture itself had emergent properties that contributed to predator occurrence. Predator abundance was highest in the Spring 2017 experiment and both linear mixture effects and nonlinear blending effects were observed. Predator occurrence decreased in subsequent experiments, which were conducted in the warmer summer months. In both Summer experiments, only linear mixture effects were observed, indicating that predator occurrence was driven by the amount of a single plant species in the test mixtures: Euphorbia milii in 2017 and Portulaca umbraticola in 2018. The results showed that not only did the species composition of a plant mixture drive predator occurrence but that proportionality of species contributed to the outcome as well. This suggests that, when formulating a plant mixture to aid in conservation biological control consideration should be given to the proportion of each plant species included in the mixture. RSM can be an important tool for achieving the goal of optimizing mixtures of plants for conservation biological control.


Assuntos
Artrópodes/fisiologia , Comportamento Predatório/fisiologia , Animais , Comportamento Alimentar/fisiologia , Plantas , Estações do Ano
6.
Proc Natl Acad Sci U S A ; 117(16): 8966-8972, 2020 04 21.
Artigo em Inglês | MEDLINE | ID: mdl-32253305

RESUMO

Identifying marine or freshwater fossils that belong to the stem groups of the major terrestrial arthropod radiations is a longstanding challenge. Molecular dating and fossils of their pancrustacean sister group predict that myriapods originated in the Cambrian, much earlier than their oldest known fossils, but uncertainty about stem group Myriapoda confounds efforts to resolve the timing of the group's terrestrialization. Among a small set of candidates for membership in the stem group of Myriapoda, the Cambrian to Triassic euthycarcinoids have repeatedly been singled out. The only known Devonian euthycarcinoid, Heterocrania rhyniensis from the Rhynie and Windyfield cherts hot spring complex in Scotland, reveals details of head structures that constrain the evolutionary position of euthycarcinoids. The head capsule houses an anterior cuticular tentorium, a feature uniquely shared by myriapods and hexapods. Confocal microscopy recovers myriapod-like characters of the preoral chamber, such as a prominent hypopharynx supported by tentorial bars and superlinguae between the mandibles and hypopharynx, reinforcing an alliance between euthycarcinoids and myriapods recovered in recent phylogenetic analysis. The Cambrian occurrence of the earliest euthycarcinoids supplies the oldest compelling evidence for an aquatic stem group for either Myriapoda or Hexapoda, previously a lacuna in the body fossil record of these otherwise terrestrial lineages until the Silurian and Devonian, respectively. The trace fossil record of euthycarcinoids in the Cambrian and Ordovician reveals amphibious locomotion in tidal environments and fills a gap between molecular estimates for myriapod origins in the Cambrian and a post-Ordovician crown group fossil record.


Assuntos
Artrópodes/fisiologia , Evolução Molecular , Fósseis , Especiação Genética , Distribuição Animal , Animais , Água Doce , Filogenia , Água do Mar , Fatores de Tempo
7.
Sci Rep ; 10(1): 4431, 2020 03 10.
Artigo em Inglês | MEDLINE | ID: mdl-32157122

RESUMO

Characteristics of host species can alter how other, interacting species assemble into communities by acting as ecological filters. Pitchers of tropical pitcher plants (Nepenthes) host diverse communities of aquatic arthropods and microbes in nature. This plant genus exhibits considerable interspecific diversity in morphology and physiology; for example, different species can actively control the pH of their pitcher fluids and some species produce viscoelastic fluids. Our study investigated the extent to which Nepenthes species differentially regulate pitcher fluid traits under common garden conditions, and the effects that these trait differences had on their associated communities. Sixteen species of Nepenthes were reared together in the controlled environment of a glasshouse using commonly-sourced pH 6.5 water. We analyzed their bacterial and eukaryotic communities using metabarcoding techniques, and found that different plant species differentially altered fluid pH, viscosity, and color, and these had strong effects on the community structure of their microbiota. Nepenthes species can therefore act as ecological filters, cultivating distinctive microbial communities despite similar external conditions, and blurring the conceptual line between biotic and abiotic filters.


Assuntos
Artrópodes/fisiologia , Bactérias/isolamento & purificação , Bactérias/metabolismo , Biodiversidade , Microambiente Celular , Ecossistema , Magnoliopsida/fisiologia , Animais , Artrópodes/microbiologia , Bactérias/classificação , Magnoliopsida/microbiologia , Microbiota , Viscosidade
8.
Sci Rep ; 10(1): 5129, 2020 03 20.
Artigo em Inglês | MEDLINE | ID: mdl-32198412

RESUMO

Thylacocephalans are enigmatic arthropods with an erratic Palaeozoic and Mesozoic fossil record. In many of the few localities where they occur, they are quite abundant. This also holds true for the Famennian Thylacocephalan Layer in the Maider (eastern Anti-Atlas of Morocco), a small epicontinental basin hosting some strata with taphonomic properties of a conservation deposit yielding exceptionally preserved gnathostomes and non-vertebrates. In a thin argillaceous interval in the earliest middle Famennian, thylacocephalans occur in such great numbers that they became eponyms of this unit. Therein, we discovered a new taxon of thylacocephalans, Concavicaris submarinus sp. nov., which represent the oldest records of thylacocephalans from Africa. In the CT-imagery, the holotype of Concavicaris submarinus sp. nov. revealed anatomical details including its eyes, appendages and other soft parts. Sedimentary facies and faunal composition of the Thylacocephalan Layer suggest that these animals populated the water column above the low-oxygen sea floor. Thus, thylacocephalans likely represented an important component of the diet of chondrichthyans and placoderms, which are quite common as well. The abundance of thylacocephalans in other conservation deposits like the Cleveland Shale (USA) and the Gogo Formation (Australia) underline their pivotal role in Late Devonian pelagic food webs.


Assuntos
Artrópodes/anatomia & histologia , Artrópodes/classificação , Fósseis/anatomia & histologia , Animais , Artrópodes/fisiologia , Evolução Biológica , Olho Composto de Artrópodes/anatomia & histologia , Cadeia Alimentar , Marrocos , Paleontologia/métodos
9.
Ecotoxicol Environ Saf ; 194: 110446, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32171122

RESUMO

Pesticides can affect all receiving compartments, especially soils, and their fate and effects may be enhanced by temperature, increasing their risk to ecological functions of soils. In Brazil, the most widely used pesticides are the insecticide Kraft 36 EC® (a.s. abamectin) and the fungicide Score 250 EC® (a.s. difenoconazole), which are commonly used in strawberry, often simultaneously as a mixture. The aim of this study was to evaluate the toxicity of realistic environmental applications, single and in mixtures, for both pesticides to the springtail Folsomia candida and the plant species Allium cepa (onion) and Lycopersicum esculentum (tomato). Mesocosms filled with Brazilian natural soil (lattosolo) were dosed with water (control), Kraft (10.8 g a.s/ha), Score (20 g.a.s/ha) and Kraft + Score (10.8 + 20 g a.s./ha). The applications were repeated every 7 days, during 18 days of experiment, and simulating rainfall twice a week. Collembola reproduction tests were conducted with soils from the first (day 1) and last day (day 18) of experiment for each treatment. Plant toxicity tests were carried out in the experimental units. The experiments were run at 23 °C and 33 °C. Kraft, alone and in the binary mixture, showed high toxicity to the springtails in soils from both days 1 and 18, especially at 23 °C where it caused 100% mortality. Score however, was not toxic to the springtails. Plant growth was reduced by Score, but responses varied depending on temperature. This study indicates a high environmental risk of the insecticide Kraft, particularly at lower temperatures (23 °C), and an influence of temperature on pesticide fate and effects.


Assuntos
Dioxolanos/toxicidade , Ivermectina/análogos & derivados , Poluentes do Solo/toxicidade , Triazóis/toxicidade , Animais , Artrópodes/fisiologia , Brasil , Exposição Ambiental , Fungicidas Industriais , Inseticidas/toxicidade , Ivermectina/toxicidade , Praguicidas/toxicidade , Solo , Temperatura , Testes de Toxicidade
10.
Sci Rep ; 10(1): 3047, 2020 02 20.
Artigo em Inglês | MEDLINE | ID: mdl-32080305

RESUMO

The springtail, Megaphorura arctica, is freeze-avoiding and survives sub-zero temperatures by cryoprotective dehydration. At the onset of dehydration there is some supercooling of body fluids, and the danger of inoculative freezing, which would be lethal. To see if the springtails are protected by antifreeze proteins in this pre-equilibrium phase, we examined extracts from cold-acclimated M. arctica and recorded over 3 °C of freezing point depression. Proteins responsible for this antifreeze activity were isolated by ice affinity. They comprise isoforms ranging from 6.5 to 16.9 kDa, with an amino acid composition dominated by glycine (>35 mol%). Tryptic peptide sequences were used to identify the mRNA sequence coding for the smallest isoform. This antifreeze protein sequence has high similarity to one characterized in Hypogastrura harveyi, from a different springtail order. If these two antifreeze proteins are true homologs, we suggest their origin dates back to the Permian glaciations some 300 million years ago.


Assuntos
Proteínas Anticongelantes/metabolismo , Artrópodes/fisiologia , Crioprotetores/metabolismo , Desidratação/metabolismo , Congelamento , Sequência de Aminoácidos , Animais , Proteínas Anticongelantes/química , Cristalização , DNA Complementar/genética , Glicina/metabolismo , Modelos Moleculares , Isoformas de Proteínas/metabolismo
11.
Arthropod Struct Dev ; 54: 100913, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32000010

RESUMO

Mate choice, copulation, genital morphology, and sperm storage are not very well understood in millipedes. The use of three-dimensional x-ray computed tomography (µCT) provides new morphological data regarding millipede reproductive systems in both the female and male, including chitinous sclerites and membranes, muscles, glands, oviducts, and sperm conduits. Here we present a complete integrated account of the morphology and function of the female genital organs in the family Polydesmidae (Diplopoda: Polydesmida) using µCT, UV fluorescence imaging, and scanning electron microscopy. These data allow us to consider competing hypotheses regarding millipede vulva formation. We additionally present the morphology of copulatory interface in Pseudopolydesmus Attems, 1898 using images of a mating pair in copula and by simulating the interface of the organs using 3D models from µCT, allowing us to tentatively identify a lock-and-key-like mechanism. Finally, we use µCT to reveal the topology of the seminal canal in the gonopod of male Pseudopolydesmus, a topic that has remained unresolved for nearly 80 years.


Assuntos
Artrópodes/anatomia & histologia , Artrópodes/fisiologia , Copulação/fisiologia , Animais , Artrópodes/ultraestrutura , Feminino , Genitália Feminina/anatomia & histologia , Genitália Feminina/ultraestrutura , Genitália Masculina/anatomia & histologia , Genitália Masculina/ultraestrutura , Masculino , Microscopia Eletrônica de Varredura , Imagem Óptica , Microtomografia por Raio-X
12.
PLoS One ; 15(1): e0226966, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31940408

RESUMO

An integrative approach employing molecular, morphological and geographical data were applied to species delimitation among Deuteraphorura congeners occupying caves of the Western Carpathian Mts. A new species of Deuteraphorura from the Western Carpathians is described. D. muranensis sp. nov. belongs among species with 4 pso at the hind margin of the head and possesses highly troglomorphic features. It is conspicuous with its distinctly elongated claws and long, hair-like body chaetae. The status of the new species was confirmed by DNA barcoding based on the mitochondrial COI marker. Populations of D. kratochvili (Nosek, 1963), the most widespread species, were studied in detail. Both ABGD and PTP analyses brought results congruent with geography, i.e. the molecular and geographic distance of the populations were positively correlated. However, some molecular separation based on pairwise distance and the number of substitutions was indicated within two of the studied populations. Despite the indistinct morphological differences, the tested populations were well isolated both geographically and genetically, which indicates that each studied population may represent a cryptic species. The troglomorphy of cave Collembola at the northernmost border of the distribution of cave-adapted species in the Europe is discussed. It is clear that the level of troglomorphy is closely associated with conditions of the microhabitat occupied by the individual subterranean species. The results of our study enhance the importance of the Western Carpathians regarding the diversity pattern of obligate cave species in Europe.


Assuntos
Artrópodes/anatomia & histologia , Artrópodes/classificação , Cavernas , Adaptação Fisiológica , Animais , Artrópodes/genética , Artrópodes/fisiologia , Ecossistema , Complexo IV da Cadeia de Transporte de Elétrons/genética , Europa (Continente) , Feminino , Masculino , Eslováquia
13.
PLoS One ; 15(1): e0227706, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31931512

RESUMO

Grazing exclusion may lead to biodiversity loss and homogenization of naturally heterogeneous and species-rich grassland ecosystems, and these effects may cascade to higher trophic levels and ecosystem properties. Although grazing exclusion has been studied elsewhere, the consequences of alleviating the disturbance regime in grassland ecosystems remain unclear. In this paper, we present results of the first five years of an experiment in native grasslands of southern Brazil. Using a randomized block experimental design, we examined the effects of three grazing treatments on plant and arthropod communities: (i) deferred grazing (i.e., intermittent grazing), (ii) grazing exclusion and (iii) a control under traditional continuous grazing, which were applied to 70 x 70 m experimental plots, in six regionally distributed blocks. We evaluated plant community responses regarding taxonomic and functional diversity (life-forms) in separate spatial components: alpha (1 x 1 m subplots), beta, and gamma (70 x 70 m plots), as well as the cascading effects on arthropod high-taxa. By estimating effect sizes (treatments vs. control) by bootstrap resampling, both deferred grazing and grazing exclusion mostly increased vegetation height, plant biomass and standing dead biomass. The effect of grazing exclusion on plant taxonomic diversity was negative. Conversely, deferred grazing increased plant taxonomic diversity, but both treatments reduced plant functional diversity. Reduced grazing pressure in both treatments promoted the break of dominance by prostrate species, followed by fast homogenization of vegetation structure towards dominance of ligneous and erect species. These changes in the plant community led to increases in high-taxa richness and abundance of vegetation-dwelling arthropod groups under both treatments, but had no detectable effects on epigeic arthropods. Our results indicate that decision-making regarding the conservation of southern Brazil grasslands should include both intensive and alleviated levels of grazing management, but not complete grazing exclusion, to maximize conservation results when considering plant and arthropod communities.


Assuntos
Artrópodes/fisiologia , Herbivoria , Poaceae/fisiologia , Animais , Artrópodes/classificação , Biodiversidade , Biomassa , Brasil , Conservação dos Recursos Naturais , Ecossistema , Pradaria , Poaceae/classificação
14.
Artigo em Inglês | MEDLINE | ID: mdl-31816427

RESUMO

Volatile monoterpenes are emitted in large quantities to both air and soil by many plant species. While studies have addressed effects of monoterpenes on aboveground invertebrates, we have much poorer understanding of the possible effects of monoterpenes on soil invertebrates. Monoterpenes play a protective role in some plant species during heat and water stress, and therefore may provide similar protection against abiotic stress to soil invertebrates. The aim of the present study was to investigate the effects of the common monoterpene, α-pinene, on the soil living springtail, Folsomia candida (Collembola; Isotomidae). We hypothesized that exposure to α-pinene would lower the transition temperature of membranes, and thereby improve cold tolerance. Controlled exposure to α-pinene, which is a volatile liquid at room temperature, was made possible by passive dosing through the air-phase using a lipid donor. This lipid-based passive dosing approach also allows linking observed effects to concentrations in membrane when equilibrium is achieved. Equilibrium membrane concentrations above 116 mmol kg-1 caused springtails to become comatose, and coma recovery time was proportional to exposure concentration. Alpha-pinene delayed time to first egg laying, while the number of eggs laid and hatchability was unaffected. Springtails exposed to α-pinene showed increased survival of cold shock (-6 °C, 2 h), but no effects on heat (34 °C, 2 h) or drought tolerance (98.2% relative humidity, 7d) were observed. The present study has demonstrated that α-pinene has direct toxic effects to F. candida, but on the other hand can improve their cold tolerance considerably at membrane concentrations above 87 mmol kg-1.


Assuntos
Artrópodes/fisiologia , Monoterpenos Bicíclicos/metabolismo , Resposta ao Choque Frio , Resposta ao Choque Térmico , Osmorregulação , Animais , Reprodução
15.
Sci Rep ; 9(1): 18288, 2019 12 02.
Artigo em Inglês | MEDLINE | ID: mdl-31792255

RESUMO

Amphibious animals adapt their body coordination to compensate for changing substrate properties as they transition between terrestrial and aquatic environments. Using behavioural experiments and mathematical modelling of the amphibious centipede Scolopendra subspinipes mutilans, we reveal an interplay between descending command (brain), local pattern generation, and sensory feedback that controls the leg and body motion during swimming and walking. The elongated and segmented centipede body exhibits a gradual transition in the locomotor patterns as the animal crosses between land and water. Changing environmental conditions elicit a mechano-sensory feedback mechanism, inducing a gait change at the local segment level. The body segments operating downstream of a severed nerve cord (no descending control) can generate walking with mechano-sensory inputs alone while swimming behaviour is not recovered. Integrating the descending control for swimming initiation with the sensory feedback control for walking in a mathematical model successfully generates the adaptive behaviour of centipede locomotion, capturing the possible mechanism for flexible motor control in animals.


Assuntos
Adaptação Fisiológica/fisiologia , Artrópodes/fisiologia , Retroalimentação Sensorial/fisiologia , Locomoção/fisiologia , Rede Nervosa/fisiologia , Natação/fisiologia , Animais , Modelos Teóricos , Caminhada
16.
Sci Rep ; 9(1): 19339, 2019 12 18.
Artigo em Inglês | MEDLINE | ID: mdl-31852943

RESUMO

Large sea-going passenger vessels can pose a high biosecurity risk. The risk posed by marine species is well documented, but rarely the risk posed by terrestrial arthropods. We conducted the longest running, most extensive monitoring program of terrestrial arthropods undertaken on board a passenger vessel. Surveillance was conducted over a 19-month period on a large passenger (cruise) vessel that originated in the Baltic Sea (Estonia). The vessel was used as an accommodation facility to house workers at Barrow Island (Australia) for 15 months, during which 73,061 terrestrial arthropods (222 species - four non-indigenous (NIS) to Australia) were collected and identified on board. Detection of Tribolium destructor Uytt., a high-risk NIS to Australia, triggered an eradication effort on the vessel. This effort totalled more than 13,700 human hours and included strict biosecurity protocols to ensure that this and other non-indigenous species (NIS) were not spread from the vessel to Barrow Island or mainland Australia. Our data demonstrate that despite the difficulties of biosecurity on large vessels, stringent protocols can stop NIS spreading from vessels, even where vessel-wide eradication is not possible. We highlight the difficulties associated with detecting and eradicating NIS on large vessels and provide the first detailed list of species that inhabit a vessel of this kind.


Assuntos
Artrópodes/fisiologia , Navios , Animais , Austrália , Estônia , Geografia , Ilhas , Oceanos e Mares , Análise de Regressão , Risco , Especificidade da Espécie
18.
BMC Evol Biol ; 19(1): 213, 2019 11 21.
Artigo em Inglês | MEDLINE | ID: mdl-31752661

RESUMO

BACKGROUND: Dispersal is essential for terrestrial organisms living in disjunct habitats and constitutes a significant challenge for the evolution of wingless taxa. Springtails (Collembola), the sister-group of all insects (with Diplura), are reported since the Lower Devonian and are thought to have originally been subterranean. The order Symphypleona is reported since the early Cretaceous with genera distributed on every continent. This distribution implies an ability to disperse over oceans, however symphypleonan Collembola have never been reported in marine water contrary to other springtail orders. Despite being highly widespread, modern springtails are rarely reported in any kind of biotic association. Interestingly, the fossil record has provided occasional occurrences of Symphypleona attached by the antennae onto the bodies of larger arthropods. RESULTS: Here, we document the case of a ~ 16 Ma old fossil association: a winged termite and ant displaying not some, but 25 springtails attached or in close proximity to the body. The collembola exhibit rare features for fossils, reflecting their courtship and phoretic behaviours. By observing the modes of attachment of springtails on different arthropods, the sex representation and ratios in springtail antennal anatomies in new and previously reported cases, we infer a likely mechanism for dispersal in Symphypleona. By revealing hidden evidence of modern springtail associations with other invertebrates such as ants and termites, new compelling assemblages of fossil springtails, and the drastic increase of eusocial insects' abundance during the Cenozoic (ants/termites comprising more than a third of insects in Miocene amber), we stress that attachment on winged castes of ants and termites may have been a mechanism for the worldwide dispersal of this significant springtail lineage. Moreover, by comparing the general constraints applying to the other wingless soil-dwelling arthropods known to disperse through phoresy, we suggest biases in the collection and observation of phoretic Symphypleona related to their reflexive detachment and infer that this behaviour continues today. CONCLUSIONS: The specific case of tree resin entrapment represents the (so far) only condition uncovering the phoretic dispersal mechanism of springtails - one of the oldest terrestrial arthropod lineages living today.


Assuntos
Artrópodes/anatomia & histologia , Artrópodes/fisiologia , Fósseis , Âmbar , Animais , Formigas , Artrópodes/classificação , Evolução Biológica , Ecossistema , Isópteros , Masculino , Solo
19.
Results Probl Cell Differ ; 68: 419-454, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31598866

RESUMO

Regeneration has fascinated both scientists and non-scientists for centuries. Many organisms can regenerate, and arthropod limbs are no exception although their ability to regenerate is a product shaped by natural and sexual selection. Recent studies have begun to uncover cellular and molecular processes underlying limb regeneration in several arthropod species. Here we argue that an evo-devo approach to the study of arthropod limb regeneration is needed to understand aspects of limb regeneration that are conserved and divergent. In particular, we argue that limbs of different species are comprised of cells at distinct stages of differentiation at the time of limb loss and therefore provide insights into regeneration involving both stem cell-like cells/precursor cells and differentiated cells. In addition, we review recent studies that demonstrate how limb regeneration impacts the development of the whole organism and argue that studies on the link between local tissue damage and the rest of the body should provide insights into the integrative nature of development. Molecular studies on limb regeneration are only beginning to take off, but comparative studies on the mechanisms of limb regeneration across various taxa should not only yield interesting insights into development but also answer how this remarkable ability evolved across arthropods and beyond.


Assuntos
Artrópodes/citologia , Artrópodes/fisiologia , Evolução Biológica , Extremidades/fisiologia , Regeneração/fisiologia , Animais , Diferenciação Celular
20.
Sci Rep ; 9(1): 14941, 2019 10 17.
Artigo em Inglês | MEDLINE | ID: mdl-31624280

RESUMO

Interactions and coordination between conspecific individuals have produced a remarkable variety of collective behaviours. This co-operation occurs in vertebrate and invertebrate animals and is well expressed in the group flight of birds, fish shoals and highly organized activities of social insects. How individuals interact and why they co-operate to constitute group-level patterns has been extensively studied in extant animals through a variety mechanistic, functional and theoretical approaches. Although collective and social behaviour evolved through natural selection over millions of years, its origin and early history has remained largely unknown. In-situ monospecific linear clusters of trilobite arthropods from the lower Ordovician (ca 480 Ma) of Morocco are interpreted here as resulting either from a collective behaviour triggered by hydrodynamic cues in which mechanical stimulation detected by motion and touch sensors may have played a major role, or from a possible seasonal reproduction behaviour leading to the migration of sexually mature conspecifics to spawning grounds, possibly driven by chemical attraction (e.g. pheromones). This study confirms that collective behaviour has a very ancient origin and probably developed throughout the Cambrian-Ordovician interval, at the same time as the first animal radiation events.


Assuntos
Artrópodes/fisiologia , Evolução Biológica , Comportamento Cooperativo , Animais , Fósseis , Marrocos
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