Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 7.914
Filtrar
1.
PLoS Biol ; 18(8): e3000814, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32797039

RESUMO

Plasmid-mediated horizontal gene transfer of antibiotic resistance and virulence in pathogenic bacteria underlies a major public health issue. Understanding how, in the absence of antibiotic-mediated selection, plasmid-bearing cells avoid being outnumbered by plasmid-free cells is key to developing counterstrategies. Here, we quantified the induction of the plasmidial sex pheromone pathway of Enterococcus faecalis to show that the integration of the stimulatory (mate-sensing) and inhibitory (self-sensing) signaling modules from the pCF10 conjugative plasmid provides a precise measure of the recipient-to-donor ratio, agnostic to variations in population size. Such ratiometric control of conjugation favors vertical plasmid transfer under low mating likelihood and allows activation of conjugation functions only under high mating likelihood. We further show that this strategy constitutes a cost-effective investment into mating effort because overstimulation produces unproductive self-aggregation and growth rate reduction. A mathematical model suggests that ratiometric control of conjugation increases plasmid fitness and predicts a robust long-term, stable coexistence of donors and recipients. Our results demonstrate how population-level parameters can control transfer of antibiotic resistance in bacteria, opening the door for biotic control strategies.


Assuntos
Proteínas de Bactérias/genética , Resistência Microbiana a Medicamentos/genética , Enterococcus faecalis/genética , Transferência Genética Horizontal , Feromônios/genética , Percepção de Quorum/efeitos dos fármacos , Antibacterianos/farmacologia , Carga Bacteriana , Proteínas de Bactérias/metabolismo , Conjugação Genética , Enterococcus faecalis/efeitos dos fármacos , Enterococcus faecalis/crescimento & desenvolvimento , Enterococcus faecalis/metabolismo , Expressão Gênica , Aptidão Genética , Modelos Estatísticos , Feromônios/biossíntese , Plasmídeos/química , Plasmídeos/metabolismo , Percepção de Quorum/genética , Virulência
2.
Proc Biol Sci ; 287(1930): 20200894, 2020 07 08.
Artigo em Inglês | MEDLINE | ID: mdl-32635873

RESUMO

Termites in the genus Macrotermes construct large-scale soil mounds above their nests. The classic explanation for how termites coordinate their labour to build the mound, based on a putative cement pheromone, has recently been called into question. Here, we present evidence for an alternate interpretation based on sensing humidity. The high humidity characteristic of the mound's internal environment extends a short distance into the low-humidity external world, in a 'bubble' that can be disrupted by external factors like wind. Termites transport more soil mass into on-mound reservoirs when shielded from water loss through evaporation, and into experimental arenas when relative humidity is held at a high value. These results suggest that the interface between internal and external conditions may serve as a template for mound expansion, with workers moving freely within a zone of high humidity and depositing soil at its edge. Such deposition of additional moist soil will increase local humidity, in a feedback loop allowing the 'interior' zone to progress further outward and lead to mound expansion.


Assuntos
Umidade , Isópteros/fisiologia , Animais , Comportamento Animal , Feromônios , Solo , Temperatura
3.
Environ Pollut ; 266(Pt 3): 115092, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32650302

RESUMO

Antidepressants discharged into natural waters are likely to become a new type of endocrine pollutant, which may impact the interspecific relationship in aquatic ecosystem. Induced defense of cladocerans plays an important role in maintaining the balance of interspecific relationships between cladocerans and higher trophic levels. Here we studied the effects of antidepressant sertraline, a selective serotonin reuptake inhibitor, on the induced defensive traits of Ceriodaphnia cornuta in response to invertebrate predator Chaoborus larvae kairomone, including morphological defense and life history traits. We also conducted the predation experiments to check the selection rate of Chaoborus larvae during directly ingesting C. cornuta that were exposed to Chaoborus larvae kairomone at high concentration of sertraline. Results showed sertraline had an interference effect on the induced morphological defense of C. cornuta in response to Chaoborus larvae kairomone, i.e. the high concentration of sertraline (20 and 100 µg L-1) significantly reduced the horns induction. However, the different concentrations of sertraline generally did not affect the life history traits of C. cornuta, regardless of presence or absence of Chaoborus larvae kairomone. The predation experiment demonstrated that the inhibition of sertraline on the induced morphological defense of C. cornuta can promote the feeding selective efficiency of Chaoborus larvae, and thus cause C. cornuta easily to be predated by Chaoborus larvae. Our results suggested that sertraline at the concentrations that are not direct harmful to life history traits of C. cornuta can seriously affect the predator-prey relationship, indicating that effects of pollutants on interspecific relationships should be considered comprehensively to avoid underestimating the potential risk of pollutants to ecosystems.


Assuntos
Ecossistema , Sertralina , Animais , Antidepressivos , Daphnia , Larva , Feromônios
4.
PLoS One ; 15(7): e0234526, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32609769

RESUMO

In social insects, collective choices between food sources are based on self-organized mechanisms where information about resources are locally processed by the foragers. Such a collective decision emerges from the competition between pheromone trails leading to different resources but also between the recruiting stimuli emitted by successful foragers at nest entrances. In this study, we investigated how an additional nest entrance influences the ability of Myrmica rubra ant colonies to exploit two food sources of different quality (1M and 0.1M sucrose solution) and to select the most rewarding one. We found that the mobilisation of workers doubled in two-entrance nests compared to one-entrance nests but that ants were less likely to reach a food source once they exited the nest. Moreover, the collective selection of the most rewarding food source was less marked in two-entrance nests, with foragers distributing themselves evenly between the two feeders. Ultimately, multiple nest entrances reduced the foraging efficiency of ant colonies that consumed significantly less sugar out of the two available resources. Our results highlight that the nest structure, more specifically the number of nest entrances, can impede the ant's ability to process information about environmental opportunities and to select the most rewarding resource. This study opens new insights on how the physical interface between the nest interior and the outside environment can act upon collective decision-making and foraging efficiency in self-organized insect societies.


Assuntos
Comportamento Animal/fisiologia , Tomada de Decisões/fisiologia , Comportamento Alimentar/fisiologia , Animais , Formigas/metabolismo , Feminino , Alimentos , Masculino , Modelos Biológicos , Feromônios , Recompensa , Comportamento Social
5.
Ying Yong Sheng Tai Xue Bao ; 31(7): 2141-2150, 2020 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-32715675

RESUMO

Plant-plant interactions is a fundamental issue in ecology. Plants are able to detect and perceive inter-specific and intra-specific neighbors and then adjust their growth, reproduction and defense strategies. Such inter-specific and intra-specific recognition and perception are mostly media-ted by secondary metabolites. Those chemical communications can initiate and activate the corresponding mechanism in allelopathy. In recent years, several novel plant-plant chemical interactions have been observed, such as kin recognition, and flowering and reproduction mediated by root communication. Till now, the inter-specific and intra-specific chemical interactions among plants mediated by volatiles have been substantially clarified. However, the mechanisms and soil-borne signaling chemicals involved in plant-plant chemical interactions mediated by root exudates remain poorly understood. Belowground chemical interactions not only determine the behavior of root invasion (approaching) and avoidance (repelling), but also regulate the flowering time and florescence. Accordingly, the chemical interactions involve the coordination between belowground and aboveground parts. On the basis of allelopathy and chemical recognition as well as corresponding allelochemicals and signaling chemicals, this review outlined recent research advances regarding plant-plant chemical interactions from kin recognition, root communication and behavior patterns, belowground chemical interactions to regulate flowering and reproduction. The efforts represented a mechanistically exhaustive view of plant-plant interactions.


Assuntos
Raízes de Plantas , Plantas , Alelopatia , Ecologia , Feromônios
6.
Ying Yong Sheng Tai Xue Bao ; 31(7): 2168-2174, 2020 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-32715678

RESUMO

Allelopathy is a plant-plant interaction mediated by the allelochemicals, which directly or indirectly influence plant growth. As the major part in response to allelochemicals, root morphological traits play an important role in allelopathy research. The global pattern of effects of exogenous allelochemicals on root morphology is not well known. We carried out a meta-analysis based on 61 studies to assess the effects of allelochemicals, including phenols, terpenoids, nitrogen-containing allelochemicals, on root morphology, especially on root length. We found that the allelochemicals significantly inhibited root length, but had little effect on root biomass, root surface area, and root volume. Phenols exhibited the most inhibitory effects on root length, while the allelochemicals had more inhibitory effect on root length of herbs than woody species as well as crops and other species. There was a linear relationship between phenols concentrations and their effect size. We quantified the dose-effect relationship of four phenolic acids, ferulic acid, p-hydroxybenzoic acid, vanillic acid and cinnamic acid. The inhibitory effect of flavonoids on root length was significantly higher than that of phenolic acids. Together, these findings suggested that the responses of target plant root traits to allelochemicals depended on allelochemicals type and dose, species identity, and culture conditions. Future studies need to decipher the mechanism underlying the allelochemicals on root traits of morphology, physiology and architecture under soil environment.


Assuntos
Alelopatia , Fenóis/análise , Produtos Agrícolas , Feromônios , Raízes de Plantas/química , Solo
7.
Ying Yong Sheng Tai Xue Bao ; 31(7): 2175-2184, 2020 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-32715679

RESUMO

To explore the influencing factors of understory plant species diversity of Eucalyptus grandis, we examined understory plant species diversity and phenolic allelochemicals in the rhizosphere soils of four-year-old and eight-year-old E. grandis plantations with different densities (1200, 1600, 2000 ind·hm-2) in Danling County of Sichuan Province. The results showed that a total of 45 plant species were recorded, belonging to 33 families and 44 genera. With the increases of stand age and decreases of stand density, plant species richness increased and their importance values were evenly distributed. Phanerophytes was the dominant life form across all stands. Shannon index and Margalef index of shrub in the four-year-old E. grandis plantations increased significantly at the density of 1600 ind·hm-2. All herbage plant diversity index except for Margalef index in four-year-old ones and Pielou index in eight-year-old plantations increased significantly with the decreases of density. Shannon index and Margalef index of shrub in 1200 ind·hm-2 were significantly higher in eight-year-old E. grandis stands than those in four-year-old ones. Five phenolic allelochemicals in the rhizosphere soils of E. grandis plantations were identified. In four-year-old stands, salicylic acid concentrations decreased significantly at the density of 1600 ind·hm-2. The concentrations of chrysin in four-year-old stands reduced significantly with the decreases of density. The concentrations of salicylic acid in eight-year-old stands increased significantly with the decreases of tree density. Salicylic acid concentrations in 2000 ind·hm-2 were significantly higher in four-year-old stands than that in eight-year-old ones, but the result was opposite in stands with density of 1600 ind·hm-2. The concentrations of chrysin in stand with density of 1200 ind·hm-2 were significantly higher in eight-year-old stands than that in four-year-old ones. Rundancy analysis (RDA) result showed that soil pH, bulk density, and the concentrations of soil organic matter, total nitrogen, total phospho-rus, and allelochemicals were the main environmental factors influencing understory plant species diversity. Therefore, prolonging rotation period and reducing stand density would improve micro-environmental condition of forests and buffer the allelopathy of E. grandis, which could facilitate the development of understory vegetation.


Assuntos
Eucalyptus , Solo , China , Florestas , Feromônios , Rizosfera
8.
Ying Yong Sheng Tai Xue Bao ; 31(7): 2236-2242, 2020 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-32715686

RESUMO

The development of new herbicides based on allelochemicals is a potential strategy of weed control in arable field. Pyrone, a novel derivative of tricin, has significant inhibitory effects on weeds. Its safety for crops, especially for millet that are sensitive to commercial herbicides, is still poorly understood. In this study, germination test and pot experiments were conducted to evaluate the safety of pyrone on 20 millet varieties, compared with 2,4-D. The results showed that, except that Jinfen109 was sensitive to high concentration 2,4-D, both pyrone and 2,4-D had no effect on the germination rates of other varieties. Results of the pot experiment showed that pyrone treatment significantly increased the chlorophyll content of millet by 9.0%-67.9%, which was the greatest for Jigu 42. Pyrone treatment did not affect maximal photochemical efficiency, potential photochemical activity, actual photochemical efficiency, and non-photochemical quenching coefficient. On the contrary, 2,4-D significantly inhibited the fluorescence parameters of millet varieties. Pyrone treatment increased the activities of superoxide dismutase, peroxidase and catalase in leaves of Dunza16, Jigu 39, Jigu 41 and Jingu 28, with the magnitude of enhancement being higher than 2,4-D. The results indicated that the allelochemical derivative pyrone is highly safe to the growth of millet seedlings and has the potential to be a new herbicide to millet field.


Assuntos
Milhetes , Pironas , Clorofila , Grão Comestível , Feromônios , Controle de Plantas Daninhas
9.
Pestic Biochem Physiol ; 167: 104594, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32527433

RESUMO

The combined use of entomopathogenic fungi and sublethal rate of chemical insecticides or other biological control agents have been proposed as an environmentally and sustainable strategy in the control of locust pests. In this paper, the quarter and the half of the recommended dose of Metarhizium anisopliae var. acridum (» and ½ Ma) and the aggregation pheromone (Phenylacetonitrile: PAN) were applied simultaneously and sequentially to Schistocerca gregaria fifth-instar nymphs. In addition, the physiological effects of PAN on locusts were assessed at the behavior, immune response, and biochemical level by evaluating for glutathione-S-transferase (GST), acetylcholinesterase inhibition (AChE), and malondialdehyde accumulation (MDA). Results showed that simultaneous application of PAN and the entomopathogenic fungus exhibited additive interaction. Synergistic interaction was also demonstrated when nymphs were exposed to PAN first, then treated with M. anisopliae var. acridum. Behavioral bioassay revealed that fifth-instar nymphs avoided the PAN odour and tended to remain away from the stimulus cup. In the choice assay, the pheromone significantly repelled the locusts at 2, 4, and 6 h of exposure which selected the PAN-free arena chamber. Moreover, treated nymphs become hyperactive and disoriented as evidenced by the cumulative distance travelled and the trajectory of locusts during the experiment. Immunological studies showed that PAN significantly decreased the differential haemocyte counts (prohemocytes and plasmatocytes) with a dose-response relationship. Data of biochemical analyzes showed that the PAN exposure reduced the activity of acetylcholinesterase and induced significantly the glutathione S-transferases and MDA concentration in the desert locust fifth-instar nymphs. Moreover, transcriptomic responses to the PAN exposure were evaluated using gene expression levels of CYP540 and GST. The transcript levels showed an up-regulation in GST expression level particularly in nymphs exposed for 4 and 6 h. A significant increase in CYP450 transcript level was also observed after 2 h of exposure, which decreased significantly after 4 and 6 h.


Assuntos
Gafanhotos , Metarhizium , Acetonitrilos , Animais , Feromônios , Transcriptoma
10.
Aquat Toxicol ; 224: 105513, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32504860

RESUMO

Ulva prolifera is a macroalgae that forms massive blooms, negatively impacting natural communities, aquaculture operations and recreation. The effects of the natural products, eugenol, ß-myrcene, citral and nonanoic acid on the growth rate, antioxidative defense system and photosynthesis of Ulva prolifera were investigated as a possible control strategy for this harmful taxon. Negative effects on growth were observed with all four chemicals, due to the excessive production of reactive oxygen species and oxidative damage to the thalli. However, the response of U. prolifera under the four chemicals stress was different at the cellular level. ß-myrcene, the most effective compound in terms of growth inhibition, induced oxidative stress as shown by the damage of total antioxidant capacity (T-AOC) and the downregulation of the glutathione-ascorbate (GSH-ASA) cycle which inhibited the antioxidative system. This chemical also inhibited photosynthesis and photoprotection mechanisms in U. prolifera, resulting in growth limitation. In contrast, U. prolifera was less affected by the second tested chemical, eugenol, and showed no significant change on photosynthetic efficiency in the presence of the chemical. The inhibition effects of the third and fourth tested chemicals, nonanoic acid and citralon, on growth and on the antioxidant defense system in U. prolifera were inferior. These results provide a potential avenue for controlling green tides in the future.


Assuntos
Antioxidantes/metabolismo , Feromônios/toxicidade , Fotossíntese/efeitos dos fármacos , Alga Marinha/efeitos dos fármacos , Ulva/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Fotossíntese/fisiologia , Alga Marinha/metabolismo , Alga Marinha/fisiologia , Ulva/crescimento & desenvolvimento , Ulva/metabolismo
11.
PLoS Comput Biol ; 16(6): e1007457, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32525874

RESUMO

Although movement ecology has leveraged models of home range formation to explore the effects of spatial heterogeneity and social cues on movement behavior, disease ecology has yet to integrate these potential drivers and mechanisms of contact behavior into a generalizable disease modeling framework. Here we ask how dynamic territory formation and maintenance might contribute to disease dynamics in a territorial, solitary predator for an indirectly transmitted pathogen. We developed a mechanistic individual-based model where stigmergy-the deposition of signals into the environment (e.g., scent marking, scraping)-dictates local movement choices and long-term territory formation, but also the risk of pathogen transmission. Based on a variable importance analysis, the length of the infectious period was the single most important variable in predicting outbreak success, maximum prevalence, and outbreak duration. Host density and rate of pathogen decay were also key predictors. We found that territoriality best reduced maximum prevalence in conditions where we would otherwise expect outbreaks to be most successful: slower recovery rates (i.e., longer infectious periods) and higher conspecific densities. However, for slower pathogen decay rates, stigmergy-driven movement increased outbreak durations relative to random movement simulations. Our findings therefore support a limited version of the "territoriality benefits" hypothesis-where reduced home range overlap leads to reduced opportunities for pathogen transmission, but with the caveat that reduction in outbreak severity may increase the likelihood of pathogen persistence. For longer infectious periods and higher host densities, key trade-offs emerged between the strength of pathogen load, the strength of the stigmergy cue, and the rate at which those two quantities decayed; this finding raises interesting questions about the evolutionary nature of these competing processes and the role of possible feedbacks between parasitism and territoriality. This work also highlights the importance of considering social cues as part of the movement landscape in order to better understand the consequences of individual behaviors on population level outcomes.


Assuntos
Comportamento Animal , Ecologia , Prevalência , Territorialidade , Animais , Simulação por Computador , Surtos de Doenças , Comportamento de Retorno ao Território Vital , Modelos Biológicos , Modelos Estatísticos , Feromônios , Probabilidade
12.
Chem Biol Interact ; 325: 109123, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32387439

RESUMO

To avoid being preyed, organisms must be able to identify predatory threats by sensing molecules released by predators (kairomones), and to employ effective strategies to prevent detection by predators. Furthermore, in the wild, organisms are also exposed to chemicals that may alter their behavioral traits, such as neuroactive pharmaceuticals. Considering the co-occurrence of both types of chemicals, their possible interaction needs to be studied. To address this topic, the aim of this study was to verify the effects of fish kairomone (FK - a chemical associated to putative predation by fish) and chlorpromazine (CPZ - neuroactive pharmaceutical drug, environmental contaminant), isolated and in combination, in different functional endpoints of Daphnia magna, such as oxygen consumption, feeding rate, behavior and reproduction. Among these endpoints, oxygen consumption was only affected by the combination of compounds (FK + CPZ). On the other hand, feeding rate was affected by all treatments, being lower than control. For life history traits and phototactic behavior, the effects of FK predominated over the ones caused by CPZ exposure, incrementing the reproductive output of females, leading to greater population growth rates and increasing negative phototactic behaviour.


Assuntos
Clorpromazina/toxicidade , Daphnia/efeitos dos fármacos , Peixes/metabolismo , Feromônios/farmacologia , Poluentes Químicos da Água/toxicidade , Animais , Comportamento Animal/efeitos dos fármacos , Daphnia/fisiologia , Interações Medicamentosas , Feromônios/metabolismo , Reprodução/efeitos dos fármacos
13.
Lett Appl Microbiol ; 71(1): 39-45, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32390273

RESUMO

Filter feeding is a biotic process that brings waterborne bacteria in close contact with each other and may thus support the horizontal transfer of their antimicrobial resistance genes. This laboratory study investigated whether the freshwater sponge Ephydatia fluviatilis supported the transfer of vancomycin resistance between two Enterococcus faecalis strains that we previously demonstrated to exhibit pheromone responsive plasmid conjugation. Microcosm experiments exposed live and dead colonies of laboratory-grown sponges to a vancomycin-resistant donor strain and a rifampicin-resistant recipient strain of Ent. faecalis. Enterococci with both resistance phenotypes were detected on double selection plates. In comparison to controls, abundance of these presumed transconjugants increased significantly in water from sponge microcosms. Homogenized suspensions of sponge cells also yielded presumed transconjugants; however, there was no significant difference between samples from live or dead sponges. Fluorescent in situ hybridization analysis of the sponge cell matrix using species-specific probes revealed the presence of enterococci clusters with cells adjacent to each other. The results demonstrated that sponge colonies can support the horizontal transfer of antimicrobial resistance although the mechanism underlying this process, such as binding of the bacteria to the sponge collagen matrix, has yet to be fully elucidated.


Assuntos
Antibacterianos/farmacologia , Conjugação Genética/genética , Farmacorresistência Bacteriana/genética , Enterococcus faecalis/genética , Poríferos/microbiologia , Resistência a Vancomicina/genética , Animais , Enterococcus faecalis/efeitos dos fármacos , Água Doce , Hibridização in Situ Fluorescente , Feromônios/farmacologia , Plasmídeos/genética , Vancomicina/farmacologia
14.
PLoS One ; 15(5): e0229055, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32396558

RESUMO

Camera traps are a unique survey tool used to monitor a wide variety of mammal species. Camera trap (CT) data can be used to estimate animal distribution, density, and behaviour. Attractants, such as scent lures, are often used in an effort to increase CT detections; however, the degree which the effects of attractants vary across species is not well understood. We investigated the effects of scent lure on mammal detections by comparing detection rates between 404 lured and 440 unlured CT stations sampled in Alberta, Canada over 120 day survey periods between February and August in 2015 and 2016. We used zero-inflated negative binomial generalized linear mixed models to test the effect of lure on detection rates for a) all mammals, b) six functional groups (all predator species, all prey, large carnivores, small carnivores, small mammals, ungulates), and c) four varied species of management interest (fisher, Pekania pennanti; gray wolf, Canis lupus; moose, Alces alces; and Richardson's ground squirrel; Urocitellus richardsonii). Mammals were detected at 800 of the 844 CTs, with nearly equal numbers of total detections at CTs with (7110) and without (7530) lure, and variable effects of lure on groups and individual species. Scent lure significantly increased detections of predators as a group, including large and small carnivore sub-groups and fisher specifically, but not of gray wolf. There was no effect of scent lure on detections of prey species, including the small mammal and ungulate sub-groups and moose and Richardson's ground squirrel specifically. We recommend that researchers explicitly consider the variable effects of scent lure on CT detections across species when designing, interpreting, or comparing multi-species surveys. Additional research is needed to further quantify variation in species responses to scent lures and other attractants, and to elucidate the effect of attractants on community-level inferences from camera trap surveys.


Assuntos
Carnívoros/fisiologia , Odorantes , Comportamento Predatório/fisiologia , Lobos/fisiologia , Alberta , Distribuição Animal/fisiologia , Animais , Cervos/fisiologia , Humanos , Feromônios/química , Gravação em Vídeo
15.
PLoS One ; 15(5): e0232492, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32413032

RESUMO

Coyotes (Canis latrans) and kit foxes (Vulpes macrotis) are desert canids that share ecological similarities, but have disparate histories with anthropogenic pressure that may influence their responses towards novel stimuli. We used remote cameras to investigate response to novel stimuli for these two species. We predicted that coyotes (heavily pressured species) would be more wary towards novel stimuli on unprotected land (canid harvest activities are permitted) than in protected areas (canid harvest activities are not permitted), whereas kit foxes (less pressured species) would exhibit no difference. We examined differences in the investigative behaviors at 660 scent stations in both protected and unprotected areas. Coyotes showed no differences between protected and unprotected land and were generally more wary than kit foxes, supporting our prediction. Kit foxes were more investigative on protected land, contrary to our expectations. Our study provides evidence that anthropogenic pressure can alter the behaviors of wildlife species.


Assuntos
Comportamento Animal/fisiologia , Coiotes/fisiologia , Raposas/fisiologia , Animais , Animais Selvagens/fisiologia , Clima Desértico , Espécies em Perigo de Extinção , Comportamento Exploratório/fisiologia , Odorantes , Feromônios/fisiologia , Fotografação , Tecnologia de Sensoriamento Remoto , Especificidade da Espécie , Utah
16.
PLoS One ; 15(5): e0233653, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32469938

RESUMO

Attempts to control invasive species using species-specific pheromones need to incorporate an understanding of interactive effects among those pathways. The larvae of invasive cane toads (Rhinella marina) utilise chemical cues to repulse, attract or suppress conspecific larvae. We can exploit these effects to reduce toad abundance, but the effects of each cue may not be additive. That is, exposure to one type of cue may lessen the impact of exposure to another cue. To assess this possibility, we exposed toad larvae to combinations of cues. Tadpoles that had been exposed to the suppression cue during larval development exhibited no response to the attraction cue, resulting in lower capture rates in attractant-baited traps. Suppression, however, did not affect a tadpole's response to the alarm cue, and exposure to the alarm cue during tadpole development did not affect response to the attraction cue. Tadpoles exposed to the suppression cue were smaller than control tadpoles at 10 days post-exposure, and consequently were more vulnerable to gape-limited invertebrate predators. Our results demonstrate that the responses by toad tadpoles to chemical cues interact in important ways, and are not simply additive when combined. Control efforts need to incorporate an understanding of such interactions if we are to most effectively use chemical-communication pathways to control invasive amphibians.


Assuntos
Bufo marinus/fisiologia , Espécies Introduzidas , Animais , Bufo marinus/crescimento & desenvolvimento , Feminino , Larva/crescimento & desenvolvimento , Larva/fisiologia , Feromônios/metabolismo , Comportamento Predatório
17.
Pestic Biochem Physiol ; 165: 104542, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32359552

RESUMO

The tea geometrid moth Ectropis obliqua Prout is one of the most serious moth pests in tea plants, and its sex pheromones have been identified as typical Type-II polyunsaturated hydrocarbons and epoxide derivatives. Therefore, the E. obliqua male olfactory system provides a good model to study the molecular basis of Type-II sex pheromone recognition as well as functional gene evolution towards structurally different types of moth sex pheromones. In this study, we identified the full-length sequence of a pheromone-binding protein, EoblPBP2 and revealed that it clustered together with the lepidopteran PBP2 subfamily, which binds Type I acetate pheromones. These findings suggest that the EoblPBP2 sequence and physiological function are conserved, although E. obliqua evolved Type II hydrocarbon and epoxide sex pheromones structurally different from Type I acetates. To examine this hypothesis, we studied the expression patterns and in vitro functions of EoblPBP2 in detail. Quantitative real-time PCR experiments showed that EoblPBP2 was predominantly expressed in male E. obliqua antennae. Fluorescence in situ hybridization further demonstrated that the EoblPBP2 gene was abundantly expressed in the pheromone-sensitive sensilla trichodea Str-I in male E. obliqua. The physiological function of recombinant EoblPBP2 was then examined using a competitive binding assay. The results showed that EoblPBP2 had high affinities for three E. obliqua Type II sex pheromone components and Type I acetate pheromones in comparison to some plant volatiles. These results indicate that PBP2 is involved in the detection of Type II pheromones in E. obliqua and it still retains high binding affinities to acetate pheromones and some green leaf ester volatiles.


Assuntos
Mariposas , Atrativos Sexuais , Animais , Proteínas de Transporte , Hibridização in Situ Fluorescente , Proteínas de Insetos , Masculino , Feromônios , Chá
18.
J Chem Ecol ; 46(4): 378-386, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32240481

RESUMO

Before weed biocontrol insects are transported and released in a new area, they are commonly collected into small paper containers, chilled, and kept under dark conditions. This process can be termed a pre-release protocol. The influence of a pre-release protocol on establishment success of a gregarious biological control agent was assessed using the northern tamarisk beetle, Diorhabda carinulata (Desbrochers), and its exotic, invasive host plant saltcedar (Tamarix spp.). Pre-release protocol impacts on aggregation pheromone production by D. carinulata were characterized under controlled conditions. Additional experiments were undertaken to determine if deployment of aggregation pheromone lures might enhance the agent's persistence at release sites. Adults that experienced the pre-release protocol produced less aggregation pheromone compared to undisturbed adults. Olfactometer bioassays indicated that a cohort of adults subjected to the pre-release protocol were less attractive to other adults than a control cohort. Efficacy of aggregation pheromone-based lures to retain adults at release sites was evaluated by comparing capture numbers of adult beetles at paired treatment and control release sites, 10-14 days after the release of 300, 500, or 1000 individuals. A greater number of adult D. carinulata were captured where the pheromone lures had been deployed compared to control release sites. Application of aggregation pheromone when a new release of D. carinulata is planned should allow biological control practitioners to increase retention of beetles at a release site.


Assuntos
Besouros/fisiologia , Controle Biológico de Vetores , Feromônios/metabolismo , Tamaricaceae , Controle de Plantas Daninhas , Animais , Besouros/metabolismo , Espécies Introduzidas , Dinâmica Populacional
19.
J Chem Ecol ; 46(4): 387-396, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32274623

RESUMO

Attractive Toxic Sugar Baits (ATSB) are used in a "lure-and-kill" approach for management of the malaria vector Anopheles gambiae, but the active chemicals were previously unknown. Here we collected volatiles from a mango, Mangifera indica, juice bait which is used in ATSBs in Tanzania and tested mosquito responses. In a Y-tube olfactometer, female mosquitoes were attracted to the mango volatiles collected 24-48 h, 48-72 h and 72-96 h after preparing the bait but volatiles collected at 96-120 h were no longer attractive. Volatile analysis revealed emission of 23 compounds in different chemical classes including alcohols, aldehydes, alkanes, benzenoids, monoterpenes, sesquiterpenes and oxygenated terpenes. Coupled GC-electroantennogram (GC-EAG) recordings from the antennae of An. gambiae showed robust responses to 4 compounds: humulene, (E)-caryophyllene, terpinolene and myrcene. In olfactometer bioassays, mosquitoes were attracted to humulene and terpinolene. (E)-caryophyllene was marginally attractive while myrcene elicited an avoidance response with female mosquitoes. A blend of humulene, (E)-caryophyllene and terpinolene was highly attractive to females (P < 0.001) when tested against a solvent blank. Furthermore, there was no preference when this synthetic blend was offered as a choice against the natural sample. Our study has identified the key compounds from mango juice baits that attract An. gambiae and this information may help to improve the ATSBs currently used against malaria vectors.


Assuntos
Anopheles/fisiologia , Controle de Insetos , Mangifera/química , Feromônios/metabolismo , Compostos Orgânicos Voláteis/metabolismo , Animais , Quimiotaxia , Comportamento Alimentar , Feminino , Cadeia Alimentar
20.
J Chem Ecol ; 46(4): 442-454, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32314119

RESUMO

Elevational gradients affect the production of plant secondary metabolites through changes in both biotic and abiotic conditions. Previous studies have suggested both elevational increases and decreases in host-plant chemical defences. We analysed the correlation of alkaloids and polyphenols with elevation in a community of nine Ficus species along a continuously forested elevational gradient in Papua New Guinea. We sampled 204 insect species feeding on the leaves of these hosts and correlated their community structure to the focal compounds. Additionally, we explored species richness of folivorous mammals along the gradient. When we accounted for Ficus species identity, we found a general elevational increase in flavonoids and alkaloids. Elevational trends in non-flavonol polyphenols were less pronounced or showed non-linear correlations with elevation. Polyphenols responded more strongly to changes in temperature and humidity than alkaloids. The abundance of insect herbivores decreased with elevation, while the species richness of folivorous mammals showed an elevational increase. Insect community structure was affected mainly by alkaloid concentration and diversity. Although our results show an elevational increase in several groups of metabolites, the drivers behind these trends likely differ. Flavonoids may provide figs with protection against abiotic stressors. In contrast, alkaloids affect insect herbivores and may provide protection against mammalian herbivores and pathogens. Concurrent analysis of multiple compound groups alongside ecological data is an important approach for understanding the selective landscape that shapes plant defences.


Assuntos
Alcaloides/metabolismo , Altitude , Ficus/química , Flavonoides/metabolismo , Cadeia Alimentar , Herbivoria , Feromônios/análise , Animais , Biota , Insetos/fisiologia , Mamíferos/fisiologia , Papua Nova Guiné , Folhas de Planta/química
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA