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1.
Science ; 367(6477): 504-506, 2020 01 31.
Artigo em Inglês | MEDLINE | ID: mdl-32001639
2.
Science ; 367(6478): 626-627, 2020 02 07.
Artigo em Inglês | MEDLINE | ID: mdl-32029614
3.
BMC Ecol ; 20(1): 8, 2020 02 10.
Artigo em Inglês | MEDLINE | ID: mdl-32039719

RESUMO

BACKGROUND: Breeding programs and research activities where artificial buzz-pollinations are required to have primarily relied upon using tuning forks, and bumble bees. However, these methods can be expensive, unreliable, and inefficient. To find an alternative, we tested the efficiency of pollen collection using electric toothbrushes and compared it with tuning forks at three vibration frequencies-low, medium, and high and two extraction times at 3 s and 16 s- from two buzz-pollinated species (Solanum lycopersicum and Solanum elaeagnifolium). RESULTS: Our results show that species, and extraction time significantly influenced pollen extraction, while there were no significant differences for the different vibration frequencies and more importantly, the use of a toothbrush over tuning fork. More pollen was extracted from S. elaeagnifolium when compared to S. lycopersicum, and at longer buzzing time regardless of the instrument used. CONCLUSIONS: Our results suggest that electric toothbrushes can be a viable and inexpensive alternative to tuning forks, and regardless of the instrument used and buzzing frequency, length of buzzing time is also critical in pollen extraction.


Assuntos
Lycopersicon esculentum , Polinização , Animais , Abelhas , Flores , Pólen
4.
Oecologia ; 192(2): 577-590, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31897723

RESUMO

Mutualistic interactions between plants and pollinators play an essential role in the organization and persistence of biodiversity. The structure of interaction networks mediates the resilience of local communities and ecosystem functioning to environmental changes. Hence, network structure conservation may be more critical for maintaining biodiversity and ecological services than the preservation of isolated species in changing landscapes. Here, we intensively surveyed seven 36 km2 landscapes to empirically investigate the effects of forest loss and landscape configuration on the structure of plant-pollinator networks in understory vegetation of Brazilian Atlantic Forest. Our results indicate that forest loss and isolation affect the structure of the plant-pollinator networks, which were smaller in deforested landscapes, and less specialized as patch isolation increased. Lower nestedness and degree of specialization (H'2) indicated that the remaining plant and bee species tend to be generalists, and many of the expected specialized interactions in the network were already lost. Because generalist species generate a cohesive interaction core in these networks, these simplified networks might be resistant to loss of peripheral species, but may be susceptible to the extinction of the most generalist species. We suggest that such a network pattern is an outcome of landscapes with a few remaining isolated patches of natural habitat. Our results add a new perspective to studies of plant-pollinator networks in fragmented landscapes, showing that those interaction networks might also be used to indicate how changes in natural habitat affect biodiversity and biotic interactions.


Assuntos
Ecossistema , Polinização , Animais , Abelhas , Brasil , Florestas , Plantas
5.
Ecol Lett ; 23(3): 545-554, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31943632

RESUMO

Preventing malnutrition through consuming nutritionally appropriate resources represents a challenge for foraging animals. This is due to often high variation in the nutritional quality of available resources. Foragers consequently need to evaluate different food sources. However, even the same food source can provide a plethora of nutritional and non-nutritional cues, which could serve for quality assessment. We show that bumblebees, Bombus terrestris, overcome this challenge by relying on lipids as nutritional cue when selecting pollen. The bees 'prioritised' lipid perception in learning experiments and avoided lipid consumption in feeding experiments, which supported survival and reproduction. In contrast, survival and reproduction were severely reduced by increased lipid contents. Our study highlights the importance of fat regulation for pollen foraging bumblebees. It also reveals that nutrient perception, nutrient regulation and reproductive fitness can be linked, which represents an effective strategy enabling quick foraging decisions that prevent malnutrition and maximise fitness.


Assuntos
Comportamento Alimentar , Pólen , Animais , Abelhas , Nutrientes , Reprodução
6.
J Environ Manage ; 257: 109983, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31989960

RESUMO

Stakeholders are critical environmental managers in human-dominated landscapes. In some contexts, stakeholders can be forced to personally act following their own observations and risk perception instead of science recommendation. In particular, biological invasions need rapid control actions to reduce potential socio-ecological impacts, while science-based risk assessments are rather complex and time-delayed. Although they can lead to important detrimental effects on biodiversity, potential time-delayed disconnections between stakeholders' action and science recommendations are rarely studied. Using the case study of western European beekeepers controlling the invasive Asian hornet Vespa velutina nigrithorax for its suspected impact on honey bee colonies, we analysed mechanisms underlying personal actions of stakeholders and how they evolved in science disconnection. Personal actions of stakeholders were causal-effect linked with their risk observation but disconnected to time-delayed science predictions and recommendations. Unfortunately, these science-disconnected actions also led to dramatic impacts on numerous species of the local entomofauna. These results highlight the need to improve mutual risk communication between science and action in the early-stages of management plans to improve the sustainably of stakeholders' practices.


Assuntos
Espécies Introduzidas , Vespas , Animais , Abelhas , Biodiversidade , Humanos , Medição de Risco
7.
Chemosphere ; 242: 125293, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31896202

RESUMO

The effects produced by the ethyl-carbamates: ethyl-4-bromophenyl carbamate (LQM 919) and ethyl-4-chlorophenyl carbamate (LQM 996) on the mortality and behavior of Apis mellifera were evaluated by the acute oral toxicity test and the acute contact toxicity test. The oral lethal dose, 50% of the ethyl-carbamates was >145.24 µg per bee, and the oral lethal dose, 50% of propoxur was 0.072 µg per bee. Therefore, according to the OECD criteria, the ethyl-carbamates were classified as relatively nontoxic orally; meanwhile, propoxur was classified as highly toxic orally. In the contact test, lethal concentrations 50% of the ethyl-carbamates were 4.83 and 2.23 µg/cm2 for LQM 919 and LQM 996, respectively; therefore, they were at least 10-fold less lethal (p < 0.05) than propoxur (0.22 µg/cm2). The ethyl-carbamates reduced the activity of A. mellifera acetylcholinesterase by up to 30%. The ki and kd values of both ethyl-carbamates were lower (p < 0.05) than those of propoxur and indicated that they are weak inhibitors and with low affinity to A. mellifera acetylcholinesterase, which along with the absence of behavioral alterations suggests that the mortality caused by ethyl carbamates is not related to damage to the nervous system. According to these results, the evaluated ethyl-carbamates can be considered a low ecotoxic risk for A. mellifera.


Assuntos
Acetilcolinesterase/metabolismo , Abelhas/efeitos dos fármacos , Carbamatos/toxicidade , Poluentes Ambientais/toxicidade , Inseticidas/toxicidade , Animais , Abelhas/enzimologia , Comportamento Animal/efeitos dos fármacos , Exposição Dietética/efeitos adversos , Exposição Ambiental/efeitos adversos , Dose Letal Mediana , Testes de Toxicidade Aguda
8.
Pestic Biochem Physiol ; 163: 138-146, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31973850

RESUMO

Honeybees ensure a key ecosystemic service by pollinating many agricultural crops and wild plants. However, since few decades, managed bee colonies have declined worldwide. This phenomenon is considered to be multifactorial, with a strong emphasis on both parasites and pesticides. Infection by the parasite Nosema ceranae and exposure to pesticides can contribute to adverse effects, resulting in a perturbation of the honeybee physiology. We thus hypothesized that probiotic treatment could be promising to treat or prevent these disturbances. The aim of this study was to evaluate the effects of probiotics on N. ceranae-infected and intoxicated honeybees (by the insecticide thiamethoxam and the fungicide boscalid). For this purpose, experiments were conducted with five probiotics. Among them, Pediococcus acidilactici (PA) showed the best protective effect against the parasite and pesticides. PA significantly improved the infected honeybee lifespan as prophylactic and curative treatments (respectively 2.3 fold and 1.7 fold). Furthermore, the exposure to pesticides induced an increase of honeybee mortality compared with the control group (p < .001) that was restored by the PA treatment. Despite its beneficial effect on honeybee lifespan, the PA administration did not induce changes in the gut bacterial communities (neither in abundance or diversity). N. ceranae and the pesticides were shown to deregulate genes involved in honeybee development (vitellogenin), immunity (serine protease 40, defensin) and detoxification system (glutathione peroxidase-like 2, catalase), and these effects were corrected by the PA treatment. This study highlights the promising use of PA to protect honeybees from both pathogens and pesticides.


Assuntos
Inseticidas , Nosema , Animais , Abelhas , Pediococcus
9.
Pestic Biochem Physiol ; 163: 94-101, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31973875

RESUMO

Imidacloprid, a widely used neonicotinoid insecticide, has led to a decline in the honey bee population worldwide. An invertebrate insect prey with neonicotinoid toxicity can adversely affect insectivores, such as echolocating bats. The aim of the current study was to examined whether imidacloprid toxicity may interfere echolocation system such as vocal, auditory, orientation, and spatial memory systems in the insectivorous bat. By comparing the ultrasound spectrum, auditory brainstem-evoked potential, and flight trajectory, we found that imidacloprid toxicity may interfere functions in vocal, auditory, orientation, and spatial memory system of insectivorous bats (Hipposideros armiger terasensis). As suggested from immunohistochemistry and western blots evidences, we found that insectivorous bats after suffering imidacloprid toxicity may decrease vocal-related FOXP2 expressions in the superior colliculus, auditory-related prestin expressions in the cochlea, and the auditory-related otoferlin expressions in the cochlea and the inferior colliculus, and cause inflammation and mitochondrial dysfunction-related apoptosis in the hippocampal CA1 and medial entorhinal cortex. These results may provide a reasonable explanation about imidacloprid-induced interference of echolocation system in insectivorous bats.


Assuntos
Quirópteros , Ecolocação , Inseticidas , Animais , Abelhas , Neonicotinoides , Nitrocompostos
10.
Nat Commun ; 11(1): 576, 2020 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-31996690

RESUMO

Urbanisation is an important global driver of biodiversity change, negatively impacting some species groups whilst providing opportunities for others. Yet its impact on ecosystem services is poorly investigated. Here, using a replicated experimental design, we test how Central European cities impact flying insects and the ecosystem service of pollination. City sites have lower insect species richness, particularly of Diptera and Lepidoptera, than neighbouring rural sites. In contrast, Hymenoptera, especially bees, show higher species richness and flower visitation rates in cities, where our experimentally derived measure of pollination is correspondingly higher. As well as revealing facets of biodiversity (e.g. phylogenetic diversity) that correlate well with pollination, we also find that ecotones in insect-friendly green cover surrounding both urban and rural sites boost pollination. Appropriately managed cities could enhance the conservation of Hymenoptera and thereby act as hotspots for pollination services that bees provide to wild flowers and crops grown in urban settings.


Assuntos
Abelhas/fisiologia , Ecologia , Insetos/fisiologia , Polinização , Urbanização , Animais , Abelhas/classificação , Biodiversidade , Cidades , Dípteros , Ecossistema , Flores , Alemanha , Himenópteros , Insetos/classificação , Lepidópteros , Filogenia
11.
Ecol Lett ; 23(2): 326-335, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31797535

RESUMO

Supporting ecosystem services and conserving biodiversity may be compatible goals, but there is concern that service-focused interventions mostly benefit a few common species. We use a spatially replicated, multiyear experiment in four agricultural settings to test if enhancing habitat adjacent to crops increases wild bee diversity and abundance on and off crops. We found that enhanced field edges harbored more taxonomically and functionally abundant, diverse, and compositionally different bee communities compared to control edges. Enhancements did not increase the abundance or diversity of bees visiting crops, indicating that the supply of pollination services was unchanged following enhancement. We find that actions to promote crop pollination improve multiple dimensions of biodiversity, underscoring their conservation value, but these benefits may not be spilling over to crops. More work is needed to identify the conditions that promote effective co-management of biodiversity and ecosystem services.


Assuntos
Biodiversidade , Ecossistema , Agricultura , Animais , Abelhas , Produtos Agrícolas , Polinização
12.
Mol Genet Genomics ; 295(1): 143-154, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31559504

RESUMO

KEY MESSAGE: Floret and seed traits are moderately correlated phenotypically in modern sunflower cultivars, but the underlying genetics are mostly independent. Seed traits in particular are governed in part by epistatic effects among quantitative trait loci. Seed size is an important quality component in marketing commercial sunflower (Helianthus annuus L.), particularly for the in-shell confectionery market, where long and broad seed types are preferred as a directly consumed snack food globally. Floret size is also important because corolla tube length was previously shown to be inversely correlated with pollinator visitation, impacting bee foraging potential and pollinator services to the plant. Commercial sunflower production benefits from pollinator visits, despite being self-compatible, and bees are required in hybrid seed production, where "female" and "male" inbred lines are crossed at field scale. Issues with pollination of long-seed confectionery sunflower suggest that there may be an unfavorable correlation between seed and floret traits; thus, our objective was to determine the strength of the correlation between seed and floret traits, and confirm any co-localization of seed and floret trait loci using genome-wide association analysis in the SAM diversity panel of sunflower. Our results indicate that phenotypic correlations between seed and floret traits are generally low to moderate, regardless of market class, a component of population substructure. Association mapping results mirror the correlations: while a few loci overlap, many loci for the two traits are not overlapping or even adjacent. The genetics of these traits, while modestly quantitative and influenced by epistatic effects, are not a barrier to simultaneous improvement of seed length and pollinator-friendly floret traits. We conclude that breeding for large seed size, which is required for the confectionery seed market, is possible without producing florets too long for efficient use by pollinators, which promotes bee foraging and associated pollination services.


Assuntos
Helianthus/genética , Locos de Características Quantitativas/genética , Sementes/genética , Animais , Abelhas , Cruzamento/métodos , Estudo de Associação Genômica Ampla/métodos , Fenótipo , Polinização/genética
13.
Insect Sci ; 27(2): 349-360, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30390389

RESUMO

Animals use diverse sensory stimuli to navigate their environment and to recognize rewarding food sources. Honey bees use visual attributes of the targeted food source, such as its color, shape, size, direction and distance from the hive, and the landmarks around it to navigate during foraging. They transmit the location information of the food source to other bees if it is highly rewarding. To investigate the relative importance of these attributes, we trained bees to feeders in two different experiments. In the first experiment, we asked whether bees prefer to land on (a) a similar feeder at a different distance on the same heading or on (b) a visually distinct feeder located at the exact same location. We found that, within a short foraging range, bees relied heavily on the color and the shape of the food source and to a lesser extent on its distance from the hive. In the second experiment, we asked if moving the main landmark or the feeder (visual target) influenced recruitment dancing for the feeder. We found that foragers took longer to land and danced fewer circuits when the location of the food source, or a major landmark associated with it, changed. These results demonstrate that prominent visual attributes of food sources and landmarks are evidently more reliable than distance information and that foraging bees heavily utilize these visual cues at the later stages of their journey.


Assuntos
Comunicação Animal , Abelhas , Percepção Visual , Animais , Comportamento Apetitivo , Sinais (Psicologia)
14.
Chemosphere ; 240: 124926, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31726586

RESUMO

Insect pollinators such as bees and syrphid flies play a crucial role in pollinating many food crops, and their diversity and abundance may be influenced by pesticide application patterns. Over three years, we assessed the ecotoxicological impacts on the diversity and abundance of bees and syrphid flies between reduced-risk pesticide programs and standard, conventional pesticide programs in paired plots at six spatially distinct commercial apple orchards. In particular, we quantified pesticide inputs, environmental impact, and community response of bees and syrphids to these pesticide programs. Relative environmental impacts of reduced-risk versus conventional pesticide programs were calculated using Environmental Impact Quotient analysis, while ecological impacts were characterized by assessing the abundance, richness, and species assemblages of bees and syrphids. Adopting a reduced-risk pesticide program for apple pest management reduced the use (in terms of kg a.i./ha) of organophosphate and pyrethroid insecticides by approximately 97.6% and 100% respectively, but increased the use of neonicotinoid pesticides (acetamiprid, imidacloprid, thiacloprid) by 40.4% compared to the orchards under standard conventional pesticide program. Regardless of pesticide inputs, abundance, richness and species assemblages of bees and syrphids did not differ between reduced-risk and conventional pest management programs. However, the environmental impact of pesticide inputs was reduced by 89.8% in reduced-risk pesticide program. These findings suggest that the implementation of reduced-risk pesticide program may reduce pesticide environmental impact, in addition to being safer to farm workers, without adversely affecting the robust community composition of bees and syrphids in commercial apple orchards in the mid-Atlantic region.


Assuntos
Produtos Agrícolas , Malus , Controle de Pragas/métodos , Praguicidas , Polinização , Animais , Abelhas , Ecotoxicologia , Meio Ambiente , Insetos , Inseticidas , Neonicotinoides , Nitrocompostos , Piretrinas , Tiazinas
15.
J Agric Food Chem ; 68(3): 907-917, 2020 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-31842537

RESUMO

Bee pollen (BP) shows profound gut-protecting potentials. BP lipids (BPLs) mainly composed by phospholipids and polyunsaturated fatty acids might be one of the important contributors, while how BPL exerts gut-protecting effects and is transported through intestinal cell monolayers need to be investigated. Here, we exploited a strategy that combines an UPLC-Q-exactive orbitrap/MS-based lipidomics approach with a human intestinal cell (Caco-2) monolayer transport model, to determine the transepithelial transportation of BPL from Camellia sinensis L. (BPL-Cs), in pathological conditions. The results showed that BPL-Cs protected Caco-2 cells against dextran sulfate sodium (DSS)-induced intestinal barrier dysfunction by improving cell viability, maintaining membrane integrity, increasing tight junctions (ZO-1 and Claudin-1), and eliciting the expressions of antioxidative-related genes (NQO1, Nrf2, Txnrd1, and GSTA1). Lipidomics analysis revealed that DSS suppressed the transport and uptake of most of BPL-Cs including glycerophospholipids, sphingomyelins, and glycosylsphingolipids. Pretreatment with BPL-Cs significantly regulated glycerophospholipid and sphingolipid metabolisms, potentially involved in building permeability barriers and alleviating intestinal oxidative stress. Finally, eight classes of lipids were identified as the potential biomarkers for evaluating DSS-induced Caco-2 cell dysfunctions and BPL-intervened modulation. These findings shed light on the development of BPL as gastrointestinal protective food supplements in the future.


Assuntos
Células Epiteliais/metabolismo , Mucosa Intestinal/metabolismo , Metabolismo dos Lipídeos , Pólen/metabolismo , Animais , Abelhas , Transporte Biológico , Células CACO-2 , Camellia sinensis/química , Claudina-1/genética , Claudina-1/metabolismo , Glutationa Transferase/genética , Glutationa Transferase/metabolismo , Humanos , Lipídeos/química , Fator 2 Relacionado a NF-E2/genética , Fator 2 Relacionado a NF-E2/metabolismo , Pólen/química
16.
Chemosphere ; 239: 124799, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31518926

RESUMO

Terrestrial adult stages of freshwater insects may be exposed to pesticides by wind drift, over-spray, contact or feeding. However, studies addressing insecticide effects on freshwater invertebrates focus primarily on the impact of pesticides reaching the streams and potentially harming the aquatic juvenile stages. This is also reflected in the current risk assessment procedures, which do not include testing of adult freshwater insects. In order to assess the potential impact of insecticides on adult stages of freshwater insects, we exposed six common species to the insecticides Karate (lambda-cyhalothrin) and Confidor (imidacloprid). Dose-response relations were established, and LD50 estimates were compared to those of the honey bee, Apis mellifera L. (Hymenoptera: Apidae), which is the standard terrestrial test insect when pesticides are evaluated prior to commercial release. Generally, the tested species were more sensitive to the studied insecticides than the honey bee. In order to examine whether the sensitivity of adult stages of freshwater insects corresponds with the sensitivity of the juvenile stages of the same species, the ranking of the two life stages with respect to the toxicity of Karate was compared, revealing some correspondence, but also some dissimilarities. Our results strongly indicate that terrestrial adult stages of aquatic insects are not adequately protected by current risk assessment procedures.


Assuntos
Insetos/efeitos dos fármacos , Insetos/fisiologia , Inseticidas/toxicidade , Neonicotinoides/toxicidade , Nitrilos/toxicidade , Nitrocompostos/toxicidade , Piretrinas/toxicidade , Animais , Abelhas/efeitos dos fármacos , Dinamarca , Relação Dose-Resposta a Droga , Ecotoxicologia/métodos , Inseticidas/administração & dosagem , Dose Letal Mediana , Neonicotinoides/administração & dosagem , Nitrilos/administração & dosagem , Nitrocompostos/administração & dosagem , Piretrinas/administração & dosagem , Rios , Especificidade da Espécie , Poluentes Químicos da Água/toxicidade
17.
Sci Total Environ ; 700: 134500, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31627045

RESUMO

Flumethrin is a typical pyrethroid varroacide widely used for mite control in beekeeping worldwide. Currently, information on the toxicological characteristics of flumethrin on bees at sublethal concentrations is still lacking. To fill this gap in information, we performed a 48-h acute oral and 14-day chronic toxicity testing of flumethrin in newly emerged adult honey bees under laboratory conditions. Results showed that flumethrin had high acute toxicity to honey bees with a 48-h LD50 of 0.47 µg/bee (95% CI, 0.39 ∼ 0.57 µg/bee), which is higher than that of many other commercial pyrethroid insecticides, but lower than that of tau-fluvalinate. After 14 days of chronic exposure to flumethrin at 0.01, 0.10, and 1.0 mg/L, significant antioxidant response, detoxification, immune reaction, and apoptosis were observed in the midguts. These findings indicated that flumethrin had potential risks to bees, and it can disturb the homeostasis of bees at sublethal concentrations under longer exposure conditions. Flumethrin is highly lipophilic and easy to accumulate in beeswax; thus, careless practices might pose risks to colony development in commercial beekeeping and native populations. This laboratory study can serve as an early warning, and further studies are required to understand the real residual level of flumethrin in bees and the risks of flumethrin in field condition.


Assuntos
Abelhas/fisiologia , Inseticidas/toxicidade , Piretrinas/toxicidade , Animais , Criação de Abelhas , Dose Letal Mediana , Testes de Toxicidade Crônica
18.
J Sci Food Agric ; 100(1): 335-342, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31584691

RESUMO

BACKGROUND: Antibacterial activity of honey is not only crucial characteristic in selection of honey for medical usage but also an important honey quality marker. The aim of the study was to characterise the antibacterial potential of 29 honey samples representing the main types of multi-floral blossom and honeydew honeys produced in Switzerland. Antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa was expressed as a minimum inhibitory and bactericidal concentrations (MIC and MBC). Furthermore, the content of bee-derived glucose oxidase (GOX) and its enzymatic product, H2 O2 , were also evaluated. RESULTS: All honey samples successfully met basic defined criteria (moisture and hydroxymethylfurfural (HMF)) tested in this study. Honeydew honeys were the most effective honey samples and generated the highest levels of H2 O2 . A strong significant correlation was found between the overall antibacterial activity and the level of H2 O2 among all honey samples. Interestingly, the content of GOX in honey samples did not correlate with their antibacterial activity as well as H2 O2 production capacity. A weak antibacterial activity was determined in five floral honeys, most likely due to increased enzymatic activity of pollen-derived catalase. CONCLUSION: This study showed that antibacterial effect of Swiss honey samples is associated mainly with H2 O2 . © 2019 Society of Chemical Industry.


Assuntos
Antibacterianos/análise , Mel/análise , Animais , Antibacterianos/farmacologia , Abelhas , Catalase/análise , Glucose Oxidase/análise , Mel/classificação , Testes de Sensibilidade Microbiana , Pseudomonas aeruginosa/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos , Suíça
19.
Oecologia ; 192(2): 489-499, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31844986

RESUMO

High-severity wildfires, which can homogenize floral communities, are becoming more common relative to historic mixed-severity fire regimes in the Northern Rockies of the U.S. High-severity wildfire could negatively affect bumble bees, which are typically diet generalists, if floral species of inadequate pollen quality dominate the landscape post-burn. High-severity wildfires often require more time to return to pre-burn vegetation composition, and thus, effects of high-severity burns may persist past initial impacts. We investigated how wildfire severity (mixed- vs. high-severity) and time-since-burn affected available floral pollen quality, corbicular pollen quality, and bumble bee nutrition using percent nitrogen as a proxy for pollen quality and bumble bee nutrition. We found that community-weighted mean floral pollen nitrogen, corbicular pollen nitrogen, and bumble bee nitrogen were greater on average by 0.82%N, 0.60%N, and 1.16%N, respectively, in mixed-severity burns. This pattern of enhanced floral pollen nitrogen in mixed-severity burns was likely driven by the floral community, as community-weighted mean floral pollen percent nitrogen explained 87.4% of deviance in floral community composition. Only bee percent nitrogen varied with time-since-burn, increasing by 0.33%N per year. If these patterns persist across systems, our findings suggest that although wildfire is an essential ecosystem process, there are negative early successional impacts of high-severity wildfires on bumble bees and potentially on other pollen-dependent organisms via reductions in available pollen quality and nutrition. This work examines a previously unexplored pathway for how disturbances can influence native bee success via altering the nutritional landscape of pollen.


Assuntos
Incêndios Florestais , Animais , Abelhas , Dieta , Ecossistema , Estado Nutricional , Pólen , Polinização
20.
Insect Sci ; 27(1): 133-142, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29740981

RESUMO

Over 50 genera of bees release pollen from flower anthers using thoracic vibrations, a phenomenon known as buzz-pollination. The efficiency of this process is directly affected by the mechanical properties of the buzzes, namely the duration, amplitude, and frequency. Nonetheless, although the effects of the former two properties are well described, the role of buzz frequency on pollen release remains unclear. Furthermore, nearly all of the existing studies describing vibrational properties of natural buzz-pollination are limited to bumblebees (Bombus) and carpenter bees (Xylocopa) constraining our current understanding of this behavior and its evolution. Therefore, we attempted to minimize this shortcoming by testing whether flower anthers exhibit optimal frequency for pollen release and whether bees tune their buzzes to match these (optimal) frequencies. If true, certain frequencies will trigger more pollen release and lighter bees will reach buzz frequencies closer to this optimum to compensate their smaller buzz amplitudes. Two strategies were used to test these hypotheses: (i) the use of (artificial) vibrational playbacks in a broad range of buzz frequencies and amplitudes to assess pollen release by tomato plants (Solanum lycopersicum L.) and (ii) the recording of natural buzzes of Neotropical bees visiting tomato plants during pollination. The playback experiment indicates that although buzz frequency does affect pollen release, no optimal frequency exists for that. In addition, the recorded results of natural buzz-pollination reveal that buzz frequencies vary with bee genera and are not correlated with body size. Therefore, neither bees nor plants are tuned to optimal pollen release frequencies. Bee frequency of buzz-pollination is a likely consequence of the insect flight machinery adapted to reach higher accelerations, while flower plant response to buzz-pollination is the likely result of its pollen granular properties.


Assuntos
Abelhas/fisiologia , Lycopersicon esculentum/fisiologia , Polinização , Animais , Brasil , Pólen , Especificidade da Espécie , Vibração
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