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1.
J Agric Food Chem ; 67(33): 9210-9219, 2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31390203

RESUMO

The insecticidal and antifeedant activities of five 7-chloro-4-(1H-1,2,3-triazol-1-yl)quinoline derivatives were evaluated against the maize armyworm, Spodoptera frugiperda (J.E. Smith). These hybrids were prepared through a copper-catalyzed azide alkyne cycloaddition (CuAAC, known as a click reaction) and displayed larvicidal properties with LD50 values below 3 mg/g insect, and triazolyl-quinoline hybrid 6 showed an LD50 of 0.65 mg/g insect, making it 2-fold less potent than methomyl, which was used as a reference insecticide (LD50 = 0.34 mg/g insect). Compound 4 was the most active antifeedant derivative (CE50 = 162.1 µg/mL) with a good antifeedant index (56-79%) at concentrations of 250-1000 µg/mL. Additionally, triazolyl-quinoline hybrids 4-8 exhibited weak inhibitory activity against commercial acetylcholinesterase from Electrophorus electricus (electric-eel AChE) (IC50 = 27.7 µg/mL) as well as low anti-ChE activity on S. frugiperda larvae homogenate (IC50 = 68.4 µg/mL). Finally, molecular docking simulations suggested that hybrid 7 binds to the catalytic active site (CAS) of this enzyme and around the rim of the enzyme cavity, acting as a mixed (competitive and noncompetitive) inhibitor like methomyl. Triazolyl-quinolines 4-6 and 8 inhibit AChE by binding over the perimeter of the enzyme cavity, functioning as noncompetitive inhibitors. The results described in this work can help to identify lead triazole structures from click chemistry for the development of insecticide and deterrent products against S. frugiperda and related insect pests.


Assuntos
Inseticidas/síntese química , Inseticidas/farmacologia , Larva/efeitos dos fármacos , Quinolinas/química , Quinolinas/farmacologia , Spodoptera/efeitos dos fármacos , Acetilcolinesterase/química , Acetilcolinesterase/metabolismo , Animais , Inibidores da Colinesterase/síntese química , Inibidores da Colinesterase/química , Inibidores da Colinesterase/farmacologia , Química Click , Simulação por Computador , Proteínas de Insetos/antagonistas & inibidores , Proteínas de Insetos/química , Proteínas de Insetos/metabolismo , Inseticidas/química , Larva/enzimologia , Larva/crescimento & desenvolvimento , Simulação de Acoplamento Molecular , Doenças das Plantas/parasitologia , Spodoptera/enzimologia , Spodoptera/crescimento & desenvolvimento , Zea mays/parasitologia
2.
Exp Parasitol ; 205: 107734, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31394093

RESUMO

Parasitism by Haemonchus contortus is one of the main limiting factors in small ruminant production around the globe. Although several studies suggest the use of integrated management practices, these parasites have been controlled essentially with synthetic anthelmintic drugs. The resistance mechanism against the imidazothiazole derivative levamisole in Haemonchus contortus has not been fully described. Recently, resistance was associated with a 63bp deletion in the Hco-acr-8b gene that encodes a subunit for a nicotinic acetylcholine receptor. This study aimed to standardize a real time PCR (qPCR) protocol for levamisole resistance diagnosis in H. contortus populations based on this polymorphism and use it to characterize 23 field H. contortus populations obtained from different localities of Ceará State, Northeast Brazil. In addition, two populations of H. contortus were used as a standard of susceptibility and resistance, Inbred Strain Edinburgh (ISE) and Kokstad, respectively. Larval development tests (LDT) were performed on five field isolates and both EC50 and EC95 were estimated. LDT EC95 values provided a wider interval between susceptible and resistant populations than EC50 values (EC95 = 1.96-57.93 µM; EC50 = 0.05-0.39 µM), and were found to be more appropriate for differentiating them. Real time PCR results showed resistance allele frequencies ranged from 20.9 to 76.7%. Our results suggest that levamisole resistance may be present in field populations but it is not as widespread as benzimidazole resistance. This methodology may be useful to monitor levamisole resistance in field populations of H. contortus.


Assuntos
Antinematódeos/farmacologia , Resistência a Medicamentos/genética , Haemonchus/efeitos dos fármacos , Levamisol/farmacologia , Animais , Benzimidazóis/farmacologia , DNA de Helmintos/isolamento & purificação , Fezes/parasitologia , Frequência do Gene/genética , Hemoncose/tratamento farmacológico , Hemoncose/parasitologia , Hemoncose/veterinária , Haemonchus/genética , Haemonchus/crescimento & desenvolvimento , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Junção Neuromuscular/efeitos dos fármacos , Junção Neuromuscular/metabolismo , Reação em Cadeia da Polimerase em Tempo Real/veterinária , Receptores Colinérgicos/efeitos dos fármacos , Receptores Nicotínicos/efeitos dos fármacos , Alinhamento de Sequência/veterinária , Ovinos , Doenças dos Ovinos/tratamento farmacológico , Doenças dos Ovinos/parasitologia , Tetramizol/farmacologia
3.
World J Microbiol Biotechnol ; 35(7): 106, 2019 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-31267229

RESUMO

Xenorhabdus nematophila HB310 secreted the insecticidal protein toxin complex. Two chitinase genes, chi60 and chi70, were found in X. nematophila toxin complex locus. In order to clarify the function of two chitinases, chi60 and chi70 genes were cloned and expressed in Escherichia coli Transetta (DE3). As a result, we found that the Chi60 and Chi70 belonged to glycoside hydrolases (GH) family 18 with a molecular mass of 65 kDa and 78 kDa, respectively. When colloidal chitin was treated as the substrate, Chi60 and Chi70 were proved to have the highest enzymatic activity at pH 6.0 and 50 °C. Chi60 and Chi70 had obvious growth inhibition effect against the second larvae of Helicoverpa armigera with growth inhibiting rate of 81.99% and 90.51%. Chi70 had synergistic effect with the insecticidal toxicity of Bt Cry 1Ac, but the Chi60 had no synergistic effect with Bt Cry 1Ac. Chi60 and Chi70 showed antifungal activity against Alternaria brassicicola, Verticillium dahliae and Coniothyrium diplodiella. The results increased our understanding of the chitinases produced by X. nematophila and laid a foundation for further studies on the mechanism of the chitinases.


Assuntos
Antifúngicos/farmacologia , Quitinases/antagonistas & inibidores , Quitinases/genética , Quitinases/metabolismo , Xenorhabdus/metabolismo , Alternaria/efeitos dos fármacos , Animais , Ascomicetos/efeitos dos fármacos , Quitina/metabolismo , Quitinases/classificação , Clonagem Molecular , Sinergismo Farmacológico , Ensaios Enzimáticos , Estabilidade Enzimática , Escherichia coli/genética , Expressão Gênica , Glicosídeo Hidrolases/genética , Concentração de Íons de Hidrogênio , Inseticidas/metabolismo , Inseticidas/farmacologia , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Peso Molecular , Mariposas/efeitos dos fármacos , Mariposas/crescimento & desenvolvimento , Micotoxinas/genética , Micotoxinas/metabolismo , Filogenia , Domínios Proteicos , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Temperatura Ambiente , Verticillium/efeitos dos fármacos , Xenorhabdus/genética
4.
J Insect Sci ; 19(4)2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-31343690

RESUMO

Bombyx mori (Lepidoptera: Bombycidae) is an important economic insect and a classic Lepidopteran model system. Although immune-related genes have been identified at a genome-wide scale in the silkworm, proteins involved in immune defense of the silkworm have not been comprehensively characterized. In this study, two types of bacteria were injected into the silkworm larvae, Gram-negative Escherichia coli (Enterobacteriales: Enterobacteriaceae), or Gram-positive Staphylococcus aureus (Bacillales: Staphylococcaceae). After injection, proteomic analyses of hemolymph were performed by liquid chromatography-tandem mass spectrometry. In total, 514 proteins were identified in the uninduced control group, 540 were identified in the E. coli-induced group, and 537 were identified in the S. aureus-induced group. Based on Uniprot annotations, 32 immunological recognition proteins, 28 immunological signaling proteins, and 21 immunological effector proteins were identified. We found that 127 proteins showed significant upregulation, including 10 immunological recognition proteins, 4 immunological signaling proteins, 11 immunological effector proteins, and 102 other proteins. Using real-time quantitative polymerase chain reaction in the fat body, we verified that immunological recognition proteins, signaling proteins, and effector proteins also showed significant increases at the transcriptional level after infection with E. coli and S. aureus. Five newly identified proteins showed upregulation at both protein and transcription levels after infection, including 30K protein, yellow-d protein, chemosensory protein, and two uncharacterized proteins. This study identified many new immune-related proteins, deepening our understanding of the immune defense system in B. mori. The data have been deposited to the iProX with identifier IPX0001337000.


Assuntos
Bombyx/genética , Bombyx/imunologia , Escherichia coli/fisiologia , Proteínas de Insetos/imunologia , Proteoma/imunologia , Staphylococcus aureus/fisiologia , Animais , Bombyx/crescimento & desenvolvimento , Bombyx/microbiologia , Proteínas de Insetos/análise , Larva/crescimento & desenvolvimento , Larva/imunologia , Larva/microbiologia , Proteoma/análise , Proteômica
5.
J Insect Sci ; 19(4)2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-31346626

RESUMO

Striacosta albicosta (Smith) is a key pest of maize and dry beans in North America. It has expanded its distribution from the western Great Plains of the United States to the Great Lakes region in the United States and Canada. There has been limited research on the baseline biological aspects of this insect under controlled conditions. The objective of this study was to detail the biological parameters of S. albicosta feeding on an artificial diet under laboratory conditions. Overall survival from neonate to adult at 26.6 ± 1°C was 36.72% and the total developmental time was approximately 110 d. Survival of the egg, larval, prepupal, and pupal stages were 75.71, 98.50, 51.78, and 95.10%, respectively. Average duration of the egg, larval, prepupal, and pupal stages was 4.64, 28.20, 41.50, and 25.91 d, respectively. During the larval stage, 92.50% of larvae developed through seven instars and the remaining through six instars. Larvae that developed through six and seven instars exhibited a mean growth ratio of 1.60 and 1.47, respectively; however, there was no difference in pupal weight. Eggs laid by field-mated moths showed a fertility of 75.71%, compared with 4.18% from laboratory-reared moths. These data suggest that S. albicosta develop primarily through seven instars and the most vulnerable developmental stage is the prepupa. Laboratory conditions strongly affected fertility success. Information presented here greatly expands our understanding of S. albicosta biology, which can be used to improve the efficiency of laboratory bioassays and management techniques for this critical crop pest.


Assuntos
Traços de História de Vida , Mariposas/fisiologia , Ração Animal/análise , Animais , Dieta , Feminino , Larva/crescimento & desenvolvimento , Larva/fisiologia , Mariposas/crescimento & desenvolvimento , Óvulo/crescimento & desenvolvimento , Óvulo/fisiologia , Pupa/crescimento & desenvolvimento , Pupa/fisiologia , Reprodução
6.
J Insect Sci ; 19(4)2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-31260529

RESUMO

Spodoptera frugiperda (J.E. Smith, 1797) is considered a key pest of maize. However, the artificial diets used for rearing this insect in the laboratory do not contain corn. The aim of this study was to evaluate the biology and to compare the food consumption by S. frugiperda, as well as the food preference of the larvae in the standard diet and the corn-based diet. Three of the following diets were evaluated: a standard diet based on beans (D1), a diet with corn flour as substitute for wheat germ (D2), and a diet replacing beans with green corn (D3). The biological parameters evaluated were period and survival of larvae and pupae; weight of male and female pupae; sex ratio; fecundity; egg incubation period; and adult longevity. The nutritional indices were determined and the biological data obtained were used to determine the parameters of fertility life tables; we also performed a multiple-choice test (feeding test). Larval development of S. frugiperda occurred in all three diets, although without oviposition by females developed from larval fed on D2. There was no difference among the diets in relation to the fertility life table parameters. The diet D2 resulted in better ingestion, digestion, assimilation, and conversion of food, but was associated with a metabolic cost to assimilate the food. Using a multiple-choice test, we observed that the larvae preferred diet D2. Based on our results, the most adequate diets for rearing S. frugiperda in the laboratory are D1 and D3.


Assuntos
Dieta , Spodoptera/crescimento & desenvolvimento , Zea mays , Animais , Larva/crescimento & desenvolvimento
7.
J Insect Sci ; 19(4)2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-31319420

RESUMO

Trichogramma spp., among the most common parasitoids used for augmentation biological control, often are mass-reared on eggs of the Mediterranean flour moth, Ephestia kuehniella (Zeller). To evaluate removal of nutritional components from the E. kuehniella larval diet and reduce production costs, colonies were maintained using one of three diets: a standard diet consisting of eight ingredients, a reduced diet containing whole wheat flour, glycerol, and Brewer's yeast, or a third minimal diet of only whole wheat flour. The standard diet sustained the fastest larval development, female pupae with the greatest mass, the highest level of adult emergence, and production of the most eggs per female. Eggs from moths reared as larvae on the standard or reduced diet had equivalent mass, length, and percent hatch. Females from larvae fed the minimal diet produced eggs with the least mass that were shorter and had the lowest percent hatch. Eggs from the three E. kuehniella colonies were exposed separately to Trichogramma brassicae Bezdenko females to determine their acceptance for oviposition. More of the eggs from the standard diet were parasitized by the females, eggs from the reduced and minimal diets being less acceptable. The percent emergence of the parasitoids was the same regardless of diet; however, the largest wasps emerged from the standard diet eggs and a greater proportion of them were females. Consequently, the standard E. kuehniella larval diet resulted in the highest rate of reproduction and robust eggs that produced superior T. brassicae wasps.


Assuntos
Dieta , Interações Hospedeiro-Parasita , Mariposas/parasitologia , Vespas/fisiologia , Animais , Feminino , Larva/crescimento & desenvolvimento , Mariposas/crescimento & desenvolvimento , Óvulo/parasitologia
8.
Rev Bras Parasitol Vet ; 28(3): 473-478, 2019 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-31340250

RESUMO

Amblyomma scalpturatum is a tick species that is unique to South America. It is commonly associated with the Amazon biome and has been reported in some Brazilian states. This tick species exhibits host specificity: it parasitizes tapirs and suidae. Its role in transmitting pathogens to humans is still unknown. Amblyomma scalpturatum is known to be a human-biting tick; however, there is only one report showing that humans make suitable hosts for this species. The knowledge of tick fauna is lacking in the Acre State. This study collected free-living ticks with the aim of finding new records in Acre State. Collections were carried out in Amazon forest fragments in Rio Branco municipality. An A. scalpturatum specimen was identified and submitted sequencing of the ITS-2 gene. This study presents the first molecular confirmation of A. scalpturatum collected in situ in Acre State, North Region, Brazil. This study also presents the first record of a successfully completed feeding by an A. scalpturatum nymph on a human host in the North region of Brazil. Further investigation is needed to ascertain the complete life cycle of this tick species, its seasonality in the environment, and its relationship to pathogens and competence to transmit them.


Assuntos
Ixodidae/classificação , Larva/crescimento & desenvolvimento , Infestações por Carrapato/parasitologia , Animais , Feminino , Humanos , Ixodidae/anatomia & histologia , Ixodidae/genética , Masculino , Filogenia , Reação em Cadeia da Polimerase
9.
Environ Monit Assess ; 191(8): 497, 2019 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-31312907

RESUMO

A few studies had determined the effects of silver nanoparticles on the development of Drosophila melanogaster. However, none had addressed its genotoxic effects on specific larval cells of the fly in details. This study was conducted to determine the effects of silver nanoparticle on the development of D. melanogaster with simultaneous evaluation of its genotoxic potential on specific larval cell types that play important roles in immunological defenses as well as growth and development. Five male and five female flies were maintained in standard Drosophila melanogaster culture medium containing varying concentrations of silver nanoparticles, i.e., 25, 50, 100, 200, and 300 mg/l with control culture medium containing no nanoparticle. Total time needed for stage-specific development, population yield, and genotoxic effects on third instar larval polytene chromosomes, hemocytes, and neuroblasts was determined. Body pigmentation of pupae and young adults was examined visually. In comparison with control, silver nanoparticles dose dependently inhibited the metamororphosis and population yields of pupae and young adults of Drosophila melanogaster. Every concentration of the nanoparticles inhibited pupa to adult conversion, with huge reduction under the influence of nanoparticle concentration of 100 mg/ml and above. Developmental inhibition was accompanied by dose-dependent and significant structural aberrations of larval polytene chromosomes and deformities of hemocytes and neuroblasts. Pupae and young adults also exhibited gradual discoloration of body with the increase in exposure to nanoparticle concentration.


Assuntos
Dano ao DNA , Drosophila melanogaster/efeitos dos fármacos , Larva/efeitos dos fármacos , Nanopartículas Metálicas/toxicidade , Células-Tronco Neurais/efeitos dos fármacos , Prata/toxicidade , Animais , Relação Dose-Resposta a Droga , Drosophila melanogaster/genética , Drosophila melanogaster/crescimento & desenvolvimento , Monitoramento Ambiental , Feminino , Larva/genética , Larva/crescimento & desenvolvimento , Masculino , Pupa/efeitos dos fármacos , Pupa/genética , Pupa/crescimento & desenvolvimento
10.
J Sci Food Agric ; 99(13): 5962-5968, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31215022

RESUMO

BACKGROUND: Cadra (=Ephestia) cautella (Walker) is a serious cosmopolitan pest that can feed on a wide variety of stored foods. It is controlled mainly by fumigation with phosphine, to which strong resistance has been documented in major stored-product insects in many countries. The need for reliable, user- and environmentally friendly alternatives is therefore high on the agenda to avoid the development of potential resistance and to reduce human exposure to toxic insecticides. Two modified atmospheres (MAs) composed of high carbon dioxide (CO2 ) and low oxygen (O2 ) (90% and 96% CO2 in air) were studied at the laboratory at 20 °C and 65 ± 3% relative humidity (RH) against C. cautella. RESULTS: Eggs (1, 2, and 3 days old), young and mature larvae (10 and 20 days old), pupae (1, 2 and 3 days old) and adults (1 day old) were exposed to two MAs consisting of high CO2 and low O2 for the range of 2 to 104 h. Eggs, old larvae, and pupae were found to be the most tolerant. Adults were rather easily killed and young larvae were the most susceptible. Lethal exposure time (LT99 ) values were between 11.74 h and 128.97 h. CONCLUSION: Modified atmospheres consisting of high CO2 and low O2 offer an affordable combination to control C. cautella effectively. From the perspective of economics and efficacy, 90% CO2 might be the concentration of choice. © 2019 Society of Chemical Industry.


Assuntos
Dióxido de Carbono/farmacologia , Controle de Insetos/métodos , Mariposas/efeitos dos fármacos , Animais , Atmosfera/análise , Dióxido de Carbono/análise , Controle de Insetos/instrumentação , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Mariposas/crescimento & desenvolvimento , Oxigênio/análise , Pupa/efeitos dos fármacos , Pupa/crescimento & desenvolvimento
11.
Mar Pollut Bull ; 142: 54-57, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31232336

RESUMO

Plastic debris in the oceans is a major and growing problem in global environmental pollution. There are increasing concerns that plastic debris is a source of contaminant, either added during manufacturing or adsorbed from the environment. However, there is little information about the acute toxicity of leachates from plastic debris on marine organisms. In this study, we conducted experiments to evaluate the toxicity of leachates from two single-use polyethylene plastic bags (PB1 and PB2) with the embryo and larvae of the commercial clam Meretrix meretrix. Results showed that fertilization of the embryos was not affected by plastic leachates, but the developments of D-veliger larvae, including survival, deformity, and shell height, were significantly affected by plastic leachates from both PB1 and PB2 compared to the controls of filtered seawater. We speculate that compounds leaching from plastic bags are responsible for the observed toxicity. Therefore, leaching toxicity from plastic debris should be considered when assessing the risks of plastic pollution in the oceans.


Assuntos
Bivalves/efeitos dos fármacos , Polietileno/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Bivalves/crescimento & desenvolvimento , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Alimentos Marinhos , Água do Mar
12.
Environ Pollut ; 251: 879-884, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31234253

RESUMO

Genotoxic analyses are commonly used in ecotoxicological studies as early biomarkers to investigate the potential effects of environmental contaminants on biological models. Several pollutants can induce DNA damage and, therefore, counting micronuclei and other nuclear abnormalities are efficient tools to evaluate genotoxicity. Some pollutants such as 4-nonylphenol (NP), a detergent used mainly in industries, and Cyproterone Acetate (CPA), an antiandrogenic medicine, have already shown genotoxic effects on some vertebrates. However, although amphibians are considered bioindicators of environmental quality and their populations are declining worldwide, the effects of these compounds on anurans are not yet known and, therefore, we believe that it is important to investigate such effects on anurans. Since water contamination is one of the ultimate causes of amphibian decline, ecotoxicological studies are important to discuss the appropriate solutions to avoid species extinction. Thus, this study investigates the genotoxic effects on Rana catesbeiana tadpoles and juveniles after being exposed to 1, 10 and 100 µg/L NP and 0.025, 0.25 and 2.5 ng/L CPA, by counting the nuclear abnormalities after exposure. The laboratory experiments lasted 28 days. The experimental conditions were the same except for the water volume since tadpoles and juveniles exhibit different habits at different developmental stages. Compared to juveniles, tadpoles were more susceptible to both compounds as indicated by the increased nuclear abnormalities observed in the highest NP concentration and all tested CPA concentrations. The juveniles, on the other hand, responded only to the two highest CPA concentrations. We concluded that CPA, even at very low concentrations, is extremely harmful to both anuran developmental stages and, particularly, to tadpoles. The significant effects observed on tadpoles is an important outcome of this study since 100 µg/L or higher NP concentrations are frequently detected in the environment.


Assuntos
Anuros/embriologia , Acetato de Ciproterona/toxicidade , Larva/efeitos dos fármacos , Fenóis/toxicidade , Rana catesbeiana/embriologia , Poluentes Químicos da Água/toxicidade , Animais , Anuros/genética , Núcleo Celular/efeitos dos fármacos , Dano ao DNA/efeitos dos fármacos , Dano ao DNA/genética , Poluição Ambiental , Larva/crescimento & desenvolvimento , Rana catesbeiana/genética
13.
Biol Bull ; 236(3): 159-173, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31167086

RESUMO

Ocean acidification poses a significant threat to calcifying invertebrates by negatively influencing shell deposition and growth. An organism's performance under ocean acidification is not determined by the susceptibility of one single life-history stage, nor is it solely controlled by the direct physical consequences of ocean acidification. Shell development by one life-history stage is sometimes a function of the pH or pCO2 levels experienced during earlier developmental stages. Furthermore, environmental factors such as access to nutrition can buffer organismal responses of calcifying invertebrates to ocean acidification, or they can function as a co-occurring stressor when access is low. We reared larvae and juveniles of the planktotrophic marine gastropod Crepidula fornicata through combined treatments of nutritional stress and low pH, and we monitored how multiple stressors endured during the larval stage affected juvenile performance. Shell growth responded non-linearly to decreasing pH, significantly declining between pH 7.6 and pH 7.5 in larvae and juveniles. Larval rearing at pH 7.5 reduced juvenile growth as a carryover effect. Larval rearing at pH 7.6 reduced subsequent juvenile growth despite the absence of a negative impact on larval growth, demonstrating a latent effect. Low larval pH magnified the impact of larval nutritional stress on competence for metamorphosis and increased carryover effects of larval nutrition on juvenile growth. Trans-life-cycle effects of larval nutrition were thus modulated by larval exposure to ocean acidification.


Assuntos
Gastrópodes/crescimento & desenvolvimento , Água do Mar/química , Fenômenos Fisiológicos da Nutrição Animal , Exoesqueleto/crescimento & desenvolvimento , Animais , Dióxido de Carbono/química , Concentração de Íons de Hidrogênio , Larva/crescimento & desenvolvimento , Metamorfose Biológica , Estresse Fisiológico
14.
Biol Bull ; 236(3): 174-185, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31167087

RESUMO

Two juvenile specimens of a new species of Oreaster were collected at Parque Nacional Arrecife Alacranes and Triángulos Oeste in the southern Gulf of Mexico. DNA of mitochondrial loci identifies them as members of the same clade as cloning larvae of Oreaster found abundantly in waters of the Florida Current-Gulf Stream system, and distinct from Oreaster clavatus and Oreaster reticulatus, the two known Oreasteridae species in the North Atlantic. Larvae from the new species of Oreaster persist as clones but also metamorphose and settle to the benthos with typical asteroid morphology.


Assuntos
Estrelas-do-Mar/classificação , Estrelas-do-Mar/crescimento & desenvolvimento , Animais , Golfo do México , Larva/classificação , Larva/crescimento & desenvolvimento , Metamorfose Biológica , Polimorfismo de Nucleotídeo Único , Análise de Sequência de DNA , Especificidade da Espécie , Estrelas-do-Mar/genética
15.
Biol Bull ; 236(3): 186-198, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31167091

RESUMO

Sporadic fluctuations in food availability may affect larval biology and post-metamorphic development in many marine invertebrates. In an experimental study in the laboratory, we investigated whether different regimes (1, 3, and 5 days) of initial starvation or feeding affect the survival and duration of the last planktotrophic larval stage (i.e., megalopa) of the neotropical mangrove fiddler crab Leptuca cumulanta. Newly metamorphosed crabs originating from megalopae starved for 1 and 3 days were cultured through the first 5 juvenile stages to further evaluate whether prior nutritional experience affects the post-larval performance of this species. All megalopae that were starved continuously died, while 80% of the larvae that were fed constantly metamorphosed successfully into the juvenile stage. Megalopae initially starved for 3 and 5 days exhibited lower survival (55% and 30% of larval metamorphosis, respectively) than larvae starved for only 1 day (85%) or fed constantly. The starvation periods (1, 3, and 5 days) also significantly prolonged the mean megalopal stage duration (12.8, 13.9, and 14.3 days, respectively) compared to the continuous feeding regime (10.6 days). Survival of the megalopae subjected to different periods of initial feeding (1, 3, and 5 days) was significantly lower (15.0%, 57.5%, and 62.5%, respectively) than survival of the larvae fed constantly. The mean megalopal stage duration, by contrast, did not vary among megalopae initially fed for 3 and 5 days or fed continuously (10.4 days). The larval starvation did not affect survival and carapace shape of juveniles, but it did alter their intermolt period, growth, and body size. These carryover effects were stronger in the first juvenile crab stage than in other juvenile stages. Our results indicate that the timing and duration of the starvation or feeding regime experienced by the megalopae may affect their successful survival and developmental period until metamorphosis to juvenile life. In addition, the preceding larval starvation associated with a prolonged larval period may also affect early juvenile performance in specific crab stages of L. cumulanta.


Assuntos
Braquiúros/crescimento & desenvolvimento , Privação de Alimentos , Metamorfose Biológica , Fenômenos Fisiológicos da Nutrição Animal , Animais , Braquiúros/fisiologia , Larva/crescimento & desenvolvimento , Larva/fisiologia
16.
Exp Appl Acarol ; 78(2): 295-314, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31154548

RESUMO

The peanut red spider mite, Tetranychus ogmophallos Ferreira and Flechtmann (Acari: Tetranychidae), is an important pest of peanut in Brazil and is considered a quarantine pest in other countries. This study investigates the development, reproduction, survival and life table parameters of T. ogmophallos on five peanut cultivars-three with high levels of oleic acid [high oleic] and recently released: Granoleico, IAC OL 3 and IAC 503; and two regular and previously used by farmers: Runner IAC 886, IAC Tatu ST 3-and two breeding lines (L. 8008 and L. 322) in the growth chamber. There were differences between the developmental times of all immature stages, the oviposition period, fecundity and adult longevity of T. ogmophallos reared on the peanut cultivars and breeding lines. The longest duration of the immature stage and lowest fecundity occurred on cultivars Granoleico and Runner IAC 886, and breeding line L. 322, which also displayed the lowest intrinsic rate of increase (r), finite rate of increase (λ) and net reproductive rate (R0) and the shortest mean generation time (T). The highest fitness occurred on the IAC Tatu ST, IAC OL 3, IAC 503 and L. 8008. Our study shows that peanut cultivars belonging to the group with high oleic trait and recently released (IAC OL 3 and IAC 503) are susceptible to T. ogmophallos, except Granoleico, which is resistant. The regular and previously used cultivar Runner IAC 886 and breeding line L. 322 are resistant to the peanut red spider mite.


Assuntos
Antibiose , Arachis/fisiologia , Tetranychidae/fisiologia , Animais , Arachis/genética , Brasil , Feminino , Fertilidade , Larva/crescimento & desenvolvimento , Larva/fisiologia , Tábuas de Vida , Longevidade , Masculino , Ninfa/crescimento & desenvolvimento , Ninfa/fisiologia , Oviposição , Tetranychidae/crescimento & desenvolvimento
17.
Forensic Sci Int ; 301: 326-330, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31202145

RESUMO

On 11 June 1959, the body of 12-year old Lynne Harper was discovered in a woodlot northeast of Clinton, Ontario. Although insect evidence was photographed and collected at the scene and autopsy, this evidence was not used in the 1959 trial. Instead, time of death was pinpointed to a 45-min window of 1900-1945 h on 9 June 1959 based on stomach content analysis. Based on circumstantial evidence and this time frame that he was the last suspect to see her alive, 14-year old Steven Truscott was convicted of her murder. He was scheduled to be hanged, but a temporary reprieve postponed his execution. In 1960, his death sentence was commuted to life imprisonment. Truscott was the youngest person to be sentenced to death in Canada, and his case provided the major impetus toward abolition of the death penalty in Canada. Truscott always maintained his innocence. In 2001, the Association in Defence of the Wrongly Convicted filed an appeal to have the case reopened. In 2006, the authors of this paper were contacted by Attorneys James Lockyer and Phil Campbell of the LCP Law Firm in Toronto to investigate this case. Fresh evidence was presented at the Ontario Court of Appeal in 2006-2007 including testimony of 3 forensic entomologists. This resulted in controversy regarding identification of the insects and assumptions of insect behaviour that affected the postmortem interval estimate. Lack of scientific evidence for the controversial theories proposed by one testifying entomologist resulted in disregarding his testimony. Instead, testimony by VanLaerhoven and Merritt was accepted. Based on their analysis and a re-creation experiment of the insect evidence, initial fly colonization occurred during daylight hours of 10 June 1959. The collected larvae were not likely to have been deposited on the body before dark (2140 h) on 9 June 1959 as this would have resulted in significantly larger and more advanced larval instar than were collected at the scene or autopsy. This analysis, together with a pathology reanalysis of stomach content analysis, demonstrated that the original estimate of time of death was unreliable. Truscott was with numerous witnesses prior to 1900 h and after 2000 h on 9 June 1959, thus the estimate of time of death was the most critical evidence in the original 1959 trial and the 2006-2007 appeal. On 28 August 2007, his conviction was overturned, declared a wrongful conviction and miscarriage of justice. Steven Truscott was acquitted of the murder charges.


Assuntos
Dípteros/fisiologia , Comportamento Alimentar , Homicídio , Mudanças Depois da Morte , Adolescente , Animais , Canadá , Criança , Entomologia , Feminino , Medicina Legal/métodos , Conteúdo Gastrointestinal , Humanos , Larva/crescimento & desenvolvimento , Masculino , Modelos Animais , Oviposição/fisiologia , Suínos
18.
Parasit Vectors ; 12(1): 311, 2019 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-31234914

RESUMO

BACKGROUND: The cuticle is an indispensable structure that protects the mosquito against adverse environmental conditions and prevents pathogen entry. While most cuticles are hard and rigid, some parts of cuticle are soft and flexible to allow movement and blood-feeding. It has been reported that 3, 4-dihydroxyphenylacetaldehyde (DOPAL) synthase is associated with flexible cuticle formation in Aedes aegypti. However, the molecular function of DOPAL synthase in the ontogenesis of mosquito remains largely unknown. In this study, we characterized gene expression profiles of DOPAL synthase and investigated its functions in larvae and female adults of Aedes agypti by RNAi. RESULTS: Our results suggest that the expression of DOPAL synthase is different during development and the transcriptional level reached its peak at the female white pupal stage, and DOPAL synthase was more highly expressed in the cuticle and midgut than other tissues in the adult. The development process from larva to pupa was slowed down strikingly by feeding the first-instar larvae with chitosan/DOPAL synthase dsRNA nanoparticles. A qRT-PCR analysis confirmed that the dsRNA-mediated transcription of the DOPAL synthase was reduced > 50% in fourth-instar larvae. Meanwhile, larval molt was abnormal during development. Transmission electron microscopy results indicated that the formation of endocuticle and exocuticle was blocked. In addition, we detected that the dsDOPAL synthase RNA caused significant mortality when injected into the female adult mosquitoes. CONCLUSIONS: Our findings demonstrate that DOPAL synthase plays a critical role in mosquito larval development and adult survival and suggest that DOPAL synthase could be a good candidate gene in RNAi intervention strategies in mosquito control.


Assuntos
Aedes/enzimologia , Aedes/genética , Descarboxilases de Aminoácido-L-Aromático/genética , Proteínas de Insetos/genética , Larva/crescimento & desenvolvimento , Interferência de RNA , Animais , Feminino , Perfilação da Expressão Gênica , Técnicas de Silenciamento de Genes , Controle de Mosquitos/métodos
19.
Environ Monit Assess ; 191(7): 454, 2019 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-31222463

RESUMO

It is well-known that the metamorphosis process in amphibians is dependent on thyroid hormones. Laboratory studies have shown that several environmental contaminants can affect the function of thyroid hormones leading to alterations in the amphibian metamorphosis. The basic idea of the present study was to elucidate if the amphibian metamorphosis might be a useful tool as biomarker for effect-based environmental monitoring, examining wild tadpoles for potential thyroid hormone disruption. A laboratory test was performed to identify the responses from exposure to 6-propylthiouracil (PTU), which has a well-known mechanism on the thyroid system, on Swedish tadpoles from the Rana genus. This was followed by an environmental monitoring study where tadpoles of Rana arvalis, R. temporaria, and Bufo bufo were sampled from various sites in Sweden. Morphological data such as body weight, histopathological measurements of the thyroid glands, and environmental parameters were recorded. The results revealed that Rana tadpoles respond similar as other amphibians to PTU exposure, with interrupted development and increased size relative to the developmental stage. Data on some wild tadpoles showed similar features as the PTU exposed, such as high body weight, thus suggesting potential thyroid disrupting effects. However, histological evaluation of thyroid glands and pesticide analyses of the water revealed no clear evidence of chemical interactions. To a minor degree, the changes in body weight may be explained by natural circumstances such as pH, forest cover, and temperature. The present study cannot fully explain whether the high body weights recorded in some tadpoles have natural or chemical explanations. However, the study reveals that it is clearly achievable to catch tadpoles in suitable stages for the use in this type of biomonitoring and that the use of these biomarkers for assessment of thyroid disruption seems to be highly relevant.


Assuntos
Antitireóideos/toxicidade , Bufonidae/embriologia , Monitoramento Ambiental/métodos , Larva/crescimento & desenvolvimento , Praguicidas/toxicidade , Propiltiouracila/toxicidade , Ranidae/embriologia , Glândula Tireoide/patologia , Animais , Metamorfose Biológica , Suécia , Glândula Tireoide/efeitos dos fármacos , Hormônios Tireóideos/metabolismo
20.
Bull Environ Contam Toxicol ; 103(2): 213-217, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31209517

RESUMO

In ecotoxicological assays, previously selected and standardized organism tests are exposed to an environmental sample. Some species of the Chironomus genus have been extensively used in ecotoxicological assays. Among these, Chironomus tentans is usually utilized in the USA and Chironomus sancticaroli in Brazil. We conducted ecotoxicological bioassays to compare a population of C. sancticaroli, kept for 6 years under laboratory conditions, with a sylvatic population of the same species, collected in the field. The aim was to test the hypothesis that populations of C. sancticaroli, maintained in the laboratory for long periods, could have a different response to stressors/substances. We analyzed the responses of C. sancticaroli for potassium chloride, zinc chloride, potassium dichromate, linear alkylbenzene sulphonate (LAS) and caffeine. The results showed no significant differences between the two populations in the analyses and seems to indicate the possible use of C. sancticaroli from populations kept in the laboratory for long periods.


Assuntos
Chironomidae/efeitos dos fármacos , Ecotoxicologia/métodos , Monitoramento Ambiental/métodos , Poluentes Químicos da Água/toxicidade , Animais , Bioensaio , Brasil , Chironomidae/crescimento & desenvolvimento , Ecotoxicologia/normas , Monitoramento Ambiental/normas , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento
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