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1.
Ecotoxicol Environ Saf ; 207: 111214, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32890949

RESUMO

The potential risk of Bt (Bacillus thuringiensis) crops on non-target organisms (NTOs) has drawn a lot of public concerns. Despite a series of risk assessments of Bt crops on NTOs has been conducted, a quantitative approach which could support a precise judgment of their safety is required. In the present work, hazard quotient (HQ) was applied in the safety evaluation of three Bt rice events (Cry1Ab, Cry1C and Cry2Aa rice) on NTOs. Eight NTOs in different functional guilds associated with Bt rice were selected to conduct the tests. The results showed that the HQs of three Bt rice events for eight NTOs were all below the trigger value 1, while the HQ of Cry1Ab rice for one target pest Chilo suppressalis was three times higher than 1. Our results assured the reliability of the HQ and indicated that the three Bt rice events would pose no risks to the eight NTOs. Further testing of three Bt proteins on biological parameters of one NTO Nasonia virtipennis under no observed adverse effect concentration (NOAEC) confirmed the robustness of HQ assessment. We recommend that the HQ could be applied in tier-1 risk assessments of Bt crops on NTOs as a reference data standard, which would provide more clear and credible safety information of transgenic crops for the public and policy makers.


Assuntos
/toxicidade , Endotoxinas/toxicidade , Proteínas Hemolisinas/toxicidade , Oryza/genética , Plantas Geneticamente Modificadas , Animais , Bacillus thuringiensis/genética , Proteínas de Bactérias/metabolismo , Produtos Agrícolas/metabolismo , Endotoxinas/metabolismo , Proteínas Hemolisinas/genética , Mariposas , Oryza/metabolismo , Controle Biológico de Vetores/métodos , Reprodutibilidade dos Testes
2.
Food Chem ; 339: 128014, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33152857

RESUMO

The research of host insect-resistance is a hot spot in the field of controlling storage pests. However, the mechanism of host resistance to storage pests is still unclear. Some researchers think it is related to grain cracking characters of rice husk, while others have linked it to volatile compounds in rice grains. In this paper, using 117 micro-core germplasm resources of rice and the investigation on the rate of insect damage, sixteen materials with different insect-resistance and four with significant difference in insect resistance were selected. Pentanamide, a volatile compound in rice, was analyzed by gas chromatography-mass spectrometry (GC-MS) and found to be negatively correlated with the rate of insect damage of rice materials. The bioassay results showed that 8% Pentanamide had a good effect on controlling storage pests and trapping pests. This study provided direct evidence for the correlation between rice volatile compounds and their host insect-resistant mechanisms.


Assuntos
Armazenamento de Alimentos , Insetos , Oryza/química , Controle Biológico de Vetores/métodos , Compostos Orgânicos Voláteis/análise , Animais
3.
J Insect Sci ; 20(6)2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-33135749

RESUMO

The entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin (Hypocreales: Cordycipitaceae) has been widely studied against a wide range of arthropod pests, including many of medical and veterinary importance. New investigators must sort through a wide array of published methods for the production, harvest, storage, and bioassay methods for this pathogen. Simplified methods for production of conidia using Sabouraud dextrose agar with yeast (SDYA) plates and two conidial harvesting methods are described. Dry harvesting yields conidia that are ready to incorporate into dusts and food baits, but the fungal product includes mycelial debris that can hamper quantification and introduces variable amounts of unwanted bulk. Wet harvesting with filtration produces a cleaner product that is immediately ready for testing in liquid formulations. Examples of bioassays with house flies are presented that include conidia applied topically to the dorsal thorax for dose-mortality assays and conidial suspensions applied to filter paper disks for concentration mortality assays.


Assuntos
Beauveria , Controle de Insetos/métodos , Muscidae/microbiologia , Micologia/métodos , Controle Biológico de Vetores/métodos , Animais
4.
PLoS One ; 15(11): e0230541, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33170844

RESUMO

The development of insecticide-resistance mechanisms in aphids has been associated with inhibitory, pleiotropic fitness costs. Such fitness costs have not yet been examined in the UK's most damaging cereal aphid, Sitobion avenae (grain aphid) (Hemiptera: Aphididae). This study aimed to evaluate the fitness trade-offs of the insecticide-resistant S. avenae clone versus an insecticide-susceptible S. avenae clone. Additionally, the parasitoid, Aphidius ervi (Hymenoptera: Braconidae), was introduced to examine its potential as a biological control agent. This study found that insecticide-resistant clones had significantly lower population growth and individual relative growth rate. Furthermore, insecticide-resistant clones suffered from a significantly greater rate of parasitisation (mummification) compared to their insecticide-susceptible counterparts. The successfulness of the parasitoid as a biological control agent could prevent the spread of the insecticide-resistant genotype. However, for this to be possible, insecticide spraying regimes need to be moderated, and habitat modification and parasitoid manipulation must be considered.


Assuntos
Afídeos/fisiologia , Himenópteros/fisiologia , Resistência a Inseticidas/genética , Inseticidas/farmacologia , Controle Biológico de Vetores/métodos , Animais , Afídeos/genética , Afídeos/imunologia , Afídeos/parasitologia , Feminino , Genótipo
5.
PLoS Genet ; 16(11): e1009180, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-33137115

RESUMO

The field performance of Sterile Insect Technique (SIT) is improved by sex-sorting and releasing only sterile males. This can be accomplished by resource-intensive separation of males from females by morphology. Alternatively, sex-ratio biasing genetic constructs can be used to selectively remove one sex without the need for manual or automated sorting, but the resulting genetically engineered (GE) control agents would be subject to additional governmental regulation. Here we describe and demonstrate a genetic method for the batch production of non-GE males. This method could be applied to generate the heterogametic sex (XY, or WZ) in any organism with chromosomal sex determination. We observed up to 100% sex-selection with batch cultures of more than 103 individuals. Using a stringent transgene detection assay, we demonstrate the potential of mass production of transgene free males.


Assuntos
Engenharia Genética/métodos , Controle de Insetos/métodos , Controle Biológico de Vetores/métodos , Cromossomos Sexuais/genética , Animais , Animais Geneticamente Modificados/fisiologia , Drosophila melanogaster/genética , Feminino , Masculino , Modelos Animais , Análise para Determinação do Sexo/métodos , Processos de Determinação Sexual/genética , Transgenes/genética
6.
Artigo em Inglês | MEDLINE | ID: mdl-33036350

RESUMO

Microbial larviciding can be an effective component of integrated vector management malaria control schemes, although it is not commonly implemented. Moreover, quality control and evaluation of intervention activities are essential to evaluate the potential of community-based larviciding interventions. We conducted a process evaluation of a larval source management intervention in rural Tanzania where local staff were employed to apply microbial larvicide to mosquito breeding habitats with the aim of long-term reductions in malaria transmission. We developed a logic model to guide the process evaluation and then established quantitative indicators to measure intervention success. Quantitative analysis of intervention reach, exposure, and fidelity was performed to assess larvicide application, and interviews with larviciding staff were reviewed to provide context to quantitative results. Results indicate that the intervention was successful in terms of reach, as staff applied microbial larvicide at 80% of identified mosquito breeding habitats. However, the dosage of larvicide applied was sufficient to ensure larval elimination at only 26% of sites, which does not meet the standard set for intervention fidelity. We propose that insufficient training and protocol adaptation, environment and resource issues, and human error contributed to low larvicide application rates. This demonstrates how several small, context-specific details in sum can result in meaningful differences between intervention blueprint and execution. These findings may serve the design of other larval source management interventions by demonstrating the value of additional training, supervision, and measurement and evaluation of protocol adherence.


Assuntos
Culicidae/parasitologia , Larva/efeitos dos fármacos , Malária/prevenção & controle , Controle de Mosquitos/métodos , Controle Biológico de Vetores/métodos , Animais , Humanos , Larva/parasitologia , Malária/transmissão , Mosquitos Vetores , População Rural , Tanzânia
7.
Arch Insect Biochem Physiol ; 105(4): e21745, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33029844

RESUMO

Chagas disease is one of the most important insect-vectored diseases in Brazil. The entomopathogenic fungus Metarhizium anisopliae was evaluated against nymphs and adults of Panstrongylus megistus, Triatoma infestans, and T. sordida. Pathogenicity tests at saturated humidity demonstrated high susceptibility to fungal infection. The shortest estimates of 50% lethal time (LT50 ) for P. megistus varied from 4.6 (isolate E9) to 4.8 days (genetically modified strain 157p). For T. infestans, the shortest LT50 was 6.3 (E9) and 7.3 days (157p). For T. sordida, the shortest LT50 was 8.0 days (157p). The lethal concentration sufficient to kill 50% of T. infestans (LC50 ) was 1.9 × 107 conidia/ml for strain 157p. In three chicken coops that were sprayed with M. anisopliae, nymphs especially were well controlled, with a great population reduction of 38.5% after 17 days. Therefore M. anisopliae performed well, controlling Triatominae in both laboratory and field studies.


Assuntos
Metarhizium/patogenicidade , Panstrongylus/microbiologia , Controle Biológico de Vetores/métodos , Triatoma/microbiologia , Animais , Brasil , Doença de Chagas/prevenção & controle , Galinhas , Abrigo para Animais , Umidade , Insetos Vetores/microbiologia , Ninfa/microbiologia
9.
Sci Rep ; 10(1): 16241, 2020 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-33004867

RESUMO

Bioinsecticides based on Bacillus thuringiensis (Bt) spores and toxins are increasingly popular alternative solutions to control insect pests, with potential impact of their accumulation in the environment on non-target organisms. Here, we tested the effects of chronic exposure to commercial Bt formulations (Bt var. kurstaki and israelensis) on eight non-target Drosophila species present in Bt-treated areas, including D. melanogaster (four strains). Doses up to those recommended for field application (~ 106 Colony Forming Unit (CFU)/g fly medium) did not impact fly development, while no fly emerged at ≥ 1000-fold this dose. Doses between 10- to 100-fold the recommended one increased developmental time and decreased adult emergence rates in a dose-dependent manner, with species-and strain-specific effect amplitudes. Focusing on D. melanogaster, development alterations were due to instar-dependent larval mortality, and the longevity and offspring number of adult flies exposed to bioinsecticide throughout their development were moderately influenced. Our data also suggest a synergy between the formulation compounds (spores, cleaved toxins, additives) might induce the bioinsecticide effects on larval development. Although recommended doses had no impact on non-target Drosophila species, misuse or local environmental accumulation of Bt bioinsecticides could have side-effects on fly populations with potential implications for their associated communities.


Assuntos
/farmacologia , Drosophila/efeitos dos fármacos , Controle Biológico de Vetores , Animais , Drosophila melanogaster/efeitos dos fármacos , Feminino , Larva , Masculino , Controle Biológico de Vetores/métodos
10.
Sci Rep ; 10(1): 16812, 2020 10 08.
Artigo em Inglês | MEDLINE | ID: mdl-33033285

RESUMO

Arboviral infections such as dengue, Zika and chikungunya are fast spreading diseases that pose significant health problems globally. In order to control these infections, an intracellular bacterium called Wolbachia has been introduced into wild-type mosquito populations in the hopes of replacing the vector transmitting agent, Aedes aegypti with one that is incapable of transmission. In this study, we developed a Wolbachia transmission model for the novel wAu strain which possesses several favourable traits (e.g., enhanced viral blockage and maintenance at higher temperature) but not cyctoplasmic incompatibility (CI)-when a Wolbachia-infected male mosquito mates with an uninfected female mosquito, producing no viable offspring. This model describes the competitive dynamics between wAu-Wolbachia-infected and uninfected mosquitoes and the role of imperfect maternal transmission. By analysing the system via computing the basic reproduction number(s) and stability properties, the potential of the wAu strain as a viable strategy to control arboviral infections is established. The results of this work show that enhanced maintenance of Wolbachia infection at higher temperatures can overcome the lack of CI induction to support wAu-Wolbachia infected mosquito invasion. This study will support future arboviral control programs, that rely on the introduction of new Wolbachia variants.


Assuntos
Aedes/virologia , Infecções por Arbovirus/prevenção & controle , Controle Biológico de Vetores/métodos , Wolbachia , Aedes/microbiologia , Aedes/fisiologia , Animais , Feminino , Masculino , Modelos Biológicos , Reprodução
11.
PLoS One ; 15(9): e0228367, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32976485

RESUMO

The Zigzag ladybird beetle, Cheilomenes sexmaculata (Fabricius) (Coleoptera: Coccinellidae), is a biological control agent that feeds on a variety of aphid species. Life table and predation data of C. sexmaculata were collected under laboratory conditions at 25±2°C, 60±5% RH and L14: D10 h in connection with feeding on four different aphid species; Lipaphis erysimi (Kaltenbach), Myzus persicae (Sulzer), Aphis nerii (Boyer de Fonscolombe) and Diuraphis noxia (Mordvilko). Larval development of C. sexmaculata was long when fed on M. persicae (12.18 days) and shorter on D. noxia (10.64 days). The male's lifespan was longer on M. persicae (26.70 days) and shorter on L. erysimi (23.67 days). Fecundity was maximum when the beetle was fed D. noxia (316.8 eggs/female) and minimum on M. persicae (199.1 eggs/female). Net reproductive rate, intrinsic rate of increase and finite rate of increase were highest on D. noxia with values of 158.4 (offspring individual-1), 0.22 d-1, and 1.24 d-1, respectively whereas the respective parameters were lowest on L. erysimi (99.5 offspring individual-1, 0.19 d-1, and 1.20 d-1, respectively). However, the mean of the generation (T) was shorter on A. nerii (22.48 d-1) and longer on M. persicae (24.68 d-1). Based on life table parameters obtained under laboratory conditions, the most appropriate host of C. sexmaculata was D. noxia. This study should help us to improve mass rearing and use of C. sexmaculata in the biological control of aphids on field and horticultural crops.


Assuntos
Afídeos/parasitologia , Besouros/fisiologia , Controle Biológico de Vetores/métodos , Comportamento Predatório/fisiologia , Animais , Afídeos/fisiologia , Feminino , Fertilidade/fisiologia , Larva , Tábuas de Vida , Longevidade/fisiologia , Masculino , Paquistão
12.
PLoS One ; 15(9): e0232306, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32986707

RESUMO

Tsetse eradication continues to be a top priority for African governments including that of Senegal, which embarked on a project to eliminate Glossina palpalis gambiensis from the Niayes area, following an area-wide integrated pest management approach with an SIT component. A successful SIT programme requires competitive sterile males of high biological quality. This may be hampered by handling processes including irradiation and the release mechanisms, necessitating continued improvement of these processes, to maintain the quality of flies. A new prototype of an automated chilled adult release system (Bruno Spreader Innovation, (BSI™)) for tsetse flies was tested for its accuracy (in counting) and release rate consistency. Also, its impact on the quality of the released sterile males was evaluated on performance indicators, including flight propensity, mating competitiveness, premating and mating duration, insemination rate of mated females and survival of male flies. The BSITM release system accurately counted and homogenously released flies at the lowest motor speed set (0.6 rpm), at a consistent rate of 60±9.58 males/min. Also, the release process, chilling (6 ± 1°C) and passing of flies through the machine) had no significant negative impact on the male flight propensity, mating competitiveness, premating and mating durations and the insemination rates. Only the survival of flies was negatively affected whether under feeding or starvation. The positive results of this study show that the BSI™ release system is promising for use in future tsetse SIT programmes. However, the negative impact of the release process on survival of flies needs to be addressed in future studies and results of this study confirmed under operational field conditions in West Africa.


Assuntos
Temperatura Baixa/efeitos adversos , Infertilidade Masculina/veterinária , Controle Biológico de Vetores/métodos , Tripanossomíase Africana/prevenção & controle , Moscas Tsé-Tsé/fisiologia , Animais , Vetores de Doenças , Feminino , Voo Animal/fisiologia , Humanos , Infertilidade Masculina/etiologia , Gado/parasitologia , Masculino , Controle Biológico de Vetores/instrumentação , Senegal , Comportamento Sexual Animal/fisiologia , Trypanosoma/patogenicidade , Tripanossomíase Africana/parasitologia , Tripanossomíase Africana/veterinária , Moscas Tsé-Tsé/parasitologia
13.
Exp Parasitol ; 218: 107982, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32866584

RESUMO

Ancylostoma caninum is a gastrointestinal parasite that affect dogs and humans, considered a worldwide public health problem. The control of these parasitosis is increasingly difficult due to the development of multi-drug resistance. Bacillus thuringiensis is an insecticidal, spore forming bacterium, often species specific. The strain GP526 of B. thuringiensis has toxic effect on the cestode Dipylidium caninum and the trematode Centrocestus formosanus, both of them zoonotic parasites. The high degrees of specificity and environment safe make B. thuringiensis suitable for use against pathogen parasites, especially those resistant to synthetic chemical insecticides. The objective of the current work was to evaluate the in vitro effect of B. thuringiensis on Ancylostoma caninum. Spore-crystal mixture of the strains was co-incubated with 120 adult nematodes (males, non-pregnant females and pregnant females) or with 4800 eggs. GP526 showed a nematicidal effect with an LT50 of 35.8 h and an LC50 of 60 µg/ml. It also showed an ovicidal effect with an LC50 of 94.9 µg/ml. Histological analyses showed detachment of the cuticle and of the uterus in adult females, and vacuolization with destruction of the eggs. The effects of GP526 strain were comparable to those of albendazole, allowing us to propose GP526 for A. caninum control, in both, the adult stage at a gastrointestinal level, and in egg stage in the environment. In addition, GP526 can be proposed as a potential broad spectrum antiparasitic drug.


Assuntos
Ancylostoma/microbiologia , Ancilostomíase/prevenção & controle , Bacillus thuringiensis/fisiologia , Zoonoses/parasitologia , Albendazol/farmacologia , Albendazol/uso terapêutico , Ancylostoma/efeitos dos fármacos , Animais , Antinematódeos/farmacologia , Antinematódeos/uso terapêutico , Bacillus thuringiensis/química , Proteínas de Bactérias/análise , Doenças do Cão/parasitologia , Cães , Eletroforese em Gel de Poliacrilamida , Feminino , Dose Letal Mediana , Masculino , Controle Biológico de Vetores/métodos , Zoonoses/prevenção & controle
14.
PLoS One ; 15(9): e0238943, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32925935

RESUMO

Inoculating plants with entomopathogenic fungi may influence plant nutrient uptake and growth, and herbivore performance. Knowledge is limited concerning the effects of this symbiosis on higher trophic levels. We examined how fungal treatment of faba bean seeds with the entomopathogenic fungus Beauveria bassiana influenced the choice-behavior and development of the aphid parasitoid Aphidius colemani. We also sampled plant material for analysis of changes in expression of genes related to plant defense pathways. While parasitoids were compatible with plants inoculated with B. bassiana initially (66 vs. 65% parasitization on inoculated and control plants, respectively; similar development times of parasitoids: 9.2 days), the emergence of adult parasitoids originating from aphids on fungus treated plants was significantly lower (67 vs. 76%, respectively). We also found that the defense response changed, similar to induced systemic resistance, when plants were treated with B. bassiana, similarly to what has been found for other plant symbiotic microorganisms. These novel findings show that although the application of entomopathogenic fungi to plants can alter the plants' defense against herbivores, it may also have an impact on beneficial insects, so their function and use should be evaluated on a case-by-case basis.


Assuntos
Beauveria/fisiologia , Controle Biológico de Vetores/métodos , Vicia faba/microbiologia , Beauveria/metabolismo , Beauveria/patogenicidade , Endófitos/fisiologia , Regulação da Expressão Gênica de Plantas/genética , Imunidade Vegetal/imunologia , Sementes/microbiologia , Simbiose , Vicia faba/metabolismo
15.
PLoS One ; 15(8): e0236249, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32804964

RESUMO

BACKGROUND: The insect predator Coccinella septempunctata can effectively control many types of pests, such as aphids, whiteflies, and small lepidopteran larvae. We previously found that C. septempunctata fed an artificial diet showed diminished biological properties(e.g. fecundity, egg hatching rate, survival rate, etc.) compared with those fed natural prey (Aphis craccivora), likely due to different nutritional characteristics of the diet. In this study, we used transcriptome sequencing analysis to identify nutrition- and metabolism-related genes of C. septempunctata that were differentially expressed depending on diet. METHODOLOGY/PRINCIPAL FINDINGS: The Illumina HiSeq2000 was used to sequence 691,942,058 total clean reads from artificial diet-fed and A. craccivora-fed C. septempunctata libraries, and the clean reads were assembled using Trinity de novo software (Tabel 2). Comparison of transcriptome sequences revealed that expression of 38,315 genes was affected by the artificial diet, and 1,182 of these genes showed a significant change in expression levels (FDR ≤ 0.05,|log2FC|≥1, "FC" stands for "fold change"). These differentially expressed genes (DEGs) were likely associated with the decreased egg laying capacity, hatching rate, longevity, and increased sex ratio (♀:♂) of adult C. septempunctata observed in the group fed the artificial diet. Furthermore, in the most DEGs metabolic pathways for C. septempunctata feeding on the artificial diet accumulated amino acid metabolic pathways, lipid metabolic pathways, and starch and glucose metabolism were down-regulated. CONCLUSIONS/SIGNIFICANCE: We found some differentially expressed genes and metabolic pathways are related to nutrition, from which a more informative feedback for diet formulation was obtained and the artificial diet could be more efficiently optimized.


Assuntos
Fenômenos Fisiológicos da Nutrição Animal/genética , Afídeos , Besouros/fisiologia , Genes de Insetos , Comportamento Predatório/fisiologia , Aminoácidos/metabolismo , Animais , Regulação para Baixo , Fertilidade/fisiologia , Perfilação da Expressão Gênica , Glucose/metabolismo , Metabolismo dos Lipídeos/genética , Longevidade/fisiologia , Redes e Vias Metabólicas/genética , Controle Biológico de Vetores/métodos , Razão de Masculinidade , Amido/metabolismo , Sequenciamento Completo do Exoma
16.
PLoS One ; 15(8): e0237675, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32797066

RESUMO

RNA interference (RNAi), a technique used to investigate gene function in insects and other organisms, is attracting attention as a potential new technology for mosquito control. Saccharomyces cerevisiae (baker's yeast) was recently engineered to produce interfering RNA molecules that silence genes required for mosquito survival, but which do not correspond to genes in humans or other non-target organisms. The resulting yeast pesticides, which facilitate cost-effective production and delivery of interfering RNA to mosquito larvae that eat the yeast, effectively kill mosquitoes in laboratory and semi-field trials. In preparation for field evaluation of larvicides in Trinidad, a Caribbean island with endemic diseases resulting from pathogens transmitted by Aedes mosquitoes, adult residents living in the prospective trial site communities of Curepe, St. Augustine, and Tamana were engaged. Open community forums and paper surveys were used to assess the potential acceptability, societal desirability, and sustainability of yeast interfering RNA larvicides. These assessments revealed that Trinidadians have good working knowledge of mosquitoes and mosquito-borne illnesses. A majority of the respondents practiced some method of larval mosquito control and agreed that they would use a new larvicide if it were proven to be safe and effective. During the community engagement forums, participants were educated about mosquito biology, mosquito-borne diseases, and the new yeast larvicides. When invited to provide feedback, engagement forum attendees were strongly supportive of the new technology, raised few concerns, and provided helpful advice regarding optimal larvicide formulations, insecticide application, operational approaches for using the larvicides, and pricing. The results of these studies suggest that the participants are supportive of the potential use of yeast interfering RNA larvicides in Trinidad and that the communities assessed in this investigation represent viable field sites.


Assuntos
Aedes/genética , Engenharia Genética/métodos , Controle de Mosquitos/métodos , Interferência de RNA , Saccharomyces cerevisiae/genética , Adulto , Animais , Feminino , Humanos , Larva/genética , Masculino , Pessoa de Meia-Idade , Mosquitos Vetores/genética , Controle Biológico de Vetores/métodos , RNA Interferente Pequeno/genética , Características de Residência , Inquéritos e Questionários , Trinidad e Tobago
17.
PLoS Pathog ; 16(7): e1008410, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32726353

RESUMO

The bacterial endosymbiont Wolbachia is a biocontrol tool that inhibits the ability of the Aedes aegypti mosquito to transmit positive-sense RNA viruses such as dengue and Zika. Growing evidence indicates that when Wolbachia strains wMel or wAlbB are introduced into local mosquito populations, human dengue incidence is reduced. Despite the success of this novel intervention, we still do not fully understand how Wolbachia protects mosquitoes from viral infection. Here, we demonstrate that the Wolbachia strain wPip does not inhibit virus infection in Ae. aegypti. We have leveraged this novel finding, and a panel of Ae. aegypti lines carrying virus-inhibitory (wMel and wAlbB) and non-inhibitory (wPip) strains in a common genetic background, to rigorously test a number of hypotheses about the mechanism of Wolbachia-mediated virus inhibition. We demonstrate that, contrary to previous suggestions, there is no association between a strain's ability to inhibit dengue infection in the mosquito and either its typical density in the midgut or salivary glands, or the degree to which it elevates innate immune response pathways in the mosquito. These findings, and the experimental platform provided by this panel of genetically comparable mosquito lines, clear the way for future investigations to define how Wolbachia prevents Ae. aegypti from transmitting viruses.


Assuntos
Aedes/microbiologia , Vírus da Dengue , Interações Microbianas/fisiologia , Mosquitos Vetores/microbiologia , Wolbachia , Animais , Dengue/prevenção & controle , Dengue/transmissão , Infecções por Bactérias Gram-Negativas , Controle Biológico de Vetores/métodos , Fenótipo
18.
Sci Rep ; 10(1): 10583, 2020 06 29.
Artigo em Inglês | MEDLINE | ID: mdl-32601289

RESUMO

Productivity of Indian mustard (B. juncea), a major oil yielding crop in rapeseed-mustard group is heavily inflicted by mustard aphid, L. erysimi. Mustard aphid, a specialist aphid species on rapeseed-mustard crops, rapidly multiplies and colonizes the plants leading to successful infestation. In contrary, legume specific cowpea aphid, A. craccivora when released on B. juncea plants fails to build up population and thus remains unsuccessful in infestation. In the present study, differential host response of B. juncea to the two aphid species, one being successful insect-pest and the other being unsuccessful on it has been studied based on transcriptome analysis. Differential feeding efficiency of the two aphid species on mustard plants was evident from the amount of secreted honeydews. Leaf-transcriptomes of healthy and infested plants, treated with the two aphid species, were generated by RNA sequencing on Illumina platform and de novo assembly of the quality reads. A comparative assessment of the differentially expressed genes due to treatments revealed a large extent of overlaps as well as distinctness with respect to the set of genes and their direction of regulation. With respect to host-genes related to transcription factors, oxidative homeostasis, defense hormones and secondary metabolites, L. erysimi led to either suppression or limited activation of the transcript levels compared to A. craccivora. Further, a comprehensive view of the DEGs suggested more potential of successful insect-pests towards transcriptional reprogramming of the host. qRT-PCR based validation of randomly selected up- and down-regulated transcripts authenticated the transcriptome data.


Assuntos
Regulação da Expressão Gênica de Plantas/genética , Mostardeira/genética , Controle Biológico de Vetores/métodos , Animais , Afídeos/patogenicidade , Afídeos/fisiologia , Expressão Gênica/genética , Perfilação da Expressão Gênica/métodos , Inseticidas , Doenças das Plantas/genética , Análise de Sequência de RNA/métodos , Transcriptoma/genética , Sequenciamento Completo do Exoma/métodos
19.
Sci Rep ; 10(1): 11139, 2020 07 07.
Artigo em Inglês | MEDLINE | ID: mdl-32636422

RESUMO

Transgenic maize plants expressing dsRNA targeting western corn rootworm (WCR, Diabrotica virgifera virgifera) DvSSJ1 mRNA, a Drosophila snakeskin (ssk) ortholog, show insecticidal activity and significant plant protection from WCR damage. The gene encodes a membrane protein associated with the smooth sepate junction (SSJ) which is required for intestinal barrier function. To understand the active RNA form that leads to the mortality of WCR larvae by DvSSJ1 RNA interference (RNAi), we characterized transgenic plants expressing DvSSJ1 RNA transcripts targeting WCR DvSSJ1 mRNA. The expression of the silencing cassette results in the full-length transcript of 901 nucleotides containing a 210 bp inverted fragment of the DvSSJ1 gene, the formation of a double-stranded RNA (dsRNA) transcript and siRNAs in transgenic plants. Our artificial diet-feeding study indicates that dsRNAs greater than or equal to approximately 60 base-pairs (bp) are required for DvSSJ1 insecticidal activity. Impact of specificity of dsRNA targeting DvSSJ1 mRNA on insecticidal activities was also evaluated in diet bioassay, which showed a single nucleotide mutation can have a significant impact or abolish diet activities against WCR. These results provide insights as to the functional forms of plant-delivered dsRNA for the protection of transgenic maize from WCR feeding damage and information contributing to the risk assessment of transgenic maize expressing insecticidal dsRNA.


Assuntos
Besouros , Controle Biológico de Vetores/métodos , Plantas Geneticamente Modificadas/genética , Zea mays/genética , Animais , Besouros/metabolismo , Proteínas de Insetos/genética , Junções Intercelulares/metabolismo , Larva , Interferência de RNA , RNA de Cadeia Dupla/genética
20.
Sci Rep ; 10(1): 12398, 2020 07 24.
Artigo em Inglês | MEDLINE | ID: mdl-32709966

RESUMO

CRISPR gene drives have potential for widespread and cost-efficient pest control, but are highly controversial. We examined a potential gene drive targeting spermatogenesis to control the invasive common wasp (Vespula vulgaris) in New Zealand. Vespula wasps are haplodiploid. Their life cycle makes gene drive production challenging, as nests are initiated by single fertilized queens in spring followed by several cohorts of sterile female workers and the production of reproductives in autumn. We show that different spermatogenesis genes have different levels of variation between introduced and native ranges, enabling a potential 'precision drive' that could target the reduced genetic diversity and genotypes within the invaded range. In vitro testing showed guide-RNA target specificity and efficacy that was dependent on the gene target within Vespula, but no cross-reactivity in other Hymenoptera. Mathematical modelling incorporating the genetic and life history traits of Vespula wasps identified characteristics for a male sterility drive to achieve population control. There was a trade-off between drive infiltration and impact: a drive causing complete male sterility would not spread, while partial sterility could be effective in limiting population size if the homing rate is high. Our results indicate that gene drives may offer viable suppression for wasps and other haplodiploid pests.


Assuntos
Sistemas CRISPR-Cas/genética , Tecnologia de Impulso Genético , Espécies Introduzidas , Controle Biológico de Vetores/métodos , Vespas/genética , Animais , Internacionalidade , Dinâmica Populacional
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