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1.
Food Control ; 145: 109441, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36875541

RESUMO

In this study, we assessed knowledge, attitude, and practices (KAP) related to tomato hygiene and food safety, among tomato vendors in the Ethiopian cities of Harar and Dire Dawa. From a total of 1498 tomato retail market vendors identified in the two cities through vendor mapping exercises, 151 outlets were randomly selected for a cross-sectional KAP survey on tomato handling, marketing, loss due to damage, safety, and hygienic practice. Tomato vendors claimed that they knew about food safety and hygiene, and risks associated with raw tomatoes. We found considerable variation in food safety knowledge, barriers, and practices during handling and marketing. The major concern of tomato traders in terms of food safety for vegetables was contamination with dirt. Around 17% of street vendors did not know about the importance of water quality and cleanliness for food safety. About 20% of tomato traders washed tomatoes after they purchased them and 43% and 14% of respondents who practiced tomato washing revealed that they cannot get the quantity and quality of water needed, respectively. Tomatoes were displayed in direct sunlight in about 85% of stalls. About 37% of vendors said rodents were present at night and could contact surfaces tomatoes are displayed on. For about 40% of outlets one or more flies were seen to be present on a third to two-thirds of their tomatoes. Overall, 40% of respondents reported they do not have adequate toilet facilities and 20% of those that use a toilet do not have water for washing hands after. The study identified areas that should be targeted by interventions aiming to improve food safety in this setting, however, without improvements in basic infrastructure to provide the pre-requisites for food safety the impact of small-scale food safety interventions may be limited.

2.
Annu Rev Entomol ; 66: 141-161, 2021 01 07.
Artigo em Inglês | MEDLINE | ID: mdl-33417822

RESUMO

Legume pod borer, Maruca vitrata, has emerged as a major pest on food legumes in Asia and Africa. It is an oligophagous pest, feeding on over 70 species in Fabaceae. We examine the species complex in Asia, Africa, Oceania, and the Americas, with an emphasis on molecular taxonomy. Studies on pheromone production and perception suggest the existence of pheromone polymorphism, especially in Asia and Africa. No Maruca-resistant varieties are available in the major food legumes including cowpea, pigeonpea, mungbean, and yard-long bean. Legume growers use chemical pesticides indiscriminately, leading to the development of pesticide resistance. However recent developments in habitat management, classical biocontrol with more efficient parasitoids, biopesticides, and judicious use of insecticides pave the way for sustainable management of M. vitrata, which can reduce the pesticide misuse. Active engagement of the private sector and policy makers can increase the adoption of integrated pest management approaches in food legumes.


Assuntos
Fabaceae , Mariposas , Controle Biológico de Vetores , África , Animais , Ásia , Dinâmica Populacional
3.
Genomics ; 112(2): 1464-1476, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31450005

RESUMO

Pieris rapae is a serious pest of brassicas worldwide. We performed de novo assembly of P. rapae transcriptome by next-generation sequencing and assembled approximately 65,727,422 clean paired-end reads into 32,118 unigenes, of which 13,585 were mapped to 255 pathways in the KEGG database. A total of 6173 novel transcripts were identified from reads directly mapped to P. rapae genome. Additionally, 1490 SSRs, 301,377 SNPs, and 29,284 InDels were identified as potential molecular markers to explore polymorphism within P. rapae populations. We screened and mapped 36 transcripts related to OBP, CSP, SNMP, PBAN, and OR. We analyzed the expression profiles of 7 selected genes involved in pheromone transport and degradation by quantitative real-time PCR; these genes are sex-specific and differentially expressed in the developmental stages. Overall, the comprehensive transcriptome resources described in this study could help understand and identify molecular targets particularly reproduction-related genes for developing effective P. rapae management tools.


Assuntos
Regulação da Expressão Gênica no Desenvolvimento , Genes de Insetos , Lepidópteros/genética , Pequeno RNA não Traduzido/genética , Animais , Feminino , Redes Reguladoras de Genes , Larva/genética , Larva/crescimento & desenvolvimento , Lepidópteros/crescimento & desenvolvimento , Masculino , Pequeno RNA não Traduzido/metabolismo , Atrativos Sexuais/genética , Atrativos Sexuais/metabolismo , Transcriptoma
4.
J Chem Ecol ; 42(8): 748-755, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27518387

RESUMO

Aggregations of the striped flea beetle Phyllotreta striolata on their crucifer host plants are mediated by volatiles emitted from feeding males. The male-specific sesquiterpene, (6R,7S)-himachala-9,11-diene (compound A), was shown previously to be physiologically and behaviorally active, but compound A was attractive only when combined with unnaturally high doses of the host plant volatile allyl isothiocyanate (AITC) in field trapping experiments. This indicated that our understanding of the chemical communication in this species is incomplete. Another male-specific sesquiterpenoid, (3S,9R,9aS)-3-hydroxy-3,5,5,9-tetramethyl-5,6,7,8,9,9a-hexahydro-1H-benzo[7]annulen-2(3H)-one (compound G), has been reported from an American P. striolata population. We confirmed the presence of compound G, and investigated its interaction with compound A and AITC in a P. striolata population in Taiwan. Compound G was attractive to Taiwanese P. striolata in laboratory bioassays, but significantly more beetles were attracted to a blend of compounds A and G. Under the same conditions, P. striolata showed no preference for the blend of A and G combined with a range of doses of AITC over the sesquiterpenoid blend alone. The sesquiterpenoid blend was tested further in field trapping experiments and attracted significantly more beetles than traps baited with compound A and ecologically relevant amounts of AITC. We conclude that A and G are components of the male-specific aggregation pheromone of P. striolata in Taiwan, and that the attractiveness of the pheromone is not reliant on the presence of AITC. Our results further indicate that the male-specific sesquiterpenoid blends differ qualitatively between the Taiwanese and American populations of P. striolata.


Assuntos
Agressão/efeitos dos fármacos , Besouros/efeitos dos fármacos , Feromônios/farmacologia , Animais , Comportamento Animal/efeitos dos fármacos , Bioensaio , Interações Medicamentosas , Isotiocianatos/farmacologia , Masculino , Feromônios/análise , Feromônios/química , Sesquiterpenos/análise , Sesquiterpenos/química , Sesquiterpenos/farmacologia , Caracteres Sexuais
5.
J Chem Ecol ; 41(12): 1155-62, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26625875

RESUMO

The legume pod borer, Maruca vitrata, is a pantropical pest on leguminous crops. (E,E)-10,12-Hexadecadienal, (E,E)-10,12-hexadecadienol, and (E)-10-hexadecenal were described previously as sex pheromone components for this nocturnal moth. A blend of these components in a ratio of 100:5:5 attracted males in field trapping experiments in Benin, but not in Taiwan, Thailand, or Vietnam. This finding suggests geographic variation in the pheromone blend between Asian and West African populations of M. vitrata. We, therefore, determined the pheromone compositions of single pheromone glands of females from the three Asian regions and from Benin by gas chromatography-mass spectrometry. Additionally, we compared the responses of males from Taiwan and Benin to calling females and to gland extracts of females from both regions in laboratory no-choice and two-choice assays. Chemical analysis revealed the presence of (E,E)-10,12-hexadecadienal and (E,E)-10,12-hexadecadienol, as well as the absence of (E)-10-hexadecenal in all four populations. The relative amounts of the detected compounds did not vary significantly among the insect populations. The behavioral bioassays showed that Taiwanese and Beninese males were similarly attracted to females from both regions, as well as to their gland extracts. As a result, we did not find geographic variation in the sexual communication system of M. vitrata between West African and Asian insect populations.


Assuntos
Mariposas/fisiologia , Atrativos Sexuais/metabolismo , Animais , Benin , Quimiotaxia , Feminino , Cromatografia Gasosa-Espectrometria de Massas , Masculino , Taiwan
6.
Environ Entomol ; 53(4): 665-676, 2024 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-38828479

RESUMO

The evolution of oviposition preference in insects is considered a key evolutionary strategy in the context of host-plant interaction. It is hypothesized that insects maximize the survival and fitness of the subsequent generations by preferring specific host plant(s), known as the "preference-performance hypothesis." In this study, we tested whether adult host preference reflects the immature performance in an oligophagous insect, Phthorimaea absoluta Meyrick, a rapidly emerging invasive pest in Asia, Africa, and Europe. Based on a preliminary survey of the potential host plants of P. absoluta, we selected 6 Solanaceae species, namely, tomato, potato, eggplant, black nightshade, sweet pepper, and tobacco, for the oviposition preference studies. The results indicated that the tomato was the most preferred host in no-, dual- and multiple-choice assays, followed by potato, eggplant, and black nightshade. Subsequently, the insect life-table parameters were found to be superior on tomato compared to other hosts. The order of oviposition preference on the host plants was strongly correlated with the life-table parameters of P. absoluta. Thus, we provide clear evidence for the preference-performance hypothesis in the host selection behavior of P. absoluta. We also emphasize the necessity of conducting oviposition behavior research at various geographic locations to develop tailor-made integrated pest management programs.


Assuntos
Mariposas , Oviposição , Solanaceae , Animais , Mariposas/fisiologia , Mariposas/crescimento & desenvolvimento , Feminino , Larva/crescimento & desenvolvimento , Larva/fisiologia , Masculino
7.
PLoS One ; 18(1): e0279026, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36595541

RESUMO

India experienced a rapid rise in COVID-19 infections from March 2021. States imposed varying levels of lockdowns and curfews to curb the spread of the disease. These restrictions severely affected the functioning of food systems. The objective of this study was to analyze how COVID-19 continues to affect agricultural production, food security and household diets of vegetable farmers. A phone-based survey was conducted with 595 vegetable farmers in the states of Andhra Pradesh, Assam, Jharkhand, Karnataka and Odisha, 60% of whom had been interviewed a year earlier. Overall, 60% of farmers experienced decreased vegetable production; over 80% reported a reduction in consumption of at least one food group; and 45% reported some level of food insecurity between May 2020 and May 2021. Farmers who reported decreased staples production, difficulty accessing seeds/seedlings, or reduced their household spending were more likely to report decreased vegetable production. Vegetable consumption was positively associated with receipt of COVID-19 relief benefits, borrowing money, or having home gardens. Farmers who received public agricultural assistance, or had reduced expenses, were more likely to have lower vegetable consumption. Greater severity of food insecurity was associated with farmers belonging to underprivileged social groups, non-Hindus, or those who experienced decrease in livestock production, weather related disruptions or received COVID-19 assistance. This is one of few studies that have conducted a longitudinal assessment of the impacts across multiple waves of COVID-19. COVID-19 is seen to be one among several shocks experienced by farm households, and exacerbated existing issues within agriculture and food security. There is a need for public policy support to strengthen both production and consumption of vegetables.


Assuntos
COVID-19 , Verduras , Humanos , Fazendeiros , Abastecimento de Alimentos , Índia/epidemiologia , COVID-19/epidemiologia , Controle de Doenças Transmissíveis
8.
Curr Opin Insect Sci ; 54: 100970, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36126875

RESUMO

Pest management in major cropping systems has long been dominated by chemical pesticides in Africa. Smallholder farmers have perceived pesticides as insurance to protect their crops. Consumers are less aware of pesticide-related food-safety issues, and markets providing economic incentives to producers who adopt alternatives to pesticides have been slow to emerge. Hence, overuse of pesticides has been constantly increasing. Although African countries have a number of pesticide-related policies, they are inadequately implemented. However, significant investment has been made on integrated pest management (IPM) innovations in recent decades. Resistant cultivars, agroecological approaches, biological control, and biopesticides have been developed against key biotic constraints in major cropping systems. They have been adopted at several pilot sites, where significant economic and ecological impacts have been documented. However, concerted efforts are necessary to harmonize policies and regulations across the continent to enhance the availability, accessibility, and affordability of IPM innovations to smallholder farmers.


Assuntos
Praguicidas , Animais , Agricultura , Controle de Pragas , Produtos Agrícolas , África
9.
J Chem Ecol ; 37(1): 85-97, 2011 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21181241

RESUMO

The chrysomelid beetle Phyllotreta striolata is an important pest of Brassicaceae in Southeast Asia and North America. Here, we identified the aggregation pheromone of a population of P. striolata from Taiwan, and host plant volatiles that interact with the pheromone. Volatiles emitted by feeding male P. striolata attracted males and females in the field. Headspace volatile analyses revealed that six sesquiterpenes were emitted specifically by feeding males. Only one of these, however, elicited an electrophysiological response from antennae of both sexes. A number of host plant volatiles, e.g., 1-hexanol, (Z)-3-hexen-1-ol, and the glucosinolate hydrolysis products allyl isothiocyanate (AITC), 3-butenyl isothiocyanate, and 4-pentenyl isothiocyanate also elicited clear responses from the antenna. The active male-specific compound was identified as (+)-(6R,7S)-himachala-9,11-diene by chiral stationary phase gas-chromatography with coupled mass spectrometry, and by comparison with reference samples from Abies nordmanniana, which is known to produce the corresponding enantiomer. The pheromone compound was synthesized starting from (-)-α-himachalene isolated from Cedrus atlantica. Under field conditions, the activity of the synthetic pheromone required concomitant presence of the host plant volatile allyl isothiocyanate. However, both synthetic (+)-(6R,7S)-himachala-9,11-diene alone and in combination with AITC were attractive in a two-choice laboratory assay devoid of other natural olfactory stimuli. We hypothesize that P. striolata adults respond to the pheromone only if specific host volatiles are present. In the same laboratory set up, more beetles were attracted by feeding males than by the synthetic stimuli. Thus, further research will be necessary to reveal the components of a more complex blend of host or male-produced semiochemicals that might enhance trap attractiveness in the field.


Assuntos
Brassica/metabolismo , Besouros/metabolismo , Atrativos Sexuais/metabolismo , Compostos Orgânicos Voláteis/metabolismo , Animais , Besouros/fisiologia , Comportamento Alimentar , Cromatografia Gasosa-Espectrometria de Massas , Espectroscopia de Ressonância Magnética , Masculino , Espectrometria de Massas por Ionização por Electrospray
10.
Insects ; 12(6)2021 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-34072729

RESUMO

Solanum viarum has been proposed as a potential dead-end trap crop for the management of Helicoverpa armigera because of its unsuitability for larval growth and survival despite being overwhelmingly preferred for oviposition. This study delved into the different S. viarum accessions for ovipositional preference and non-suitability for larval growth and survival of H. armigera. Besides, foliage trichomes, acylsugars, and phenolic content of S. viarum plants were assessed and compared with tomato. Since there is no significant variation in the ovipositional preference and larval performance of H. armigera, our result revealed that all those evaluated accessions of S. viarum have the potential to be used as a dead-end trap crop for the management of H. armigera. However, significant variation among the S. viarum accessions in terms of H. armigera oviposition was also evident in a no-choice experiment. Because of high-density glandular trichomes, acylsugars, and phenolic content, S. viarum significantly impaired H. armigera larval growth and survival compared to the tomato. Hence, our study elucidated that the S. viarum plant fits with the criteria for dead-end trap crop, and has the potential as a dead-end trap crop for the H. armigera, which needs to be tested under large, open-field conditions.

11.
Insects ; 12(11)2021 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-34821763

RESUMO

The South American tomato leaf miner, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), one of the most important invasive insect pests affecting tomato production worldwide, was for the first time detected in Myanmar. Preliminary surveys on pest occurrence on tomato crops in Myanmar suggested the presence of T. absoluta in Southern Shan State, but there was no official survey conducted until the end of 2019. Therefore, this study aimed to confirm the presence of T. absoluta in Myanmar. The presence of T. absoluta was specifically observed in the Southern Shan State, which is the largest tomato production area in Myanmar, where tomato is grown under two cultivation methods, floating and land cultivation. The highest T. absoluta infestation was recordedat Kalaw with (82%), followed by Inle Lake (i.e., floating cultivation) (20%) and Pin Ta Ya (10%). The amount of T. absoluta larvae was significantly higher in the lower third of the plants, followed by the middle section and upper section, respectively, in three fields surveyed. Potential and severe economic damage may be expected if management practices are not in place to reduce the presence of this invasive pest. It is of immediate importance that plant protection and quarantine offices of ASEAN member states coordinate their response to T. absoluta and build their capacity to monitor the pest and develop a strategy for when it arrives. In addition, a suitable management strategy is needed to reduce the occurrence of this invasive pest.

12.
Plants (Basel) ; 10(1)2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33401425

RESUMO

Bacterial wilt (BW) is one of the most economically important diseases of tomato and eggplant in the tropics and subtropics, and grafting onto resistant rootstocks can provide an alternative and effective solution to manage soil-borne bacterial in these crops. This study was conducted to evaluate the BW resistance and agronomic potential of newly identified eggplant accessions as rootstocks for tomato grafting. Five BW resistant eggplant accessions (VI041809A, VI041943, VI041945, VI041979A, and VI041984) from the World Vegetable Center were evaluated as rootstocks for grafting with two different fresh market tomato cultivars (Victoria and TStarE) as scion under open field conditions in Taiwan. Graft compatibility using the tube grafting method as well as BW wilting percentage, disease index, fruit yield and quality parameters were assessed. All the rootstocks showed good graft compatibility (93% and above) and grafted plants showed low wilting percentage (0.0-20.0%) and disease index (0.0-20.8%) following inoculation with BW. Yield for the eggplant rootstock grafted tomato plants was higher compared to the non-grafted tomatoes and self-grafted tomato. Fruit quality was not affected by grafting, although some differences in antioxidant activities were observed. The new eggplant rootstocks can be considered as alternatives to the rootstocks currently used for commercial production of tomatoes during the hot-wet season.

13.
Sci Rep ; 11(1): 8990, 2021 04 26.
Artigo em Inglês | MEDLINE | ID: mdl-33903703

RESUMO

Therophilus javanus (Bhat & Gupta) is an exotic larval endoparasitoid newly imported from Asia into Africa as a classical biological control agent against the pod borer Maruca vitrata (Fabricius). The parasitoid preference for the five larval instars of M. vitrata and their influence on progeny sex ratio were assessed together with the impact of larval host age at the time of oviposition on development time, mother longevity and offspring production. In a choice situation, female parasitoids preferred to oviposit in the first three larval instars. The development of immature stages of the parasitoid was observed inside three-day-old hosts, whereby the first two larval instars of T. javanus completed their development as endoparasites and the third larval instar as ectoparasite. The development time was faster when first larval instars (two- and three-day-old) of the host caterpillars were parasitized compared to second larval instar (four-day-old). The highest proportion of daughters (0.51) was observed when females were provided with four-day-old hosts. The lowest intrinsic rate of increase (r) (0.21 ± 0.01), the lowest rate of increase (λ) (1.23 ± 0.01), and the lowest net reproductive rate (Ro) (35.93 ± 6.51) were recorded on four-day-old hosts. These results are discussed in the light of optimizing mass rearing and release strategies.


Assuntos
Mariposas/parasitologia , Controle Biológico de Vetores , Vespas/fisiologia , Animais , Feminino , Larva/parasitologia , Masculino , Reprodução
14.
Toxins (Basel) ; 13(7)2021 07 19.
Artigo em Inglês | MEDLINE | ID: mdl-34357975

RESUMO

Meteorus pulchricornis (Ichneumonoidea, Braconidae) is an endoparasitoid wasp of lepidopteran caterpillars. Its parasitic success relies on vesicles (named M. pulchricornis Virus-Like Particles or MpVLPs) that are synthesized in the venom gland and injected into the parasitoid host along with the venom during oviposition. In order to define the content and understand the biogenesis of these atypical vesicles, we performed a transcriptome analysis of the venom gland and a proteomic analysis of the venom and purified MpVLPs. About half of the MpVLPs and soluble venom proteins identified were unknown and no similarity with any known viral sequence was found. However, MpVLPs contained a large number of proteins labelled as metalloproteinases while the most abundant protein family in the soluble venom was that of proteins containing the Domain of Unknown Function DUF-4803. The high number of these proteins identified suggests that a large expansion of these two protein families occurred in M. pulchricornis. Therefore, although the exact mechanism of MpVLPs formation remains to be elucidated, these vesicles appear to be "metalloproteinase bombs" that may have several physiological roles in the host including modifying the functions of its immune cells. The role of DUF4803 proteins, also present in the venom of other braconids, remains to be clarified.


Assuntos
Metaloproteases/metabolismo , Venenos de Vespas/genética , Animais , Feminino , Perfilação da Expressão Gênica , Interações Hospedeiro-Parasita , Larva , Mariposas , Proteômica , Venenos de Vespas/metabolismo , Vespas
15.
Insects ; 11(9)2020 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-32825771

RESUMO

The legume pod borer (Maruca vitrata) is one of the most serious legume pests due to its wide host range and high damage potential. Pheromone components on M. vitrata have been previously identified, allowing research on more environmentally friendly IPM tools for its control. M. vitrata produces a three-component pheromone blend containing (E, E)-10,12-hexadecadienal (major), (E, E)-10,12-hexadecadienol (minor), (E)-10-hexadecenal (minor). This study focused on the efficacy of synthetic pheromone lures and their blend components for mating disruption in M. vitrata. Under laboratory conditions, the mating behavior of M. vitrata pairs was observed from 18:00 to 02:00 h in an interval of 20 min to assess the efficacy of different pheromone lures. The scotophase behavior results show that the complete pheromone blend (E, E)-10,12-hexadecadienal + (E, E)-10,12-hexadecadienol + (E)-10-hexadecenal with a blend ratio of 1:1:1 effectively disrupted mating. The impact on mating disruption was evident from the lower fecundity and egg hatch/eclosion. The same lures were evaluated in a small-scale caged field study. The results show that the pheromone blend of (E, E)-10,12-hexadecadienal + (E, E)-10,12-hexadecadienol + (E)-10-hexadecenal in a1:1:1 ratio significantly disrupted the normal mating, leading to lower flower and pod damage and higher mung bean yield.

16.
J Nanosci Nanotechnol ; 9(1): 533-8, 2009 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-19441346

RESUMO

Nanofluids are identified suitable for micro and nano scale heat transfer applications where a high heat flux is required. These fluids are still in their early developmental stage and the exact heat transfer mechanism in them is not known yet. Due to this situation, there exists no suitable theoretical model for predicting the thermal conductivity of nanofluid. In this paper two new models for nanofluid thermal conductivity are developed. The first model which is based on Weber formula is used to predict the nanofluid thermal conductivity. The thermal conductivity of Al2O3/water, CuO/water, TiO2/water and TiO2/ethylene glycol nanofluids predicted by this model were compared with the published experimental data. The second model is used to analyze the influence of the effects of particle shape, nanolayer thickness and Brownian motion in enhancing thermal conductivity of nanofluids.

17.
J Nanosci Nanotechnol ; 9(10): 5966-72, 2009 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-19908482

RESUMO

This paper describes a simple chemical co-precipitation method for preparing nano-sized zinc oxide (ZnO) nanospheres. The morphological, thermal, structural, and chemical features of ZnO nanospheres were systematically studied and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermo gravimetric analysis-differential scanning calorimetric analysis, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy. The SEM micrographs reveal that the particles are spherical in nature and the precipitating agent ammonia plays a critical role in controlling the morphology of the nanospheres. Crystalline ZnO phase is obtained at higher annealing temperature and there by reduce the contents of the hydrated species. Powder XRD pattern indicated that the nanospheres exhibit wurtzite hexagonal ZnO phase. The average crystallite sizes of the ZnO nanospheres were calculated to be 14 nm for as-prepared sample and 16 nm for 500 degrees C annealed sample. The peak broadening in ZnO nanospheres due to lattice deformation was analyzed by plotting various modified form of W-H analysis such as uniform deformation model, uniform stress deformation model, and uniform deformation energy density model. From the three models, the strain values epsilon and the crystallite size D(v) were estimated and tabulated. The growth and the formation of ZnO were predicted and the results were confirmed by FT-IR studies.

18.
J Nanosci Nanotechnol ; 9(11): 6747-52, 2009 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-19908594

RESUMO

Here we demonstrate the preparation of samarium doped yttrium oxide nanoparticles using samarium chloride as a samarium source by co-precipitation method. The samarium doped yttria nanoparticles are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and Fourier transform infra-red spectroscopy (FT-IR). The XRD results revealed that all the synthesized samples exhibit cubic phase with average grain size of the nanoparticles in the order of 9-20 nm, calculated by Scherer's formula. The strain present in the annealed sample is estimated from Williamson-Hall (W-H) plot which is in the order of 3 x 10(-3). SEM and HRTEM results showed that the samples are composed of aggregated nanoparticles with uniform shape and size. The particles are highly crystalline which is also confirmed by XRD results. The position of the absorption peak is shifted towards the lower wavelength side when particles sizes reduced around 10 nm is observed by UV-visible (UV-vis) spectrometer. The direct band gap is estimated from UV-vis absorption spectrum, the calculated value is 5.98 and 5.87 eV for as-prepared and annealed sample (800 degrees C) respectively. The high intense red emission band observed at 608 nm from 4G(5/2)-6H(7/2) transition for Y2O3:Sm3+ under excitation at 214 nm using fluorescence spectrometer.

19.
Sci Rep ; 9(1): 3515, 2019 03 05.
Artigo em Inglês | MEDLINE | ID: mdl-30837549

RESUMO

Spoladea recurvalis is one of the most destructive insect pests of amaranth, a leafy vegetable in both Asia and Africa. The present study characterized the pheromone biosynthesis-activating neuropeptide (DH-PBAN) and pheromone/odorant binding proteins in S. recurvalis. The open reading frame of 600 base pairs encodes a 200-amino acid protein possessing five neuropeptide motifs (DH, PBAN, α-, ß-, and γ- subesophageal ganglion neuropeptides) and shares a characteristic conserved C-terminal pentapeptide fragment FXPRL. The full-length genome of Spre-DH-PBAN was 4,295 bp in length and comprised of six exons interspersed by five introns. Sequence homology and phylogenetic analysis of Spre-DH-PBAN have high similarity to its homologs in Crambidae of Lepidopteran order. We quantitatively measured the relative expression level (qRT_PCR) of Spre-DH-PBAN gene, the binding proteins such as odorant binding proteins (OBPs) and pheromone binding protein (PBPs) at different developmental stages. The results confirmed their role in recognition and chemoreception of sex pheromone components, and they were distinct, tissue- and sex-specific. This is the first report on the molecular analysis of PBAN gene and binding proteins, which can improve the understanding of molecular mechanisms of growth, development, and reproductive behavior of S. recurvalis, and may become effective targets for controlling this insect.


Assuntos
Proteínas de Insetos/metabolismo , Neuropeptídeos/metabolismo , Sequência de Aminoácidos , Animais , Sequência de Bases , Proteínas de Transporte/classificação , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Clonagem Molecular , Feminino , Expressão Gênica , Proteínas de Insetos/classificação , Proteínas de Insetos/genética , Masculino , Mariposas/crescimento & desenvolvimento , Mariposas/metabolismo , Neuropeptídeos/classificação , Neuropeptídeos/genética , Filogenia , Ligação Proteica , Receptores Odorantes/classificação , Receptores Odorantes/genética , Receptores Odorantes/metabolismo , Alinhamento de Sequência , Atrativos Sexuais/metabolismo
20.
Pest Manag Sci ; 75(9): 2446-2454, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31074055

RESUMO

Vegetables are one of the important crops which could alleviate poverty and malnutrition among the smallholder farmers in tropical Asia and Africa. However, a plethora of pests limit the productivity of these crops, leading to economic losses. Vegetable producers overwhelmingly rely on chemical pesticides in order to reduce pest-caused economic losses. However, over-reliance on chemical pesticides poses serious threats to human and environmental health. Hence, biopesticides offer a viable alternative to chemical pesticides in sustainable pest management programs. Baculoviruses such as nucleopolyhedrovirus (NPV) and granulovirus (GV) have been exploited as successful biological pesticides in agriculture, horticulture and forestry. Maruca vitrata multiple nucleocapsid NPV (MaviMNPV) was found to be a unique baculovirus specifically infecting pod borer on food legumes, and it has been successfully developed as a biopesticide in Asia and Africa. Entomopathogenic fungi also offer sustainable pest management options. Several strains of Metarhizium anisopliae and Beauveria bassiana have been tested and developed as biopesticides in Asia and Africa. This review specifically focuses on the discovery and development of entomopathogenic virus and fungi-based biopesticides against major pests of vegetable legumes and brassicas in Asia and Africa. © 2019 Society of Chemical Industry.


Assuntos
Agentes de Controle Biológico/administração & dosagem , Brassica , Fabaceae , Controle Biológico de Vetores/métodos , África , Ásia , Brassica/crescimento & desenvolvimento , Fabaceae/crescimento & desenvolvimento , Verduras/crescimento & desenvolvimento
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