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1.
Braz J Biol ; 83: e240842, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34550279

RESUMO

This research aimed to investigate various mosquitocidal activities of Chenopodium botrys whole- plant n-hexane extract against Culex quinquefasciatus. The extract showed remarkable larvicidal, pupicidal, adulticidal, oviposition deterrent and adult emergence inhibitory activities against Cx. quinquefasciatus. During the larvicidal and pupicidal activities, the 24-hour lethal concentration (LC50) of extract against 2nd instar larvae, 4th instar larvae and pupae were 324.6, 495.6 and 950.8 ppm, respectively. During the CDC (Centers for Disease Control and Prevention) bottle bioassay for adulticidal activity, the median knockdown times (KDT50) at 1.25% concentration was 123.4 minutes. During the filter paper impregnation bioassay for adulticidal activity, the KDT50 value at 0.138 mg/cm2 concentration was 48.6 minutes. The extract was fractionated into 14 fractions through silica gel column chromatography which were then combined into six fractions on the basis of similar retention factor (Rf) value. These fractions were screened for adulticidal activity by applying CDC bottle bioassay. The fraction obtained through 60:40 to 50:50% n-hexanes-chloroform mobile phase with 0.5 Rf value showed 100% adulticidal activity at 0.2% concentration. During oviposition deterrent activity, the highest concentration (1000 ppm) showed 71.3 ± 4.4% effective repellence and 0.6 ± 0.1 oviposition activity index. During adult emergence inhibition activity, the median emergence inhibition (EI50) value was 312.3 ppm. From the outcome of the present investigation, it is concluded that the n-hexane extract of C. botrys whole- plant possesses strong larvicidal, pupicidal, adulticidal, oviposition deterrent and adult emergence inhibitory activities against Cx. quinquefasciatus.


Assuntos
Chenopodium , Culex , Inseticidas , Animais , Hexanos , Inseticidas/farmacologia , Larva , Extratos Vegetais/farmacologia , Folhas de Planta
2.
Int J Mol Sci ; 22(16)2021 Aug 18.
Artigo em Inglês | MEDLINE | ID: mdl-34445622

RESUMO

Vector-borne diseases have appeared or re-emerged in many Southern Europe countries making the transmission of infectious diseases by mosquitoes (vectors) one of the greatest worldwide health threats. Larvicides have been used extensively for the control of Aedes (Stegomyia) albopictus (Skuse, 1895) (Diptera: Culicidae) and Culex pipiens Linnaeus, 1758 (Diptera: Culicidae) mosquitoes in urban and semi-urban environments, causing the increasing resistance of mosquitoes to commercial insecticides. In this study, 27 curcuminoids and monocarbonyl curcumin derivatives were synthesised and evaluated as potential larvicidal agents against Cx. pipiens and Ae. albopictus. Most of the compounds were more effective against larvae of both mosquito species. Four of the tested compounds, curcumin, demethoxycurcumin, curcumin-BF2 complex and a monocarbonyl tetramethoxy curcumin derivative exhibited high activity against both species. In Cx. pipiens the recorded LC50 values were 6.0, 9.4, 5.0 and 32.5 ppm, respectively, whereas in Ae. albopictus they exhibited LC50 values of 9.2, 36.0, 5.5 and 23.6 ppm, respectively. No conclusive structure activity relationship was evident from the results and the variety of descriptors values generated in silico provided some insight to this end.


Assuntos
Aedes/efeitos dos fármacos , Culex/efeitos dos fármacos , Curcumina/química , Curcumina/farmacologia , Inseticidas/farmacologia , Larva/efeitos dos fármacos , Mosquitos Vetores/efeitos dos fármacos , Animais , Anti-Inflamatórios não Esteroides/química , Anti-Inflamatórios não Esteroides/farmacologia , Feminino , Inseticidas/química
3.
Pestic Biochem Physiol ; 178: 104911, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34446187

RESUMO

Commercial insecticide aerosol sprays are widely used in households for controlling Aedes aegypti and Culex quinquefasciatus, the primary vectors of dengue virus and filarial worm, respectively. In Thailand, however, both mosquitoes are resistant to pyrethroids conferred by knockdown resistance (kdr) mutations, V1016G and F1534C in Ae. aegypti and L1014F in Cx. quinquefasciatus. This study evaluated the efficacy of five sprays (coded as AS1-AS5) with different formulations of pyrethroids against wild mosquitoes by using a cage bioassay in a furnished bedroom of a house. Five cages containing wild mosquitoes and five cages containing a pyrethroid susceptible strain of Ae. aegypti (25 females each), as a bio-indicator, were allocated in the room and spraying was operated for 15 s. Survivors and dead mosquitoes were genotyped individually for the kdr mutations using allele-specific PCR methods. Both mosquito species showed a high resistance to permethrin and deltamethrin with 12.5-58.0% mortality rates. For controlling Ae. aegypti, the spray AS4 showed the highest efficacy (mortality rates 76.0-100.0%, mean 95.2%), followed by AS2 (73.0-100.0%, mean 93.8%). For controlling Cx. quinquefasciatus, the best result was obtained from AS4 (66.0-98.0% mortality, mean 89.8%), followed by AS2 (73.0-97.0%, mean 84.5%). The sprays (AS4 and AS2) containing both type I and type II pyrethroids were more effective than those containing only type I pyrethroids or pyrethrum with the synergist piperonyl butoxide. The mutant G1016 and F1014 allele frequencies were significantly higher in the survivor groups than the dead groups of Ae. aegypti and Cx. quinquefasciatus, respectively, (P < 0.05). The efficacy of the sprays varied depending on the mosquito species, formulations, nozzles and locations of caged mosquitoes. The V1016G and L1014F mutations are associated with the reduced efficacy of sprays used in households for controlling resistant Ae. aegypti and Cx. quinquefasciatus mosquitoes, respectively.


Assuntos
Aedes , Culex , Inseticidas , Piretrinas , Aedes/genética , Aerossóis , Animais , Culex/genética , Resistência a Inseticidas/genética , Inseticidas/farmacologia , Mosquitos Vetores/genética , Tailândia
4.
Pestic Biochem Physiol ; 178: 104912, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34446188

RESUMO

Intracellular effects exerted by phytochemicals eliciting insect growth-retarding responses during vector control intervention remain largely underexplored. We studied the effects of Zanthoxylum chalybeum Engl. (Rutaceae) (ZCE) root derivatives against malaria (Anopheles gambiae) and arbovirus vector (Aedes aegypti) larvae to decipher possible molecular targets. We report dose-dependent biphasic effects on larval response, with transient exposure to ZCE and its bioactive fraction (ZCFr.5) inhibiting acetylcholinesterase (AChE) activity, inducing larval lethality and growth retardation at sublethal doses. Half-maximal lethal concentrations (LC50) for ZCE against An. gambiae and Ae. aegypti larvae after 24-h exposure were 9.00 ppm and 12.26 ppm, respectively. The active fraction ZCFr.5 exerted LC50 of 1.58 ppm and 3.21 ppm for An. gambiae and Ae. aegypti larvae, respectively. Inhibition of AChE was potentially linked to larval toxicity afforded by 2-tridecanone, palmitic acid (hexadecanoic acid), linoleic acid ((Z,Z)-9,12-octadecadienoic acid), sesamin, ß-caryophyllene among other compounds identified in the bioactive fraction. In addition, the phenotypic larval retardation induced by ZCE root constituents was exerted through transcriptional modulation of ecdysteroidogenic CYP450 genes. Collectively, these findings provide an explorative avenue for developing potential mosquito control agents from Z. chalybeum root constituents.


Assuntos
Aedes , Culex , Inseticidas , Zanthoxylum , Animais , Transtornos do Crescimento , Inseticidas/toxicidade , Larva , Controle de Mosquitos , Mosquitos Vetores , Extratos Vegetais
5.
Parasite ; 28: 60, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34374642

RESUMO

Between 2016 and 2020, the Medical and Veterinary Entomology unit of the Institut Pasteur du Cambodge collected over 230,000 mosquitoes. Based on this sampling effort, a checklist of 290 mosquito species in Cambodia is presented. This is the first attempt to list the Culicidae fauna of the country. We report 49 species for the first time in Cambodia. The 290 species belong to 20 genera: Aedeomyia (1 sp.), Aedes (55 spp.), Anopheles (53 spp.), Armigeres (26 spp.), Coquillettidia (3 spp.), Culex (57 spp.), Culiseta (1 sp.), Ficalbia (1 sp.), Heizmannia (10 spp.), Hodgesia (3 spp.), Lutzia (3 spp.), Malaya (2 spp.), Mansonia (5 spp.), Mimomyia (7 spp.), Orthopodomyia (3 spp.), Topomyia (4 spp.), Toxorhynchites (4 spp.), Tripteroides (6 spp.), Uranotaenia (27 spp.), and Verrallina (19 spp.). The Cambodian Culicidae fauna is discussed in its Southeast Asian context. Forty-three species are reported to be of medical importance, and are involved in the transmission of pathogens.


Assuntos
Aedes , Culex , Culicidae , Animais , Camboja , Lista de Checagem , Mosquitos Vetores
6.
Proc Biol Sci ; 288(1956): 20210881, 2021 08 11.
Artigo em Inglês | MEDLINE | ID: mdl-34375559

RESUMO

Food limitation is a universal stressor for wildlife populations and is increasingly exacerbated by human activities. Anthropogenic environmental change can significantly alter the availability and quality of food resources for reservoir hosts and impact host-pathogen interactions in the wild. The state of the host's nutritional reserves at the time of infection is a key factor influencing infection outcomes by altering host resistance. Combining experimental and model-based approaches, we investigate how an environmental stressor affects host resistance to West Nile virus (WNV). Using American robins (Turdus migratorius), a species considered a superspreader of WNV, we tested the effect of acute food deprivation immediately prior to infection on host viraemia. Here, we show that robins food deprived for 48 h prior to infection, developed higher virus titres and were infectious longer than robins fed normally. To gain an understanding about the epidemiological significance of food-stressed hosts, we developed an agent-based model that simulates transmission dynamics of WNV between an avian host and the mosquito vector. When simulating a nutritionally stressed host population, the mosquito infection rate rose significantly, reaching levels that represent an epidemiological risk. An understanding of the infection disease dynamics in wild populations is critical to predict and mitigate zoonotic disease outbreaks.


Assuntos
Culex , Culicidae , Aves Canoras , Febre do Nilo Ocidental , Vírus do Nilo Ocidental , Animais , Humanos , Insetos Vetores , Febre do Nilo Ocidental/epidemiologia , Febre do Nilo Ocidental/veterinária
7.
Parasitol Res ; 120(9): 3083-3090, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34338859

RESUMO

Mosquitoes (Diptera: Culicidae) are the largest group of blood-feeding insects that disturb not only humans but also other mammals and birds. This study reports the presence of native mosquito species in the regional unit of Thessaloniki and the monitoring of their population. In total, 13 mosquito species belonging to four genera were identified. The most dominant species was Culex pipiens, followed by Aedes caspius. In the present study, we report for the first time the presence of Ae. vittatus in Greece and of Anopheles plumbeus in the regional unit of Thessaloniki. Regarding the seasonal variation, species of the genus Aedes were the ones that first appeared in late March, followed by Culex species at the end of April and finally species of the genus Anopheles in July. Species of the Aedes genus were found to be the most abundant in the first quarter of the year (late March to early April). Population of Cx. pipiens remained at high levels from late April to late September. Species of the genus Anopheles were found in high densities from early August to October. The current study contributes to the knowledge of the mosquito species composition and their relative abundance in an area where West Nile virus caused severe epidemic outbreaks.


Assuntos
Aedes , Culex , Animais , Grécia , Mosquitos Vetores , Saúde Pública , Estações do Ano
8.
Molecules ; 26(12)2021 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-34204264

RESUMO

The present research investigated the chemical characterization and insecticidal activity of n-Hexane extracts of Epaltes divaricata (NH-EDx) along with their chief derivatives n-Hexadecanoic acid (n-HDa) and n-Octadecanoic acid (n-ODa) against the dengue vector Aedes aegypti and lepidopteran pest Spodoptera litura. Chemical screening of NH-EDx through GC-MS analysis delivered nine major derivatives, and the maximum peak area percentage was observed in n-Hexadecanoic acid (14.63%) followed by n-Octadecadienoic acid (6.73%). The larvicidal activity of NH-EDx (1000 ppm), n-HDa (5 ppm), and n-ODa (5 ppm) against the A. aegypti and S. litura larvae showed significant mortality rate in a dose-dependent way across all the instars. The larvicidal activity was profound in the A. aegypti as compared to the S. litura across all the larval instars. The sublethal dosages of NH-EDx (500 ppm), n-HDa (2.5 ppm), and n-ODa (2.5 ppm) also showed alterations in the larval/pupal durations and adult longevity in both the insect pests. The enzyme activity revealed that the α- and ß-carboxylesterase levels were decreased significantly in both the insect pests, whereas the levels of GST and CYP450 uplifted in a dose-dependent manner of NH-EDx, n-HDa, and n-ODa. Correspondingly, midgut tissues such as the epithelial layer (EL), gut lumen (GL), peritrophic matrix (Pm), and brush border membrane (BBM) were significantly altered in their morphology across both A. aegypti and S. litura against the NH-EDx and their bioactive metabolites. NH-EDx and their bioactive metabolites n-HDa and n-ODa showed significant larvicidal, growth retardant, enzyme inhibition, and midgut toxicity effects against two crucial agriculturally and medically challenging insect pest of ecological importance.


Assuntos
Aedes/efeitos dos fármacos , Asteraceae/metabolismo , Extratos Vegetais/farmacologia , Spodoptera/efeitos dos fármacos , Animais , Asteraceae/efeitos dos fármacos , Culex/efeitos dos fármacos , Dengue/prevenção & controle , Hexanos/química , Inseticidas/farmacologia , Larva/efeitos dos fármacos , Mosquitos Vetores/efeitos dos fármacos , Folhas de Planta/química , Solventes/química
9.
Molecules ; 26(14)2021 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-34299452

RESUMO

In recent decades, demands for novel insecticides against mosquitoes are soaring, yet candidate chemicals with desirable properties are limited. Kathon is a broad-spectrum isothiazolinone microbicide, but other applications remain uncharacterized. First, we treated larvae of Culex quinquefasciatus and Aedes albopictus, two major mosquito vectors of human viral diseases, with Kathon at 15 mg/L (a concentration considered safe in cosmetic and body care products), and at lower concentrations, and found that Kathon treatment resulted in high mortality of larvae. Second, sublethal concentration of Kathon can cause significantly prolonged larval development of C. quinquefasciatus. Third, we explored the effects of two constituents of Kathon, chloromethylisothiazolinone (CMIT) and methylisothiazolinone (MIT), on the survival of larvae, and found that CMIT was the major toxic component. Further, we explored the mechanisms of action of Kathon against insect cells and found that Kathon reduces cell viability and adenosine triphosphate production but promotes the release of lactate dehydrogenase in Drosophila melanogaster S2 cells. Our results indicate that Kathon is highly toxic to mosquito larvae, and we highlight its potential in the development of new larvicides for mosquito control.


Assuntos
Culicidae/efeitos dos fármacos , Tiazóis/química , Tiazóis/farmacologia , Aedes/efeitos dos fármacos , Animais , Anopheles/efeitos dos fármacos , Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Culex/efeitos dos fármacos , Culicidae/metabolismo , Inseticidas/química , Larva/efeitos dos fármacos , Controle de Mosquitos/métodos , Mosquitos Vetores
10.
Sci Total Environ ; 794: 148606, 2021 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-34225145

RESUMO

Mosquitoes and the diseases they transmit are a global public health threat that affects most human populations. Mosquito abundances are strongly linked to the number of suitable larval habitats available. However, it is still not well understood how different land uses impact larval habitat quality in different parts of the world. We investigated links between land use practices and abundance of mosquito larvae in temporary ponds located in different land uses in a malaria expansion zone in Tanzania. Temporary ponds are often cited as important sources of mosquitoes but are also of substantial conservation concern being home to a unique fauna and flora. Often, they also have high socio-economic importance. Overall, encountered mosquito larval abundances were very low, both for the collected Anopheles gambiae s.l. and Culex quinquefasciatus. Although temporary ponds are important mosquito larval habitats in other parts of Africa, currently they are unlikely to be an important factor affecting the prevalence of mosquito borne diseases in the Manyara study region. Larval abundances in temporary ponds were higher in agricultural areas where more eutrophic conditions were found and minimal in residential areas. Overall, even though temporary ponds are often modified as rice paddies in the rainy season, they were in a good ecological condition and hosted a diverse assemblage of aquatic predators that likely prevented larval mosquitoes from reaching high densities. Maintaining this good condition by preventing pesticide and nutrient input as much as possible, can be important to prevent pond degradation that is likely to make these habitats more suitable for mosquitoes in the future.


Assuntos
Anopheles , Culex , Malária , Animais , Ecossistema , Humanos , Larva , Lagoas , Tanzânia
11.
Microb Pathog ; 158: 105093, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34271121

RESUMO

Bacillus thuringiensis is the most popular mosquitocidal bacteria, strains of which are effective against almost all mosquito larvae. It has host specificity and thus, has no adverse effect on non-target species of the ecosystem. Culex tritaeniorhynchus, a vector of Japanese encephalitis (JE), breeds in vast area of rice fields in Burdwan district of West Bengal, India, which has already confronted JE epidemic. Entomological investigation and ecological studies on this vector mosquito showed that JE epidemic may reoccur anytime in the area. A strain of Bt (BU55) was isolated from rice field soil, efficacy was tested against Cx. tritaeniorhynchus and mosquitocidal role was confirmed against Cx. quinquefascistus also. The LC50 of Bacillus thuringiensis BU55 against Cx. tritaeniorhynchus and Cx. quinquefascistus after 72 h was 8.59 ml (final dose 2.49 x107 CFU/ml) and 7.52 ml (final dose 2.20 x 107 CFU/ml), respectively. Insecticidal crystal protein profile of BU55 produced 136.89, 64.80, 43.45, 33.65 and 26.98 kDa bands. Among them 136.89, 64.29, 26.98 kDa proteins are comparable to actual toxins viz. Cry1Ac (138.3 kDa, Lepidoptera specific), Cry4D (68.0 kDa, Diptera specific) and Cyt (27.4 kDa, Diptera specific). The results clearly showed that the Bt strain is a potent dipteran larvicide and can be used against the JE vectors to control the disease.


Assuntos
Bacillus thuringiensis , Culex , Oryza , Animais , Ecossistema , Índia , Mosquitos Vetores , Solo
12.
Am J Trop Med Hyg ; 105(3): 813-817, 2021 07 19.
Artigo em Inglês | MEDLINE | ID: mdl-34280147

RESUMO

Japanese encephalitis virus (JEV) is transmitted between swine, migratory birds, and Culex mosquitoes, and has circulated indigenously in Asia for almost a century. Despite being the country with the highest JEV diversity, surveillance targeting of Indonesia's vectors is scarce. This study collected mosquitoes from several locations in Tabanan Regency, Bali Island, Indonesia. We captured and classified 3,032 adult Culex mosquitoes into seven species, with Culex vishnui subgroup mosquitoes making up approximately 90% of the total. Japanese encephalitis virus was identified by next-generation sequencing (NGS) analysis of a Cx. vishnui mosquito pool. Genetic and phylogenetic analysis revealed the JEV as genotype (G) IV. The nucleotide identity was 99% with other JEV GIV isolates obtained from swine sera in 2017 on Bali Island and from a human patient in Australia with a travel history to Bali in 2019. This finding indicated that JEV GIV persists in restricted areas and is circulating between swine-mosquito vectors.


Assuntos
Culex/virologia , Vírus da Encefalite Japonesa (Espécie)/isolamento & purificação , Insetos Vetores/virologia , Animais , Vírus da Encefalite Japonesa (Espécie)/genética , Genótipo , Indonésia
13.
Acta Trop ; 222: 106065, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34303690

RESUMO

The use of efficient mosquito sampling methods in vector surveillance programs is crucial to inform control actions and prevent outbreaks. amongst existing trapping methods, the BG sentinel trap is widely used for collecting mosquitoes from the subgenus Stegomyia. However, studies state that the BG-sentinel trap underestimates the relative abundance of mosquito vectors. In this study, we used mice to enhance the effectiveness of the BG-sentinel trap to collect Aedes aegypti (Linnaeus) and follow the species' daily abundance under local conditions. The Latin square method was used to compare different combinations in three different seasons. Of the 35,107 mosquitoes collected, Ae. aegypti (53.82%) and Culex quinquefasciatus (46.07%) were dominant. The combination of BG-Lure + 3 mice captured more Ae. aegypti individuals (apparent density per trap/day (ADT = 187.65 ± 133.53; p < 0.001) followed by the 3 mice-baited BG-sentinel trap (ADT = 163.47 ± 117.32), the BG-sentinel trap without attractant (ADT = 74.15 ± 117.07) and the BG-sentinel trap + BG-Lure (ADT = 47.1 ± 115.91). Aedes aegypti showed two peaks of activity in the day, one following the sunrise and one before the sunset, influenced by temperature and relative humidity. Our study suggests the use of mice to enhance the efficiency of the BG-Sentinel trap to catch Ae. aegypti. However, its application in large scale entomological monitoring programs should be difficult because of ethical and operational constraints.


Assuntos
Aedes , Controle de Mosquitos , Animais , Culex , Camundongos , Mosquitos Vetores , Senegal
14.
Cutis ; 107(5): 244-247, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-34288851

RESUMO

West Nile virus (WNV) commonly presents cutaneously as a maculopapular rash on the trunk and extremities that most often appears around the time of defervescence and may serve as a positive prognostic indicator. Several laboratory tests can aid in diagnosis of WNV, including an IgM enzyme-linked immunosorbent assay (ELISA), but an antibody response may not be detectable for up to 8 days after symptom onset. Taking a comprehensive history in any patient presenting with a generalized maculopapular rash, fever, nonspecific symptoms, or neurologic changes can aid the astute dermatologist in promptly recognizing the possibility of WNV.


Assuntos
Culex , Culicidae , Febre do Nilo Ocidental , Vírus do Nilo Ocidental , Animais , Anticorpos Antivirais , Humanos , Febre do Nilo Ocidental/diagnóstico
15.
Parasitol Res ; 120(7): 2343-2350, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34110501

RESUMO

Arthropod vectors are frequently exposed to a diverse assemblage of parasites, but the consequence of these infections on their biology and behavior are poorly understood. We experimentally evaluated whether the ingestion of a common protozoan parasite of avian hosts (Haemoproteus spp.; Haemosporida: Haemoproteidae) impacted the survivorship of Culex quinquefasciatus (Say) (Diptera: Culicidae). Blood was collected from wild northern cardinals (Cardinalis cardinalis) in College Station, Texas, and screened for the presence of Haemoproteus spp. parasites using microscopic and molecular methods. Experimental groups of Cx. quinquefasciatus mosquitoes were offered Haemoproteus-positive cardinal blood through an artificial feeding apparatus, while control groups received Haemoproteus-negative cardinal blood or domestic canary (Serinus canaria domestica) blood. Culex quinquefasciatus mosquitoes exposed to Haemoproteus infected cardinal blood survived significantly fewer days than mosquitoes that ingested Haemoproteus-negative cardinal blood. The survival of mosquitoes fed on positive cardinal blood had a median survival time of 18 days post-exposure and the survival of mosquitoes fed on negative cardinal blood exceeded 50% across the 30 day observation period. Additionally, mosquitoes that fed on canary controls survived significantly fewer days than cardinal negative controls, with canary control mosquitoes having a median survival time of 17 days. This study further supports prior observations that Haemoproteus parasites can be pathogenic to bird-biting mosquitoes, and suggests that Haemoproteus parasites may indirectly suppress the transmission of co-circulating vector-borne pathogens by modulating vector survivorship. Our results also suggest that even in the absence of parasite infection, bloodmeals from different bird species can influence mosquito survivorship.


Assuntos
Culex/fisiologia , Culex/parasitologia , Haemosporida/fisiologia , Mosquitos Vetores/fisiologia , Mosquitos Vetores/parasitologia , Passeriformes/parasitologia , Animais , Doenças das Aves/parasitologia , Doenças das Aves/transmissão , Canários/sangue , Canários/parasitologia , DNA de Protozoário/sangue , Passeriformes/sangue , Reação em Cadeia da Polimerase/veterinária , Probabilidade , Modelos de Riscos Proporcionais , Infecções Protozoárias em Animais/parasitologia , Infecções Protozoárias em Animais/transmissão , Texas
16.
Arch Microbiol ; 203(7): 4587-4592, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34160628

RESUMO

The two-component Cry48Aa/Cry49Aa toxin produced by Lysinibacillus sphaericus shows specifically toxic to Culex quinquefasciatus mosquito larvae. Cry49Aa C-terminal domain is responsible for specific binding to the larval gut cell membrane, while its N-terminal domain is required for interaction with Cry48Aa. To investigate functional role of cysteine in Cry49Aa, four cysteine residues at positions 70, 91, 183, and 258 were substituted by alanine. All mutants showed similar crystalline morphology and comparable yield to that of the wild type except that the yield of the C91A mutant was low. Four cysteine residues did not involve in disulfide bond formation within or between Cry49Aa molecules. Cys91, Cys183, and Cys258 are essential for larvicidal activity against C. quinquefasciatus larvae, while Cys70 is not. Substitution at C91, C183, and C258 caused weaker Cry48Aa- Cry49Aa interaction, while mutations at C183 and C258 reduced the binding capacities to the larval gut cell membrane. Thus, Cysteine residues at position 91, 183, and 258 in Cry49Aa are required for full toxicity of Cry48Aa/Cry49Aa toxin.


Assuntos
Toxinas Bacterianas , Culex , Animais , Bacillaceae/genética , Bacillaceae/patogenicidade , Toxinas Bacterianas/genética , Toxinas Bacterianas/toxicidade , Culex/efeitos dos fármacos , Culex/microbiologia , Cisteína/genética , Larva/efeitos dos fármacos
17.
Exp Parasitol ; 226-227: 108120, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34089701

RESUMO

The bio-efficacy of crude ethyl acetate extract, fractions and a compound phenyl acetic acid from the ethyl acetate extract of Streptomyces collinus was evaluated on Culex quinquefasciatus Say and Aedes aegypti L. mosquitoes (Diptera: Culicidae). The larvae were exposed to concentrations of 2.5, 5.0, 7.5 and 10.0 ppm for fractions and 0.5, 1.0, 1.5 and 2.0 ppm for compound. After 24 h, the larval mortality was assessed and the LC50 and LC90 values were calculated. Similarly, per cent ovicidal activity was calculated for eggs after 120 h post treatment for phenyl acetic acid. Among the eleven fractions screened, fraction 7 from the ethyl acetate extract of Streptomyces collinus exhibited good larvicidal activity against both mosquito species. The LC50 and LC90 values of fraction 7 were 4.42, 6.23 ppm against Cx. quinquefasciatus larvae and 5.13, 14.51 ppm against Ae. aegypti larvae, respectively. Further, the isolated compound, phenyl acetic acid from fraction 7 recorded 100% larvicidal activity at 2 ppm concentration with LC50 and LC90 values of 2.07, 4.87 ppm on Cx. quinquefasciatus larvae and 3.81, 9.87 ppm on Ae. aegypti larvae, respectively. Phenyl acetic acid presented 50.3% and 42.0% ovicidal activity against Cx. quinquefasciatus and Ae. aegypti eggs at 2 ppm concentration after 120 h post treatment. The compound, phenyl acetic acid could be used in mosquito control programme.


Assuntos
Aedes , Culex , Fenilacetatos , Streptomyces/química , Aedes/efeitos dos fármacos , Aedes/enzimologia , Aedes/crescimento & desenvolvimento , Análise de Variância , Animais , Bioensaio , Culex/efeitos dos fármacos , Culex/enzimologia , Culex/crescimento & desenvolvimento , Esterases/antagonistas & inibidores , Glutationa Transferase/antagonistas & inibidores , Índia , Larva/efeitos dos fármacos , Dose Letal Mediana , Óvulo/efeitos dos fármacos , Fenilacetatos/química , Fenilacetatos/isolamento & purificação , Fenilacetatos/farmacologia
18.
Parasit Vectors ; 14(1): 338, 2021 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-34174948

RESUMO

BACKGROUND: Clusters of sex-specific loci are predicted to shape the boundaries of the M/m sex-determination locus of the dengue vector mosquito Aedes aegypti, but the identities of these genes are not known. Identification and characterization of these loci could promote a better understanding of mosquito sex chromosome evolution and lead to the elucidation of new strategies for male mosquito sex separation, a requirement for several emerging mosquito population control strategies that are dependent on the mass rearing and release of male mosquitoes. This investigation revealed that the methylthioribulose-1-phosphate dehydratase (MtnB) gene, which resides adjacent to the M/m locus and encodes an evolutionarily conserved component of the methionine salvage pathway, is required for survival of female larvae. RESULTS: Larval consumption of Saccharomyces cerevisiae (yeast) strains engineered to express interfering RNA corresponding to MtnB resulted in target gene silencing and significant female death, yet had no impact on A. aegypti male survival or fitness. Integration of the yeast larvicides into mass culturing protocols permitted scaled production of fit adult male mosquitoes. Moreover, silencing MtnB orthologs in Aedes albopictus, Anopheles gambiae, and Culex quinquefasciatus revealed a conserved female-specific larval requirement for MtnB among different species of mosquitoes. CONCLUSIONS: The results of this investigation, which may have important implications for the study of mosquito sex chromosome evolution, indicate that silencing MtnB can facilitate sex separation in multiple species of disease vector insects.


Assuntos
Aedes/enzimologia , Anopheles/enzimologia , Culex/enzimologia , Hidroliases/metabolismo , Proteínas de Insetos/metabolismo , Aedes/genética , Aedes/crescimento & desenvolvimento , Animais , Anopheles/genética , Anopheles/crescimento & desenvolvimento , Culex/genética , Culex/crescimento & desenvolvimento , Feminino , Hidroliases/genética , Proteínas de Insetos/genética , Larva/enzimologia , Larva/genética , Larva/crescimento & desenvolvimento , Masculino , Ribulosefosfatos/metabolismo
19.
Zootaxa ; 4974(1): 191192, 2021 May 19.
Artigo em Inglês | MEDLINE | ID: mdl-34186861

RESUMO

While adding taxon names to the Systema Dipterorum database (Evenhuis Pape 2021), one of us (NLE) discovered that Humboldt (1819) had spelled the proposed name of a nominal mosquito species in two ways. He described the species, which was found in swampy places along the Magdalena River near Tenerife, Colombia, as Culex cyanopennis on page 340 and afterwards referred to it as Culex cyanopterus on pages 345 and 349. Both names have the same meaning: cyano- (Gr. kyanos, dark blue), pennis (L. penna, feather, wing) and pteron (Gr. feather, wing). The species was named for the perceived color of the wings: "Alæ cæruleæ, splendore semi-metallico…" (wings blue, a bright semi-metallic). On page 345, Humboldt states, translated from the French: "We have been informed in the Rio de la Magdalena that in Simitì no other Culex than the jejen [je·jén: Sp., gnat, mosquito] was known in the past. You can spend the night there quietly, because the jejen is not a nocturnal insect. Since the year 1801, the big blue-winged mosquito (Culex cyanopterus) has shown itself in such abundance that the poor inhabitants of Simitì do not know how to get a peaceful sleep." Thus, in addition to having the same meaning, the two names are associated with the same locality.


Assuntos
Culex/classificação , Animais , Colômbia , Idioma , Masculino , Rios , Terminologia como Assunto
20.
Parasit Vectors ; 14(1): 331, 2021 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-34158103

RESUMO

BACKGROUND: Although American crows are a key indicator species for West Nile virus (WNV) and mount among the highest viremias reported for any host, the importance of crows in the WNV transmission cycle has been called into question because of their consistent underrepresentation in studies of Culex blood meal sources. Here, we test the hypothesis that this apparent underrepresentation could be due, in part, to underrepresentation of crow nesting habitat from mosquito sampling designs. Specifically, we examine how the likelihood of a crow blood meal changes with distance to and timing of active crow nests in a Davis, California, population. METHODS: Sixty artificial mosquito resting sites were deployed from May to September 2014 in varying proximity to known crow nesting sites, and Culex blood meal hosts were identified by DNA barcoding. Genotypes from crow blood meals and local crows (72 nestlings from 30 broods and 389 local breeders and helpers) were used to match mosquito blood meals to specific local crows. RESULTS: Among the 297 identified Culex blood meals, 20 (6.7%) were attributable to crows. The mean percentage of blood meals of crow origin was 19% in the nesting period (1 May-18 June 2014), but 0% in the weeks after fledging (19 June-1 September 2014), and the likelihood of a crow blood meal increased with proximity to an active nest: the odds that crows hosted a Culex blood meal were 38.07 times greater within 10 m of an active nest than > 10 m from an active nest. Nine of ten crow blood meals that could be matched to a genotype of a specific crow belonged to either nestlings in these nests or their mothers. Six of the seven genotypes that could not be attributed to sampled birds belonged to females, a sex bias likely due to mosquitoes targeting incubating or brooding females. CONCLUSION: Data herein indicate that breeding crows serve as hosts for Culex in the initial stages of the WNV spring enzootic cycle. Given their high viremia, infected crows could thereby contribute to the re-initiation and early amplification of the virus, increasing its availability as mosquitoes shift to other moderately competent later-breeding avian hosts.


Assuntos
Doenças das Aves/fisiopatologia , Corvos/fisiologia , Corvos/virologia , Culex/fisiologia , Culex/virologia , Febre do Nilo Ocidental/veterinária , Vírus do Nilo Ocidental/fisiologia , Animais , Doenças das Aves/virologia , Corvos/sangue , Comportamento Alimentar , Feminino , Masculino , Comportamento de Nidação , Febre do Nilo Ocidental/fisiopatologia , Febre do Nilo Ocidental/virologia , Vírus do Nilo Ocidental/genética , Vírus do Nilo Ocidental/isolamento & purificação
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