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1.
Zhongguo Xue Xi Chong Bing Fang Zhi Za Zhi ; 33(5): 501-504, 2021 Aug 24.
Artigo em Chinês | MEDLINE | ID: mdl-34791848

RESUMO

OBJECTIVE: To investigate the susceptibility of Anopheles sinensis to malathion, deltamethrin and lambda-cyhalothrin in Puyang City, Henan Province, so as to provide the scientific basis for local malaria vector control. METHODS: An. sinensis was captured from Puyang County, Puyang City of Henan Province in September 2018 and July 2020, and the susceptibility of field captured An. sinensis to malathion, deltamethrin and lambda-cyhalothrin was tested using the filter-paper bioassay recommended by WHO. The insecticide resistance level was assessed based on the WHO criteria. RESULTS: In 2018 and 2010, the half knock-down times (KT50) of malathion were 91.08 min and 40.95 min for An. sinensis, with knock-down rates of 37.50% and 60.87% 60 min post-exposure to malathion and 24-hour mortality rates of 90.91% and 100%, respectively, and the insecticide resistance levels were moderately resistant (M) and susceptible (S). The KT50 of deltamethrin were 415.56 min and 341.19 min for An. sinensis in 2018 and 2020, with knock-down rates of 22.92% and 16.98% 60 min post-exposure to malathion and 24-hour mortality rates of 22.92% and 16.98%, and the insecticide resistance levels were all resistant (R). The KT50 of lambda-cyhalothrin were 164.22 min and 236.22 min for An. sinensis in 2018 and 2020, with knock-down rates of 30.39% and 38.30% 60 min postexposure to malathion and 24 h mortality rates of 19.60% and 21.28%, respectively, and the insecticide resistance levels were all R. CONCLUSIONS: An. sinensis is relatively susceptible to malathion but has developed high-level resistance to deltamethrin and lambda-cyhalothrin in Puyang City, Henan Province..


Assuntos
Anopheles , Inseticidas , Malária , Piretrinas , Animais , Resistência a Inseticidas , Inseticidas/farmacologia , Controle de Mosquitos , Mosquitos Vetores , Nitrilas/farmacologia , Piretrinas/farmacologia
2.
Zhongguo Xue Xi Chong Bing Fang Zhi Za Zhi ; 33(5): 510-512, 2021 Oct 25.
Artigo em Chinês | MEDLINE | ID: mdl-34791850

RESUMO

OBJECTIVE: To investigate the distribution and density of Culex mosquito populations and the resistance of Culex pipiens pallens to insecticides in Jiangsu Province in 2018 and 2019. METHODS: During the period from June to October in 2018 and 2019, six counties (districts, cities) were sampled in southern, northern and central Jiangsu Province as surveillance sites. The density of Culex mosquitoes was measured overnight using the light trapping technique. In addition, Culex pipiens pallens mosquitoes were collected from Hai'an of Nantong City and Yandu District of Yancheng City, central Jiangsu Province, and the sensitivity of female first filial generations to dichlorodiphenyltrichloroethane (DDT), malation, proposur, beta cypermethrin and deltamethrin was tested using the standard WHO insecticide susceptibility test assay. RESULTS: A total of 104 423 Culex mosquitoes were captured in six surveillance sites of Jiangsu Province in 2018 and 2019, and Culex quinquefasciatus (49.11%), Culex pipiens pallens (28.38%), and Culex tritaeniorhynchus (21.04%) were predominant species. The density of Culex mosquitoes started to increase since early June, peaked in July and tended to be low in late October. Culex pipiens pallens mosquitoes captured from Hai'an was susceptible to malation, while those from Yandu District were moderately resistant to malation. Culex pipiens pallens mosquitoes from both Yandu and Hai'an were moderately resistant to proposur, and were resistant to DDT, beta cypermethrin and deltamethrin. CONCLUSIONS: Culex quinquefasciatus, Culex pipiens pallens and Culex tritaeniorhynchus are predominant Culex species in Jiangsu Province. Culex pipiens pallens is resistant to DT, beta cypermethrin and deltamethrin in central Jiangsu Province.


Assuntos
Culex , Culicidae , Inseticidas , Piretrinas , Animais , Bioensaio , Feminino , Resistência a Inseticidas , Inseticidas/farmacologia , Piretrinas/farmacologia
3.
Arch Insect Biochem Physiol ; 108(3): e21842, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34499777

RESUMO

Glyphodes pyloalis Walker has become one of the most significant mulberry pests, and it has caused serious economic losses in major mulberry growing regions in China. Peptidoglycan recognition proteins (PGRPs) are responsible for initiating and regulating immune signalling pathways in insects. However, their roles responding to chemical pesticides is still less known. This study aimed to investigate the possible detoxication function of GpPGRP-S2 and GpPGRP-S3 in G. pyloalis in response to chlorfenapyr and phoxim. The chlorfenapyr and phoxim treatment significantly induced the expression level of GpPGRP-S3 at 48 h. In addition, the expression levels of GpPGRP-S2 and GpPGRP-S3 in the chlorfenapyr/phoxim treatment group were significantly higher in midgut than those in the control group at 48 h. The results of the survival experiment showed that silencing either GpPGRP-S2 or GpPGRP-S3 would not influence the survival rate of G. pyloalis which treated with phoxim, however, silencing GpPGRP-S2 or GpPGRP-S3 would cause G. pyloalis to be more easily killed by chlorfenapyr. The expression of carboxylesterase GpCXE1 was significantly induced by chlorfenapyr/phoxim treatment, while it was suppressed once silenced GpPGRP-S2 followed with chlorfenapyr treatment or silenced GpPGRP-S3 followed with phoxim treatment. These results might suggest that under the chlorfenapyr/phoxim treatment condition, the connection between GpPGRPs and detoxification genes in insect was induced to maintain physiological homeostasis; and these results may further enrich the mechanisms of insects challenged by insecticides.


Assuntos
Proteínas de Transporte , Inseticidas , Mariposas , Animais , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Inseticidas/metabolismo , Inseticidas/farmacologia , Mariposas/efeitos dos fármacos , Mariposas/genética , Mariposas/metabolismo , Compostos Organotiofosforados/metabolismo , Compostos Organotiofosforados/farmacologia , Controle de Pragas/métodos , Piretrinas/metabolismo , Piretrinas/farmacologia
4.
Ticks Tick Borne Dis ; 12(6): 101818, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34537543

RESUMO

Rhipicephalus microplus is posing a serious threat to productive animal husbandry. Excessive use of synthetic chemicals in tick management has led to the development of resistant tick populations. Characterization of resistance to deltamethrin, cypermethrin, coumaphos and ivermectin in ticks is necessary to develop a suitable and sustainable control strategy. Based on adult immersion test and larval packet test, the resistance ratios (RR50) for adults and larvae of R. microplus populations from two Indian states ranged from 3.8 to 19.4 and 1.35-25.0 against deltamethrin, 0.061-26.3 and 0.22-19.2 against cypermethrin, and 0.2-9.5 and 0.01-3.1 against coumaphos, respectively, were recorded. Moreover, the RR50 for adults ranged from 0.212 to 3.87 against ivermectin. The RR50 for different acaricides was significantly (p<0.01) correlated with esterases, Glutathione S-transferase and monooxygenase activity. A point mutation at the 190th position of the domain II S4-5 linker region of the sodium channel gene in synthetic pyrethroids (SP) resistant populations was also detected. An antitick natural formulation prepared from the plant Azeratum conyzoides and containing two major compounds, Precocene-I (7­methoxy-2, 2-dimethyl 2H-chromene) and Precocene II (6, 7-dimethoxy-2, 2-dimethyl- 3-chromene), was developed and tested against the resistant ticks. The LC50 values of the natural formulation against the resistant populations were in the range of 4.31-5.33% irrespective of their RR50 values. Multi-acaricide resistant populations of R. microplus are established in India and the A. conyzoides based natural formulation can be used for its management.


Assuntos
Acaricidas/farmacologia , Ageratum/química , Rhipicephalus/efeitos dos fármacos , Animais , Cumafos/farmacologia , Resistência a Medicamentos , Feminino , Índia , Ivermectina/farmacologia , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Masculino , Nitrilas/farmacologia , Piretrinas/farmacologia , Rhipicephalus/crescimento & desenvolvimento
5.
Mar Biotechnol (NY) ; 23(5): 710-723, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34564738

RESUMO

The role of miRNAs in pharmacological responses through gene regulation related to drug metabolism and the detoxification system has recently been determined for terrestrial species. However, studies on marine ectoparasites have scarcely been conducted to investigate the molecular mechanisms of pesticide resistance. Herein, we explored the sea louse Caligus rogercresseyi miRNome responses exposed to delousing drugs and the interplaying with coding/non-coding RNAs. Drug sensitivity in sea lice was tested by in vitro bioassays for the pesticides azamethiphos, deltamethrin, and cypermethrin. Ectoparasites strains with contrasting susceptibility to these compounds were used. Small-RNA sequencing was conducted, identifying 2776 novel annotated miRNAs, where 163 mature miRNAs were differentially expressed in response to the drug testing. Notably, putative binding sites for miRNAs were found in the ADME genes associated with the drugs' absorption, distribution, metabolism, and excretion. Interactions between the miRNAs and long non-coding RNAs (lncRNAs) were also found, suggesting putative molecular gene regulation mechanisms. This study reports putative miRNAs correlated to the coding/non-coding RNAs modulation, revealing novel pharmacological mechanisms associated with drug resistance in sea lice species.


Assuntos
Antiparasitários/farmacologia , Copépodes/efeitos dos fármacos , Resistência a Medicamentos/genética , MicroRNAs/metabolismo , Animais , Copépodes/metabolismo , Resistência a Medicamentos/efeitos dos fármacos , Doenças dos Peixes/parasitologia , Perfilação da Expressão Gênica , Regulação da Expressão Gênica/efeitos dos fármacos , Organotiofosfatos/farmacologia , Piretrinas/farmacologia , RNA Longo não Codificante/genética , Salmo salar/parasitologia
6.
Trop Anim Health Prod ; 53(5): 460, 2021 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-34542704

RESUMO

The chemical-based tick management method is gradually losing its clutch due to the establishment of resistant ticks. For development of region-specific tick management strategies, the present study was aimed to evaluate the comparative resistance profile of Rhipicephalus microplus isolates collected from seven districts of Uttar Pradesh, a northern state of India. Comparative analysis of the dose-response data using adult immersion test (AIT) against coumaphos, malathion, deltamethrin, ivermectin, and fipronil revealed that all the isolates were resistant to discriminating concentration of deltamethrin having LC50 of 295.12-436.52 ppm with a resistance ratio of 22.02-32.58. An emerging low level of ivermectin resistance (resistance ratio, RR50 = 1.03-2.26) with LC50 in the range of 22.39-48.98 ppm was found across the isolates. The coumaphos was highly effective against all except Amethi (AMT) isolate. Similarly, malathion was efficacious against most of the isolates except Pratapgarh (PRT) and Sultanpur (SUL) isolates showing LC50 of 5128.61 and 5623.41 ppm, respectively. All the isolates were responsive to fipronil. Comparative detoxifying enzymes profiles revealed a significant correlation between the increased activity of esterase and deltamethrin resistance. The GST activity was 51.2% correlated with RR50 of malathion while esterase activity was significantly correlated (68.9%) with RR50 of coumaphos. No correlation between the ivermectin resistance and enzyme activity was established. Multiple sequence analysis of S4-5 linker region of the sodium channel gene of all the isolates revealed a point mutation at 190th position (C190A) which is associated with deltamethrin resistance. The possible tick management strategies in this part of the country are discussed.


Assuntos
Acaricidas , Piretrinas , Rhipicephalus , Acaricidas/farmacologia , Animais , Cumafos , Índia , Resistência a Inseticidas , Ivermectina/farmacologia , Malation/farmacologia , Nitrilas , Pirazóis , Piretrinas/farmacologia
7.
Insect Biochem Mol Biol ; 138: 103647, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34530119

RESUMO

The overexpression and overactivity of key cytochrome P450s (CYP450) genes are major drivers of metabolic resistance to insecticides in African malaria vectors such as Anopheles funestus s.s. Previous RNAseq-based transcription analyses revealed elevated expression of CYP325A specific to Central African populations but its role in conferring resistance has not previously been demonstrated. In this study, RT-qPCR consistently confirmed that CYP325A is highly over-expressed in pyrethroid-resistant An. funestus from Cameroon, compared with a control strain and insecticide-unexposed mosquitoes. A synergist bioassay with PBO significantly recovered susceptibility for permethrin and deltamethrin indicating P450-based metabolic resistance. Analyses of the coding sequence of CYP325A Africa-wide detected high-levels of polymorphism, but with no predominant alleles selected by pyrethroid resistance. Geographical amino acid changes were detected notably in Cameroon. In silico homology modelling and molecular docking simulations predicted that CYP325A binds and metabolises type I and type II pyrethroids. Heterologous expression of recombinant CYP325A and metabolic assays confirmed that the most-common Cameroonian haplotype metabolises both type I and type II pyrethroids with depletion rate twice that the of the DR Congo haplotype. Analysis of the 1 kb putative promoter of CYP325A revealed reduced diversity in resistant mosquitoes compared to susceptible ones, suggesting a potential selective sweep in this region. The establishment of CYP325A as a pyrethroid resistance metabolising gene further explains pyrethroid resistance in Central African populations of An. funestus. Our work will facilitate future efforts to detect the causative resistance markers in the promoter region of CYP325A to design field applicable DNA-based diagnostic tools.


Assuntos
Anopheles/genética , Sistema Enzimático do Citocromo P-450/genética , Proteínas de Insetos/genética , Resistência a Inseticidas/genética , Inseticidas/farmacologia , Mosquitos Vetores/genética , Piretrinas/farmacologia , África Central , Animais , Anopheles/metabolismo , Simulação por Computador , Sistema Enzimático do Citocromo P-450/metabolismo , Feminino , Proteínas de Insetos/metabolismo , Malária/transmissão , Simulação de Acoplamento Molecular , Mosquitos Vetores/metabolismo
8.
Molecules ; 26(16)2021 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-34443500

RESUMO

Prostaglandins are a group of important cell-signaling molecules involved in the regulation of ovarian maturation, oocyte development, egg laying and associated behaviors in invertebrates. However, the presence of prostaglandin E2 (PGE2), the key enzymes for PGE2 biosynthesis and its interference by drugs were not investigated previously in the ovary of ticks. The present study was undertaken to assess the modulation of the PGE2-mediated pathway in the eclosion blocking effect of flumethrin and terpenoid subfraction isolated from Artemisia nilagirica in Rhipicephalus annulatus ticks. The acaricidal activities and chemical profiling of the terpenoid subfraction were performed. The localization of the cyclooxygenase1 (COX1) and prostaglandin E synthase (PGES) enzymes and the quantification of PGE2 in the ovaries of the ticks treated with methanol (control), flumethrin and terpenoid subfraction were also undertaken. In addition, the vitellogenin concentration in hemolymph was also assayed. Both flumethrin and the terpenoid subfraction of A. nilagirica elicited a concentration-dependent inhibition of fecundity and blocking of hatching of the eggs. The COX1 could not be detected in the ovaries of treated and control ticks, while there was no significant difference observed in the concentration of vitellogenin (Vg) in them. The presence of PGES in the oocytes of control ticks was confirmed while the immunoreactivities against PGES were absent in the vitellogenic oocytes of ticks treated with flumethrin and terpenoid subfraction. The levels of PGE2 were below the detection limit in the ovaries of the flumethrin-treated ticks, while it was significantly lower in the ovaries of the terpenoid subfraction-treated ticks. Hence, the prostaglandin E synthase and PGE2 were identified as very important mediators for the signaling pathway for ovarian maturation and oviposition in ticks. In addition, the key enzyme for prostaglandin biosynthesis, PGES and the receptors for PGE2 can be exploited as potential drug targets for tick control. The detection of PGES by immunohistochemistry and quantification of PGE2 by LC-MSMS can be employed as valuable tools for screening newer compounds for their eclosion blocking acaricidal effects.


Assuntos
Artemisia/química , Dinoprostona/metabolismo , Piretrinas/farmacologia , Rhipicephalus/efeitos dos fármacos , Terpenos/isolamento & purificação , Terpenos/farmacologia , Animais , Anticorpos/metabolismo , Feminino , Cromatografia Gasosa-Espectrometria de Massas , Hemolinfa/metabolismo , Imersão , Ovário/efeitos dos fármacos , Ovário/enzimologia , Peroxidase/metabolismo , Prostaglandina-E Sintases/metabolismo , Vitelogeninas/metabolismo
9.
Molecules ; 26(15)2021 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-34361721

RESUMO

To improve the proinsecticidal activity and phloem mobility of amino acid-tralopyril conjugates further, nine conjugates were designed and synthesized by introducing glutamic acid to tralopyril, and the length of the linker between glutamic acid and tralopyril ranged from 2 atoms to 10 atoms. The results of insecticidal activity against the third-instar larvae of P. xylostella showed that conjugates 42, 43, 44,and 45 (straight-chain containing 2-5 atoms) exhibited good insecticidal activity, and their LC50 values were 0.2397 ± 0.0366, 0.4413 ± 0.0647, 0.4400 ± 0.0624, and 0.4602 ± 0.0655 mM, respectively. The concentrations of conjugates 43-45 were higher than that of conjugate 42 in the phloem sap at 2 h, and conjugate 43 showed the highest concentration. The introduction of glutamic acid can improve phloem mobility. The in vivo metabolism of conjugates 42 and 43 was investigated in P. xylostella, and the parent compound tralopyril was detected at concentrations of 0.5950 and 0.3172 nmol/kg, respectively. According to the above results, conjugates 42 and 43 were potential phloem mobile pro-insecticide candidates.


Assuntos
Ácido Glutâmico/química , Inseticidas/farmacologia , Larva/efeitos dos fármacos , Mariposas/efeitos dos fármacos , Pró-Fármacos/farmacologia , Pirróis/farmacologia , Animais , Transporte Biológico , Biotransformação , Concentração Inibidora 50 , Inseticidas/síntese química , Inseticidas/metabolismo , Larva/crescimento & desenvolvimento , Larva/metabolismo , Longevidade/efeitos dos fármacos , Mariposas/crescimento & desenvolvimento , Mariposas/metabolismo , Floema/metabolismo , Floema/parasitologia , Plantas/metabolismo , Plantas/parasitologia , Pró-Fármacos/síntese química , Pró-Fármacos/metabolismo , Piretrinas/metabolismo , Piretrinas/farmacologia , Pirróis/síntese química , Pirróis/metabolismo , Relação Estrutura-Atividade
10.
Toxicol Appl Pharmacol ; 428: 115676, 2021 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-34389319

RESUMO

The insecticide deltamethrin of the pyrethroid class mainly targets voltage-gated sodium channels (Navs). Deltamethrin prolongs the opening of Navs by slowing down fast inactivation and deactivation. Pyrethroids are supposedly safe for humans, however, they have also been linked to the gulf-war syndrome, a neuropathic pain condition that can develop following exposure to certain chemicals. Inherited neuropathic pain conditions have been linked to mutations in the Nav subtypes Nav1.7, Nav1.8, and Nav1.9. Here, we examined the effect of deltamethrin on the human isoforms Nav1.7, Nav1.8, and Nav1.9_C4 (chimera containing the C-terminus of rat Nav1.4) heterologously expressed in HEK293T and ND7/23 cells using whole-cell patch-clamp electrophysiology. For all three Nav subtypes, we observed increased persistent and tail currents that are typical for Nav channels modified by deltamethrin. The most surprising finding was an enhanced slow inactivation induced by deltamethrin in all three Nav subtypes. An enhanced slow inactivation is contrary to the prolonged opening caused by pyrethroids and has not been described for deltamethrin or any other pyrethroid before. Furthermore, we found that the fraction of deltamethrin-modified channels increased use-dependently. However, for Nav1.8, the use-dependent potentiation occurred only when the holding potential was increased to -90 mV, a potential at which the tail currents decay more slowly. This indicates that use-dependent modification is due to an accumulation of tail currents. In summary, our findings support a novel mechanism whereby deltamethrin enhances slow inactivation of voltage-gated sodium channels, which may, depending on the cellular resting membrane potential, reduce neuronal excitability and counteract the well-described pyrethroid effects of prolonging channel opening.


Assuntos
Inseticidas/farmacologia , Canal de Sódio Disparado por Voltagem NAV1.7/fisiologia , Canal de Sódio Disparado por Voltagem NAV1.8/fisiologia , Nitrilas/farmacologia , Piretrinas/farmacologia , Relação Dose-Resposta a Droga , Células HEK293 , Humanos , Potenciais da Membrana/efeitos dos fármacos , Potenciais da Membrana/fisiologia , Canal de Sódio Disparado por Voltagem NAV1.9/fisiologia
11.
Pest Manag Sci ; 77(12): 5589-5598, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34398490

RESUMO

BACKGROUND: Pyrethroid insecticides such as deltamethrin have been massively used against Aedes aegypti leading to the spread of resistance alleles worldwide. In an insecticide resistance management context, we evaluated the temporal dynamics of deltamethrin resistance using two distinct populations carrying resistant alleles at different frequencies. Three different scenarios were followed: a continuous selection, a full release of selection, or a repeated introgression with susceptible individuals. The responses of each population to these selection regimes were measured across five generations by bioassays and by monitoring the frequency of knockdown resistance (kdr) mutations and the transcription levels and copy number variations of key detoxification enzymes. RESULTS: Knockdown resistance mutations, overexpression and copy number variations of detoxification enzymes as a mechanism of metabolic resistance to deltamethrin was found and maintained under selection across generations. On comparison, the release of insecticide pressure for five generations did not affect resistance levels and resistance marker frequencies. However, introgressing susceptible alleles drastically reduced deltamethrin resistance in only three generations. CONCLUSION: The present study confirmed that strategies consisting to stop deltamethrin spraying are likely to fail when the frequencies of resistant alleles are too high and the fitness cost associated to resistance is low. In dead-end situations like in French Guiana where alternative insecticides are not available, alternative control strategies may provide a high benefit for vector control, particularly if they favor the introgression of susceptible alleles in natural populations. © 2021 Society of Chemical Industry.


Assuntos
Aedes , Arbovírus , Inseticidas , Piretrinas , Aedes/genética , Animais , Variações do Número de Cópias de DNA , Guiana Francesa , Humanos , Resistência a Inseticidas/genética , Inseticidas/farmacologia , Mosquitos Vetores/genética , Nova Caledônia , Nitrilas , Piretrinas/farmacologia
12.
PLoS One ; 16(8): e0253106, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34388169

RESUMO

A potential pesticide degrading bacterial isolate (2D), showing maximum tolerance (450 mg∙L-1) for cypermethrin, fipronil, imidacloprid and sulfosulfuron was recovered from a pesticide contaminated agricultural field. The isolate degraded cypermethrin, imidacloprid, fipronil and sulfosulfuron in minimal salt medium with 94, 91, 89 and 86% respectively as revealed by high performance liquid chromatography (HPLC) and gas chromatography (GC) analysis after 15 days of incubation. Presence of cyclobutane, pyrrolidine, chloroacetic acid, formic acid and decyl ester as major intermediate metabolites of cypermethrin biodegradation was observed in gas chromatography mass spectrometry (GC-MS) analysis. Results based on 16S rDNA sequencing, and phylogenetic analysis showed maximum similarity of 2D with Bacillus cereus (Accession ID: MH341691). Stress responsive and catabolic/pesticide degrading proteins were over expressed in the presence of cypermethrin in bacteria. Enzymatic kinetics of laccase was deduced in the test isolate under normal and pesticide stress conditions which suggested that the production of enzyme was induced significantly in pesticide stress (163 µg.µL-1) as compare to normal conditions(29 µg.µL-1) while the Km value was decreased in pesticides stress condition (Km = 10.57 mM) and increases in normal condition (Km = 14.33 mM).Amplification of laccase gene showed a major band of 1200bp. The present study highlights on the potential of 2D bacterial strain i.e., high tolerance level of pesticide, effective biodegradation rate, and presence of laccase gene in bacterial strain 2D, could become a potential biological agent for large-scale treatment of mixture of pesticide (cypermethrin, fipronil, imidacloprid and sulfosulfuron) in natural environment (soil and water).


Assuntos
Bacillus cereus/metabolismo , Proteínas de Bactérias/metabolismo , Praguicidas/farmacologia , Proteômica , Piretrinas/farmacologia , Estresse Fisiológico/efeitos dos fármacos , Bacillus cereus/classificação , Cromatografia Líquida de Alta Pressão , Cromatografia Gasosa-Espectrometria de Massas
13.
Pest Manag Sci ; 77(11): 5202-5212, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34272799

RESUMO

BACKGROUND: The common bed bug, Cimex lectularius L., and the tropical bed bug, Cimex hemipterus (F.), are now widely regarded as important public health pests following their rapid global resurgence, largely due to insecticide resistance and an increased rate of global travel. The insecticide resistance mechanisms are well documented in C. lectularius, however, only one mechanism is validated in C. hemipterus thus far. This demands further understanding on the resistance mechanisms involved in C. hemipterus. RESULTS: Here, we identified differences in resistance to fenitrothion (organophosphate) and imidacloprid (neonicotinoid) related cuticle thickness in C. hemipterus. There is evidence of a possible association between cuticle thickness and resistance, but the association can be tenuous, likely because resistance is multifactorial in C. hemipterus. We also discovered a novel T1011 residue in domain IIS6 of the voltage-gated sodium channel that likely enhanced susceptibility to deltamethrin (pyrethroid) despite the presence of a L1014F mutation known to confer pyrethroid resistance in C. hemipterus. Our findings also confirmed that the M918I mutation enhanced resistance to pyrethroid when present with the L1014F mutation, which was consistent with a super-kdr phenotype, as reported previously. Multiple resistance mechanisms can be found within a single C. hemipterus population, and the presence of both M918I + L1014F mutations likely masked the influence of cuticle thickness in conferring resistance against deltamethrin. The elevated metabolic enzyme activities in some strains were not necessarily associated with increased insecticide resistance. CONCLUSION: This study has enhanced our understanding on the penetration resistance mechanism and target site insensitivity of sodium channels in C. hemipterus.


Assuntos
Percevejos-de-Cama , Resistência a Inseticidas , Inseticidas , Piretrinas , Canais de Sódio Disparados por Voltagem , Animais , Percevejos-de-Cama/genética , Fenitrotion , Inseticidas/farmacologia , Mutação , Neonicotinoides , Nitrocompostos , Piretrinas/farmacologia , Canais de Sódio Disparados por Voltagem/genética
14.
Parasit Vectors ; 14(1): 347, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34210362

RESUMO

BACKGROUND: Long-lasting insecticidal nets (LLINs) have played an important role in reducing the global malaria burden since 2000. They are a core prevention tool used widely by people at risk of malaria. The Vector Control Prequalification mechanism of the Word Health Organization (WHO-Vector Control PQ) established the testing and evaluation guidelines for LLINs before registration for public use. In the present study, two new brands of deltamethrin-impregnated nets (Yahe® LN and Panda® Net 2.0) were evaluated in an experimental hut against wild pyrethroid-resistant Anopheles gambiae s.l. in M'Bé nearby Bouaké, central Côte d'Ivoire. METHODS: The performance of Yahe® LN and Panda® Net 2.0 was compared with that of PermaNet 2.0, conventionally treated nets (CTN), and untreated net to assess the blood-feeding inhibition, deterrence, induced exophily, and mortality. RESULTS: Cone bioassay results showed that Panda® Net 2.0, PermaNet 2.0 and Yahe® LN (both unwashed and washed 20 times) induced > 95% knockdown or > 80% mortality of the susceptible Anopheles gambiae Kisumu strain. With the pyrethroid-resistant M'Bé strain, mortality rate for all treated nets did not exceed 70%. There was a significant reduction in entry and blood feeding (p < 0.05) and an increase in exophily and mortality rates (p < 0.05) with all treatments compared to untreated nets, except the CTNs. However, the personal protection induced by these treated nets decreased significantly after 20 washes. The performance of Panda® Net 2.0 was equal to PermaNet® 2.0 in terms of inhibiting blood feeding, but better than PermaNet® 2.0 in terms of mortality. CONCLUSION: This study showed that Yahe® LN and Panda® Net 2.0 met the WHO Pesticide Evaluation Scheme (WHOPES) criteria to undergo phase III trial at the community level. Due to an increasing spread and development of pyrethroid resistance in malaria vectors, control of malaria transmission must evolve into an integrated vector management relying on a large variety of efficient control tools.


Assuntos
Anopheles/efeitos dos fármacos , Bioensaio/normas , Resistência a Inseticidas , Mosquiteiros Tratados com Inseticida/normas , Inseticidas/farmacologia , Mosquitos Vetores/efeitos dos fármacos , Nitrilas/farmacologia , Piretrinas/farmacologia , Animais , Anopheles/fisiologia , Bioensaio/métodos , Ensaios Clínicos Fase II como Assunto , Costa do Marfim , Malária/parasitologia , Malária/prevenção & controle , Controle de Mosquitos/métodos , Controle de Mosquitos/normas , Mosquitos Vetores/parasitologia
15.
PLoS Negl Trop Dis ; 15(7): e0009549, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34252110

RESUMO

Aedes aegypti is a primary vector of viral pathogens and is responsible for millions of human infections annually that represent critical public health and economic costs. Pyrethroids are one of the most commonly used classes of insecticides to control adult A. aegypti. The insecticidal activity of pyrethroids depends on their ability to bind and disrupt the voltage-sensitive sodium channel (VSSC). In mosquitoes, a common mechanism of resistance to pyrethroids is due to mutations in Vssc (hereafter referred as knockdown resistance, kdr). In this study, we found that a kdr (410L+V1016I+1534C) allele was the main mechanism of resistance in a pyrethroid-resistant strain of A. aegypti collected in Colombia. To characterize the level of resistance these mutations confer, we isolated a pyrethroid resistant strain (LMRKDR:RK, LKR) that was congenic to the susceptible Rockefeller (ROCK) strain. The full-length cDNA of Vssc was cloned from LKR and no additional resistance mutations were present. The levels of resistance to different pyrethroids varied from 3.9- to 56-fold. We compared the levels of resistance to pyrethroids, DCJW and DDT between LKR and what was previously reported in two other congenic strains that share the same pyrethroid-susceptible background (the ROCK strain), but carry different kdr alleles (F1534C or S989P + V1016G). The resistance conferred by kdr alleles can vary depending on the stereochemistry of the pyrethroid. The 410L+1016I+1534C kdr allele does not confer higher levels of resistance to six of ten pyrethroids, relative to the 1534C allele. The importance of these results to understand the evolution of insecticide resistance and mosquito control are discussed.


Assuntos
Aedes/efeitos dos fármacos , Aedes/genética , Proteínas de Insetos/genética , Resistência a Inseticidas , Inseticidas/farmacologia , Piretrinas/farmacologia , Canais de Sódio Disparados por Voltagem/genética , Aedes/metabolismo , Alelos , Animais , Colômbia , Técnicas de Silenciamento de Genes , Proteínas de Insetos/metabolismo , Mutação , Canais de Sódio Disparados por Voltagem/metabolismo
16.
PLoS Genet ; 17(7): e1009556, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34228718

RESUMO

Insecticide resistance in Anopheles mosquitoes is a major obstacle in maintaining the momentum in reducing the malaria burden; mitigating strategies require improved understanding of the underlying mechanisms. Mutations in the target site of insecticides (the voltage gated sodium channel for the most widely used pyrethroid class) and over-expression of detoxification enzymes are commonly reported, but their relative contribution to phenotypic resistance remain poorly understood. Here we present a genome editing pipeline to introduce single nucleotide polymorphisms in An. gambiae which we have used to study the effect of the classical kdr mutation L1014F (L995F based on An. gambiae numbering), one of the most widely distributed resistance alleles. Introduction of 1014F in an otherwise fully susceptible genetic background increased levels of resistance to all tested pyrethroids and DDT ranging from 9.9-fold for permethrin to >24-fold for DDT. The introduction of the 1014F allele was sufficient to reduce mortality of mosquitoes after exposure to deltamethrin treated bednets, even as the only resistance mechanism present. When 1014F was combined with over-expression of glutathione transferase Gste2, resistance to permethrin increased further demonstrating the critical combined effect between target site resistance and detoxification enzymes in vivo. We also show that mosquitoes carrying the 1014F allele in homozygosity showed fitness disadvantages including increased mortality at the larval stage and a reduction in fecundity and adult longevity, which can have consequences for the strength of selection that will apply to this allele in the field.


Assuntos
Anopheles/efeitos dos fármacos , Anopheles/genética , Sistemas CRISPR-Cas , Resistência a Inseticidas/genética , Mutação , Animais , Animais Geneticamente Modificados , DDT/farmacologia , Feminino , Fertilidade/genética , Genoma de Inseto , Glutationa Transferase/genética , Proteínas de Insetos/genética , Masculino , Nitrilas/farmacologia , Permetrina/farmacologia , Butóxido de Piperonila/farmacologia , Piretrinas/farmacologia
17.
Malar J ; 20(1): 316, 2021 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-34261475

RESUMO

BACKGROUND: Following agricultural use and large-scale distribution of insecticide-treated nets (ITNs), malaria vector resistance to pyrethroids is widespread in sub-Saharan Africa. Interceptor® G2 is a new dual active ingredient (AI) ITN treated with alpha-cypermethrin and chlorfenapyr for the control of pyrethroid-resistant malaria vectors. In anticipation of these new nets being more widely distributed, testing was conducted to develop a chlorfenapyr susceptibility bioassay protocol and gather susceptibility information. METHODS: Bottle bioassay tests were conducted using five concentrations of chlorfenapyr at 12.5, 25, 50, 100, and 200 µg AI/bottle in 10 countries in sub-Saharan Africa using 13,639 wild-collected Anopheles gambiae sensu lato (s.l.) (56 vector populations per dose) and 4,494 pyrethroid-susceptible insectary mosquitoes from 8 colonized strains. In parallel, susceptibility tests were conducted using a provisional discriminating concentration of 100 µg AI/bottle in 16 countries using 23,422 wild-collected, pyrethroid-resistant An. gambiae s.l. (259 vector populations). Exposure time was 60 min, with mortality recorded at 24, 48 and 72 h after exposure. RESULTS: Median mortality rates (up to 72 h after exposure) of insectary colony mosquitoes was 100% at all five concentrations tested, but the lowest dose to kill all mosquitoes tested was 50 µg AI/bottle. The median 72-h mortality of wild An. gambiae s.l. in 10 countries was 71.5, 90.5, 96.5, 100, and 100% at concentrations of 12.5, 25, 50, 100, and 200 µg AI/bottle, respectively. Log-probit analysis of the five concentrations tested determined that the LC95 of wild An. gambiae s.l. was 67.9 µg AI/bottle (95% CI: 48.8-119.5). The discriminating concentration of 203.8 µg AI/bottle (95% CI: 146-359) was calculated by multiplying the LC95 by three. However, the difference in mortality between 100 and 200 µg AI/bottle was minimal and large-scale testing using 100 µg AI/bottle with wild An. gambiae s.l. in 16 countries showed that this concentration was generally suitable, with a median mortality rate of 100% at 72 h. CONCLUSIONS: This study determined that 100 or 200 µg AI/bottle chlorfenapyr in bottle bioassays are suitable discriminating concentrations for monitoring susceptibility of wild An. gambiae s.l., using mortality recorded up to 72 h. Testing in 16 countries in sub-Saharan Africa demonstrated vector susceptibility to chlorfenapyr, including mosquitoes with multiple resistance mechanisms to pyrethroids.


Assuntos
Anopheles/efeitos dos fármacos , Resistência a Inseticidas , Mosquiteiros Tratados com Inseticida , Inseticidas/farmacologia , Piretrinas/farmacologia , Animais , Relação Dose-Resposta a Droga
18.
Malar J ; 20(1): 328, 2021 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-34315480

RESUMO

BACKGROUND: The selection and the spread of insecticide resistance in malaria vectors to the main classes of insecticides used in vector control tools are a major and ongoing challenge to malaria vector control programmes. This study aimed to determine the intensity of vector resistance to insecticides in three regions of Benin with different agro-ecological characteristics. METHODS: Larvae of Anopheles gambiae sensu lato (s.l.) were collected from September to November 2017 in different larval sites in three northern Benin communes: Parakou, Kandi and Malanville. Two to five-day-old, non-blood-fed, female mosquitoes were exposed to papers impregnated with deltamethrin, permethrin and bendiocarb at dosages of 1 × the diagnostic dose, 5 × and 10 × to determine the intensity of resistance in these vectors. Molecular frequencies of the kdr L1014F and ace-1R G119S insecticide resistance mutations and levels of detoxification enzymes were determined for mosquitoes sampled at each study site. RESULTS: Resistance to pyrethroids (permethrin and deltamethrin) was recorded in all three communes with mortality rates below 60% using the diagnostic dose (1x). The results obtained after exposure of An. gambiae to permethrin 10 × were 99% in Kandi, 98% in Malanville and 99% in Parakou. With deltamethrin 10x, mortality rates were 100% in Kandi, 96% in Malanville and 73% in Parakou. For the diagnostic dose of bendiocarb, suspected resistance was recorded in the communes of Malanville (97%) and Kandi (94%) while sensitivity was observed in Parakou (98%).Using the 10 × dose, mortality was 98% in Kandi, 100% in Malanville and 99% in Parakou. The frequencies of the kdr L1014F allele varied between 59 and 83% depending on the sites and species of the An. gambiae complex, while the frequency of the ace-1R G119S gene varied between 0 and 5%. Biochemical tests showed high levels of oxidase and esterase activity compared to the susceptible colony strain of An. gambiae sensu stricto (Kisumu strain). CONCLUSION: Anopheles gambiae showed a generalized loss of susceptibility to permethrin and deltamethrin but also showed moderate to high intensity of resistance in different regions of Benin. This high intensity of resistance is a potential threat to the effectiveness of vector control.


Assuntos
Anopheles/efeitos dos fármacos , Resistência a Inseticidas , Inseticidas/farmacologia , Mosquitos Vetores/efeitos dos fármacos , Nitrilas/farmacologia , Permetrina/farmacologia , Fenilcarbamatos/farmacologia , Piretrinas/farmacologia , Animais , Anopheles/crescimento & desenvolvimento , Benin , Feminino , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Mosquitos Vetores/crescimento & desenvolvimento
19.
Parasit Vectors ; 14(1): 355, 2021 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-34229739

RESUMO

BACKGROUND: Triatomine control campaigns have traditionally consisted of spraying the inside of houses with pyrethroid insecticides. However, exposure to sublethal insecticide doses after the initial application is a common occurrence and may have phenotypic consequences for survivors. Here, using Triatoma infestans (the main vector of Chagas disease in the Southern Cone of South America) as a model species, we quantified the effects of exposure to a sublethal dose of pyrethroid insecticide on wing morphology. We tested if the treatment (i) induced a plastic effect (change in the character mean); (ii) altered environmental canalisation (higher individual variation within genotypes); (iii) altered genetic canalisation (higher variation among genotypes); and (iv) altered developmental stability (higher fluctuating asymmetry [FA]). METHODS: Each of 25 full-sib families known to be susceptible to pyrethroid insecticides were split in two groups: one to be treated with a sublethal dose of deltamethrin (insecticide-treated group) and the other to be treated with pure acetone (control group). Wings of the emerging adults were used in a landmark-based geometric morphometry analysis to extract size and shape measurements. Average differences among treatments were measured. Levels of variation among families, among individuals within families and among sides within individuals were computed and compared among treatments. RESULTS: Wing size and shape were affected by a sublethal dose of deltamethrin. The treated insects had larger wings and a more variable wing size and shape than control insects. For both wing size and shape, genetic variation was higher in treated individuals. Individual variations and variations in FA were also greater in deltamethrin-treated insects than in control ones for all full-sib families; however, the patterns of shape variation associated with genetic variation, individual variation and FA were different. CONCLUSIONS: Insects exposed to a sublethal dose of deltamethrin presented larger, less symmetrical and less canalised wings. The insecticide treatment jointly impaired developmental stability and genetic and environmental canalisation. The divergent patterns of shape variation suggest that the related developmental buffering processes differed at least partially. The morphological modifications induced by a single sublethal exposure to pyrethroids early in life may impinge on subsequent flight performance and consequently affect the dynamics of house invasion and reinfestation, and the effectiveness of triatomine control operations.


Assuntos
Adaptação Fisiológica , Piretrinas/farmacologia , Triatoma/efeitos dos fármacos , Triatoma/fisiologia , Asas de Animais/efeitos dos fármacos , Asas de Animais/fisiologia , Animais , Doença de Chagas/prevenção & controle , Doença de Chagas/transmissão , Estudos Transversais , Relação Dose-Resposta a Droga , Feminino , Controle de Insetos/métodos , Insetos Vetores/efeitos dos fármacos , Resistência a Inseticidas , Triatoma/genética , Asas de Animais/anatomia & histologia
20.
Parasit Vectors ; 14(1): 361, 2021 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-34247634

RESUMO

BACKGROUND: Dengue suppression often relies on control of the mosquito vector, Aedes aegypti, through applications of insecticides of which the pyrethroid group has played a dominant role. Insecticide resistance is prevalent in Ae. aegypti around the world, and the resulting reduction of insecticide efficacy is likely to exacerbate the impact of dengue. Dengue has been a public health problem in Saudi Arabia, particularly in Jeddah, since its discovery there in the 1990s, and insecticide use for vector control is widespread throughout the city. An alternative approach to insecticide use, based on blocking dengue transmission in mosquitoes by the endosymbiont Wolbachia, is being trialed in Jeddah following the success of this approach in Australia and Malaysia. Knowledge of insecticide resistance status of mosquito populations in Jeddah is a prerequisite for establishing a Wolbachia-based dengue control program as releases of Wolbachia mosquitoes succeed when resistance status of the release population is similar to that of the wild population. METHODS: WHO resistance bioassays of mosquitoes with deltamethrin, permethrin and DDT were used in conjunction with TaqMan® SNP Genotyping Assays to characterize mutation profiles of Ae. aegypti. RESULTS: Screening of the voltage-sensitive sodium channel (Vssc), the pyrethroid target site, revealed mutations at codons 989, 1016 and 1534 in Ae. aegypti from two districts of Jeddah. The triple mutant homozygote (1016G/1534C/989P) was confirmed from Al Safa and Al Rawabi. Bioassays with pyrethroids (Type I and II) and DDT showed that mosquitoes were resistant to each of these compounds based on WHO definitions. An association between Vssc mutations and resistance was established for the Type II pyrethroid, deltamethrin, with one genotype (989P/1016G/1534F) conferring a survival advantage over two others (989S/1016V/1534C and the triple heterozygote). An indication of synergism of Type I pyrethroid activity with piperonyl butoxide suggests that detoxification by cytochrome P450s accounts for some of the pyrethroid resistance response in Ae. aegypti populations from Jeddah. CONCLUSIONS: The results provide a baseline for monitoring and management of resistance as well as knowledge of Vssc genotype frequencies required in Wolbachia release populations to ensure homogeneity with the target field population. Vssc mutation haplotypes observed show some similarity with those from Ae. aegypti in southeast Asia and the Indo-Pacific, but the presence of the triple mutant haplotype in three genotypes indicates that the species in this region may have a unique population history.


Assuntos
Aedes/efeitos dos fármacos , Aedes/genética , Resistência a Inseticidas/genética , Inseticidas/farmacologia , Mutação , Piretrinas/farmacologia , Canais de Sódio/genética , Wolbachia/fisiologia , Animais , Bioensaio/métodos , Bioensaio/estatística & dados numéricos , Dengue/prevenção & controle , Dengue/transmissão , Feminino , Controle de Mosquitos/métodos , Controle de Mosquitos/estatística & dados numéricos , Arábia Saudita
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