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Insects Nov 2022The occurrence and spread of insecticide resistance has had a negative effect on the efficacy of insecticide-based tools and is distributed worldwide, including the...
The occurrence and spread of insecticide resistance has had a negative effect on the efficacy of insecticide-based tools and is distributed worldwide, including the Greater Mekong Subregion (GMS). This study aims to determine the insecticide susceptibility of malaria and dengue vectors in malaria and dengue hotspots on the Thai-Myanmar border. Mosquito larvae and pupae were obtained from water sources from December 2019 to April 2020 in Tha Song Yang District, Tak province, western Thailand. WHO bioassay susceptibility tests were conducted with three classes of insecticides to evaluate the knockdown and mortality rates of and female adults. V1016G and F1534C mutations in the voltage-gated sodium channel of were identified using a multiplex PCR. A total of 5764 female mosquitoes were bioassayed in this study, including spp. (92.63%) and F1 (7.37%). After 24 h of observation, s.l. ( = 3885) and s.l. ( = 1138) in Suan Oi (SO) and Tala Oka (TO) were susceptible to pyrethroids, organophosphates and carbamates (except bendiocarb) with 98-100% mortality (MR). Resistance to bendiocarb was detected with a mortality rate of 88.80%, 88.77%, and 89.92% for s.l. ( = 125, 125) and s.l. ( = 66), respectively. The first generation of . adult females were suspected of resistance to deltamethrin ( = 225, MR = 96.89%) and confirmed resistance to permethrin ( = 200, MR = 20.00%). V1016G and F1534C mutations were detected in three genotypes, heterozygote and homozygote forms. The correlation between the alleles and deltamethrin resistance was significant. In conclusion, bendiocarb resistance was found in primary malaria vectors, s.l. and s.l. F1 population was pyrethroids-resistant, associated with alleles. Therefore, molecular analysis should be conducted to gain insights into the mechanism of insecticide resistance. Routine malaria vector control programmes, such as fogging implementation in hotspot villages to induce resistance available in peri-domestic sites, are questionable.
PubMed: 36354859
DOI: 10.3390/insects13111035 -
Parasites & Vectors Dec 2020Arboviral diseases, including dengue and chikungunya, are major public health concerns in Bangladesh where there have been unprecedented levels of transmission reported...
BACKGROUND
Arboviral diseases, including dengue and chikungunya, are major public health concerns in Bangladesh where there have been unprecedented levels of transmission reported in recent years. The primary approach to control these diseases is to control the vector Aedes aegypti using pyrethroid insecticides. Although chemical control has long been practiced, no comprehensive analysis of Ae. aegypti susceptibility to insecticides has been conducted to date. The aim of this study was to determine the insecticide resistance status of Ae. aegypti in Bangladesh and investigate the role of detoxification enzymes and altered target site sensitivity as resistance mechanisms.
METHODS
Eggs of Aedes mosquitoes were collected using ovitraps from five districts across Bangladesh and in eight neighborhoods of the capital city Dhaka, from August to November 2017. CDC bottle bioassays were conducted for permethrin, deltamethrin, malathion, and bendiocarb using 3- to 5-day-old F-F non-blood-fed female mosquitoes. Biochemical assays were conducted to detect metabolic resistance mechanisms, and real-time PCR was performed to determine the frequencies of the knockdown resistance (kdr) mutations Gly1016, Cys1534, and Leu410.
RESULTS
High levels of resistance to permethrin were detected in all Ae. aegypti populations, with mortality ranging from 0 to 14.8% at the diagnostic dose. Substantial resistance continued to be detected against higher (2×) doses of permethrin (5.1-44.4% mortality). Susceptibility to deltamethrin and malathion varied between populations while complete susceptibility to bendiocarb was observed in all populations. Significantly higher levels of esterase and oxidase activity were detected in most of the test populations as compared to the susceptible reference Rockefeller strain. A significant association was detected between permethrin resistance and the presence of Gly1016 and Cys1534 homozygotes. The frequency of kdr (knockdown resistance) alleles varied across the Dhaka Aedes populations. Leu410 was not detected in any of the tested populations.
CONCLUSIONS
The detection of widespread pyrethroid resistance and multiple resistance mechanisms highlights the urgency for implementing alternate Ae. aegypti control strategies. In addition, implementing routine monitoring of insecticide resistance in Ae. aegypti in Bangladesh will lead to a greater understanding of susceptibility trends over space and time, thereby enabling the development of improved control strategies.
Topics: Aedes; Animals; Arbovirus Infections; Bangladesh; Insecticide Resistance; Insecticides; Mosquito Vectors; Pyrethrins
PubMed: 33317603
DOI: 10.1186/s13071-020-04503-6 -
Journal of Arthropod-borne Diseases Sep 2016Insecticide resistance is one of the serious problems for German cockroach control program. This study was conducted to determine the bendiocarb and Carbaryl resistance...
Detection of Bendiocarb and Carbaryl Resistance Mechanisms among German Cockroach Blattella germanica (Blattaria: Blattellidae) Collected from Tabriz Hospitals, East Azerbaijan Province, Iran in 2013.
BACKGROUND
Insecticide resistance is one of the serious problems for German cockroach control program. This study was conducted to determine the bendiocarb and Carbaryl resistance mechanisms in German cockroaches using the piperonyl butoxide (PBO).
METHODS
Bioassay tests were conducted with 4 to 6 different concentrations of both insecticides with four replicates of 10 susceptible strain cockroaches per concentration to determine of discriminative concentration. After determining discriminative concentration, the result was compared to wild strain. The levels of susceptibility and resistance ratio (RR) and synergism ratio (SR) were calculated for each five wild strains. Moreover resistance mechanisms in wild strains were determined using PBO synergist in vivo.
RESULTS
Hospital strains showed different levels of resistance to bendiocarb and carbaryl compared to susceptible strain. The bendiocarb and carbaryl resistance ratios ranged from 2.11 to 7.97 and 1.67 to 2 at LD50 levels, respectively. The synergist PBO significantly enhanced the toxicity of bendiocarb and carbaryl to all strains with different degrees of synergist ratio, 1.31, 1.39, 3.61, 1.78, 1.62 and 2.1 fold for bendiocarb, 1.19, 1.18, 1.12. 1.29, 1.45 and 1.11-fold for carbaryl, suggesting monooxygenase involvement in bendiocarb and carbaryl resistance.
CONCLUSION
The synergetic effect of PBO had the highest effect on bendiocarb and resistance level was significantly reduced, which indicates the important role of monoxidase enzyme in creating resistance to Bendiocarb. Piperonyl butoxide did not have a significant synergistic effect on carbaryl and did not significantly break the resistance.
PubMed: 27308298
DOI: No ID Found -
Parasites & Vectors Jan 2022Dengue fever is a major public health concern in Cambodia, with thousands of cases every year in urban, suburban and rural areas of the country. The main vector of...
BACKGROUND
Dengue fever is a major public health concern in Cambodia, with thousands of cases every year in urban, suburban and rural areas of the country. The main vector of dengue fever in Cambodia is Aedes aegypti. The organophosphate larvicide temephos and adulticides belonging to the pyrethroid family have been widely used for decades by public health authorities to fight dengue vectors, but resistance of Ae. aegypti to these insecticides has been previously described for Cambodia.
METHODS
In order to adapt the vector control strategy presently used in Cambodia, we tested 14 adulticides belonging to the carbamate, organochlorine, organophosphate, and pyrethroid insecticide families and three larvicides [temephos, spinosad and Bacillus thuringiensis ser. israelensis (Bti)] belonging to three different insecticide families (organophosphates, spinosyns and entomopathogenic bacteria). The standard procedures used here to test the adults and larvae of an Ae. aegypti population from Phnom Penh followed World Health Organization guidelines.
RESULTS
For adults, high mortality rates were observed with carbamate, organophosphate and organochlorine (with the exception of dichlorodiphenyltrichloroethane) insecticides (i.e. between 87.6 and 100%), while low mortality rates were observed with all of the tested pyrethroid insecticides (i.e. between 1 and 35%). For larvae, no resistance against Bti was detected [resistance ratio (RR < 1.6)], but moderate resistance was observed for temephos and spinosad (RR < 5.6).
CONCLUSIONS
The results of this study indicate that (i) Bti should be considered a serious alternative to temephos for the control of Ae. aegypti larvae; and (ii) the carbamate adulticides propoxur and bendiocarb should be employed instead of the widely used pyrethroid insecticides for the control of adult Ae. aegypti on land under mosaic farming and crop rotation in Cambodia, as the insects were found to be resistant to the latter types of insecticide. Research focusing on insecticide resistance and innovative and effective vector control strategies should be undertaken as a public health priority in Cambodia.
Topics: Aedes; Animals; Biological Assay; Cambodia; Dengue; Insecticide Resistance; Insecticides; Larva; Mosquito Vectors
PubMed: 35101104
DOI: 10.1186/s13071-022-05156-3 -
PLoS Neglected Tropical Diseases Jul 2020Owing to the increased reports in Aedes-borne diseases in the Caribbean and Latin America, the United States Agency for International Development assisted the Jamaican...
Owing to the increased reports in Aedes-borne diseases in the Caribbean and Latin America, the United States Agency for International Development assisted the Jamaican Ministry of Health and Wellness in conducting insecticide susceptibility tests on Aedes aegypti populations. Sentinel sites were established in seven parishes of Jamaica (St. Catherine, Kingston and St. Andrew, St. Thomas, Portland, St. Mary and St. Ann) and Aedes aegypti eggs were collected, reared to adults per collected population and their susceptibility to varying pyrethroids and organophosphates were tested using the World Health Organization paper bioassays for these insecticides. The Centers for Disease Control and Prevention bottle bioassay was used to assess susceptibility to the carbamate, bendiocarb. The voltage gated sodium channel gene mutations V1016I and I1011V, normally associated with pyrethroid resistance, were also analysed. The results showed that Aedes aegypti collected from all parishes exhibited resistance to pyrethroids at the following concentrations, permethrin 0.25-2.5%; deltamethrin 0.03-0.15%; lambda-cyhalothrin 0.03-0.3%; and etofenprox 0.5-2.5%. The insecticide deltamethrin at concentration 0.3% was the only pyrethroid tested that resulted in high mortality, 94.9 ± 0.34% knockdown within 1 hour of exposure and 98.95 ± 0.01% mortality (p <0.01) at 24 hours post exposure. The frequency of the voltage gated sodium channel gene mutation V1016I was high in the tested population, possibly accounting for the reduced sensitivity to pyrethroids. Organophosphate resistance was also observed in all populations tested. Mortality rates for 0.8% Malathion was 0.8 ± 0.70-60.68 ± 0.38% after 24 hour and 0.00-47.10 ± 3.02%, for pirimiphos-methyl 0.21%. Bendiocarb applied as 12.5 μg/ bottle resulted in mortality rates of 76.25 ± 4.30-100 ± 0.00% after 30 minutes of exposure. The results showed that Ae. aegypti from the seven parishes analysed demonstrated resistance to the insecticides tested. Deltamethrin and bendiocarb at concentrations 0.3% and 12.5μg respectively, were considered most effective, causing high mortality in the local populations. Routine monitoring and evaluations of Ae. aegypti populations from the included parishes are recommended. Additionally, the study results represent the most comprehensive testing to date with local Aedes aegypti populations distributed across different parishes of Jamaica and should be useful to guide national and sub national strategies for vector control and surveillance.
Topics: Aedes; Animals; Female; Insecticide Resistance; Insecticides; Jamaica
PubMed: 32716942
DOI: 10.1371/journal.pntd.0008490 -
Veterinary Research Forum : An... Sep 2022Mosquitoes are involved in the transmission of a wide range of diseases and among them, , acts as a vector of avian malaria, tularemia and several arboviruses like West...
Mosquitoes are involved in the transmission of a wide range of diseases and among them, , acts as a vector of avian malaria, tularemia and several arboviruses like West Nile fever. The current study was conducted to determine the susceptibility of against deltamethrin 0.05% (pyrethroids), fenitrothion 1.00% (organophosphate) and bendiocarb 0.10% (carbamate). Mosquitoes were collected from different parts of Urmia county, the capital of West Azerbaijan. In the current study, 443 empty 3 - 5 days old adult female were used for susceptibility tests. The susceptibility status of was determined using WHO's recommended procedure. The results indicated higher mortality rates of against studied insecticides. , was resistant to all studied insecticides (deltamethrin, mortality rate: 62.50%, fenitrothion, mortality rate: 35.96% and bendiocarb, mortality rate: 20.16%). The current study represents the first report of susceptibility status of to fenitrothion and bendicarb in Iran. Considering the climatic diversity and geographical conditions of northwestern Iran, reports of resistance of other mosquitoes' of this region, the susceptibility status of medically and veterinary important mosquitoes should be given serious attention.
PubMed: 36320294
DOI: 10.30466/vrf.2020.134833.3025 -
Tropical Medicine & International... Apr 2021To evaluate the entomological efficacy and the residual activity of indoor residual spraying with Fludora Fusion 562.5 WP-SB, a combination formulation containing...
Small-scale field evaluation of the entomological efficacy and the residual activity of Fludora Fusion WP-SB indoor residual spraying against Anopheles culicifacies s.l. in Gujarat, India.
OBJECTIVES
To evaluate the entomological efficacy and the residual activity of indoor residual spraying with Fludora Fusion 562.5 WP-SB, a combination formulation containing clothianidin, a neonicotinoid and deltamethrin, a pyrethroid, against the main rural malaria vector, Anopheles culicifacies s.l., in India in a small-scale trial.
METHODS
In three study villages, suitable households were randomly allocated to five treatments: Fludora Fusion 562.5 WP-SB (target dose 225 mg active ingredient AI/m ); clothianidin 70 WG (target dose 200 mg AI/m ); K-Othrine 250 WG (deltamethrin, target dose 25 mg AI/m ); Ficam VC 80 WP-SB (bendiocarb, target dose 400 mg AI/m ) and unsprayed control. Insecticides were sprayed by hand compression sprayers with control flow valves and 8002E nozzles. Post-spray cone bioassays were done on insecticide-treated walls using a colonised, deltamethrin-resistant strain of An. culicifacies. Mosquitoes were collected from treated rooms by different methods. The insecticide content on filter papers collected from the sprayed walls was determined by chemical assay to assess the spray quality.
RESULTS
The ratios of applied to target doses of insecticides were within 0.84 to 1.4, showing a good spray quality. The cone bioassays revealed residual action lasting 7 months for all insecticides without significant differences in mortality between different surfaces treated nor between the four treatment arms (P > 0.05). Considering all entomological parameters such as indoor resting density, excito-repellency, blood-feeding inhibition and delayed mortality, the overall efficacy of Fludora Fusion WG-SB was equal or better compared with other insecticides.
CONCLUSIONS
Fludora Fusion showed overall equal or better efficacy than deltamethrin and bendiocarb alone against a pyrethroid-resistant malaria vector population and can be considered as an alternative product for management of pyrethroid resistance in malaria vectors.
Topics: Animals; Anopheles; Biological Assay; Culicidae; Family Characteristics; Guanidines; Humans; Insecticide Resistance; Insecticides; Malaria; Mosquito Control; Mosquito Vectors; Neonicotinoids; Nitriles; Pyrethrins; Thiazoles
PubMed: 33423364
DOI: 10.1111/tmi.13549 -
PloS One 2022Prevention and control of Aedes-borne viral diseases such as dengue rely on vector control, including the use of insecticides and reduction of larval sources. However,...
Prevention and control of Aedes-borne viral diseases such as dengue rely on vector control, including the use of insecticides and reduction of larval sources. However, this is threatened by the emergence of insecticide resistance. This study aimed to update the spatial distribution, the insecticide resistance profile of A. aegypti and A. albopictus and the potential resistant mechanisms implicated in the city of Douala. Immature stages of Aedes were collected in August 2020 in eight neighbourhoods in Douala and reared to adult stages. Adult bioassays, and piperonyl butoxide (PBO) synergist assays were carried out according to World Health Organization recommendations. Expression of some candidate metabolic genes including Cyp9M6F88/87, Cyp9J28a, Cyp9J10 and Cyp9J32 in A. aegypti, and Cyp6P12 in A. albopictus were assessed using qPCR. A. aegypti adults G0 were screened using real time melting curve qPCR analyses to genotype the F1534C, V1016I and V410L Aedes kdr mutations. Overall, A. aegypti is the predominant Aedes species, but analyses revealed that both A. albopictus and A. aegypti coexist in all the prospected neighbourhoods of Douala. High level of resistance was observed to three pyrethroids tested in both Aedes species. In A. aegypti a lower mortality rate was reported to permethrin (5.83%) and a higher mortality rate to deltamethrin (63.74%). Meanwhile, for A. albopictus, lower (6.72%) and higher (84.11%) mortality rates were reported to deltamethrin. Similar analysis with bendiocarb, revealed for A. aegypti a loss of susceptibility. However, in A. albopictus samples, analyses revealed a susceptibility in Logbessou, and confirmed resistance in Kotto (59.78%). A partial recovery of mortality was found to insecticides after pre-exposure to PBO. Cyp6P12 was found significantly overexpressed in A. albopictus permethrin resistant and Cyp9M6F88/87 for A. aegypti deltamethrin resistant. F1534C, V1016I and V410L mutations were detected in A. aegypti from different neighbourhoods and by considering the combination of these three kdr 14 genotypes were found. These findings provide relevant information which should be capitalised in the implementation of arbovirus vector control strategies and insecticide resistance management.
Topics: Animals; Insecticide Resistance; Aedes; Insecticides; Permethrin; Cameroon; Mosquito Vectors; Pyrethrins
PubMed: 36512581
DOI: 10.1371/journal.pone.0278779 -
PloS One 2022Emergence and spread of malaria vectors resistant to the available insecticides required a new and efficacious insecticide. Residual efficacy of Fludora® Fusion was...
Emergence and spread of malaria vectors resistant to the available insecticides required a new and efficacious insecticide. Residual efficacy of Fludora® Fusion was evaluated against insecticide susceptible Anopheles arabiensis in ten circular huts similar to the residential huts. Fludora® Fusion WP-SB 56.25, FICAM WP80 and Clothianidin WG70 were sprayed, by experienced technician, on interior wall surfaces: paint, dung, smooth mud, and rough mud. WHO cone bioassays were carried out a month after spraying and thereafter on monthly intervals for 12 months. Knockdown was recorded at 60 minutes and mortality at 24 hours, 48 hours and 72 hours holding time post-exposure. Fludora Fusion induced 100% An. arabiensis mortality during the first four months post-treated on all surface types at 24 hours holding time post-exposure. Its activity remained over 80% from the fifth to the twelfth month post-treated on the surfaces with the exception of two assessment points, at seventh month and eleventh month, on paint and smooth mud surfaces. FICAM induced 100% mortality rate during the first 4 months and 92% mortality during the fifth month post-treatment on painted surfaces. Its activity was over 96% mortality 1-month post-treatment on smooth mud and rough mud surfaces and 92% mortality 2-month post-treatment on dung surfaces. Clothianidin caused 89% and 86% mortality 1-month post-treatment on smooth mud and rough mud surfaces. Fludora Fusion can be used as alternative indoor residual insecticide spraying against An. arabiensis in Ethiopia.
Topics: Aerosolized Particles and Droplets; Animals; Anopheles; Drug Combinations; Ethiopia; Female; Guanidines; Housing; Mosquito Control; Neonicotinoids; Nitriles; Phenylcarbamates; Pyrethrins; Surface Properties; Thiazoles; Time Factors
PubMed: 35148353
DOI: 10.1371/journal.pone.0263840 -
TheScientificWorldJournal 2020Despite the considerable progress made so far, the effectiveness and mass application of odour-baited outdoor mosquito control devices in pipelines is limited by several...
Despite the considerable progress made so far, the effectiveness and mass application of odour-baited outdoor mosquito control devices in pipelines is limited by several factors. These include the design and size of the devices, optimal placement of attractive blends, and nature of materials into which the blends are impregnated. The primary aim of this study was to manipulate these factors to improve the attractiveness of our recently developed passive outdoor host seeking device (POHD) to outdoor biting . Specifically, the study aimed to determine optimal placement of odour blends and killing bioactives in POHD for maximum attraction and killing of and to assess the effects of blend types, formulation, and residual activity on attractiveness of the POHD to . The POHDs baited with attractive blends, carbon dioxide (CO), and bendiocarb-treated electrostatic netting were placed either towards the top or bottom openings, and other modifications were exposed to under the semifield system at Ifakara Health Institute (IHI). Each night, a total of 100 starved female, 3-7-day-old, semifield reared mosquitoes were released, collected the next morning (alive or dead), counted, and recorded. Live mosquitoes were maintained in the semifield insectary and monitored for 24 hours mortality. Each treatment combination of the POHD was tested in three replicates. Overall, the results indicated that the proportion of mosquitoes attracted to and killed in the POHD varied with position of attractants and killing agent (bendiocarb). The POHD with bottom placed attractants and bendiocarb attracted and killed higher proportion of mosquitoes compared to the POHD with top placed attractants and bendiocarb. The highest mortalities were observed when the POHD was baited with a combination of attractive blends and CO. Moreover, the residual activity of attractive blends applied inside POHD varied with type and formulation of attractive blend. The POHD packed with Mbita and Ifakara blend in microencapsulated pellets (granules) attracted higher proportion of mosquitoes than that baited with soaked nylon-strip formulation of either blends. Interestingly, POHD baited with Mbita blend in microencapsulated pellets (granules) formulation attracted and killed higher proportion of mosquitoes (>90%) than that baited with Ifakara blend even 9 months after application. Conclusively, the POHD remained effective for a relatively longer period of time when baited with bottom placed synthetic blends and CO combination, thus warranting further trials under real life situations.
Topics: Animals; Anopheles; Behavior, Animal; Carbon Dioxide; Female; Host-Seeking Behavior; Humans; Mosquito Control; Mosquito Vectors; Odorants; Pheromones
PubMed: 32547328
DOI: 10.1155/2020/8938309