Irritability of malaria vector, Anopheles sacharovi to different insecticides in a malaria-prone area

Detection of L1014F knockdown resistance mutation in Culex tritaeniorhynchus populations

Culex tritaeniorhynchus is a major Japanese encephalitis virus vector distributed in Southeast Asia and surrounding countries. The aim of the present study is to investigate insecticide resistance status among 10 Cx. tritaeniorhynchus populations of the Mediterranean region of Turkey. Bioassay results indicated that all of the populations were resistant or at least possibly resistant to 1,1'-(2,2,2-Trichloroethane-1,1-diyl) bis (4-chlorobenzene) (DDT) (4%), [(dimethoxyphosphorothioyl) sulfanyl] butanedioate, Diethyl (malathion) (5%), and 2-[(Propan-2-yl) oxy] phenyl methylcarbamate (propoxur) (0,1%). Whereas, some of the populations were still susceptible to 3-Phenoxybenzyl (1RS)-cis, trans-3-(2,2-dichlorovinyl)-2,2-dimethyl cyclopropane carboxylate (permethrin) (0,75%) and (S)-Cyano (3-phenoxy phenyl) methyl (1R,3R)-3-(2,2-dibromoethen-1-yl)-2,2-dimethylcyclopropane-1-carboxylate (deltamethrin) (0,05%). Biochemical analysis results showed altered alpha esterase, beta esterase, para-nitrophenyl acetate (PNPA), and glutathione-s-transferase (GST) levels in some populations while all of the populations had increased oxidase levels except for the Yumurtalık population. Additionally, all of the populations had sensitive acetylcholinesterase (AChE) levels similar to the control group except for the Erzin population. Correlation analysis showed a significant correlation between mortality rates for deltamethrin and alpha esterase, beta esterase, PNPA, and GST levels while mortality rates for permethrin were significantly correlated with GST levels. An allele-specific polymerase chain reaction (AS-PCR) detected high L1014F allele frequency in the populations. Overall results indicate the urgent need for monitoring and mapping of insecticide resistance in Cx. tritaeniorhynchus populations of the study area for effective vector control management.

Monitoring of synthetic insecticides resistance and mechanisms among malaria vector mosquitoes in Iran: A systematic review

BACKGROUND

In Iran, the prospect of malaria control relies mainly on insecticides used against the genus Anopheles (Diptera: Culicidae) as important vectors of malaria, arboviruses, and so on. Only eight out of 30 malaria mosquito vectors (Anopheles species) have been examined for insecticide resistance in Iran. This study aimed to review articles related to the incremental trend in insecticide resistance and their mechanisms among anopheline malaria vectors in Iran.

METHODS

A literature review was conducted based on such search engines as Iran doc, Web of Science, SID, PubMed, Scopus, and Google Scholar websites using the following keywords: "Anopheles," "Malaria," "Resistance," "Vectors," "Insecticide Resistance," and "Iran" for data collection. Published papers in English or Persian covering 1980 to 2020 were reviewed.

RESULTS

A total of 1125 articles were screened, only 16 of which were filtered to be pertinent in this review. While most of the mosquito vectors of malaria, such as Anopheles stephensi, were resistant to DDT, dieldrin, malathion, and becoming less susceptible to deltamethrin and other synthetic pyrethroid insecticides, few like Anopheles fluviatilis s. l. were susceptible to all insecticides. A disseminating trend in insecticide resistance among different anopheline mosquito vector species was evident. Metabolic and insecticide target-site resistance mechanisms were involved with organochlorines and pyrethroids, respectively.

CONCLUSIONS

Insecticide resistance is becoming a severe scourge to the effectiveness of vector-borne disease management measures. This event is especially critical in developing and marginalized communities that applied chemical-based vector elimination programs for malaria; therefore, it is crucial to monitor insecticide resistance in malaria vectors in Iran using biochemical and molecular tools.

Airport Malaria in Non-Endemic Areas: New Insights into Mosquito Vectors, Case Management and Major Challenges

Despite the implementation of preventive measures in airports and aircrafts, the risk of importing Plasmodium spp. infected mosquitoes is still present in malaria-free countries. Evidence suggests that mosquitoes have found a new alliance with the globalization of trade and climate change, leading to an upsurge of malaria parasite transmission around airports. The resulting locally acquired form of malaria is called Airport malaria. However, piecemeal information is available, regarding its epidemiological and entomological patterns, as well as the challenges in the diagnosis, treatment, and prevention. Understanding these issues is a critical step towards a better implementation of control strategies. To cross reference this information, we conducted a systematic review on 135 research articles published between 1969 (when the first cases of malaria in airports were reported) and 2020 (i.e., 51 years later). It appears that the risk of malaria transmission by local mosquito vectors in so called malaria-free countries is not zero; this risk is more likely to be fostered by infected vectors coming from endemic countries by air or by sea. Furthermore, there is ample evidence that airport malaria is increasing in these countries. From 2010 to 2020, the number of cases in Europe was 7.4 times higher than that recorded during the 2000-2009 decade. This increase may be associated with climate change, increased international trade, the decline of aircraft disinsection, as well as delays in case diagnosis and treatment. More critically, current interventions are weakened by biological and operational challenges, such as drug resistance in malaria parasites and vector resistance to insecticides, and logistic constraints. Therefore, there is a need to strengthen malaria prevention and treatment for people at risk of airport malaria, and implement a rigorous routine entomological and epidemiological surveillance in and around airports.

Bioefficacy of bendiocarb WP80 in vector-borne and zoonotic diseases areas in borderline of Iran and Pakistan

Malaria and leishmaniasis are the public health problems in southern Iran. The main activity of vector control is indoor residual spraying using pyrethroids, using different insecticides as larviciding and impregnated bednets. The aim of study was to evaluate the biological assays of bendiocarb wettable powder (WP) at different surfaces of wall. The residual effect of bendiocarb WP80 at 400 milligram/meter square (mg/m²) was evaluated on various local surfaces of rooms such as mud and plaster as well as thatch roofs and wooden. World Health Organization standard cones using contact bioassays were carried out using laboratory reared sugar-fed, 48-72 h old females of Anopheles stephensi. Contact bioassays were carried out on sprayed surfaces for 150 days. Contact bioassay on surfaces treated with bendiocarb WP80 at different surfaces was estimated about 2 months. Fumigant tests of bendiocarb WP80 at 400 mg/m² revealed 50-93.83% mortality with 1 month persistency. The results showed that carbamate insecticide could be used as rotation with pyrethroids for malaria vector control. Monitoring and evaluation of environmental toxicology of pesticides is important for decision making for choosing appropriate pesticides for disease vector control.

Monitoring and Mapping of Insecticide Resistance in Medically Important Mosquitoes (Diptera: Culicidae) in Iran (2000-2020): A Review

BACKGROUND

Mosquitos due to their role in the transmission of different pathogens to humans are considered as an important group in the phylum Arthropoda. According to the WHO and FAO guideline different groups of insecticide applied for controlling pests in both the agricultural and public health sectors.

METHODS

All the data published about resistant status of the mosquitoes Anopheles, Culex, Aedes and Culiseta species were searched on PubMed, Elsevier, Web of Science, Magiran and google scholar. The objectives of this study was to review the trend of resistance to insecticides during 2000-2020 in medically important mosquitoes in Iran. The criteria for resistant are followed according to WHO guideline.

RESULTS

The Results showed that there are widespread, multiple resistances in the country to different organochlorine, organophosphates, carbamate and pyrethroids insecticides in the mosquitoes.

CONCLUSION

The effect of pesticide residues on the environment could be a cause for selection pressure on mosquitos and lead to insecticides resistance to them. Insecticides resistance is main challenge of the vector control program. Also result will provide a guideline for control of the mosquito-borne diseases in the country as well as the world.

Evaluation of Susceptibility of Aedes caspius (Diptera: Culicidae) to Insecticides in a Potent Arboviral-Prone Area, Southern Iran

Background:

Southern part of the country is a high risk for mosquito transmitted Arboviruses. This study was carried out to determine the base line susceptibility of the Aedini mosquitoes to the WHO-recommended insecticide.

Methods:

Larval collection was carried out by dipping method and adult collection occurred by suction tube from January to December 2017. The adult susceptibility test was assessed to Bendiocarb 0.1%, DDT 4%, Deltamethrin 0.05%, Lambda-cyhalothrin 0.05%, Malathion 5% and, Permethrin 0.75% at different interval times as well as at discriminative dose recommended by WHO. The larval susceptibility test was occurred using Temephos and Bacillus thuringiensis serotype H-14, at different concentrations. The LT₅₀, LT₉₀ and LC₅₀, LC₉₀ values were calculated for plotting the regression line using Microsoft office Excel software ver. 2007.

Results:

Aedes caspius was quite resistant to DDT, Malathion, Bendiocarb and showed susceptible or tolerant to other insecticides.The LT₅₀ and LT₉₀ values to DDT in this species were 157.896, and 301.006 minutes, respectively. The LC₅₀ and LC₉₀ values of Ae. caspius to Temephos were 0.000068, and 0.000130ppm, the figures for B. thuringiensis was 111.62 and 210.2ppm, respectively.

Conclusion:

A routine and continuous study for monitoring and evaluation of different species of Aedes to insectides is recommend at different parts of country for decision making.

Current insecticide resistance status in Anopheles sacharovi and Anopheles superpictus populations in former malaria endemic areas of Turkey

Anopheles sacharovi and Anopheles superpictus have a significant public health importance since they are primer and seconder malaria vectors of Turkey, respectively. As a result of intensive insecticide usage in historically malaria endemic regions of Turkey for long years, insecticide resistance problem has occurred inevitably. In this study, we aimed to investigate the involvement of the detoxification enzymes in insecticide resistance in Turkish An. sacharovi and An. superpictus populations in the Mediterranean and South-eastern Anatolia region where have a malaria history in the past. Bioassay results indicated that both An. sacharovi and An. superpictus populations are resistant to DDT, resistant or possible resistant to organophosphates and carbamates and finally mostly susceptible to pyrethroids. Although bioassays results indicated high DDT resistance in all mosquito populations, biochemical assays did not show significantly high GST levels in all strains. Almost all An. sacharovi and An. superpictus populations had an increased α and β esterase activity levels while nearly half of the overall populations had an increased p-NPA esterase than the control group. Elevated levels of MFO frequency have been shown in the majority of the populations. Consequently, our results reveal that biochemical resistance mechanisms may play an important role in insecticide resistance in Turkish An. sacharovi and An. superpictus populations. These results give useful cues to monitor the insecticide resistance before it spreads throughout an entire population, enabling early intervention.

A standard photomap of the ovarian nurse cell chromosomes for the dominant malaria vector in Europe and Middle East Anopheles sacharovi

Background

Anopheles sacharovi is a dominant malaria vector species in South Europe and the Middle East which has a highly plastic behaviour at both adult and larval stages. Such plasticity has prevented this species from eradication by several anti-vector campaigns. The development of new genome-based strategies for vector control will benefit from genome sequencing and physical chromosome mapping of this mosquito. Although a cytogenetic photomap for chromosomes from salivary glands of An. sacharovi has been developed, no cytogenetic map suitable for physical genome mapping is available.

Methods

Mosquitoes for this study were collected at adult stage in animal shelters in Armenia. Polytene chromosome preparations were prepared from ovarian nurse cells. Fluorescent in situ hybridization (FISH) was performed using PCR amplified probes.

Results

This study constructed a high-quality standard photomap for polytene chromosomes from ovarian nurse cells of An. sacharovi. Following the previous nomenclature, chromosomes were sub-divided into 39 numbered and 119 lettered sub-divisions. Chromosomal landmarks for the chromosome recognition were described. Using FISH, 4 PCR-amplified genic probes were mapped to the chromosomes. The positions of the probes demonstrated gene order reshuffling between An. sacharovi and Anopheles atroparvus which has not been seen cytologically. In addition, this study described specific chromosomal landmarks that can be used for the cytotaxonomic diagnostics of An. sacharovi based on the banding pattern of its polytene chromosomes.

Conclusions

This study constructed a high-quality standard photomap for ovarian nurse cell chromosomes of An. sacharovi and validated its utility for physical genome mapping. Based on the map, cytotaxonomic features for identification of An. sacharovi have been described. The cytogenetic map constructed in this study will assist in creating a chromosome-based genome assembly for this mosquito and in developing cytotaxonomic tools for identification of other species from the Maculipennis group.

Susceptibility and irritability of adult forms of main malaria vectors against insecticides used in the indoor residual sprays in Muzaffargarh District, Pakistan: a field survey

In southern Punjab, Pakistan, Muzaffargarh District is known to have insecticide-resistant Anopheles and drug-resistant Plasmodium spp. In this part of the country, five anopheline mosquitoes, Anopheles stephensi Liston, Anopheles culicifacies Giles, Anopheles fluviatilis James, Anopheles superpictus Grassi, and Anopheles subpictus Grassi (Diptera: Culicidae) are known as malaria vectors. Among these, An. culicifacies is the primary and An. stephensi is the secondary malaria vector. Outbreaks of malaria usually occur after rainy episodes. We conducted field surveys to collect field strains of An. culicifacies and An. stephensi mosquitoes from different areas of Muzaffargarh District. We determined susceptibility and irritability levels of their adult stages to the discriminative dose of different insecticides. For this purpose, we used World Health Organization's established criteria for assessment. Mortality was calculated after 1 h exposure and for 24 h recovery period for various insecticides. An. stephensi was found to be significantly resistant to dichlorodiphenyltrichloroethane (DDT, an organochlorine), dieldrin (a chlorinated hydrocarbon), and malathion (organophosphorus), with lethal times (LT50) of 83.17, 52.48, and 37.53, respectively. However, the species was significantly sensitive to permethrin, deltamethrin (pyrethroids), and fenitrothion (organophosphate) with LT50 of 2.85, 2.34, and 13.18, respectively. Among these, permethrin showed more promising results against adult An. stephensi. When analyzed for irritancy, we found that among pyrethroids, permethrin was the most irritant insecticide for both An. stephensi and An. culicifacies. DDT and dieldrin showed least irritancy with 0.42 +/- 0.08 and 0.77 +/- 0.12 takeoffs per minute per adult, respectively, against An. stephensi. The mean number of takeoffs per minute per adult with permethrin showed significant irritancy for permethrin when compared with DDT. Based on this study, we conclude that the use of organochlorine (DDT) and chlorinated hydrocarbon (dieldrin) should not be reintroduced in Malaria Control Programme in Pakistan until there is enough evidence to do so at any stage in future, and the use of pyrethroids should continue, with preference to permethrin for better control of malariaby indoor residual spraying.

Indication of pyrethroid resistance in the main malaria vector, Anopheles stephensi from Iran

OBJECTIVE

To investigate insecticide resistance in target species for better insecticide resistance management in malaria control programs.

METHODS

The status of insecticide resistance to different imagicides in Anopheles stephensi (An. stephensi) including DDT 4%, lambdacyhalothrin 0.50%, deltamethrin 0.05%, permethrin 0.75%, cyfluthrin 0.15% and etofenprox 0.50% was performed according to WHO standard method.

RESULTS

The mortality rate to lambdacyhalothrin, permethrin, cyfluthrin, deltamethrin, etofenprox and DDT was (88.0 ± 3.2), (92.0 ± 2.7), (52.0 ± 5.0), (96.0 ± 2.2), (90.0 ± 3.0) and (41.0 ± 5.7) percent, respectively at diagnostic dose for one hour exposure time followed by 24 h recovery period.

CONCLUSIONS

These results showed first indication of pyrethroid resistance in An. stephensi in a malarious area, from southern Iran. There is widespread, multiple resistances in the country in An. stephensi to organochlorine and some report of tolerance to organophosphate insecticides and recently to pyrethroids. However, results of this paper will provide a clue for monitoring and mapping of insecticide resistance in the main malaria vector for implementation of any vector control.