Evaluation of organophosphorus and synthetic pyrethroid insecticides against six vector mosquitoe species

Three organophosphorus compounds- malathion, folithion and temephos- and two synthetic pyrethroids- alphamethrin and deltamethrin- were used for monitoring the susceptibility status of larvae and adults of six vector mosquitoe species: Culex quinquefasciatus (Filariasis) and Aedes albopictus (Dengue) (both laboratory and field strains); laboratory strains of Aedes aegypti (Dengue), Anopheles slephensi and Anopheles culicifacies (Malaria), and Culex tritaeniorhynchus (Japanese encephalitis) in India. From the LC50 values obtained for these insecticides, it was found that all mosquito species including the field strains of Cx. quinquefasciatus and Ae. albopictus were highly susceptible Except for Cx. quinquefasciatus (field strain) against malathion, 100% mortality was observed at the discriminating dosages recommended by World Health Organization. The residual effect of alphamethrin, deltamethrin, malathion and folithion at 25 mg (ai)/m² on different surfaces against six species of vector mosquitoes showed that alphamethrin was the most effective on all four treated surfaces (mud, plywood, cement and thatch). Nevertheless, residual efficacy lasted longer on thatch than on the other surfaces. Therefore, synthetic pyrethroids such as alphamethrin can be effectively employed in integrated vector control operations.

Download Full-text

Insecticides Susceptibility Status of Malaria Vectors in a High Malaria Endemic Tribal District Gadchiroli (Maharashtra) of India

JOURNAL OF COMMUNICABLE DISEASES ◽

10.24321/0019.5138.202137 ◽

2021 ◽

Vol 53 (03) ◽

pp. 33-50

Author(s):

RK Singh ◽

Keyword(s):

World Health ◽

Malaria Vectors ◽

Synthetic Pyrethroids ◽

Lambda Cyhalothrin ◽

Deltamethrin Resistance ◽

Cone Bioassay ◽

Susceptibility Tests ◽

Health Organization ◽

Susceptibility Status ◽

Major Malaria Vector

Background and Objective: The current study was undertaken to determine insecticide susceptibility of malaria vectors in various villages of high malaria endemic PHCs of Gadchiroli district of Maharashtra. Methods: Adult malaria vectors were collected from the human dwellings/ cattle sheds of 156 villages of 18 malaria endemic PHCs. Susceptibility tests were carried out for different insecticides against An. culicifacies and An. fluviatilis mosquitoes as per the World Health Organization (WHO) procedure. Cone bioassays were also done to assess the quality and efficacy of indoor residual spray. Results:An. fluviatilis could be collected from 23 villages only and all the populations were fully susceptible to synthetic pyrethroid (deltamethrin) while being tolerant to organophosphorous (malathion). Susceptibility of An. culicifacies from 156 villages indicated that only 3 populations of An. culicifacies were resistant to deltamethrin while 57 populations were fully susceptible and other 96 populations were tolerant to deltamethrin. Resistance was recorded in 25 populations of An. culicifacies against malathion and 30 populations were tolerant to malathion insecticide. Remaining populations of An. fluviatilis and An. culicifacies were highly resistant to organochlorine. Results of cone bioassay revealed the mortality ranged from 32.5-51.1% on cemented and 27.5-43.3% on the mud wall sprayed with lambda cyhalothrin. Conclusion: The current study indicates that resistance has developed to synthetic pyrethroids in the major malaria vector An. culicifacies. Therefore, there is an urgent need for the evaluation of new insecticide molecules for better control of malaria vectors.

Download Full-text

Insecticide susceptibility status of human biting mosquitoes in Muheza, Tanzania

Tanzania Journal of Health Research ◽

10.4314/thrb.v19i3.9 ◽

2017 ◽

Vol 19 (3) ◽

Author(s):

Basiliana Emidi ◽

William N. Kisinza ◽

Robert D. Kaaya ◽

Robert Malima ◽

Franklin W. Mosha

Keyword(s):

Vector Control ◽

Mosquito Species ◽

World Health ◽

Malaria Vector Control ◽

Limited Information ◽

Insecticide Susceptibility ◽

North Eastern ◽

Sub Saharan ◽

Health Organization ◽

Susceptibility Status

Background: There has been a rapid emergence in insecticide resistance among mosquito population to commonly used public health insecticides. This situation presents a challenge to chemicals that are currently used to control mosquitoes in sub-Saharan African. Furthermore, there is limited information on insecticide susceptibility status of human-biting mosquitoes in some areas of Tanzania. This study aimed to determine insecticide susceptibility status of human biting mosquitoes in a rural area of north-eastern Tanzania.Methods: The study was conducted in two villages in Muheza district, Tanzania. Insecticide susceptibility bioassays were performed according to the World Health Organization standard operating procedures on two to five-day old human biting mosquitoes. The mosquitoes of each species were exposed to four classes of insecticides commonly used for malaria vector control. Mosquito mortality rates (%) were determined after 24 hours post insecticide exposure.Results: Mosquito species tested were Anopheles gambiae s.l., An. funestus, Aedes aegypti, and Culex quinquefasciatus species. Real-time PCR have showed that the main sibling species of An. gambiae complex and An. funestus group were An. gambiae s. s. (58.2%) and An. funestus s. s. (91.1%), respectively. All mosquitoes, except Ae. aegypti formosus were susceptible to pirimiphos-methyl (0.25%). An. gambiae s. l. was found to be resistant to permethrin (0.75%) but showed possibility of resistance to DDT (4%) and bendiocarb (0.1%). Our findings have shown that, An. funestus was fully susceptible to all insecticide tested.Conclusion: The present study has revealed different levels of insecticide susceptibility status to four classes of commonly used insecticides in the most common mosquito vectors of human diseases in north-eastern Tanzania. The findings of the present study call for integrated vector control interventions.

Download Full-text

Insecticide Resistance in Anopheles stephensi in Somali Region, Eastern Ethiopia

10.21203/rs.2.18020/v2 ◽

2020 ◽

Cited By ~ 1

Author(s):

Solomon Yared ◽

Araya Gebressielasie ◽

Lambodhar Damodaran ◽

Victoria Bonnell ◽

Karen Lopez ◽

...

Keyword(s):

Insecticide Resistance ◽

Anopheles Stephensi ◽

Mortality Rates ◽

Resistance Mechanisms ◽

World Health ◽

Malaria Vectors ◽

Eastern Ethiopia ◽

Pyrethroid Insecticides ◽

Pirimiphos Methyl ◽

Health Organization

Abstract Background: The movement of malaria vectors into new areas is a growing concern in the efforts to control malaria. The recent report of Anopheles stephensi in eastern Ethiopia has raised the necessity to understand the insecticide resistance status of the vector in the region to better inform vector-based interventions. The aim of this study was to evaluate insecticide resistance in An. stephensi in eastern Ethiopia using two approaches: 1) World Health Organization (WHO) bioassay tests in An. stephensi and 2) genetic analysis of insecticide resistance genes in An. stephensi in eastern Ethiopia. Methods: Mosquito larvae and pupae were collected from Kebridehar. Insecticide susceptibility of An. stephensi was tested with malathion 5%, bendiocarb 0.1%, propoxur 0.1%, deltamethrin 0.05%, permethrin 0.75%, Pirimiphos-methyl 0.25% and DDT 4%, according to WHO standard protocols. Results: All An. stephensi samples were resistant to carbamates, with mortality rates 23% and 21% for bendiocarb and propoxur, respectively. Adult An. stephensi was also resistant to pyrethroid insecticides with mortality rates 67% for deltamethrin and 53% for permethrin. Resistance to DDT and malathion was detected in An. stephensi with mortality rates of 32% as well as An. stephensi was resistance to pirimiphos-methyl with mortality rates 14%. Analysis of the voltage gate sodium channel gene (vgsc) revealed the absence of kdr L1014 mutations. Conclusion: Overall, these findings support that An. stephensi is resistant to several classes of insecticides, most notably pyrethroids. However, the absence of the kdr L1014 gene may suggest non-target site resistance mechanisms. Continuous insecticide resistance monitoring should be carried out in the region to confirm the documented resistance and exploring mechanisms conferring resistance in An. stephensi in Ethiopia.

Download Full-text

Michael Elliott CBE. 30 September 1924 — 17 October 2007

Biographical Memoirs of Fellows of the Royal Society ◽

10.1098/rsbm.2016.0018 ◽

2016 ◽

Vol 62 ◽

pp. 109-123 ◽

Cited By ~ 1

Author(s):

John Pickett

Keyword(s):

Food Production ◽

Insect Pests ◽

World Health ◽

Individual Contribution ◽

Pyrethroid Insecticides ◽

New Class ◽

Structure Activity ◽

The World ◽

Health Organization ◽

Global Food

Michael Elliott was the leader of work at Rothamsted that invented and subsequently commercially developed the pyrethroids, a new class of insecticides. Michael made probably the greatest individual contribution to the control of insect pests that not only constrain global food production but also affect the health of ourselves and our livestock. In one of the first pioneering structure–activity relationship studies, Michael led the multidisciplinary team that invented the major pyrethroid insecticides bioresmethrin, permethrin, cypermethrin and deltamethrin. In the 1980s these represented two-thirds of the global pyrethroid market; at that time pyrethroids captured more than 25% of the total insecticide market and were used on 33 million hectares of crops (Wirtz et al . 2009). In 2002 deltamethrin was the world's largest-selling pyrethroid, with annual sales worth $208 million (information from Cropnosis Ltd). In terms of human health, in 2009 it was estimated that pyrethroid-treated bednets significantly decreased the number of deaths due to malaria among children under five years of age by about one-fifth as well as reducing all incidents of malaria, and in 2011 the World Health Organization recommended its vastly expanded use. Reference Wirtz, K., Bala, S., Amann, A. & Elbert, A. 2009 A promise extended—future roles of pyrethroids in agriculture. Bayer CropSci. J. 62 , 145–158.

Download Full-text

Bio-efficacy and Wash-fastness of a Lamda-cyhalothrin Long-lasting Insecticide Treatment Kit (ICON® Maxx) Against Mosquitoes on Various Polymer Materials

10.21203/rs.3.rs-564533/v1 ◽

2021 ◽

Author(s):

Patrick Tungu ◽

Wema Sudi ◽

Harparkash Kaur ◽

Stephen Magesa ◽

Mark Rowland

Keyword(s):

Malaria Prevention ◽

Home Treatment ◽

Polymer Materials ◽

World Health ◽

Insecticide Treated Nets ◽

Pyrethroid Insecticides ◽

Wash Fastness ◽

Lambda Cyhalothrin ◽

Efficacy Criteria ◽

Health Organization

Abstract BackgroundLong-lasting efficacy of insecticide treated nets is a balance between adhesion, retention and migration of insecticide to the surface of netting fibres. ICON® Maxx is a twin-sachet ‘home-treatment kit’ of pyrethroid plus binding agent, recommended by the World Health Organization for long-lasting, wash-fast treatment of polyester nets. While knitted polyester netting is widely used, fine woven polyethylene netting is increasingly available and nets made of cotton and nylon are common in Africa and Asia. It is important to investigate whether ICON Maxx is able to fulfill the WHO criteria of long-lasting treatment on a range of domestic fabrics to widen the scope for malaria protection.Method This study was a controlled comparison of the bio-efficacy and wash-fastness of lambda-cyhalothrin CS, with or without binder, on nets made of cotton, polyethylene, nylon, dyed and undyed polyester. Evaluation compared an array of bioassays, WHO cone and cylinder, median time to knockdown and WHO tunnel tests using Anopheles mosquitoes. Chemical assay revealed further insight. ResultsICON Maxx treated polyethylene and polyester netting met the WHO cone and tunnel test bio-efficacy criteria for LLIN after 20 standardized washes. Although nylon and cotton netting failed to meet the WHO cone and cylinder criteria, both materials passed the WHO tunnel test criterion of 80% mortality after 20 washes. All materials treated with standard lambda-cyhalothrin CS without binder failed to meet any of the WHO bio-efficacy criteria within 5 washes. ConclusionThe bio-efficacy of ICON Maxx against mosquitoes on netting washed up to 20 times demonstrated wash durability on a range of synthetic polymer and natural fibres: polyester, polyethylene, nylon and cotton. This raises the prospect of making the insecticide-binder kit into an effective approach for turning untreated nets, curtains, military clothing, blankets - and tents and tarpaulins as used in disasters and humanitarian emergencies - into effective malaria prevention products. It may provide a solution to the problem of reduced LLIN coverage between campaigns by converting commercially sourced untreated nets into LLINs through community or home treatment. It may also open the door to binding of non-pyrethroid insecticides to nets and textiles for control of pyrethroid resistant vectors.

Download Full-text

Evaluation of the Residual Efficacy of Actellic300 CS in Simple Huts in Central Ethiopia

Journal of Medical Entomology ◽

10.1093/jme/tjab096 ◽

2021 ◽

Author(s):

Sisay Dugassa ◽

Sileshi Mekonnen ◽

Peter W Muthee ◽

Rose Peter ◽

David Zinyengere ◽

...

Keyword(s):

Malaria Transmission ◽

Indoor Residual Spraying ◽

World Health ◽

Efficacy Trials ◽

History Of ◽

Residual Efficacy ◽

History Of Use ◽

Health Organization ◽

Long Lasting Insecticidal Nets

Abstract Indoor residual spraying (IRS) is one of the key vector control tools with a long history of use in the world. Ethiopia has set a goal to eliminate malaria from selected districts mainly by applying IRS and the distribution of long-lasting insecticidal nets. IRS is applied in low malaria transmission districts which are epidemic prone and in districts with high malaria transmission. Ethiopia uses insecticides that are recommended by World Health Organization; these insecticides must also be registered in Ethiopia. The registration of new and potential products requires confirmatory, local efficacy trials to be performed. Actellic 300CS, now registered, is one of such potential product. Actellic 300CS showed average mortalities of 99.6%, 99.6%, and 99.0% on the sprayed surfaces in the experimental huts, the top, middle, and bottom sections, respectively during the first 6 mo of the study period. Beyond 6 mo, (7, 8, and 9 mo) follow-up, mortalities for the top, middle, and bottom sections were 85.2%, 86.3%, and 85.2%, respectively. The results showed that the residual efficacy of Actellic 300CS was up to 9 mo with the first 6 mo exhibiting mortalities of greater than 99% while the next 3 mo showed mortalities exceeding 85%. Actellic 300CS was effective against fully susceptible laboratory-reared Anopheles arabiensis on all four surface types (rough, smooth, dung, and painted surfaces) tested in this study and could be used as one of the chemical insecticides of choice for the ongoing IRS programs in Ethiopia.

Download Full-text

New Challenges in Malaria Elimination

Current Topics and Emerging Issues in Malaria Elimination - Infectious Diseases ◽

10.5772/intechopen.96532 ◽

2021 ◽

Author(s):

Susanta Kumar Ghosh ◽

Chaitali Ghosh

Keyword(s):

Malaria Elimination ◽

New Technologies ◽

Point Of Care ◽

Artemisinin Resistance ◽

Sub Saharan Africa ◽

Chloroquine Resistance ◽

World Health ◽

Synthetic Pyrethroids ◽

Sub Saharan ◽

Health Organization

In recent years, efforts to eliminate malaria has gained a tremendous momentum, and many countries have achieved this goal — but it has faced many challenges. Recent COVID-19 pandemic has compounded the challenges due to cessation of many on-field operations. Accordingly, the World Health Organization (WHO) has advocated to all malaria-endemic countries to continue the malaria elimination operations following the renewed protocols. The recent reports of artemisinin resistance in Plasmodium falciparum followed by indication of chloroquine resistance in P. vivax, and reduced susceptibility of synthetic pyrethroids used in long lasting insecticide nets are some issues hindering the elimination efforts. Moreover, long distance night migration of vector mosquitoes in sub-Saharan Africa and invasion of Asian vector Anopheles stephensi in many countries including Africa and Southeast Asia have added to the problems. In addition, deletion of histidine rich protein 2 and 3 (Pfhrp2/3) genes in P. falciparum in many countries has opened new vistas to be addressed for point-of-care diagnosis of this parasite. It is needed to revisit the strategies adopted by those countries have made malaria elimination possible even in difficult situations. Strengthening surveillance and larval source management are the main strategies for successful elimination of malaria. New technologies like Aptamar, and artificial intelligence and machine learning would prove very useful in addressing many ongoing issues related to malaria elimination.

Download Full-text

Discriminating Lethal Concentrations for Transfluthrin, a Volatile Pyrethroid Compound for Mosquito Control in Thailand

Journal of the American Mosquito Control Association ◽

10.2987/19-6832.1 ◽

2019 ◽

Vol 35 (4) ◽

pp. 258-266 ◽

Cited By ~ 2

Author(s):

Chutipong Sukkanon ◽

Michael J. Bangs ◽

Jirod Nararak ◽

Jeffrey Hii ◽

Theeraphap Chareonviriyaphap

Keyword(s):

Mosquito Control ◽

Mosquito Species ◽

World Health ◽

Testing System ◽

Test Field ◽

Complex Species ◽

Control Programs ◽

High Vapor ◽

Health Organization ◽

Routine Assessment

ABSTRACT Pyrethroids are commonly used to control malaria and dengue vectors in Thailand. The lack of specific lethal discriminating concentrations (DCs) for specific mosquito species has possibly compromised more accurate assessments of physiological susceptibility to various chemicals over time. Previous studies have established DCs of various residual pyrethroids against specific mosquitoes in Thailand. However, DCs for transfluthrin (TFT), a highly volatile pyrethroid compound, against mosquito vectors in Thailand has been lacking. The aim of this study was to determine the DCs and susceptibility baselines of TFT against pyrethroid-susceptible laboratory strains of Aedes aegypti, Anopheles minimus, and An. dirus using the World Health Organization adult susceptibility tube method. Final DCs of TFT of each species were determined based on doubling the 99% lethal concentration at the following percentages: Ae. aegypti (0.06824%), An. minimus (0.06382%), and An. dirus (0.01508%). Subsequently, the respective TFT DCs were used to test field-collected populations of Ae. aegypti, An. harrisoni (Minimus Complex species), and An. dirus. Anopheles harrisoni and An. dirus were found completely susceptible (100% mortality), whereas Ae. aegypti from Nonthaburi Province was resistant to TFT. The suitability of the testing system and procedures is discussed. Routine assessment of insecticide susceptibility should include pyrethroids with high-vapor-pressure characteristics for informing control programs and consumers of product and chemical effectiveness.

Download Full-text

Predicting intensities of Zika infection and microcephaly using transmission intensities of other arboviruses

10.1101/041095 ◽

2016 ◽

Cited By ~ 5

Author(s):

Isabel Rodriguez-Barraquer ◽

Henrik Salje ◽

Justin Lessler ◽

Derek AT Cummings

Keyword(s):

Zika Virus ◽

Strong Correlation ◽

Mosquito Species ◽

World Health ◽

Detailed Knowledge ◽

Crude Incidence ◽

Force Of Infection ◽

Dengue Transmission ◽

Health Organization ◽

Virus Emergence

The World Health Organization has declared Zika Virus a Public Health Emergency of International Concern due to the virus' emergence in multiple countries globally and the possible association of Zika virus with microcephaly and neurological disorders. There is a clear need to identify risk factors associated with Zika infection and microcephaly in order to target surveillance, testing and intervention efforts. Here, we show that there is a strong correlation between the incidence of Zika in Colombian departments and the force of infection (but not the crude incidence) of dengue, a virus transmitted by the same mosquito species, Aedes aegypti (R2 = 0.41, p<0.001). Furthermore, we show that there is also a strong correlation between the incidence of microcephaly in Brazilian states and the force of infection of dengue (R2 = 0.36, p<0.001). Because dengue, Zika and Chikungunya are transmitted by the same vector, these associations provide further support to the supposition that Zika virus infection during pregnancy causes microcephaly. In addition, they provide an opportunity to project the expected incidence of microcephaly in multiple dengue endemic locations across Colombia and the American continent. Detailed knowledge of dengue transmission should be use to target efforts against Zika and other flaviviruses.

Download Full-text

A new malaria vector in Africa: Predicting the expansion range of Anopheles stephensi and identifying the urban populations at risk

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2003976117 ◽

2020 ◽

Vol 117 (40) ◽

pp. 24900-24908 ◽

Cited By ~ 2

Author(s):

M. E. Sinka ◽

S. Pironon ◽

N. C. Massey ◽

J. Longbottom ◽

J. Hemingway ◽

...

Keyword(s):

Anopheles Stephensi ◽

Close Association ◽

Mosquito Species ◽

Full Range ◽

Spatial Models ◽

Urban Environments ◽

World Health ◽

Horn Of Africa ◽

Populations At Risk ◽

Health Organization

In 2012, an unusual outbreak of urban malaria was reported from Djibouti City in the Horn of Africa and increasingly severe outbreaks have been reported annually ever since. Subsequent investigations discovered the presence of an Asian mosquito species; Anopheles stephensi, a species known to thrive in urban environments. Since that first report, An. stephensi has been identified in Ethiopia and Sudan, and this worrying development has prompted the World Health Organization (WHO) to publish a vector alert calling for active mosquito surveillance in the region. Using an up-to-date database of published locational records for An. stephensi across its full range (Asia, Arabian Peninsula, Horn of Africa) and a set of spatial models that identify the environmental conditions that characterize a species’ preferred habitat, we provide evidence-based maps predicting the possible locations across Africa where An. stephensi could establish if allowed to spread unchecked. Unsurprisingly, due to this species’ close association with man-made habitats, our maps predict a high probability of presence within many urban cities across Africa where our estimates suggest that over 126 million people reside. Our results strongly support the WHO’s call for surveillance and targeted vector control and provide a basis for the prioritization of surveillance.

Download Full-text