scholarly journals Effect of Bendiocarb Indoor Residual Spraying on Entomological Inoculation Rate of Anopheles arabiensis in Northwestern Highlands of Ethiopia

2020 ◽  
Author(s):  
Alemayehu Abate ◽  
Melaku Wale
Keyword(s):  
Entomological Inoculation Rate ◽  
Anopheles Arabiensis ◽  
Indoor Residual Spraying

scholarly journals Insecticide resistance status of Anopheles arabiensis in irrigated and non-irrigated areas in western Kenya

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Pauline Winnie Orondo ◽  
Steven G. Nyanjom ◽  
Harrysone Atieli ◽  
John Githure ◽  
Benyl M. Ondeto ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Vector Control ◽  
Anopheles Arabiensis ◽  
Crop Protection ◽  
Indoor Residual Spraying ◽  
Malaria Vectors ◽  
Western Kenya ◽  
Animal Protection ◽  
Selection Of ◽  
Selection Of Resistance

Abstract Background Malaria control in Kenya is based on case management and vector control using long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS). However, the development of insecticide resistance compromises the effectiveness of insecticide-based vector control programs. The use of pesticides for agricultural purposes has been implicated as one of the sources driving the selection of resistance. The current study was undertaken to assess the status and mechanism of insecticide resistance in malaria vectors in irrigated and non-irrigated areas with varying agrochemical use in western Kenya. Methods The study was carried out in 2018–2019 in Homa Bay County, western Kenya. The bioassay was performed on adults reared from larvae collected from irrigated and non-irrigated fields in order to assess the susceptibility of malaria vectors to different classes of insecticides following the standard WHO guidelines. Characterization of knockdown resistance (kdr) and acetylcholinesterase-inhibiting enzyme/angiotensin-converting enzyme (Ace-1) mutations within Anopheles gambiae s.l. species was performed using the polymerase chain reaction (PCR) method. To determine the agricultural and public health insecticide usage pattern, a questionnaire was administered to farmers, households, and veterinary officers in the study area. Results Anopheles arabiensis was the predominant species in the irrigated (100%, n = 154) area and the dominant species in the non-irrigated areas (97.5%, n = 162), the rest being An. gambiae sensu stricto. In 2018, Anopheles arabiensis in the irrigated region were susceptible to all insecticides tested, while in the non-irrigated region reduced mortality was observed (84%) against deltamethrin. In 2019, phenotypic mortality was decreased (97.8–84% to 83.3–78.2%). In contrast, high mortality from malathion (100%), DDT (98.98%), and piperonyl butoxide (PBO)-deltamethrin (100%) was observed. Molecular analysis of the vectors from the irrigated and non-irrigated areas revealed low levels of leucine-serine/phenylalanine substitution at position 1014 (L1014S/L1014F), with mutation frequencies of 1–16%, and low-frequency mutation in the Ace-1R gene (0.7%). In addition to very high coverage of LLINs impregnated with pyrethroids and IRS with organophosphate insecticides, pyrethroids were the predominant chemical class of pesticides used for crop and animal protection. Conclusion Anopheles arabiensis from irrigated areas showed increased phenotypic resistance, and the intensive use of pesticides for crop protection in this region may have contributed to the selection of resistance genes observed. The susceptibility of these malaria vectors to organophosphates and PBO synergists in pyrethroids offers a promising future for IRS and insecticide-treated net-based vector control interventions. These findings emphasize the need for integrated vector control strategies, with particular attention to agricultural practices to mitigate mosquito resistance to insecticides. Graphic abstract

scholarly journals Effect of LongRange™ eprinomectin on Anopheles arabiensis by feeding on calves treated with the drug

2019 ◽  
Vol 18 (1) ◽  
Author(s):  
Aklilu Belay ◽  
Beyene Petros ◽  
Teshome Gebre-Michael ◽  
Meshesha Balkew
Keyword(s):  
Anopheles Arabiensis ◽  
Control Method ◽  
Indoor Residual Spraying ◽  
Adult Emergence ◽  
Malaria Vector Control ◽  
Egg Hatchability ◽  
Kaplan Meier ◽  
Recorded Data ◽  
Long Lasting Insecticidal Nets ◽  
Nylon Cloth

Abstract Background Misuse of long-lasting insecticidal nets together with resistance of vectors to most of the insecticides for indoor residual spraying and impregnated nets threaten malaria vector control interventions, requiring search for alternative control methods. Reports have shown that Anopheles mosquitoes die when they feed on endectocidal drugs used to treat humans and animals. A study was designed to investigate the efficacy of LongRange™ (eprinomectin 5%) on laboratory reared Anopheles arabiensis fed on treated calves. Methods Anopheles arabiensis from insectary colony was fed on three calves treated with therapeutic dose of LongRange™ eprinomectin (1 ml/50 kg) and on non-treated three other calves as control arm. For the feeding, mosquitoes were placed in paper cups covered with nylon cloth mesh and then allowed to feed on the necks of calves. Subsequently, mosquito survival, fecundity, egg hatchability, larval development and adult emergence were recorded. Data were entered and analysed by using SPSS version 20. The Kaplan–Meier survival analysis and independent sample t-test were used. Results All mosquitoes that fed on LongRange™ Eprinomectin treated calves died within 7 days following blood ingestion. The drug also slightly affected fecundity and hatchability of An. arabiensis. Conclusion Treating livestock with LongRange™ (eprinomectin 5%) may serve as a supplementary control method for zoophagic An. arabiensis.

scholarly journals Species Diversity and Entomological Inoculation Rate of Anophelines Mosquitoes in an Epidemic Prone Areas of Bure District, Northwestern Ethiopia

2020 ◽  
Author(s):  
Tilahun Adugna Wassie ◽  
Delensaw Yewhelew Gebru ◽  
Emana Emana Getu (Prof.) Degaga
Keyword(s):  
Species Diversity ◽  
Disease Transmission ◽  
Entomological Inoculation Rate ◽  
Indoor Residual Spraying ◽  
Northwest Ethiopia ◽  
Malaria Vectors ◽  
Insecticide Treated Nets ◽  
Source Reduction ◽  
Sporozoite Rate ◽  
Control And Prevention

Abstract Background: Malaria is the leading health problem in Ethiopia. The country has been prevented malaria vectors mostly using long-lasting insecticide-treated nets, the application of indoor residual spraying chemicals, and source reductions. Before interventions, identifying the responsible malaria vector in disease transmission (sporozoite rate) is very vital; hence, the present study was designed to assess species diversity and entomological inoculation rate of Anopheles mosquito in Bure district, Northwest Ethiopia. Methods: Adult mosquitoes were collected from July 2015 to June 2016 using the center for disease control and prevention light traps, pyrethrum spray catches, and artificial pit shelters. Mosquitoes were morphologically identified. Following this, An. gambiae s.l was identified molecularly. Head-thorax sporozoite infectivity of the adult female Anopheles mosquitoes was assessed using enzyme-linked immunosorbent assays. Results: Morphologically, nine species of the genus Anopheles were identified in the three villages, composed of Anopheles demeilloni, An. arabiensis, An. funestus, An. coustani, An. squamosus, An. cinereus, An. pharoensis, An. rupicolus, and An. natalensis. Of these species, An. demeilloni was the most predominant, whereas An. cinereus, An. rupicolus and An. natalensis were the least representative species (p < 0.0001). Greater number of adult Anopheles mosquitoes were collected in Shnebekuma, non-irrigated villages than non- irrigated village (Workmidr) and irrigated village (Bukta) (p < 0.0001). The overall Plasmodium infective rate (P. falciparum and P. vivax) in the district was 0.31%. The overall annual sporozoite rate in non-irrigated villages (Shnebekuma and Workmidr) was 0.35%, whereas zero in irrigated village (Bukta). The overall estimated EIR of Anopheles mosquitoes was 5.7 infectious bites /person /year for both P. falciparum and P. vivax in the district. The annual EIR Anopheles species in non-irrigated villages was 5.65 ib/p/y, which was higher than irrigated village (0 ib/p/y). Conclusions: Both the primary (An. arabiensis) and secondary (An. funestus and An. pharoensis) malaria vectors of Ethiopia were identified in the three villages. Three of Anopheles species, An. arabiensis, An. funestus, and An. coustani were found to be infected only in irrigated villages. Source reduction and proper usage of long-lasting insecticide nets and indoor residual spraying could be implemented in the non- irrigated villages to cut the vector abundance and EIR.

scholarly journals The Current Insecticide Resistance in Main Malaria Vector Anopheles arabiensis in Yemen

2020 ◽  
Vol 2020 ◽  
pp. 1-5
Author(s):  
Zalalham Al-Koleeby ◽  
Ahmed El Aboudi ◽  
Mithaq Assada ◽  
Mohamed Al-Hadi ◽  
Mohammed Abdalr Ahman ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Malaria Vector ◽  
Anopheles Arabiensis ◽  
Resistance Management ◽  
Indoor Residual Spraying ◽  
Malaria Vectors ◽  
Test Procedures ◽  
Phenotypic Resistance ◽  
Lambda Cyhalothrin ◽  
Susceptibility Tests

Control of malaria vectors in Yemen relies on both indoor residual spraying using carbamate (bendiocarb) and long-lasting pyrethroids-treated nets. This paper reports the results of studies conducted to monitor the insecticide resistance of the main malaria vector, Anopheles arabiensis, to the insecticides currently used in the vector control in four different locations. Susceptibility tests were performed following the WHO test procedures. Two pyrethroids (lambda-cyhalothrin 0.05% and deltamethrin 0.05%) and one carbamate (bendiocarb 0.1%) were tested at diagnostic doses (DD). The five-fold DD of lambda-cyhalothrin and deltamethrin (0.25%) were also used to yield information on the intensity of resistance. Besides, tests with synergists were performed to assess the involvement of detoxifying enzyme in the phenotypic resistance of the populations of An. arabiensis to pyrethroids. The results of the performed susceptibility bioassay showed that the vector is susceptible to bendiocarb and resistant to lambda-cyhalothrin and deltamethrin in the four studied areas. The pyrethroids resistance is solely metabolic. This information could help policy-makers to plan insecticide resistance management. Bendiocarb is still an effective insecticide in the form of IRS. Concerning LLINS, it would be interesting to assess their effectiveness, combining a pyrethroid with PBO for the control of the pyrethroid-resistant malaria vector.

scholarly journals Reduced human-biting preferences by the African malaria vectors Anopheles arabiensis and Anopheles gambiae in an urban context: Controlled, competitive host-preference experiments in Tanzania

2020 ◽  
Author(s):  
Yeromin P Mlacha ◽  
Prosper P. Chaki ◽  
Athuman Muhili ◽  
Dennis J. Massue ◽  
Marcel Tanner ◽  
...  
Keyword(s):  
Anopheles Gambiae ◽  
Anopheles Arabiensis ◽  
Host Preference ◽  
Indoor Residual Spraying ◽  
Urban Setting ◽  
Sub Saharan Africa ◽  
Rural Setting ◽  
Malaria Vectors ◽  
Baited Traps ◽  
The Impact

Abstract BackgroundHost preference is a critical determinant of human exposure to vector-borne infections and also the impact of interventions. Widespread use of long-lasting insecticides treated nets (LLINs) and, indoor residual spraying (IRS) across sub-Saharan Africa, which protect humans against mosquitoes, may select for altered host preference traits of malaria vectors over the long term. Here, the host preferences of Anopheles arabiensis and Anopheles gambiae sensu stricto was experimentally assessed in the field, using direct host-preference assays in two distinct ecological settings in Tanzania. MethodsEight Ifakara Tent Trap (ITT), half of them baited with humans or bovine calves were simultaneously used to catch malaria vectors in open field sites urban and rural Tanzania. The numbers of mosquitoes collected in human-baited traps versus calf-baited traps were used to estimate human feeding preference of each malaria vector species present at each site. ResultsThe estimated proportion [95% confidence interval (CI)] of mosquitoes attacking humans rather than cattle was 0.60 [0.40, 0.77] for An. arabiensis in the rural setting and 0.61 [0.32, 0.85] for An. gambiae in the urban setting, indicating no preference for either host in both cases (P=0.32 and 0.46, respectively) and no difference in preference between the two (Odds Ratio (OR) [95%] = 0.95 [0.30, 3.01], P=0.924). However, only a quarter of An. arabiensis in the urban setting attacked humans (0.25 [0.09, 0.53]), indicating a preference for cattle that approached significance (P=0.08). Indeed, urban An. arabiensis were less likely to attack humans rather than cattle when compared to the same species in the rural setting (OR [95%] = 0.21 [0.05, 0.91], P =0.037). ConclusionUrban An. arabiensis had a stronger preference for cattle than the rural population in this or previous studies, all of which reported similar traits for this species in rural contexts. Furthermore, the urban An. gambiae assessed here had a weaker preference for humans over cattle than reported by previous studies of the same species in rural contexts. Cattle keeping may therefore particularly limit the impact of human-targeted vector control interventions in Dar es Salaam and perhaps in other African towns and cities.

scholarly journals Indoor residual spraying with microencapsulated DEET repellent (N, N-diethyl-m-toluamide) for control of Anopheles arabiensis and Culex quinquefasciatus

2014 ◽  
Vol 7 (1) ◽  
pp. 446 ◽  
Author(s):  
Jovin Kitau ◽  
Richard Oxborough ◽  
Johnson Matowo ◽  
Franklin Mosha ◽  
Stephen M Magesa ◽  
...  
Keyword(s):  
Culex Quinquefasciatus ◽  
Anopheles Arabiensis ◽  
Indoor Residual Spraying

scholarly journals Comparative assessment of insecticide resistance phenotypes in two major malaria vectors, Anopheles funestus and Anopheles arabiensis in south-eastern Tanzania

2020 ◽  
Vol 19 (1) ◽  
Author(s):  
Polius G. Pinda ◽  
Claudia Eichenberger ◽  
Halfan S. Ngowo ◽  
Dickson S. Msaky ◽  
Said Abbasi ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Malaria Transmission ◽  
Anopheles Arabiensis ◽  
Pyrethroid Resistance ◽  
Anopheles Funestus ◽  
Indoor Residual Spraying ◽  
Sub Saharan Africa ◽  
World Health ◽  
Malaria Vectors ◽  
South Eastern

Abstract Background Long-lasting insecticide-treated nets (LLINs) and indoor residual spraying (IRS) have greatly reduced malaria transmission in sub-Saharan Africa, but are threatened by insecticide resistance. In south-eastern Tanzania, pyrethroid-resistant Anopheles funestus are now implicated in > 80% of malaria infections, even in villages where the species occurs at lower densities than the other vector, Anopheles arabiensis. This study compared the insecticide resistance phenotypes between the two malaria vectors in an area where pyrethroid-LLINs are widely used. Methods The study used the World Health Organization (WHO) assays with 1×, 5× and 10× insecticide doses to assess levels of resistance, followed by synergist bioassays to understand possible mechanisms of the observed resistance phenotypes. The tests involved adult mosquitoes collected from three villages across two districts in south-eastern Tanzania and included four insecticide classes. Findings At baseline doses (1×), both species were resistant to the two candidate pyrethroids (permethrin and deltamethrin), but susceptible to the organophosphate (pirimiphos-methyl). Anopheles funestus, but not An. arabiensis was also resistant to the carbamate (bendiocarb). Both species were resistant to DDT in all villages except in one village where An. arabiensis was susceptible. Anopheles funestus showed strong resistance to pyrethroids, surviving the 5× and 10× doses, while An. arabiensis reverted to susceptibility at the 5× dose. Pre-exposure to the synergist, piperonyl butoxide (PBO), enhanced the potency of the pyrethroids against both species and resulted in full susceptibility of An. arabiensis (> 98% mortality). However, for An. funestus from two villages, permethrin-associated mortalities after pre-exposure to PBO only exceeded 90% but not 98%. Conclusions In south-eastern Tanzania, where An. funestus dominates malaria transmission, the species also has much stronger resistance to pyrethroids than its counterpart, An. arabiensis, and can survive more classes of insecticides. The pyrethroid resistance in both species appears to be mostly metabolic and may be partially addressed using synergists, e.g. PBO. These findings may explain the continued persistence and dominance of An. funestus despite widespread use of pyrethroid-treated LLINs, and inform new intervention choices for such settings. In short and medium-term, these may include PBO-based LLINs or improved IRS with compounds to which the vectors are still susceptible.

scholarly journals Evaluation of the efficacy of DDT indoor residual spraying and long-lasting insecticidal nets against insecticide resistant populations of Anopheles arabiensis Patton (Diptera: Culicidae) from Ethiopia using experimental huts

2014 ◽  
Vol 7 (1) ◽  
pp. 131 ◽  
Author(s):  
Abebe Asale ◽  
Yehenew Getachew ◽  
Weriessaw Hailesilassie ◽  
Niko Speybroeck ◽  
Luc Duchateau ◽  
...  
Keyword(s):  
Anopheles Arabiensis ◽  
Indoor Residual Spraying ◽  
Experimental Huts ◽  
Long Lasting Insecticidal Nets
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