Residual and Fumigant Effects of Bendiocarb WP80 in a Malarious Areas in Borderline of Iran and Pakistan

Mohammad Reza Abai Tehran University of Medical Sciences Hassan Vatandoost (  hvatandoost1@yahoo.com ) Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Hossein Dorzadeh Tehran University of Medical Sciences Mansoreh Shayeghi Tehran University of Medical Sciences Ahmad Ali Hana -bojd Tehran University of Medical Sciences Ahmad Raeisi Tehran University of Medical Sciences


Background
Malaria is one of the most important communicable diseases transmitted by anopheline mosquitoes (Diptera: Culicidae) to humans. More than 80% of malaria cases in Iran are reported from three provinces in southern and southeastern areas of the country. The most routes of malaria cases are immigration from Afghanistan and Pakistan to southern and southeastern areas of the country (WHO, 2017) (1). From 1952 by using DDT, malaria vector control was started and then replaced by other insecticides. The chemical control of vectors now is restricted to endemic malarious areas of south-eastern part of the country with deltamethrin and bendiocarb as rotation strategy as well as ong lasting permethrin impregnated nets (Olyset) for personal protection. For larviciding the Bacillus thuringiensis is applying in the breeding places.

Materials And Methods
Study area; Malarious and Leishmaniais area of Sistan and Baluchistan province, southern Iran was selected for experiments ( Fig. 1) .
2.2 Insecticide sued: Bendicocarb WP80 were used (Fig. 2) Composition of mosquitoes in the region The fauna of Anopheles mosquito in the study area are Anopheles culicifacies, An. stephensi, An. uviatilis, An.dthali, An.miticolor, An.turkudi (Fig. 3) Strain used for bioassay test the adult females of Anophels stephensi collectd from eld were used for bioassay tests Chossing different surfaces for bioassay tests. Diffferent surfaces including plaster, mud, wood which are the structures of the houses in the region were selected and sprayed with bendiocarb WP80 according the standar method which is described by World Health Organization. Indoor residual spraying of insecticides is normally done using portable compression sprayers (Hudson). Before starting a spray operation, the equipment must be checked. Faulty sprayers may result in poor control or over-treatment.
The sprayer visually were examined to ensure that all parts are present, assembled correctly and in good working order. Correct type of nozzle should be tted and is not damaged or worn. The nozzle tip should be of hardened stainless steel, ceramic or equivalent material to withstand erosion of the nozzle where water contains sand particles (Fig. 4).

Method of bioassay tests
Bioassay aspirator tubes especially narrow with glass arm were used. The conical exposure chamber made of transparent polished plastic and then adhesive sponge plastic for lining rim of exposure chamber (Fig. 5).

Method of fumigant effects
3 cylindrical cages (14 × 20 cm) were employed. The number of mosquitoes per cage was 30-35, female, unfed, 2-3 days old. They were exposed 60 min in conical chamber and then the mortality was calculated after 24-hours (Fig. 6).

Results
Result of contact bioassay Bendicocarb WP80. The results of bioassay test on different surfaces are illustrated in Figs. 7-10.

Residual effect of Bendiocarb at 400 mg/m 2 in plaster surfaces
In plaster surface a total of 696 mosquitoes were used. The standard mortality which is 70% could be obtained 60 days after application. After 30 day of application, a total mortality of 89.59 ± 3.55 were observed.

Residual effect of Bendiocarb at 400 mg/m 2 in Mud surfaces
In mud surface a total of 292 mosquitoes were used. The standard mortality which is 70% could be obtained 60 days after application .After 75 days of application 100% mortality were observed Residual effect of Bendiocarb at 400 mg/m 2 in Wood surfaces In wood surface a total of 212 mosquitoes were used. The standard mortality which is 70% could be obtained 60 days after application. After 75 days 100% mortality were observed.
Fumigant effect Bendicocarb at 400 mg/m 2 The fumigant effect of Bendicarb is presented in Fig. 11. In fumigant test a total of 929 mosquitoes were used and 50% mortality were obtained after 30 days.

Discussion
The persistency of bendiocarb WP80 at 400 a.i. mg/m2 was one month. The fumigation effect of bendiocarb WP80 was showed 50-69.70% mortalities during one-month persistency. The residues of bendiocarb WP80 on Whatman papers was estimated 1.1 mg/m2 during 120-150 days evaluation Bioassay tests revealed that persistence of insecticide against An. culicifacies mortality was observed for about 10, 8, and 10 weeks on mud, cement, and brick wall surfaces, respectively (4). An experimental hut trial comparing the effectiveness of bendiocarb sprayed on ve substrates (cement, wood, tin, mud, and vegetative materials) was carried out against Anopheles species in two study sites located in the eastern foothills of Madagascar. No signi cant difference was detected in either exophily or blood-feeding rates between treated and untreated huts. The mortality rate was signi cantly greater in treated huts compared to untreated huts. E cacy up to 80% was found for 5 months post treatment (5). Residual e cacy of the insecticides used for PMI/USAID-supported IRS campaigns was measured in Benin, Burkina Faso, Ethiopia, Ghana, Kenya, Liberia, Madagascar, Malawi, Mali, Mozambique, Nigeria, Rwanda, Senegal, Tanzania, Uganda, Zambia and Zimbabwe. The WHO cone bioassay tests were used to assess the mortality rate of mosquitoes exposed to insecticide-treated mud, wood, cement, and other commonly used housing materials. The residual e cacy of bendiocarb ranged from 2 weeks to 7 months (average = 2.8 months) and failed to achieve proposed minimum e cacy on 14 occasions. Lastly, long-lasting pirimiphos-methyl e cacy ranged from 2 months to 9 months (average = 5.3 months), but reported 13 incidents of underperformance (6) .In a study the effect of temperature on the standard insecticide resistance test, using resistant or susceptible strains of two major malaria vectors (An. arabiensis and An. funestus) were performed. Toxicity of the pyrethroid, deltamethrin and the carbamate bendiocarb was assessed at different temperatures (18, 25 or 30º). Results show that temperature impacts toxicity of both insecticides, but in a different way. Bendiocarb lost e cacy at higher temperatures for both species, regardless if they were resistant or susceptible (7).

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The results of study revealed that bendicocarb as recommended dosage as residual spraying may be control the malaria vector during the transmission season. If here is resistant to pyrehtroids in malaria vector, then bendiocrab could be used as rotation measure. There are several works in the country on different aspects of malaria including insecticide resistance monitoring, using bednets and long lasting impregnated nets ,vector control (8)(9)(10)(11)(12)(13)(14)(15)(16). Monitoring and mapping of insecticide resistance to WHO recommended adulticide is recommended periodically.

Declarations
Ethics approval and consent to participate:Not applicable Consent for publication: Applicabe Competing interests: The authors declare there is no con ict of Interest.
Funding: Tehran University of Medical Sciences provided grant to do the research. The code number is 92-02-27-23550.
Authors' contributions: All authors are involved