Larvicidal Activity of Mousticide RH and WP Against Anopheles sp.


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Larvicidal Activity of Mousticide RH and WP Against Anopheles sp.

  1. 1. Jabatan Sains Bioperubatan Departmentof Biomedical Science Larvicidal Activity ofMousticideTM Rice Husk andWettable Powder Formulation Against Anopheles Sinensis Testing Performed by: Saiful Azlan Nordin Noor Shareena Aisha bt Abdul Khalid Aimi Syamima bt Abdul Manap Murni Binti Soed Under the Supervision of: Professor Dr. Hidayatulfathi Othman University Kebangsaan Malaysia
  2. 2. Jabatan Sains Bioperubatan Departmentof Biomedical ScienceINTRODUCTION Trypsin-modulating oostatic factor (TMOF), a mosquito decapeptide,terminates trypsin biosynthesis in the mosquito gut. The hormone is secreted fromthe ovary, starting 18·h after the blood meal, circulates in the hemolymph, binds to agut receptor and stops trypsin biosynthesis by exerting a translational control ontrypsin mRNA [6]. Feeding of TMOF mixed with the blood meal to female Ae. aegyptistopped trypsin biosynthesis and inhibited egg development in the ovaries [7].Research conducted using TMOF in combination with Bacillus thuringiensisisraeliensis (Bti) against Ae. aegypti 1st instar larvae in the laboratory was found toimprove the activity of these product by giving quick mortality within 1 hour treatmentwith prolonged residual effect (no larvae survived) against all larval stages up to fourweeks following treatment [8]. TMOF-Bti is the combination of TMOF and Bacillusthuringiensis israeliensis which showed an increased of efficacy in killing mosquitolarvae. TMOF-Bti developed into a finished product, Mousticide™, with formulations,a granular formula on rice husk and a wettable powder. Various studies have beenconducted to prove the efficacy of Mousticide™ both in the laboratory and in the fieldagainst Aedes aegypti, as an initiative to move forward in the prevention ofmosquito-vectored diseases. Testing of the larvicidal effects of Mousticide™ onAnopheles sinensis was carried out to combat another vector borne disease -Malaria. Malaria is common in sub-Saharan African countries, and WHO states thatnearly 90% of the deaths in Africa are caused by Malaria. With this new technology,we hope that the number of victims of malaria can be reduced.
  3. 3. Jabatan Sains Bioperubatan Departmentof Biomedical ScienceOBJECTIVE 1. To assess the efficacy of Mousticide™ in wettable powder formulation and rice husk formulation against third instar larvae of Anopheles sinensis. 2. To compare the larvicidal activity between Mousticide™ n wettable powder formulation and rice husk formulation to Abate™.PROCEDUREThe bioassays for Mousticide™rice husk and wettable powder against Anopheles sp.were conducted using WHO standard protocols (WHO, 1981). Twenty (20) secondinstar larvae are introduced into a fresh paper cup containing 200 ml distilled waterand the different larvicides added at the desired concentrations. No larvicideadditions were made to the control cups. A minimum of three replicates are madefor each formulation. The concentration of rice husk and wettable powder used inthis test was 5 mg/200 ml and 1 mg/200 ml respectively. Abate™, a “gold standard”positive control chemical larvicide was assayed in parallel using the recommendedWHO dose of 0.012mg/L. As a control, 200 ml of distilled water only was used in thisstudy. Twenty (20) second instar larvae of Anopheles sp. were transferred from thebreeding tray into the all the paper cups. Data were recorded at post one hour, 24,48 and 72 hours to assess the mortality rate of the larvae
  4. 4. Jabatan Sains Bioperubatan Departmentof Biomedical ScienceRESULTS AND DISCUSION Chart 1 shows the comparison of mean larval mortality percentages usingMousticide™ wettable powder formulation and rice husk formulation, to Abate™.From the chart we can see that in 1 hour, mean larval mortality was showed byMousticide™ in rice husk formulation was 15%. After 24 hours, the mean larvalmortality increased to 100%. Mousticide™ in wettable powder formulation did show any larval mortality in 1hour after the application. However, after 24 hours of application, the larval mortalityrecorded were 96.7% and increase to 100% after 72 hours. Surprisingly, Abate™, a neurotoxic chemical pesticide commonly used as amosquito larvicide showed only limited larvicidal activity at 24 hours (3.3% whichgradually increased with time). Abate™ would be expected to rapidly causemortality of the mosquito larvae based on its neurotoxic mechanism. The prolongedtime required for Abate™ efficacy suggests that the mosquito larvae are able toforestall its toxic effect (resistance). The fact that resistance is present in alaboratory-reared mosquito population is disturbing as laboratory-reared strains arecommonly used to assess biological activity of test and commercial larvicidalcompounds. In this study, Mousticide™ was compared to Abate™, a gold standard chemicallarvicide used in controlling vector borne diseases caused by mosquitoes worldwide.Compared to Abate™, it was demonstrated that Mousticide™ can effectively controlAnopheles sinensis, a vector for malaria. Mousticide™ was able to provide 100%larval mortality of Anopheles sinensis in 24 hours while Abate™ only showed 3.33%larval mortality. In our previous study, Mousticide™ gave 100% mortality againstAedes aegypti in 24 hours after application, both in the laboratory and in the field. Afield trial in a dengue endemic site at Gombak, Malaysia, demonstrated that a single
  5. 5. Jabatan Sains Bioperubatan Departmentof Biomedical Scienceapplication of Mousticide™ rice husk was able to control dengue for 5 months. Theresults from the present study suggest that Mousticide™ can also be an effectiveagent to control Malaria, a deadly disease vectored by Anopheles sp. This studydemonstrated that Mousticide™ is very effective against the larvae of Anophelessinensis and can be an important tool to fight malaria. From the results, we concludethat both Mousticide™ in wettable powder formulation and rice husk formulation arevery effective against the third instar larvae of Anopheles sinensis compared toAbate™.The results of Mousticide™ on the larvae of Anopheles sp demonstrates that it is avery effective larvicide against various species of mosquito larvae which areimportant disease vectors.
  6. 6. Jabatan Sains Bioperubatan Departmentof Biomedical ScienceChart 1 : Mean Larval Mortality Percentages Against MousticideTM and AbateTMCONCLUSIONThe result from this test allows us to conclude that Mousticide™ in rice husk andwettable powder formulation are very effective against larvae of Anopheles sinensis.ACKNOWLEDGEMENTWe would like to acknowledge Entogenex Industries Sdn. Bhd. for providing theresearch grant for this study and Vector Control Research Unit, Universiti SainsMalaysia for providing Anopheles sinensis larvae and facilities to do this study
  7. 7. Jabatan Sains Bioperubatan Departmentof Biomedical Science