Spotters in "Environment and Health: Mosquito control Measures" for CFM & MPH students
The integrated approach of mosquito control:
This is an approach that avoids the excessive use of any one method (e.g insecticides) but tries to combine one or more methods with a view to obtain maximum results with minimum inputs and also to prevent environmental pollution with toxic chemicals & development of insecticide resistance. The various methods of mosquito control are as follows:
1. Anti- Larval Measures:
(a) Environmental Control:
Source reduction: Mainly the elimination of mosquito breeding places by minor engineering methods such as
- Filling- of cesspools & open ditches and arrangement for adequate collection, removal, and disposal of sewage & wastewater.
- Leveling & getting rid of water-holding containers such as discarded tins, empty pots, broken bottles, coconut shells, etc.
- Drainage of breeding places, and
- Water management (e.g intermittent irrigation) & removal of aquatic plants or destruction by herbicides.
- Rendering the water unsuitable for breeding- changing salinity of the water.
(b) Chemical control:
(i) Mineral Oils:
- One of the oldest methods.
- Widely used oils are diesel oil, fuel oil, kerosene, various fractions of crude oil & special oils (e.g mosquito larvicidal oil).
- Mechanism of action: Oils kill larvae & pulse within a short time by spreading over the water surface & forming a thin film that cuts off the air supply.
- It also has specific toxic action on stages of insects.
- The application rate is 40 to 90 liters per hectare once a week.
- Disadvantages: Oils render water unfit for drinking & kill fishes.
(ii) Paris green/ Copper acetoarsenite:
- It is an emerald green, micro-crystalline powder practically insoluble in water.
- A good sample must contain 50% arsenious oxide.
- Mechanism of action: It is a stomach poison. Kills mainly surface feeders (e.g anopheles larvae) but bottom feeders can also be killed if the special granular form is applied.
- Applied as 2% dust prepared by 2 kg of Paris green & 98 kg of diluent (e.g soapstone powder or soaked lime) in a 'rotary mixer' and the resulting mixture is of size 20-25 microns.
- Dusting is done by hand blowers or rotary blowers.
- The recommended dose is 1 kg of actual peris green per hectare of water surface.
- It does not harm fishes, humans, or domestic animals.
(iii) Synthetic insecticides:
- The most effective insecticides are Fenthion, Chlorpyrifos, and Abate.
- Mechanism of action: These organophosphorus compounds hydrolyze quickly in water. Abate (at a concentration of 1.0 ppm) is a very effective larvicide and the least toxic.
- Dosage: Abate 56-112 g/ ha, Malathion 224-672 g/ ha, Fenthion 22-112 g/ ha, Chloropyrifos 11-16 g/ha.
- The organochlorine compounds (e.g DDT, HCH) are not recommended due to their long residual effect, water contamination & an increased risk of developing resistance.
(c) Biological control:
- Gambusia affinis & Lebister reticulatus (Barbados Millions) are fishes that feed readily on mosquito larvae.
- These can be used in burrow pits, sewage oxidation ponds, ornamental ponds, cisterns, and farm ponds.
2. Anti- Adult Measures:
(a) Residual sprays:
- These are most effective against adult mosquitoes. DDT is the insecticide of choice but where DDT resistance is encountered, malathion, propouxur & lindane are recommended.
- Dosage: DDT 1-2 g/ m2 for 6-12 months, Lindane 0.5 g/m2 for 3 months, Malathion 2 g/m2 for 3 months, OMS-33 2 g/m2 for 3 months.
(b) Space sprays:
- These formulations are sprayed into the atmosphere in the form of a mist or fog to kill insects. Common space sprays are
- (i) Pyrethrum extract- the active principle (pyrethrin) is a nerve poison & kills insects instantly on mere contact. Dosage is 1 oz (0.1%) per 1000 C. ft. of space. No residual action.
- (ii) Residual insecticides- Extensively used insecticides used for ULV (ultra-low volume) fogging are malathion and fenitrothion.
(c) Genetic control:
- Control of mosquitoes by genetic methods such as sterile male technique, cytoplasmic incompatibility, chromosomal translocation, sex distortion, gene replacement has been explored well.
- Advantages- These are cheaper, more efficient & no vector resistance.
3. Protection Against Mosquito Bites:
(a) Mosquito net:
- Offers protection during sleep.
- The material should be white to detect mosquitoes.
- The best pattern is a rectangular net.
- The size of openings in the net should not exceed 0.0475 inches in any diameter.
- The number of holes in one square inch is usually 150.
- Screening of buildings with copper & bronze gauze having 16 messes to the inch is recommended.
- The aperture should not be larger than 0.0475 inches.
- Screening of buildings is costly but gives excellent results.
(c) Repellents/ Culicifuges:
- Used mainly for application on the skin.
- Diethyltoluamide (deet) is an outstanding, all-purpose repellent & remain active for 18-20 hours against C. fatigans.
- Other repellents are indalone, dimethyl phthalate, dimethyl garbage, ethyl hexanediol, etc.
- The chief advantage is the short duration of protection.
- Park, K. (2019). Park's textbook of preventive and social medicine. 25th. Jabalpur, India: M/S Banarsidas Bhanot.
- Kadri AM. (2019). IAPSM's Textbook of Community Medicine. 1st. New Delhi, India: Jaypee Brothers Medical Publishers (P) Ltd.
- https://firstname.lastname@example.org/dengue-awareness-for-kids-3dcf6d9e1cb2 photo credit
- https://www.open.edu/openlearncreate/mod/oucontent/view.php?id=92&printable=1 photo credit
- https://www.csrd.bc.ca/services/mosquito-control photo credit
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- https://www.amsoil.com/p/signature-series-max-duty-synthetic-diesel-oil-10w-30-dtt/ photo credit
- https://www.indiamart.com/proddetail/mosquito-larvicide-oil-16038578991.html photo credit
- https://pyrodata.com/chemicals/Paris-Green photo credit
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- https://www.indiamart.com/proddetail/abate-1sg-12943344391.html photo credit
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- https://www.mytools.my/ch-fenthion-50-1l photo credit
- https://www.britannica.com/animal/mosquitofish photo credit
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- https://in.all.biz/lindane-termiticide-g341963 photo credit
- https://www.ebay.com.au/itm/SHARP-SHOOTER-NATURAL-PYRETHRUM-INSECT-SPRAY-250ml-Concentrate-Pyrethrin-Extract-/161822561264 photo credit
- https://barmac.com.au/product/methograin-fenitrothion-insecticide/ photo credit
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- https://www.amazon.in/Popular-Mosquito-Control-Double-Annoying/dp/B082M99F8Z/ref=asc_df_B082M99F8Z/?tag=googleshopdes-21&linkCode=df0&hvadid=397083481436&hvpos=&hvnetw=g&hvrand=12323886802432512749&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9050522&hvtargid=pla-852739377033&psc=1&ext_vrnc=hi photo credit
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- https://www.amazon.in/Odomos-Mosquito-Repellent-Cream-100/dp/B01GTEAD6G photo credit
- https://alchetron.com/DEET photo credit