Saturday, September 8, 2012
A PAPER PRESENTED BY SANITARIAN M.A. SOMOYE AT THEMATIC TRAINING ON PEST MANAGEMENT CONTROL HELD AT FILBON HOTEL, UPPER CHIME AVENUE ENUGU ON 6TH SEPTEMBER, 2012.
Four key factors should be considered when selecting insecticide application equipment:
(1). Will it do the Job?
Each piece of equipment should be moderate to operate. It is good economy to buy the best equipment available. Simplicity of operation and ease of maintenance should be key factors in making a selection.
(2). Is it safe?
Safety should be a prime consideration in all insect control operations. Hazard to the equipment operator, the general public and the environment should be considered.
(3). Is it of good quality?
Poor quality equipment may do great harm to the public relations aspect of insect control programme.
(4). Is it expensive?
Purchase of low quality items may save initially, but the long-range expensive cost should be weighed against such factors as durability of equipment, availability of spare parts and repair facilities and degree of care that can be expected from workers who use it.
The equipments are sub-divided into four categories viz a viz:
(1). Hand Sprayers: which comprise of
(a). The Compressed air sprayers
(b). Aerosol Dispenser
(c). Hand pump atomizer
(d). Pistol sprayer
(e). Knapsack sprayer
(f). Trombone sprayer
(g). Hand duster
(h). Bulb duster
I will discuss on few of these machines especially the most pronounced among them.
THE COMPRESSED AIR SPRAYER:
This is the mainstay of most public health insect control projects. It is used particularly to apply residual sprays for mosquito, fly, and flea control, larvicides for mosquito and fly control, spot treatment for cockroaches, ants, ticks, bugs and many other types of household insects.
The compreseed air sprayer consists of a tank, air pump, outlet pipe, spray hose, valve, ward and nozzle.
THE AEROSOL DISPENSER OR “bug bomb”, is more widely used by the general public than any other type of insecticide applicator.
Insecticide aerosol dispensers are sold in two general types: (a). Small low pressure, disposable “bug bombs” used by the average householder, and (b) larger high-pressure, re-fill able aerosol dispensers used in some public health programme and by pest control operators.
The small low-pressure aerosol bomb consists of a can with a discharge valve and nozzle at the top, and a tube extending from the valve to the bottom of the can.
The insecticide in a concentrated oil solution is mixed with a propellant (usually the nontoxic gas Freon in liquid form) and placed in the can at the time it is assembled.
When the discharge valve is pressed, propellants gas within the can forces the insecticide – propelland mixture through the nozzle and it is atomized into spray.
One of the most common types of bug bombs for flies and mosquitoes contains prethrum, allenthrin, or synthetic pyrethrum for quick knockdown , a synergist such as piperonyl butoxide, and a synthetic insecticide such as methoxychlor or the kill.
THE HAND PUMP ATOMIZER or “flit gun” is a familiar household item. A piston pump forces s stream of air over the tip of the siphon tube. This creates a partial vacuum in the tube. The insecticide is sucked from the tank attached to the pump into the airstreams, which breaks the insecticide into spray.
There are two types of hand pump atomizers.
The intermittent hand sprayer produces a spray of insecticide only while the pump plunger is being pushed forward.
The continuous hand sprayer forces air into the tank to develop and maintain a constant pressure and deliver a continuous spray discharge. Pneumatic paint sprayers operate upon the same basic principle as the “flit gun” but are powered by an electric or gasoline motor. They are sometimes used for space spraying in larger buildings where hand equipment is inadequate.
THE PISTOL SPRAYER is very much like the “gun” used for oiling automobile springs. Pulling the trigger on the gun produces a fine, solid stream of insecticide. It is especially valuable when small amounts of solution or emulsion need to be applied to cracks and crevices in buildings for cockroach, bugs and ant control.
It has been used to apply small amounts of insecticide to collections of water in small containers, such as tin cans, saucers under flowerpots, old tyres or water drums.
They were used extensively on the Aedes aegypti eradication programme and may play a part in many urban mosquito control programs.
THE KNAPSACK SPRAYER is borne on the back of the operator, has shoulder straps so that it can be carried on both shoulders. A simple diaphragm or piston pump and a mechanical agitator are mounted inside the tank and actuated by a lever worked by the operator’s right hand.
The insecticide is under liquid pressure during each stroke of the pump. Knapsack sprayers are used chiefly in treatment of small garden, and to a lesser extent for mosquito larviciding in very swampy areas where it is difficult to pump up a compressed air sprayer.
THE BULB DUSTER is also designed for careful in door work. A 4” rubber bulb is filled with a screw cap containing a dust nozzle. After the bulb is filled with dust, and the cap replaced, hand pressure on the bulb disperses the dust.
2. POWER SPRAYERS
(a). Hydraulic power sprayers
(b). Boat mounted power duster
Hydraulic Power Sprayers, originally designed for use on field crops, orchard and shade trees and live stock, are frequently used by public health workers to apply insecticides as residual sprays to control adult mosquitoes and flies as laravicides to control mosquito and fly larva, and as area treatments to control fleas, ticks and chiggers. The spray liquid is pressurized by means of a power – driven hydraulic pump with suitable regulators provided to maintain the desired pressure.
BOAT MOUNTED POWER DUSTER is used in some mosquito control districts. These machines have several advantages: they can be used from the open water side of mosquito – breeding places, they have a wide effective swath over water with only floating or low surface vegetatio., and they do not require access roads in difficult, swampy terrain.
MIST AND FOG APPLICATORS
Mist and fog applications are used for space spraying with contact insecticides. Mist and fog machines control insects by he same principle as that utilized by hand sprayers and aerosol dispensers – contact killing.
Mists- are composed of droplets 50 – 100 microns in diameter, particles of sufficient size to settle 4o the earth fairly rapidly, but remain a 200 – 300 foot swath with only a light wind to promote distribution. This settling will occur despite the fact that there may be thermal air currents rising from the heated earth during the daytime.
Fogs - Are composed of much finer droplets, from 0.1 to 50 microns in diameter, that remain suspended for a long period of time, settling only in relatively still air. These particles are likely to rise in the daytime and produce little or no kill of insects during this period.
The above considerations indicate that the moist blowers are especially suitable for daytime operations such as fly control and that fog applicators are most effective during the evening, night and early morning hours, particularly for adult mosquito control.
The chief advantages of mist and fog applicators are (1) Economy of operation due to their low manpower requirements. (2) Ability to apply small amount of concentrated materials to a large area and (3) Large portions of a city may be treated in a short period of time during disasters and in period of high insect abundance.
The chief disadvantage in their use for treating urban are as is the fact cars and windows may be spotted by the insecticide and shrubbery may be burned by the oil if machines are not properly operated.
OTHER APPLICATION EQUIPMENT
Pouring of chemicals may be of value under certain conditions. Measured amounts of insecticide may be poured into fast – flowing streams for black fly control. A sprinkler can is useful for mosquito larviciding of catch basins.
DRAGGING bags of chemical through water, or laying the bags in moving water may serve to control black fly larvae or other water – dwelling forms. Calculations should be made to assure adequate control without damage to fish or other wild life, and also not pollute human water supplies.
DRIP CANS are superior to pouring or dragging for water treatment because insecticide dosage can be controlled more exactly. They are better to use in moving than in still water.
PAINT BRUSHES are very effective for applying controlled amounts of insecticides to areas where insects hide and run.
They are especially suited for controlling household insects such as cockroaches and termites. There is less change of damaging materials such as synthetic floor tiles or painted woodwork when applying insecticide with a paintbrush than with a sprayer.
POISON BAITS are used occasionally by public health workers. Chicken watering fountains containing sugar water and an organic phosphorus compound such as dichlovors are used to control flies in chicken houses. Shallow trays covered with hardware cloth containing granular fly baits may be placed in areas with high fly populations such as dairy barns.
GELATINOUS CAPSULES (“TOSSITS” containing mosquito larvicide are useful for immediate treatment of small bodies of water. Inspectors can easily use them, saving the expense of sending out a control crew.
PRESSURE INJECTORS to inject phosphide into egg, very useful in baiting snakes.
RESIN STRIPS containing dich (or DDVP) are used to control insects in buildings, such as cockroaches under sinks, silver fish, clothes moths and carpet beetles in closets. These strips are used at a rate of one strip per 1000 cubic feet. They are also used to control mosquito larvae in catch basins.
They are effective for 3 to 4 months dripping cotton cord in organic phosphorus insecticides such as parathion, diazinon, or ronnel. When installed in diary barns, loading docks, and similar situations at a rate of 30 linear feet per 100 square feet of floor space, fly cords often provide effective fly control for 3 months or longer.
CARE AND MAINTENANCE OF INSECTICIDAL EQUIPMENT
Manufacturer of insecticidal equipment usually provide information on the care and maintenance of each type of applicator. Follow these instructions for lubrication, operation, and maintenance.
All applicator equipment requires diligence if it is to be kept operating properly. Many complaints about equipment malfunction are traceable to improper maintenance.
HAND SPRAYERS are generally a greater maintenance problem than dusters. Several basic rules should be followed in the care of a sprayer.
1. Handle it carefully
2. Keep it clean
3. Strain formulations through cheesecloth to keep particles out of it.
4. Rinse it out thoroughly after every use
5. Every evening after use rinse it and then pump 1/3 gallon of clean water through it.
6. Do not let water freeze in it.
7. Every 3 months:
a. Disassemble it completely.
b. Put small metal parts into kerosene allow to set, then clean with a small bottlebrush.
c. Soak nozzles, wands, and tank with trisodium phosphate solution, then clean with a scrubbing brush, then rinse thoroughly.
d. Replace worn gaskets, broken parts etc.
e. Reassemble it.
f. Pump 2 changes of water (with 1 cup of vinegar per gallon of water) through it.
g. Pump clean water through it.
h. Oil certain parts, as in the spray gun.
POWER EQUIPMENT should be covered when not in use.
Have regular preventive maintenance on all motors.
Replace damaged parts immediately.
Allow only experienced personnel to operate power equipment.
TYPES OF INSECTICIDES
An insecticide is a substance used for killing insects and their close relatives, ticks, mites and spiders. A perfect insecticide, would be: (1) highly toxic to harmful insects and related arthropods; (2) harmless to man and to beneficial animals, insects and plants; (3) attractive to insects and not unpleasant to humans; (4) inexpensive, easy to produce and readily available; (5) Chemically stable for residual applications, (6) Unstable for use in aerial applications that will not grossly contaminate the environment, killing insects rapidly and breaking down subsequently into harmless compounds, (7) nonflammable, (8) no corrosive (9) no staining and (10) easily prepared into any desired formulation.
Insecticides are classified traditionally according to the way they kill insects: as
(1). STOMACH POISONS must be swallowed to cause death. Poison baits are stomach poisons mixed with materials such as sugar to attract insects.
(2). CONTACT INSECTICIDES - Penetrate the body wall or the tarsi of arthropods. They include residual sprays applied to walls and ceilings of building to kill insects that rest on the treated surface, aerosols and space sprays that adhere to and kill flying insects, and larvicide’s that penetrate the tracheae and body walls to kill insect larvae.
FUMIGANTS - are volatile chemicals whose vapors enter insects bodies through the breathing pores (spiraclås) and through body surfaces.
Methyl bromide, for example, is a nonflammable, deeply penetrating fumigant used to kill insects in fabrics, foods and other stored products.
DESSICANTS – are sorptive dusts, which scratch or abrade the body wall, or absorb its fatty, or waxy, protective outer coating, causing the insect to loose body fluids and die by dehydration.
The insecticides used to kill arthropods of public health importance may be divided conveniently into six groups viz a viz:
1. The minerals – fuel oil, kerosene, sulfur and borax – contain some of the oldest insecticides still widely used.
2. The botanicals – pyrethrum and rotenone which were in use before 1900 still are favorites because they pose no problem of toxic residues. Synthetic pyrethroids play an important role because they can be manufactured and standardized in quantity.
3. The Chlorimated hydrocarbons - such as D.D.T, lindane, and chlordane, were the most widely used insecticides from the 1940’s through the 1960’s. however, problems of resistance and environmental contamination arose and the use of this group of toxicants is now limited.
4. The Organophosphates – such as malathion and diazinon, have generally replaced the chlorinated hydrocarbons because they control resistant insects they are biodegradable, and do not contaminate the environment.
5. The Carbamates – such as carbaryl and propoxur are a relatively new class of contact insecticides, which may supplement the organophosphates.
6. The Fumigants – include well known materials such as naphthalene and Para dichlorobenzene used by the general public, and other very toxic materials such as methyl bromide or hydrogen cyanide which are so dangerous that they should be used only by specially trained personnel.