As a pest the rats are considered quite harmful for the mankind in various respects. So a proper measure is necessary to take for the rat control. A control operation reducing the rat population to 5—10% of its original level considered to be a fair success. A single method may not achieve this level of rat control. It is therefore necessary that in an operation, more than one control methods should used in an integrated manner.
There are many ways by which we can control the rats, such as hunting, trapping, poisoning by baiting and by fumigation, biological control etc.
Hunting as a process of rat control
Trained peoples dug the rat-burrows, so that the rats come out from the burro then the trained dogs and cats killed them. Sometimes the rat-burrows are filled with water; then the rats are coming outside the burrow and killed them by mechanical process.
Trapping process for rat control
This is one of the oldest methods of rat control which is reported from the early civilization. A variety of traps can be used for capturing rats. Though only trapping cannot control a rat population in large areas. It can be used as a follow-up action as chemical control operation. Common snap traps and trap boxes are used for lesser bandicoots. The traps are to be set in the passage through which the rats move on.
Poisoning Bait by Rodenticides
The rodenticides are chemicals that kill the rats. Most of the rodenticides are in powder form. Rodenticides are usually classified as two types, such as acute poisoning and chronic poisoning. These two types of classification are based upon mode of their action rather than their chemical structure or physiological action.
Rat control by Acute Poisoning
Chemicals that are acting quickly on rodent pests and kill the rats with single dose are known as acute poisoning. A single dose of poison when administered with food kills the rat, such as: Zinc phosphide, Barium carbonate, Strychnine, Red squill etc.
Zinc phosphide—This chemical is probably the most common single dose rodenticide which is used in many countries. This chemical is a grey black powder with distinct garlic-like odor.
Preparation of poison bait: One part of Zinc phosphide is to be mixed with 40 parts of most preferred food especially wheat flour and 3 part with molasses, and then needed amount of water is to be added. After mixing, small pellets are prepared and these pellets will be more attractive to rats along with additives like vegetable oils, sugar and salt. These baits are to be placed just outside of the burrow or on the path of movement of rats.
Poison effect on pests: Zinc phosphide baits are quite stable in air or non-ac media. But when the pests ingest the bait, the acid of the stomach of the pest react with Zinc phosphide of the bait, as a result phosphine gas is released. This gas produces necrotic lesions and also damages the kidneys. As a result, there is death of the rat from heart failure. Generally, death may occur within two hours of intake.
(i) The dead rats should be immediately removed from field after death.
(ii) Zinc phosphide is equally toxic to man, domestic animals and even more toxic to poultry birds. Therefore, highest care should be taken in preparing baits from this toxic chemical.
(iii) If 1 % tartar emetic in zinc phosphide baits is added then it increases safety to ion-target animals and man ; but the acceptability of bait to the rat will be reduced and hence affect in rat control.
Rat control by chronic poisoning
Rodenticides which are used repeatedly in subsequent days for killing the rat pests ire known as chronic poisons, i.e., multiple doses of rodenticides are administered that ire poisoning slowly on rat-pests. Various chronic rodenticides have different chemical structures but their physiological action remains the same, i.e., anti-coagulants. This type of rodenticides interferes with the blood clotting mechanism which results in fatal bleedings. These chemicals have cumulative effect and must be ingested daily for several days to reduce coagulating property of the blood and rat dies of bleeding that occurs both externally and internally.
These chemicals are to be used repeatedly. When the chronic rodenticides are administered with food or water, the rat-pests may lot accept it. For this reason, it is advocated that these rodenticides may be spread on the path of the rat-pests. While cleaning their body and paws, the rat-pests engulf some »f these rodenticides; as a result, the effects of the chemicals are produced on the rat-bst.
Examples of Chronic rodenticide for rat control: Warfarin, Fumarin, Diphacinone and Coumatetralyl.
Apart the above process rat control may be done by fumigation. Chemicals which evolve poison gases to kill the pests are known s fumigants and the process of using is known as fumigation. Fumigants or poison gases are now widely been used against rat-pest.
Fumigants are not involved in the use of bait material and the danger to other grazing animals is nil. Lethal concentration of fumigants is built up quickly in the burrows and persisted for a considerable duration. Fumigation should always be carried out after zinc phosphide treatment. In the morning or afternoon when the rats remain inside the burrows, fumigants are administered in the rat holes.
Name of some rat control fumigants: Hydrocyanide , Aluminium phosphide, Methyl romide and Ethylene bromide.
Biological process of rat control
Biological control is the suppression of a pest population either by increasing predation, by using anti-fertility agents or by pathogens. Biological control is an effective measure for controlling vertebrate pests and can bring down their population below economic injury level.
Predation is another rat control process created by nature. Kites, Owls and Snakes are usually natural predators of rats in the field. Be employing predators as means of biological control, one must analyses basic predator prey interactions.
Rat control by antifertility agents
It has been observed that a number of Chemo-sterilants are producing sterility in the rats. Use of furadantin and colchicine sterilized male and female Bandicota bengale respectively. Chemosterilant like furdantin when administered orally for seven days to male bandicoot, causes permanent sterility. Antifertility agents can only maintain the population at a low level after some other control operation.