Today the common people and the farmers in particular have realized that the rat is a pest and the damages inflicted by them to their food and fodder crops, store materials and other valued commodities are of sizable nature. Rats have always been known to us as a mammalian pest, ever since the primitive man became an agriculturist and started having granaries. So it is very essential to have some idea about the rat problem. The role of rats also in epidemiology of plague was highlighted in the reports of the Indian Plague Commission and in the Indian Journal of Medical Research.
The field rat or rural rat is commonly known as Lesser Bandicoota which belongs to the class Mammal, order Rodentia. The scientific name of which is Bandicotabengalensis. This type of rat is now available not only in rural areas but also in urban areas. Now it has become the most common rodent pest which is treated as the major mammalian pest of agricultural crops and stored food-grains. In addition to these damages, they cause railway train derailments by gnawing the 'sleepers', fires by biting electric wires, breaches in earthen dams and threaten soil conservation work by their burrowing habit. So the rat problem is becoming serious and not a matter of overlook.
Is the rat a pest?
The definition of a pest can be very subjective, varying according to many criteria iut in the widest sense any organism, plant or animal causing harm or damage to man, is animals, his crops or possessions, even if ji:st causing annoyance, qualifies for the 2rm pest. Various insects, rats etc., are the examples of pest.
HABIT AND HABITAT of RatLesser bandicoots dig the soil with their powerful claws ; hence they are regardi as good burro wers. They dig the soft soil of bund of the cultivating field and its burro extends to a depth of more than one metre and the burrow ramifies laterally upto 9 12 metres. There is a central chamber in a burrow from which lateral extensions a made. The burrow has several openings and all these openings are kept lightly clos< so that they can come out easily. Bandicoots store food inside the burrow. Thus the; burrows are giving extra protect'onto the bandicoots as well as these burrows a acting as store house of food. They are fossorialand are nocturnal in habit. So after sunset they are coming out from the burrow and actively collect their food from the field. Lesser bandicoots generally prefer wheat and paddy. Each Lesser bandicoo consumes nearly 11.5 gm. of grain per day and destroys the grains many times daily. Lesser bandicoots are remained in the burrows during the day time. When these rat are seen during the day time, it indicates that the population of rats has increased. They are also good swimmers as well as climbers. They are aggressive in nature. So, it creates the rat problem in various ways.
FEEDING HABIT of ratRats are known for their versatile feeding habit. Their versatility depends upon the change of seasons which affects the availability of natural food to the rats. The selection of food depends on its nutritional richness indicating a preference to high calorie food. Bandicotbengalensis prefers rice wheat, maize, sorghum, milk etc., as food. This specie of rat problem creators prefers small sized food rather than whole grains.
BREEDING HABIT of Rats
Adult bandicoots breed all the year round but exhibit peak reproductive activity during monsoon and winter. This activity is at its minimum during summer month when climatic conditions are not conducive and the food is scarce. Female Bandicoot produces 2 to 14 offsprings which are sexually mature by 3 to 5 months. Life span of this species is about 200 days.
CHANGING HABITATS AND REPLACEMENT OF SPECIES
A number of field rats change their habitats, and shift from grasslands to crop fields, from crop fields to urban environment, and from peri-domestic surroundings back to the fields. This knowledge on the species diversity and occurrence of multiple rodent species in a single habitat is extremely important for their proper rat problem management.
Nature of Damage done by Rats
Rats are damaging to human beings in two ways, such as damage the crops in field and stored foods as well as damage the human health by carrying germs. These are described under
Rat Problem at Agricultural FieldRat problem is one of the major pest problems of agricultural crops. The rats damage the crops from seedling stage to ripening stage of the crops. Bandicotabengalensiscuts the entire paddy earheads and eats only a few grains. A fair amount of losses, caused by the bandicoot, occurs due to their hoarding propensity. The mean daily amount of food removed by bandicoot is 67 g, compared to the mean daily consumption of 13 g by this species. Hence, each bandicoot hoarded about 54 g daily in the burrow. It is confirmed that bandicoot rats may store 5 times in their burrows the amount of food they eat. It is reported that the hoarding of paddy is to the tune of 10% of the total yield per hectare.
Rat problem at stored food grains
Damages to stored food-grains by rats vary to a great extent. It is estimated that overall losses of grains from rats in India at about 25% to 30% in storage. In a \ 00m2 space in godowns at Howrah, the loss of grains due to rats was reported to be 4,200 kg.
Rat problem for human health
Rats carry deadly germs and spread diseases to man. Some such diseases are mentioned below.
(a) Plague : This fatal disease is caused by bacteria known as Pasteurellapestis. This bacteria is transferred from rodent to rodent by rat fleas (Scnopeyllacheopis). The man is infected through the infected rat fleas.
(b) Rat-bite fever : When a persion is bitten by rat, the germs which are present in the teeth and gum of rat are injected in the body of human being. As a result, there is fever to man.
So the rat problem is quite serious to the mankind and the rat control is quite necessary. Now click for ►