Rodents and their management

• Rats are the most notorious pests of different commodities in the fields as well as when these commodities are stored.

• A number of crops like vegetables, oilseeds, cereals etc., at early stage in field, are eaten and contaminated by rats.

• They are also seen playing a vital role in transmission of public health diseases viz., plague, leptospirosis etc. to humans and other animals.

Rodents and their management

Introduction

Some common species of rats:

Basis of their shelter, rats can broadly be divided in to two groups.A. House rats B. Field rats

A. House rats: Following species are main in this group1. Rattus rattus (House rat)2. Mus musculus (House mouse)

B. Field rats: This group comprises following species of rats 1. Bandicota bengalensis (Lesser bandicoot)2. Tetera omdoca (Indian gerbil)3. Nesokia indica (Short tail mole rat)4. Rattus meltoda (Soft fur field rat)5. Mus booduga (Field mouse)

C. Common species of rats found in both field as well as houses1. Rattus norgegicus (Norvey rat)2. Rattus rattus rufescens3. Bandicota indica (Large bandicoots)

Rodents are like breeding machines ………..

Biology

Life span : 1-3 years

Age at puberty : 6-16 weeks

Oestrous cycle : 3-7 days

Duration of heat : 9-24 hours

Mating habit : Promiscuous

Gestation period : 18-30 days

Breeding season : Round the year

Litter size : 1-22

Post - partum heat : 4-96 hours

Breeding potential/pair/year

: 800-1500

Habits

Sources:Technical bulletin on “Rodent management in Arid Zone” Published by Project Coordinator, AICNP on Rodent Management, Jodhpur

•Mostly nocturnal •Can not vomit•Omnivorous and cannibalistic •Neophobic / Neophilic

The House Rat, Rattus rattus

The House Mouse, Mus musculus

Indian field mouse, Mus booduga The Indian Gerbil, Tatera indica

Soft furred field rat, Millardia meltada

Rodent species

Sources:Technical bulletin on “Rodent management in Arid Zone” Published by Project Coordinator, AICNP on Rodent Management, Jodhpur

• Prolonged drought/dry spell followed by heavy rains

• Failure of monsoon in preceding year

• Flash floods leading to unusual increase in the subsequent carrying capacity of the

environment and sporadic flowering of melocanan propensity of the rodent pests die

to increased carrying capacity

Rodent’s outbreaks resulted in famine like conditions due to

Crop Extent of loss (%) Rodent pest species Habitat/distribution of species

Rice 1.1- 44.5 Bandicota bengalensisMillardia meltadaMus boodugaRattus nitidusRattus rattus brunneusculus

Irrigated fieldsSemi irrigated fieldsIrrigated fieldsJhum fields in north eastJhum fields in Mizoram

Wheat 2.7 - 21.3 Bandicota bengalensisMillardia meltadaTatera indicaMeriones hurrianae

Irrigated fieldsIrrigated dry fieldsRainfed fieldsDesert soils in Indian desert

Groundnut 2.9 - 7.3 Tatera indicaMillardia meltadaBandicota bengalensis

Irrigated dry fieldsIrrigated dry fieldsIrrigated fields

Coconut 4.5 - 55 Rattus rattus Throughout India

Cocoa 30-50 Rattus rattus wroughtoniFunambulus palmarumFunambulus tristriatus

South IndiaAndhra Pradesh & TamilnaduKerala and Karnataka

Storage 2.5 Rattus rattusMus musculus

Residential premises and farm level storage

Extent crop loss due to rodent pests, pests species and their distribution in India

Rodent management

1. It has been noticed that the rats restrict their activity within 5-10 meter radius around the burrow.

2. Methods of killing rats are effective only when carried out on a large scale, covering large contiguous areas and are repeated time and again. The aim should be to kill more than 90 per cent of the population otherwise they breed so fast that population reaches the same level within a few months.

3. The migration of rats from one place to other is also important to born in mind while planning to mange rat population. The cooperative efforts made by the farmers, grain handlers and administrators will not provide protection unless as a scheduled programming is done with a system approach. It should thus occupy a key position in operational plan for agricultural production and protection.

Rat management is a very complicated problem. It needs a through approach to minimize the rat menace. Before planning we should know some facts about rats

Some methods are given below to deal with the problem.

It checks the movements of house rats and mice into or outside the house, farm, storage and other building. For this purpose, all smallest and larger openings are completely, sealed and closed. The edges of all doors, windows and other inlets and outlets are covered with metal sheets. Concrete walls and shallow foundations should be constructed. Devices should be installed to keep the door closed. Food grains and other materials may be kept in metallic container or boxes.

Rat proofing

The heaps of trash, garbage and sweepings should not be allowed for a longer period near the houses and godowns. The food materials should not be kept in the open containers. It is very essential to launch clean up programme in the rat infested areas so that rats may not harbour themselves in the want of food and shelter. In this way rat population can be minimized.

Cleanliness:

The traps are employed in the places where rat infestation is small and chemical control like poison baiting, fumigation is impracticable. There are many types of traps viz., cage traps, wooden traps, wire traps, snap traps and bamboo traps which are commonly used in the country. Now the traps manufactured at Jalgaon, Maharastra by galvanized wires based on the designs recommended by Hoffkins Institute Bombay viz., Bandicoot trap, double mouth sure success trap and union trap etc., are more efficient, for trapping of rats. The traps should be cleaned by water after each installation and fresh and attractive bait materials like breads, fruits etc. should be used.

Traps

Sources:Technical bulletin on “Rodent management in Arid Zone” Published by Project Coordinator, AICNP on Rodent Management, Jodhpur

Contd…..

This group is generally used to kill the rats with various rodenticides. The rodenticides can be divided in to two groups

1. Single dose poison: This group comprises acute poison which kill the rats by single exposure to poison baits. Ex. zinc phosphide

2. Multiple dose poison: These chemicals are effective only after the multiple feeding of poison baits by rats, because their cumulative effects lead the death of animals. Ex. warfarin, ratanfin, rodafrin etc.

Some newer rodenticides: Vacor (RH-782), silmurin and bromadiolone are of very recent origin. They are found to be most effective against rats. Their single dose of poison baits kills the rats. No bait shyness reflex build up by the use of these poisons. They are safer to human beings and domestic animals.

Poison baiting and fumigants

Preparation of poison bait with zinc phosphide

For 1 kg of Pre-bait : 980 g cereal + 20 g oil mix thoroughly with bare hands

For 1 kg poison bait : 960 g cereal + 20 g oil + 20-25 g Zn3P2 powder mixed with the help of any stick

Pre-baiting is required prior to Zn3P2 poison baiting

Do not prepare the poison bait with bare hands. Use gloves and stick for mixing

For 1 kg Bromadiolone : 960 g cereal + 20 g oil + 20 g bromadiolone bait concentrate (0.25%) mix thoroughly with the help of stick

• Do not prepare the poison bait with bare hands. Use gloves and stick for mixing.

• Use any broad leaf as spoon for bait application in burrows/ stations/making packets

Preparation of poison bait with bromadiolone

Poison bait preparation

Burrow baiting

Station baiting

Sources:Technical bulletin on “Rodent management in Arid Zone” Published by Project Coordinator, AICNP on Rodent Management, Jodhpur

Application of poison bait in field

A. BURROW BAITING

For Zinc Phosphide:

Pre-baiting: @ 8-10 g/burrow 2-3 days prior to poison baiting. (Pre-baiting helps in acclimatization of rodents to feed on new food at an specific place).

Poison baiting: 6-8 g/borrow for one day only (in largest possible area and in the same burrows where pre-baiting was done).

For Anticoagulants:

Bromadiolone (0.005%) @ 15-20 g/burrow

Bait placement

Keys to ensure effective control by poison baits

• Installation of fresh baits and bait points in rodents high activity area.• Placement of enough bait points to ensure better access of rodents to poison baits.• Matching the right bait formulation (loose grain baits/ wax blocks/ pellets)

(eg. if the area is infested by M. musculus only, large number of bait points be required.)

1. Community mobilization and Campaign mode

2. Rain fed crops: Zinc phosphide (2%) baiting.

3. Grasslands and forestry plantations: Zinc phosphide (2%) baiting

4. Irrigated crops: Zinc phosphide (2%) baiting followed by bromadiolone loose bait ( 0.005%) OR Bromadiolone loose bait ( 0.005%) baiting followed by bromadiolone.

5. AlP fumigation ( pellets only @ 2 pellets/burrow) in case of very severe infestation.

6. Bait application technique: Burrow baiting/ station baiting.

The rodent management technologies …………..!

Calendar of operation in crop fields

Day 1 : Plugging of burrows and estimation of bait, man power and poison, etc., removal of weeds, harbourage, etc.

Day 2-3 : Identification of live burrows/ pre-baiting.

Day 4 : Zinc phosphide baiting (2.0%).

Day 5 : Collection and burying of dead rodents.

Day 7 : Plugging of burrows/de-plugging of bandicoot burrows.

Day 8 : Bromadiolone (0.005%) baiting (loose bait/wax cake).

After 10 days, all burrows to be plugged for assessing the success of control operation.