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Management ofRats as Pests of Sugarcane

V T F 'ICAR . ,- .Sugarcane Breeding Institute

.+ - b4 .,! - , . Indian Council of Agricultural Research-.L-,J -z ' - - Coimbatore - 641 007 y::$p!-,..* r .I> 4. * ..

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. > . . . .. . ..z , .... I=.. ....~anagement f Rats i s ~ e s b 'f Sugarcane

(GZ~nEighteen species of rodents (rats, squirrels) are pests in agriculture,horticulture, forestry, animal and human dwellings and rural and urbanstoragefacilities in India.Theirhabitat, distribution,abundanceandeconomicsignificancevary in differentcrops, seasonsand geographical regions of thecountry.Among the different rat species, Bandicota bengalensis is the mostpredominant and widespread pest of agfwlture in wet and irrigated soils aswell as in houses and godowns. In dry land agriculture, Tatera indica andMerioneshurrianaeare the predominant rat pests. Some species like Rattusmeltada,MusrnusculusandMusboodugaoccur inbothwet anddrylands.(Natureand extent of damaaeThe predominant rat species that inflictdamage to sugarcane are Bandicotabengalensis, Rattusmeltada, Tatera indicaandMusrnusculus.They begintodamage the canes around 90 days after planting and the damage increaseswith the age of the crop. Damage is mainly caused by gnawing through therind of the lower internodes of canes and by damage to the roots duringdigging of burrowsby rats, particularly the highly fossorial B. bengalensis.Asa resultof gnawingof rootsand looseningofsoil during burrowing,canes maylodge when irrigated or due to wind if not properly wrapped and propped.Lodged canes and ratoon crops are generally known to suffer greaterdamage. Rats have been reported to partially damage 8.6% - 12.1% caneswith mostof the damage restrictedto lower internodes.These canesweighedabout 31.5% less than healthy canes and also contained about 24.5% lesssugar content. Compared to other crops the cane fields harbour higher ratpopulations because they provide an undisturbed habitat for their burrowing,feeding and breeding activities, a protectivecover from avian predators andanabundantamountof highenergy foodfor mostof theyear. Inaddition to theresident population of rats, frequent waves of immigrationfrom surroundingfields as a result of disturbancecaused by ploughing,harvestingand floodingwith irrigationor rainfalloften enhancerodentpopulation ncanefields.(*urnsDue to variations in geographical and climatic factors, systems of cropproduction and post-harveststorage, biology of the pest species, the natureand extent of problems caused by the rats, and the perceptions andsocioeconomic conditions of the people, no single strategy or method ofcontrol is feasible or applicable under different situations. The availablemanagementoptions can be grouped into two basic approaches: non-lethalo r ~ r e v e n t i v e and le tha l orred ic t iona l . The non-lethal orpreventive measures involveenvironmental, cul tural and

more lasting effect. However, thelethal approach, particularly the useof rodenticides and trapping, whichprovidesan immediatesolutionto theproblem, is often considered themost practical, econom~calandeffectlvemethodofcombatingrats.E n v i r o n m e n t a l a n d cu l tu ra lI methodsA clean environment, particularlyremovalof wild vegetation or weeds,

1 i s c o u r a q e s r o d e n t s f romDamaged canes e s t a b l i s h i n g i n a n a r e a

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Mechanizationofagriculturealso reduceswastelands andwildvegetationoncrop field boundaries which otherwise provide suitable breedinggroundslhabitat and alternative food to rodents. Bandicoot rats makeextensiveburrows usually in bunds and the earthen embankmentsof waterchannels. They prefer tall and thick bunds for burrowingand a reduction in. bundthickness andheightdiscourages hem.Certain cultural practices affect the incidence of rats and their damage to Icrops. Deep tillage and ploughing of vacant land around fields destroy rat Iburrows and drives them away. Being a lang duration crop, cane fields arefrequently threatened by waves of rodent immigration related to agriculturaloperations in the adjoiningfields like paddy. Rotationof paddywith crops likesunflower may break the food cycle and reduce immigration to sugarcane.Since ratscausemoredamageto a lodgedcrop, adoptionof techniques suchas wrapping and propping of the standing crop, irrigation according to windintensity and the use of varieties which may not lodge indirectly help topreventdamagebyrats. Insugarcanemoredamageoccurstovarietieswithathin barrel,soft rind, lowfibreandlodginghabit han inthevarietieswith athickbarrel,hardrind,morefibreandnon-lodginghabit.(~echanlcalmethodsMechanicaltechniquessuchashunting,killingandtrappingoften involvehighlabourcostsandare lesspracticableover largeareas. However,thesecanbeintegratedwith chemicalcontrol techniques o achievebetter controlsuccess.Bandicootratscanbedrivenout of burrowsby ploughingthe fields duringtheperiod betweencrops, floodingof burrowswith irrigationwater anddiggingorsmokingthe burrowsbyburningcowdungcakeor ricestraw.Acommon old practiceis trapping rats in fields and premisesusingtwo basictypes of traps, the snap or kill trap and the live trap. The common kill trapsusedareTanjore Bowtrap,wooden snaptrap, urangor arrow trap andbreak-back spring loadedsnaptraps with wooden or jawed iron base. Live trappingis done usingprimitivetype pit fall or pottrap, foldable ironsheet boxeswith aspring loadedshutter andwonder trapsofdifferentsizesandshapes.( ChemicalmethodsThe use of rodenticides is the most common aplagricultural, ruralandurbanenvironments.Theireffectiveness depends upon the selectionof anappropriate compound, its formulation, and themethodandtimingofapplication.Thecommonlyused I recommended rodenticides in India arethe acute rodenticides, viz. zinc phosphideandaluminium phosphide, and the anticoagulantswarfarin, racumin and bromadiolone. It will beuseful to close or smoke the burrows a daybeforeto locatethe activeburrows inthefield.

proach to control rodents in

Zinc phoshide is an acuterodenticideandhencesingle dose is sufficient to bring about rodentmortality. For controlling rats, cereal bait I(mixture of brokenwheat grains, sugar powder Lane snoo, awing

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6 , . ~,..--and groundnut oil (96 : 2 : 2)recommended.For the baits to bebait aversion bv rats. This is donecontaining no i i n c phosphide to acclimatize th; field populations of rats with:. ::qthe food source. On the 3' day, 10 grams of the zinc phosphide bait is placed ., ,*in the live burrows for controlling the pest. Besides pre-baiting, bait aversion-can also be reduced by changing the cereal base and its texture, and leaving ~ -. .a sufficient time gap between two consecutive treatments. Fumigation of' '-1 ifburrows with aluminium phosphide is generally effective in damp soils but itsimportance is limited by toxicity hazards, cost of application and low efficacy :aga~nstpecies likeB.bengalensis. 1The chronic rodenticide warfarin is another chemical used in India for rodentcontrol. Unlike zinc phosphide, warfarin is an anticoagulant poison and lesstoxic to non-target organisms. However, warfarin 0.025% baits have to beconsumed for 5-7 days to bring about desired results. Since warfarin is amultiple dose rodenticide it increases the cost of operation of rodent control.In order to overcome the problem of prolonged prebaiting, hazardous natureand possibility of development of resistance to single dose acute rodenticidelike zinc phosphide and multiple dose chronic rodenticide like warfarin,second generation anticoagulants like br~mad io lone re now widely used forrat control. Bromadiolone 0.005% bait combines the better qualities of acuteand chronic rodenticides as it is a single dose anticoagulant and less toxic tonon-target species. Bromadiolone baits will be more suitable than aluminiumphosphideforthe control of immigrant populations.

PackageofrecommendationsAn integrated approach incorporating the following methods will ensure long-t e n prevention and management of both resident and immigrant populationsof rats. It is imperative to adopt control measures involving all farmers, on acampaign basis over large areas, for successful rodent management insugarcaneand other crops.

Removalofw ild vegetation or weedsReduction n bund thicknessand heightDeep tillage and ploughing of vacant land around fieldsRotation of paddy with crops like sunflower to reduce immigration to caneWrappingand propping of the standing cropTrapping n fields using suitable devicesFumigationof burrowswith aluminium phosphide tabletsUse of baits (zinc phosphide/bromadiolone)

ExtensionPublicationNo.148(2007)Script by

Prepared byPublishedby

Printed by

: Dr. B. Singaravelu, Dr. J.Srikanth,Dr. N. Geetha, Dr. R. Jayanthi: Dr. T. Rajula Shanthy, Dr. R.Thiagarajan,Dr.D. Puthira Prathap

Dr. N. Vijayan NairDirector,Sugarcane Breeding InstituteCoimbatore641007Printrite, Coimbatore