some aspects on the ecology and chemicai, control …ejtafs.mardi.gov.my/jtafs/10-2/ecology.pdf ·...

MARDI Res. Bull., (1982) 10,2: (210-230)

SOME ASPECTS ON THE ECOLOGY AND CHEMICAI, CONTROL OFNILAPARVATA LUGENS (STAL) AND SOGA TELLA FURCIFERA (HORV.)

ON RICE IN TANJONG KARANG, MALAYSIA

MD. JUSOH, M.* and G.S. LIM*

Keywords : Planthoppers, Ecology, Chemicai control.

RINGKASAN

Bena perang dan bena belakang putih menduduki habitat yang hampir santa pada pokok pacli

dan populasinl-a hidup bersama. Di Tanjong Karang paras populasi bena-bena didapati memuncak

selepas 60-70 har i d i tanam bagi kedua-dua musim. Walaubagaimanapun, paras populasi pentangsa

didapati memuncak 3-4 minggu kemudian pada luar musim, tetapipada musim utama paras memun-

cakny'a hampir sama dengan populasi perosak. Tidak terdapat corak pembentukan dan pengaruh

popr.rlasi vang tetap pada tiap-tiap musim diantara ketlua-dua spesies bena. Walaubagaimanapun.

dalam populasi campuran, bena belakang putih lebih banyak pada peringkat awal tanaman sementara

bena perang lebih banyak pada peringkat akhir tanaman. Ketinggian peratus ini adalah tern,""ata ketika

luar musim yang mana biasanva paras populasi ada persamaan dengan paras memuncak populasi.

Pemangsa labah-labah l.vcosa didapati paling banyak (90%) semasa peringkat awal tanaman (10-40

hari selepas tanam). Pemangsa mftid Cyrntrhinus lividipennis beransur menambah populasinla pada 70

har i selepas menanam yang mana berkebetulan memuncaknya populasi bena-bena. Dar i peni la ian

bahan kimia, formulasi debu BPMC dan carbarl'l adalah disyorkan untuk penggunaan dengan mene-

gunakan penyembur "maruvama mut i i -hole v invi tubing".

INTRODUCTION

After the first recorded outbreak ofwhitebacked planthoppers (WBPH),Soqatella furcifera (Horv.), in Krian in 1925(N{Ir-mn and PAGDEN, 1930), rice farmers inMalaysia have suffered from planthopperproblems on several occasions (Uu, 1971;IIM and FIEONG, 1977 ; andUM et al. , 1978).Today, high infestations of planthoppers arefairly common with yearly buildupsincreasing since 1974. There was also agradual increase in areas affected in TanjongKarang, the biggest loss to planthopperoutbreak was in 1977 , where a total of I,829hactares of rice were damaged by hopper-burn (Uttr et al; 1978). In 1979, although21,492 hactares of rice in the MUDAirrigation scheme were infested with WBPH,only I976 hactares eventually sufferedhopperburn (OoI and RAnIu, 1979). BothWBPH and the brown planthopper (BPH),Nilaparvata lugens (Stal), share almost thesame habitat in the rice ecosystem and existtogether in a mixed population. It is believedthat in many hopper outbreaks these two

pests are involved (Uv and FIEONG 1977).Depending on the season, locality and cropstage, one species may be more dominant.Apparently, WBPH is more predominant atthe early cropping stage while BPH at thelater stage (HABIBUDDTN et al., 1980). In thispaper, several aspects of the ecology andchemical control of both these two species arediscussed.

MATERIALS AND METHODS

Ecological Studies

A plot of 0.2 ha was planted, in SungaiBurong with rice variety Mat Candu for fourconsecutive seasons, beginning from the1978 off-season to the 1979-1980main-season. All agronomic practicesadopted locally were followed. Sampling ofboth BPH and WBPH, and their predatorswere carried out at three to ten day intervals,beginning just after transplanting and up toharvesting. In this study direct counting on25 hil ls/plot was adopted. The number ofnymphs, brachypterous and macropterousadults, and the common predator specieswere recorded separately.

*Crop Protect ion Branch. MARDI. Serdang, Selangor. Malavsia

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Chemical control Studies

For all the experiments, the plant-

hoppers and their predators were countedone day prior to insecticide application and

one day after. At least tu'o to six successiveadditionai cclunts were made at three to ten

days intervals extending up to 7--' l-5 da"v's

l l ter inscct ic idc appl icat ion.

Five f re ld exper iments (Expts. 1.2,1,4.and ,5) were conducted in lour consecutiveseasons f rom 1978: Expt . I in Sekincan,Expts, f ,4 , and 5 in Sungai Burong. andExpt, 3 in Sawah Sempadan. All the experi-rnents were conducted r-in the ricc varietlMat Candu, and with the treatment in plotsof size 0.2 ha each" l-he insecticidesevaluated (Table 1/ were appiied once as afoliar spra.v (Expts. 1,2, and 3) at 65 daysafter transplanting (DAT) for Expt. l, .1,5

DAT for Expts. and 60 DAT for Expt. 3, ortwice (Expt. 4) at 50 DAT and 63 DAI-. InExpt. 5, dusting was carried out once at .1-5

DAT using a motorized 'Maruyama'multi-

hole vinly tube duster.

RESULTS

The Effects of Crop Stages and SeasonalVariations on the Abundance of Planthoppersand their Predators

In Sungai Burong (Tg. Karang), f ieldinfestation of rice planthoppers wereotrserved to occur as earlv as ten days aftertritnsplaniins (DA"I'; {I-t igurt, l i .

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essenf ially the migratclrv macropterousaduits. [n bt;th the main and otiseas<lns. thepopulation levels pealied ar 60 to 7i) DA"frvhich enincii led wlth the r:ionths of . lanuar,_- Fehruan' * : . iune - lu lv respect i re l l ' .However, for the off-scasr:n cri)ps. the f,re-dators usual lv peaked at 8 i ) to 90 DAT r .e"three to four weeks after that of the piant-hoppers. ln contrast, thel' ciosely coincidedwith tl:e pcak for the planthoppe rs during fhemain-seas()ir crrlp. This clifference expl:rinswhy p lanthopper populat iuns are h igher inthe ofl--ceason crops.

Apparenf l r ' . thc d i i fercnt s i tuat ionsbetu'ecn ths otf-seastrn ".rnd ahe main-seasorrcr{lps :{:ere l;trgclv dur: tr. ' the existence *f a

rice tree period of one month from mid-March to mid-April. This resulted in thegradual build up of planthopper populationsfrom early migrants in the off-season crop topeak in the middle of crop. The predatorsthen folloq'ed and peaked later. thri.exerting their impact only towardc the end ,:f

the off-season by which time some cr()pdamage has already been infl icted^ On theother hand, the predators build up in theoff-season were able to continue over in:r>the main-season to help suppress the plant-hopper populations, due to staggering artdoverlapping of the two crop seasons.

Field Composition of BPH and WBPH inRelation to Cmp Stages and SeasonalVariation

In the off-season of l97ti and mairr-season 1978179, BPH was predominurrtthroughout the cropping stages. wherezisWBPH occurred only in the early sta8,e(10-60 DAT), and gradually diminished iisthe crop l.natured (Figure 2). For thc oll-season 1 9 79 . hon er er. \1' l l PH u ar the dottt , -

t rant species betu 'een I0 * 1{) DA I , t t h i i tBPH becamc dorninat i l on l l i l r thr la ter cro l rstage. The dominance of WilPil was eve trmore brief in the main-season crop of 917ti780. where BPH became predominant as earlv-as 25 DAT.

Field Composition of Planthopper Stages arAffected b1' the Crop Stages and Seasonr,:rl!'ariations

In general i t can be notec l that there wlr .no f ixecl piitte rn on rleveloprnent end domirr-ancc l retween thc- rno species of p lar i -hopper' ! l ; igu n' 2l Pll i ,..r ir lr thc conrltcl it i r eness o ! c r t he r i on t i nancc b r tueen the tu , .species in the paddv fields are dcpenclent onnumeriXis interrelating factclrs, such as cr01stages, lhe selsons, natura l enemies, cu l tur ; r lpract ices. etc . Present ly . in format io l :re lat ing to these aspects are st i i l re lat ive i rhn i t eC .

As shown m F'ipure,r-, the nrajorit! ' , rtthe planthi:ppers ar the very earlv crop stagc:{10- 30 Dr\1-) was of nlacropterous forr.. i.For abr:ut 50 davs i-l i l 9(l DAT) rhe occur-

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Figure 2: Vaiations in the field population composition of adult brown planthopper (BPH)and whitebacked planthopper (\|BPH) throughout the uop stage and season in

paddy fied without insecticide application Sg. Burong, Tg. Karang.

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Species Composition of Predators and

}'opulation Change as Affected by the Crop

"itages and Seasonal Variations

At the earh ' s tage. of the crop (10-- - l ( ): )AT) more than 9( ] ' i o f the predator

lrecies occurring in the field were l.rctt.su

l r i t le rs (F igur t 11. i -hc r r r i r ic i p l 'ec i l i lor .'. t rtorhinu.r lividipennis build up onlylradually and became predominant at 70i )AT, and th is pers is ted unt i l up to 100i),4T. after which its population began to,iccline again. However. Paetlents fuscipe:; 'tr i others (( 's.snoiden intrrstit iult.y., ' i tt ' t ' inellu ur(uula ) uccurred in sntalleii i , imbe rs thrclughout the cropping ireriotl. In

t rncrra l , therc w-as no c: lear pat tern in thr. peciers composition ol the preclators as. ' i iected bv the seasonal v i r r ia t ion. a l though'"t" ';rsollt l chenges ssenred t(] have some, ' i iccts on thc <rvc: ra l l abundance of ' the' r l *dators.

I 'hemical l lva luat ions

i: rperiment I

T'ihlt ' 2 shr:* etl t l l tt BP)ti( hii" ,.,; r r :n i f icanf iv l i iehcr J lcrccntagr k i i l l lp lanthr lppers a\ compared t ( ) endusui larr"Hou'cve r . the mean numbe r t r f p lanthoppersup to 36 c lavs af ter span' ing (DASi sho*.cr . lno s igni f icant d i f lererncc i re! r . r 'een [ ] l ' \ lC nnr lendosul fan a l thoueh hrr th o l thern r i l f t t " ' r r . is igni f icant l r ' (P<( ' | .0- i l to th l t o f t i rc c , r r r i rc ]\ rVi th l rne appl icat ion, c t r r l r I lP l \ ' l ( ' nas af , l r 'to rer iue the p lanrhopper populat ions belorrt t rar of the threshold o l 2t } adul t \ ih i l i ar 7()DAT. FIone,ucrr . i t was onl l 'e f lec l r re up to 9DAS and hevond th is the popr: la t i t rn bcgarrto increase and ercee d thc thre shoid ier e l . I r :relaticn to pred.'rtt lrs the cffects o!' lhe$e tw(l

insecticides were relativelv less (Table 3).For edosulfan the kil l was 30.7c/c and fortlPN'IC 35.6'1. In spite of the treatments.wi th in 9 DAT, thc predators were noted toerceed that of the pre-sprav s i tuat ion. Upto 3(| DAS. there was no significantd i f ference rn the mean number ofpredators ih i l l t re t* 'een the t reatments.'f irese

obsen'ations seem to seggest thatendosul fan and BPMC have less ef fectson the predators as compared to that onthe p lanthoppers.

Experiment 2

Carbofuran was fbund to have lls igni f icant lv (P<(1.{15) h ieher k i l l on theplanthoppers than monocrotoph,os i-{ubltJ l . l { r lwever, no s isn l f ic i in t d i f tercnce \ ' . 'a5observed in the mean number of p lanthopperup to 30 DAS between i rcatrner ts wi thcarbofuran and monocrotophos.

-l 'he

pli lnth<.rppers pclpulatiorr rvts ntrfgd tu bel<lwth* thrcshold levc l (7 adul ts t ' r l5 nvrr : ; ' rh ih i l i t On the t i thcr hancJ. thcr pcrccntagc k i i l{ ) l p rcdtl{)rs shor', ed no -ci En ; i ir. i ;rrr t cl iffc rt:ncetratx'i:cn monocroicphos ;rrri- i cartrr.rfurant'T'thle -5/. The nuinber ttf pre datorrexce ceied that of the prc-sprav lcvel wtrhin l"iDAS indicat ing that these 2 insect ic ides ur : rcdetrirnental to the preilators.

Fixperiment 3

Thc percentauc k i l l anrJ the meannt tnr t l t : r o f p lanthcpper i rh; l l r rn t r i I L)Al i:hor\ 'er l i t0 S()F! ' l i ] i i ( l int r .1i i l i i ' r :- ; i ' r . : l l f t ! ' " fCIl

l lP \ iq . ' . \ {P lv { ( ' r rn i i \ {_ ' l h t i . i r ! , { r '5 r f ( j ih , r ilhc r i ' l t . i ve r im!1ar c f fcc t i . . r - . t i r "s r t : - , l f t rp ian thr ,ppcr r i / i ; l ; l r .6 l . l { r : r ie r .e ; . . u i th , r * !1

ttne ;rpplrcatior at 6l i DAT, thc rcrjr l i ialp lan th*pocr i rc i ru l l ; ion i t i l l i : r i ;ecd t : i , ! ih i :t l t re . l to l ' i r i t ' l . i l l r r .

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number of predators/hill up to 7 DASshowed no significant difference betweenBPMC, MPMC and MTMC but weresignificantly lower than the control whicnshowed that the carbamates did reduce thepredator populations to same extent.

Experiment 4

Of the eight insecticides tested, onlyfenvalerate was observed to be ineffectiveagainst the planthoppers. Carbosulfan,propoxur and BPMC were noted to be highlyeffective, ensuring a percentage kill ofgreater than9SVa (Table 8).It was also notedthat plots treated with propoxur and BPMChave exceptionally higher planthoppernumber just 9 days after first spraying(DAFS), suggesting some resurgence effectsof thetwo insecticides.

In general one application of theinsecticides at 50 DAT was insufficient asmay be noted from the planthoppersnumber/hill at 9 DAFS which farexceeded the threshold of 20 adults/hill witna second application at 63 DAT, theplanthopper populations declined andremained below the threshold level for up to32 days after the second spraying. In terms oftheir effects on the predators, it was foundthat carbosulfan, endosulfan and fenvaleratewere extremeh..' 16*i., destroying more than95ctb of ti:e predators. However the predjltorpopulalitxrs were found to be able to deve lopback the pre-spray level within 9 DAFS(Table 91

Experiment 5

Dust formulations of BPMC lnclcarbaryl evaluated were found to be equallyeffectir-e .against planthoppers with thepercentage kill of 96.47':/{ and 93.7,,1'i .respectively (T'able I0). The mean numbdr ()fplanthr.rppers/hill up to l7 DAS in thcMPMC dust treatment was found to besignificantlv higher than thar of the cartraryldust-treated plot. This shorvs that carbarylhas much longer residual e ffects. Frompopulation levels of planthoppers recorded

at 5, 9 and 17 DAS in the BPMC plot, thepopulation level of planthoppers exceeededthe threshold level of 7 adults of 15 nymphs//hil l even at 5 DAS. In the carbaryl plot,however, the threshold was not exceededeven up to 17 DAS. The effect of thesedust formulations on the predators wasminimal judging from the low mortalityinflicted upon the predators (Table I t ).However, the mean number of predatorslhil l was significantly higher (P<0.05) inBPMC plot as compared to carbaryl plotdue to longer resiudal effect of thecarbaryl dust.

DISCUSSION

Since the timing of rice cropping wasfound to have significant effects on the pest-predator situation, it is imperative that thisaspect must be given due consideration in theoverall pest management programme.Presently however, there is still limitedunderstanding with regard to thisrelationship. As such, more comprehensivestudies pertaining to this aspect is urgentlyrequired so as to ensure a rapid and moreefficient exploitation concering plantingmanagement for the regulation of pestspecies involved.

The above consideration is alsosimilarly true with regards to the aspectsre lat ing tc BPH and WIIPH,: i , .n ipor i t i tn . I r rany case. I r { )m whate!er l i rn j ted in format io i }avai lable i r resent ly , , t i - . fa i r l ) ' c lear thatWBPH hrs a tendencv to occrlr earlier thanBPH in .i crop pericd.

'fo some ertent thepresent sira{egies fol u:ntrr.rl of thcse pe.tswould nc*rJ to take thr i in to, ;onsidcrat ion.

It iva: also quite evident irom thc abovethat the situations ln the rnain and off-seasons are interrelared and ct:rrld influenceone another. As such the rerlevant pestsituation in a precedil iu. r.:rop should never ttedisregarded. lt mustr, however. be fu!hconsidered in the tot;l l management of thepest species. AJso mrire studies would seemneeded in the further understi inding of theirrelationship and inflrrencing iactors rn thepaddy ecosvstem.

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From the chemical evaluations,obvious differences were found to exist in thedifferent chemicals in both theireffectiveness over planthoppers and theadverse effects on predators. Suchdifferences were also noted for differentformulation and chemical groupings. Ingeneral, it was quite obvious that thecarbamates (BPMC. MPMC, MTMC,carbofuran, carbosulfan, propoxur andcarbaryl) were most effective against theplanthoppers while their effects on predatorsranged from being the safest in the case ofcarbaryl to the most hazardous, vizcarbosulfan. On the other hand theorganochlorine (endosulfan) andorganophosphate (monocrotophos) weremoderately effective on planthoppers buthazardous to predators. The syntheticpyrethroid (fenvalerate), on the contrary,was completely ineffective against theplanthoppers and at the same time highlyhazardous to the predators.

Among the three formulationevaluted, it was found that the dustformulations were far superior in controllingthe planthoppers while having similar effects(if not less) on the predators when comparedto the two formulations (emulsifiableconcentrates and wettable powders). Thegreater effectiveness of the dust forrnultionon planthoppers may be attributed to thebetter coverage and penetration achievedwith the use of the 'Maruyama' multi-holevinyl tube duster as compared to the'knapsack' sprayer used for the other two

formulations. Besides, multi-hole vinyl tubeduster have the advantage of coverage speedover the 'knapsack' sprayer.

Based mainly on the effectiveness andsafe use of the chemicals evaluated, the dustformultions of BPMC and carbaryl, may berecommended for use with 'Maruyama'

multi-hole vinyl tubing applicator in thecontrol of the planthoppers. However, theemulsifiable concentrate formultion ofBPMC and wettable powders of MTMC,MPMC, and' propoxur may also beemployed. Under high infestations of theplanthoppers, two applications would beneeded; the secound application at aninterval of 1O-12 days after the first when theeconomic threshold is again exceeded.

It is generally noted that informationwith respect to the pest-predator ecologyespecially in relation to the use of chemicalinsecticides is still lacking. A clearunderstanding with regards to this is not onlyessential but also critical, since the need forinsecticidal use would inevitably arise onsome occasions, be it with respect toplanthopper control or for some other pests.As such, more comprehensive studies in thisarea should be given substantial emphasis.

ACKNOWLEDGEMENTS

The authors wish to express theirsincere appreciation to En. Yaakub Kasinfor f ie ld assistance, and En. Ahmad Shokrib. Haji Othman for statistical analysis.

SUMMARY

Both brown and whitebacked planthoppers share almost the same habitat in the rice ecosystem andexist together in a mixed population. In Tanjong Karang, the planthopper population levels were found topeak at 60-70 days after transplanting (DAT) in both the main and off-season. The predator populationlevels were observed to peak 3-4 weeks later during the off-season in contrast to the main-season wherethey closely coincided with that ofplanthoppers. There was no fixed pattern ofpopulation developmentand dominance within each crop period between the two species of planthoppers. However, in a mixedpopulation the whitebacked was dominant in the early crop period while brown planthoppers at the laterperiod. A high percentage of nymph was very pronounced during the off-season crop which usuallycoincided with peak population levels. Predator Lycosa spiders were found to be the dominant species(907c) during the early crop stage (10-40 DAT). The mirid predator, Cyrtorhinw lividipennis build uponly gradually and become predominant at 70 DAT which coincided with peak population levels ofplanthoppers. From the chemical evaluation, the dust formulation of BPMC and carbaryl wererecommended for use with the'Maruvama'multihole vinyl tubing applicator.

229

REFERENCES

HastsuoorN, H., CFreNc, p.M. andVRroEN, G.V. (1980). Planthoppers -the problem and control strategies inMalaysia. Paper no. 13 presented atThe National Rice ConferenceMalaysia, Kuala Lumpur, February26-28,1980, 37 pp.

Uu, G.S. (1971). Screening of insecticidesagainst Nilaparvata lugens (Stal).Malays. Agric. J. 48(2): 104-21.

and I-IEONG, K.L. (1977).Habitat modification for regulatingpest population of rice in Malaysia.MARDI Report No. 50, MARDI,Malaysia,23pp.

OoI, A.C. and KoH, A.K.(1978). Outbreak and control of therice brown planthopper [Nilaparvatalugens (Stal)l in Tanjong Karang,Malaysia. Proc. Pl. Prot. Conf., KualaLumpur, March 22-25, 1918, p.r91-2r3 .

NfiLLER, N,C. and PAGDEN. H.T. (1930).

Preliminary observations on Sogataspp. pests of paddy. Malays. agric. J.18:238-211.

OoI. A.C. and Ranrrna, S. (1979). Outbreaksof two delphacid planthoppers in theMUDA irrigation scheme and theircontrol. Joint Report of Crop Prot.Div. , Dept . of Agr ic . , PeninsularMalaysia and MUDA AgriculturalDevelopment Authority.

230