JARQ 26, 81-87 (1992) Prospects for Integrated Pest Management in Rice Cultivation
Keizi KIRITANI
Food and Fertilizer Technology Center for the Asian and Pacific Region (14 Wenchow St. Taiwan, ROC)
Abstract Paddy fields are interconnected by an irrigation drainage system, and form part of a water-dependent natural ecosystem. The rice insect pest fauna in Asia is so rich that each niche in the paddy field in both the temperate and tropical zones is almost fully occupied by the same species, or by the ecological homologues of different species. Paddy fields as a semi-permanent agroecosystem of an annual crop provide a habitat for both migratory and residential pests. An increase in rice yield and its stabilization by means of high-yielding varieties have been the first priority of agricultural programs, after which the production of high-quality grain rice by cost-and labor-effective methods has been pursued. These changes were associated with a decrease in residential species, e.g. borers, while migratory pests, e.g. planthoppers, became more serious. However, the so-called BPH problems will be overcome eventually by the integrated use of selective insecticides, resistant varieties and cultural practices. Leafhoppers are an intermediate species, and remain important as virus vectors, as do planthoppers. The rise in temperature due to the greenhouse effect will have a profound influence on virus epidemiology. Since virus diseases require the most sophisticated system for integrated pest management (1PM), the systems approach will become important. In particular, the efficient utilization oflocal information on pest occurrence, in terms of decision-making for control, should be encouraged.
Discipline: Insect pest Additional keywords: agroecosystem, IPM, rice pest fauna
management for rice in any particular area. Introduction This paper attempts to review current changes in rice pest status in Asia, which have been associated It is estimated that rough rice production in the with the changes in rice production system. Precise world must increase by around 700/o during the com .understanding on the mechanisms involved is a pre ing 30 years to keep up with world population requisite in predicting target species and establishing growth. However, many countries, particularly those an adequate stqllegy for rice 1PM for the future. in Asia, lack unused arable land where rice produc tion can be extended. Most of the need for more Rice pest fauna rice must therefore be met by increasing the produc tivity of existing ricelands, while sustaining their fer I) Regional differences tility and protecting the environment9>. The beginning of rice cultivation dates back to With regard 10 field losses caused by rice insects, 10,000 years in river valleys in south and southeast Cramer"> estimated the loss of rice production in Asia Asia. The insect pest fauna of rice is therefore com at 16.2%. Pest faunas are closely correlated with posed of the species native to Asia in general or to the production system used for rice, and are the main selective regions in Asia with a few exceptions such determinant of how to implement an integrated pest as rice water weevil (Lissorhop1rus oryzophilus), 82 JARQ 26(2) 1992
which invaded Japan, Korea and Taiwan, in 1976, that Asia has a more complex fauna of insect pests 1988 and 1990, respectively. Such indigenousness than the other regions. In fact, the absence of major of pest fauna may possibly be related lo the general problems of rice stem borers, planthoppers, and failures of biological control attempts that have been insect-vectored diseases in the United States prc.sents made to control rice insects in the past, in spite of a striking contrast to the situation in Asia5>. the facl that there is a large parasitic and preda 10 cious fauna in that area >. 2) Differences between temperate
Table I. Comparison of ecological homologucs of rice pests in lempcrute and tropical Asia
Temperate Tropics Pinnt suckers: Mealy bug absent Pseudococcus spp. Rice bug Leptocori:;o chi11e11sis L. oratorius Rice black bug Scoti11ophorll lurid(I S. coarctata Green slink bug Nezara (11t1en11ata c) N. viriduta Green leafhopper Nephotellix cincticeps N. virescens Plan1hopper Laodelphax strituellus Ni/aparvata /ugens•l Sogarella furcifera•l Stem borers/Stem feeders: Stem borers Chilo suppressalis C. po/ychrysus C. suppressalis Scirpophoga incertutas S. i1111otata S. i11cert11/as Sesm11ia iuferens S. it1fere11s Gall midge absent Orseolill oryzaebl
Leaf feeders/ Root feeders: Leaffolder Marasmia exigua<> Cnaplwlocrocis 111edi11alis•> Caseworm Pampo11yx villa/is<> Nymphula dep1mctalis ( = P. stagnalis) Armywor111 Pseudllletia separata P. separata Spodoptero mauritia S. 111,111,itia Spodoptern lilura S. litura Rice skipper Pamara gullata Pelopidas mathias Telicoro augias Leaf beetle/Hispa 011tema orywe Dictadispa 11rmigera Rice waler weevil Lissorhoptrns oryzophi/11sd> absent Rice plam weevil Echi11oc11e11111s squameus absent Rice whorl maggol N. griseolo H. phi/ippina a): The pests that immigrate into the temperate areas, but cannot overwinter. b): The pes1 not found in Malaysia and the Philippines. c): Minor pests of rice. d): The pes1 in vaded Japan, Korea and Taiwan in 1976, 1988 and 1990, respec1ively. 83
Table 2. Ecological traits of insect pests in tem1>erate areas in rela tion to the type of agroccosystcm
Crop and culture Ecological traits Agroecosystem condition or insect Open system : Evergreen perennial crop Citrus orchard Residential with/without diapause Deciduous perennial crop Apple Residential with diapause Continuous cropping of Paddy Residential with diapause annual crop + migratory without diapausc Single cropping or annual crop Soybean, Vegetables Residential with diapause + migratory without diapausc Closed System: Single cropping of annual crop Green/Vinyl house culture Residential without diapause and under structures of vegetables parthenogenic reproduction Storage facilities Stored products e.g. grain Residential without diapausc In warehouses, etc.
and rice plant weevil, Echi11oc11emus squameus, in methods. temperate Asia. These changes were associated with a decrease in residential species, e.g. borers, while the incidences 3) Ecological characlerislics of the fauna of migratory pests, e.g. planthoppcrs, became more Southwood and Way181 have specified some serious. Table 3 presents a list of those rice pest characterisLics for each agroecosystem based on sta species which have recently changed their pest sta bility and isolation. Several agroccosystems, includ tus in temperate and sub-tropical Asia, including ing the paddy field, have been classified on the basis Japan, Korea, Taiwan and mainland China. of these criLeria (Table 2). Unlike upland crops, In general, univoltine and rnono/oligophagous spe irrigated rice plants are generally grown successively cies were the insect pests which showed a marked in the same field wiLhout any deleterious effoct from decrease during that period. In contrast, those spec continuous cropping. Paddy fields, therefore, pro cies that thrived in Lhe same period could be charac vide a habitat for both migratory and residential pests terized as polyphagous, multivoltine, small in body 71 as a semi-permanent agroccosysiem of an annual size and with relatively high mobility • Consequent crop. As shown in Table 2, a greater difference ly, outbreaks of virus diseases, e.g. stripe, dwarf, between the two types of rice pests, i.e. migratory etc., transmitted by leafl1oppers and planthoppers, ru1d residential, takes place in diapause responses in occurred during that period. the temperate zone as compared with the tropics. In Japan, Scirpophaga incerlulas began to decrease sharply in 1952-53; no measurable infestation has Recent changes in rice pest status been reported since 1960. Scotinophara lurida and 101 Oxya spp. also disappeared already before 1960 • I) Temperate zone Similarly, in Taiwan, ROC, the populations of ln the past 40 years, the pest status of rice insects Dicladispa armigera, Oulema oryzae, Scotinophara in Asia has undergone a great change, which was lurida, and Scirpophaga i11certulas declined in num related with an extensive use of synthetic insecticides ber or even disappeared in paddy fields before 3 16 in the temperate areas and an expanded cultivation 1970 • >. A decrease in light trap calches in areas of high-yielding varieties in the tropics. During Lhat infested by C. suppressalis was observed first in the period, in Japan for example, an increase in rice yield late 1950s in Japan, followed by the same pallern with stabilized production was the top-priority ob in Taiwan and Korea successively131 • The decline in jective to be attained, which was followed after this Chilo has been reported after the decline of S. was achieved, by pursuance of production of high incerlulas, wi th a time lag of 15 years in Japan and quality grain rice with cost- and labor-effective S-6 years in Taiwan. 84 JARQ 26(2) 1992
Table 3. n eecnt changes in U,c starus of riec pests in Asia
Temperate Tropical Species decreased : Chilo suppressalis Chilo suppressa/is Dic/adispa armigera Chilo polychrys11s Do11aci" provosti Gry/lo((l/pa orientalis £chinoc11e11111s squameus Locusta migratoria 111a11ilensis Lagy110IOI/IU$ elo11g(l(11S Pse11dale1ia (Mythima) spp. Ou/emu orywe Scirpophaga i1111otata Oxya spp. Spodoptera spp. Scirpophag" /11cer1t1/as Sco1i11opharo lurida Species increased: C11aphalocrocis med/110/is c,,aphalocrocis medi11alis Nephotellix sp1>. Hydrellia philippi11a Nilaparva/t1 lugens N/1ranga ae11tsce11s Sogate/lu Jurcifera Nephotellix vlrescens Nilaparvata /11ge11s Nymph11/a dep1111c1alis Rivulo otimeta Scirpophoga lncertulas Stink bugs Sogote/la Jurcifera
lo mainland China, Oulema o,yzae, Oxya chi11e11- Scirpophoga incertulas. Likewise, C. suppressalis sia and Dicladispa armigera declined in the 1950s, has been replaced by S. incertulas in Laguna, the Lagy11otomus elongalus (Niphe elongallt), Echi11ocne Philippines. Finally, two species of monophagous m11s squameus and Donacio provosri in the 1960s; plant suckers, Nephoreuix virescens and Nilaparvata while the control of S. i11cerr11/as and C. suppressa Juge11s, have been responsible for major crop losses lis was successfully achieved in eastern China and since the early l 970s in many tropical and subtropi the northern part of central China in the l 970s2>. cal countries in Asia. Futhermore, double cropping of rice with direct seeding induced more frequem out 2) Tropical zo11e breaks of stink bugs, Scoti11ophara coarcrara, Nezara The seed dissemination of high-yielding varieties viridula and leptocorisa orarorius, and rice leaf 8 with phmoperiod insensitivity and early maturity has roller, Cnaphalocrocis medinalis, in Malaysia '. developed double or even triple cropping farming, In general, a certain sort of specialized pest fauna 11 where irrigation or rainfall is adequate • >. The spread is now predominant in each of the intensively cu lti of dry season cultivation has led 10 a number of con vated rice areas. It is responsible for increased crop sequences on rice insects. losses in both absolute and proportional terms. As shown in Table 3, acstivating larvae of Asian white rice borer, Scirpohaga innorata, are destroyed Predicted changes in pest status in relation to by dry season land preparation. Species dependent va ried rice production systems on standing water, such as Hydrellia philippilta, Nymphula depunctalis, Nanmga t1e11esce11s, and I) Past /Uvula atimew, have become more abundant, but Table 4 summarizes the foregoing accounts of the mole cricket has diminished in importance. A changes in the rice production system and in rice reduction in the ar~a planted to alternate crops has pests. Cultivation of dry season rice in the tropics favored specialized rice pests with monophagous and increased the stability of the paddy agroccosystem, oligophagous habits at the expense of those which and Lhis stabilized condition has worked in favor of are polyphagous. mono/ollgophagous residential species. In Malaysia, the polyphagous borer, Chilo poJy In the temperate zone, a single cropping of rice chrysus, has been replaced by monophagous during the summer season without any rice plants S5
Table 4. Projcclcd changes in pcsl status in rcla lion lo rice production systems {I)
Objectives of Resources & Cropping Change in pest siatus rice production technology system Temperate Tropics Decreased l)ccreascd Mono/oligophagous, Polyphagous, migra residential. univohinc tory spp. Pest icides Early and s1aggered spp. l ncreasc and Hos1 resistance planting Increased Increased stabilir.a1ion of HYV Polyphagous, Mono/oligophagous, rice yield Irrigation Dry season cropping residential. multivol residential, vector spp. Fcr1ili1.er tine, vector spp. No change Muhivoltinc, non diapausc 111igra1ory spp.
Table 5. Projected changes in 11es1 status in relation to rice production sys1ems (2)
Objec1ivcs of Resources & Cropping Change in pcs1 Stalus rice prod11ction technology system Temperate Tropics Mechanization: nee reused Decreased High and diversi- combine har- Synchroni zed crop- Polyphagous, multi- Monophagous, fied quali1y of ves1er, planting ping of a few vollinc, residential residential spp.: stem rice machine & major varie1ies spp.: stem borers & borers & lea010ppcr$ t ilicr virus diseases Nursery-tray Increased Increased Minimum labor & trca1ment Rota1io11 wilh 01her Polyphagous, mulli- Mono/oligophagous, low cos! rice Use of Cf/EIL crops or fallow voh ine, residential migratory spp.: prod uction Selective pesticide pes1s: slink bugs planthoppers & stink (IGR) (spollecl grains) bugs
in winter, excep1 stubbles in fallow, is the common with rice plants at a vulnerable stage during the time ecological condition for rice peSLS . Residential spe of their immigration. cies pass the winier season in a diapause s1a1e in and The decline of Chilo observed in Japan, Taiwan around paddy fields. Some of them arc univoltine. and Korea during this period seems to have been in The intensive use of chlorinated hydrocarbon inse·c duced by rhe early planting of rice, which seriously ticides, i.e. BHC, DDT, etc., is likely to be respon affected 1he survival rate of overwintering larvae by sible for the decline in particular of monopl1agous depriving them of food before they were well 12 and univoltine residential species such as Scirpoplw nourished for overwintering • 13> ga, Scotinophara, Oxya, Oulema and Dic/adispa. Multivol1ine residential species in temperate areas 2) Prese111 have survived imcnsive chemical controls through The year 1970 was the turning point for rice developing their resistance against insecticides. This production systems in Japan (Table 5): a 300/o was true of Nephotetlix ci11c1iceps, Laodelphax reduction plan in rice produc1ion was introduced by s1ria1ellus, and to a lesser extent Chilo suppressalis. the Government and the mechanization of rice Earl y and late cultivation of rice has resulted in stag cropping by means of transplantcrs and combine gered planting in a locality, which has worked in harvesters started in that year. The mechanized favor of multivohine species, but not for the univol planting of rice seedlings considerably advanced rhe tine. Staggered cropping also encouraged the multi planting time. The nursery tray treated wi1h inscc- plication of migratory insects, by providing them 1icidcs came into a practice, which replaced the 86 JARQ 26(2) 1992
Table 6. Projected changes in 11cs1 slnlUs in rcla1io11 10 rice produclion S)'Slems (3)
Objec1ivcs of Resource.~ & Croppi11g Change in pest sia1us in rice produc1 ion 1cchnology sys1c111 1he 1empcra1 e & tropics Organic farming Increased Rice cropping as I 111egra1cd pest Minimum tillage I.ow-density & rcsidcmial low inpu1 and management pcs1 spp.: stink bugs, sustainable Increased dissemina1ion Direct sowing virus diseases vec1ored by agricu l1 ure of pest information lea Oloppers Mechanization wi1h Muhicropping contract farming broadcasting or insecticides. also have the same implications. The priority in the na1ional rice production pro Direc1 sowing may work in favor of virus epidem gram was shirted from the increase and stabili7.ation ics, si nce the susceptible s1age during which rice plants of rice yields to the labor-saving production of high are exposed to the attack or vectors lasts longer, as quality rice. The use or a control threshold (CT) in the case of minimum tillage by increasing the den for making decisions about insec1icidc applica1 ions si ty or overwintering vector popula1ion. The rise in became more popular. Mechanized rice produc1 ion temperature may not only assist a northward exten has intensified environmental resistance against Chilo. sion in the disLribution range of virus vectors, but having resu lted in a continuous decline in Chilo after also accelerate the revolution ra1e or epidemic cycles 1970. of virus diseases resulting in the expansion or range The other cultural practices. such as synchronizedl of occurrence to the further nonh1 •>. cropping, raising or seedlings under special faci lities Since vi ru s diseases require 1he mos1 sophisticated and insecticidal 1rca11nen1s for nursery trays, also 1PM practices, the systems approach will become con1ributed greatly to the reduced incidence of important. Surveillance and monitoring may con various virus diseases I ransmilled by leafhoppers. trad ict with the demand for cost- and labor-effective Various kinds or hcteropterous stink bugs, which are rice production systems. In particular, the lack or polyphagous, muh ivoltine and residential pests, have· in -field walking space in direct-seeded fields may be gained economic significance because of the spotted one of 1he main factors all owing pest multiplication grains caused by thei r sucking. to escape early detection8>, Therefore, the demand In view of the successful experience in Japan, for detailed information on pest will further increase monophagous and residential pests will be controlled to promote low input and sustainable agricuhure. when synchronized cropping with a fallow period be Pest popu.la1ion information is expected to con- comes widely prac1 ieed in the tropics. 1ribu1e to lessening crop losses and reducing pesti cide use, thereby stabili7.ing fa rm incomes. Pest Prospects and conclusion populations, however, vary from farm to farm . In managing Lhe pests, 1101 all farmers may be wi lli ng In futu.re, BPH problems will be overcome even to take an equal risk of pest damage. Recognizing tually by the imcgra1ed use of selective insecticides tha1 the control threshold is highl y site-specific">, such as IGR, resistant varieties and managemem of one of the major problems for the implementaLion cropping system (refer to Sawada ct al. in this issue). or an area-wide pes1 managemenl program is, there Leafhoppcrs arc an intermediate species •5>, and are fore, how to determine an appropriate level or pest likely to remain imponant as virus vectors, as in the suppression 10 be provided'>. With the purpose of case of planthoppers. The expansion or mlnimurn assis1ing individual small-scale farmers, an efficient tillage practices and direct sowing in rice production and effec1ive method for utili zi ng local information sys1cms may have a profound influence on the virus abou1 pest occurrence in their decision-making abou1 epidemiology (Table 6). In addition, the possible rise pest control, should be established through st rength in temperature due to the greenhouse effect may ened I.PM studies. 87
epidemiology in insect borne rice virus diseases. JAUQ, References IS , 92- 99. 12) Kiritani. K. (1988): What has happened to the rice borers during the past 40 years in Japan? JARQ, 21, I) Carlson, G. A . (1979): Insurance, information, and 264-268. organization option~ in pest management. 111111. Rev. 13) Kiritani, K. ( 1990): Recent population trends of Chilo PhylOf)(lthol., 17, 149-161. suppressalis in temperate and subtropical Asia. Insect 2) Chen, C. M. et al. (1979): Integrated comrol or ric:e Sci. Applic., 11 (4/5), 555-562. pests. In Integrated control of major pests or agricul 14) Loevinsohn, M. E., Litsinger, J. A. & Heinrichs, E. A. tural crops in China. ed. Inst. Zoology, Academia (1988) : Rice insect pests and agricultural change. /11 Sinica, 123 - 191 (In Chinese). The cmomology of indigenous and naturalized systems 3) Cheng, C. H. (1988) : Introduction 10 rice insect pcscs. in agriculture. eds. Harris & Rogers, 161 - 182. !11 Color illustration or diseases and insect pests or 15) Riley, J. R. & Reynolds, D. R. (1987) : T he migra major cro1)s in Taiwan. ed. DOAF, Taiwan Provin tion of Nilaparvoto luge11s (StAI) (Delphacidae) and cial Government. 89 (In Chinese). other Herniptcra associated with rice d uring the dry 4) Cramer, H. H. (1967) : Plant protection and world season in the Philippines. Study using radar, visual crop production. P/lanzensch111z Nachr., 20, 1-524. observations, aerial netting and ground trapping. /Jul/. 5) Grigarick, A. A. (1984) : General problems with rice E111omol. Res., 77, 145-169. invertebrate pests and their control in the United States. 16) Smith, R. F. ( 1972): 111e impact or the green revolu Prot. Ecol., 1 , 105-11 4. tion on plant protection in tropical and subtropical 6) Grist, D. H. & Lever, R. J. A. W. (1969): Pests of areas. Bull. Entomol. Soc. Am., 18 , 7-14. rice. Lo ngman, Green and Co., London, 520. 17) Smith, J. ct al. (1989): Economic thresholds for 7) Hirano, C. & Kiritani, K. ( 1975) : Paddy ecosystem insecticide application to rice: profitability and risk affected by nitrogenous fertilizer and insecticides. !11 analysis to Filipino farmers. J. Plant Prat. Tropics, Proc. Int. Congr. Human Environ. Kyoto, 197-206. 6, 67-87. 8) Hirao, J. & Ho, N. K. (1987): Status of rice pests 18) Southwood, T . R. E. & Way, R. (1970): Ecological and measures of control in the double cropping area background 10 pest management. /11 Concepts of pest of the Muda irrigation scheme, Malaysia. Trap. Agr. management. eds. Rabb & Guthrie, 6-28. Res. Ser., 20. 107~ 11 5. 19) Wilson. M. R. & Claridge, M. F. (1991): Handbook 9) IRRI (1989): JRRI rice facts 1988, June 1989. for the identification or lcan1oppers and plant hoppers 10) Kiritani, K. ( 1979) : Pest management in rice. Ann . of rice. CAB International, Oxon, UK, 150. Rev. £11101110/., 24 , 279-312. 11 ) Kiritani, K. (1981): Spacio-temporal aspects of (Received for publication, Aug. 13, 1991)