Recent Studies on Natural Enemies of the Gall Midge, Orseolia oryzae (Wood-Mason)

By TERUNOBU HIDAKA*, ERMA BUDIYANTO**, VANICH YA-KLAI*** and RAVINDRA C. JOSHI****

* Division of Entomology, National Institute of Agro-Environmental Sciences (Tsukuba, Ibaraki, 305 Japan) ** Directorate of Food Crop Protection (Pasarminggu, Indonesia) *** Entomology and Zoology Division, Department of Agriculture (Bangkhen, Bangkok, 10900 Thailand) **** Department of Entomology, International Rice Research Institute (P.O. Box 933, Manila, Philippines)

colored adults of Platygaster sp. were also Introduction found from RGM in India10>. An alternate host of the natural enemies was clarified in The rice gall midge (RGM) in the family Indonesia5> . , Diptera, is one of the im­ In the present paper, the authors introduce portant pests of rice in tropical Asia. briefly the results obtained from the recent Biological studies on the natural enemies of studies on natural enemies on RGM occurring the insect have been fragmentarily carried out in tropical Asia. in , , Indonesia, Sri Lanka, and Thailand. However, recently advanced studies Occurrence of parasitoids and on the natural enemies of RGM have been predators conducted in the following aspects. Several kinds of parasitoids and predators of RGM In Thailand, food-chain relationshi p be­ were identified38>, and relationship between tween RGM and its natural enemies was parasitic activities and developmental stages clarified. A total of six parasitoids and 11 of the host insect were also clarified. Morpho­ predators attacking RGM were reported3Sl. logical investigations on developmental stages Illustrations of five of the parasitoids of parasitoids such as Platygaster oryzae and and some of predators were also provided so> . P. foersteri were also conducted in detail in The parasitic activities of Neanastatus Thailand20 ,2 1 > and then, parasitic competition gralla1ius and Propicroscystus mi?-ificus were between both parasitoids was demonstrated21>. studied in wild rice fields. N . g1·allarii1s was Effectiveness of parasitoids and predators for an external larval parasitoid but not host­ control of RGM was recognized in high land specific as it occasionally made an attack on fields in West Java, Indonesiaij ,30>. The brown mummies of RGM containing pupae of the parasitoids P. oryzae or on pupae of P. miri­ Present address: ficus, as the secondary or tertiary parasitoids. * Research Information Division, Tropical Agri­ P. mirificus was the secondary parasite that culture Research Center (Tsukuba, Ibaraki, attacked pupae of P. oryzae, although it some­ 305 Japan) times pat·asitized RGM 10> . 176 JARQ Vol. 22, No. 3, 1988

In Indonesia, a total of five parasitoids were found in Java Island. Of them, P. Parasitization oryzae and N. 01·yzae were well distributed, foJlowed by P. miriffoits and a species of In India, parasitization of P. oryzae in Jaya Eitrytoma~aJ. The most important parasi toid rice stubble and in wild rice in 1982 peaked was P. oryzae during the wet season in Pusa­ from Jan. 29 to Feb. 11. Suppressed galls kanegara, West Java13>. Several kinds of were maximum on April 9 to 15. Parasitiza­ hymenopterous parasitoids such as P. oryzc,e, tion in wild rice, 0. perennis, was higher P. 'tnirificus, E. setitibia, and T1·icho1·pia sp. and most galls were suppressed. RGM infesta­ were recorded, and N. oryzae/ P. oryzae and N. tion and parasitization followed a wax and oryzae were considered to be important. The wane cycle0 >. degree of parasitization ranged from 30 td RGM was heavily parasitized by two chalcid 70%35) , parasitoids, N. grallariits (Masi ) and P. oryzae In a brief review of RGM, a total of six (Cameron) in Raipur, India, during 1981 hymenopternus paeasitoids i.e., P. oryzae, .P. Kharif. Parasitization ranged from 21 to sp., P. di71losicie, N . cinctiventris, N. sp., and 94% in October and November. N. gralla1-i1.1s N. grallarius were described with special ref­ (Euplelmidae) parasitized RGM pupae one erence to the host stage, locality of country, month earlier than P. 01·yzcie. A peak of biological and parasitic observations, and parasitization ,vas 75 %, which was the first references. These hymenopterous parasi toids record of heavy parasitization in Indiam . The showed high parasitization in the late season parasitization of Plat11r1aster sp. on l'atoon of the rice crop, while low parasitism in the rice was studied during off season at Tamil early stage of rice growing. Three kinds of Nadu, India and recorded to be 37.8% 13 >. predators were also listed such as Ccisonoides It is revealed that the parasitized galls by interstitalis and Ophionia inclica (Carabidae) , P. oryzae showed distinct external differences and Ncibis capsifonnis ( N abidae) 12> . from non-parasitized galls. The appearance P. oryzae and N. {Jrallarius were t·earecl of parasitized galls was as follows: 1) shorter from galls collected at Karnataka, India when in length, bl'oader in diameter and lighter in 49 slender-grain cultivars of rice were tested weight, 2) brown lesions at one ot· several for susceptibility to attack by RGM. Tetras­ places and 3 to 5 minute emergence holes tichus sp., Gyroccim,va sp. (Brnconidae) , Gelis only at the spongy region, 3) wall was trans­ cireator (Panz.) and unidentified ceratopogonid lucent, pale green and broken off easily. were also foundwJ. ExternaJly the pupal mass of the parasitoid The brown colored Platygaster sp. was 1·e­ is visible10>. corded for the first time on RGM in Cumbum Parasitization to RGM by N . ,qrallarius in India. The species is similar to the bi-own ranged from 21 to 94% was observed in Platygaster sp. attacking midge on Panicitm October and November at Raipur during 1981 sp. at Cuttack, Orissa. The parasitoid activity Kharif and parasitization was 75% in the was observed from the middle of October 1981 3rd week of Novemberm . There was a 4:1 to February 1982 with its peak during De­ ratio of exposed to suppressed galls at Bhu­ cember 1981 1~> . baneswar, India. Parasitization in the sup­ A new pupal parasitoid, Blc1,11lwo11eza sp. pressed galls was higher during early April, (Diptera, Empididae), was found in India to May, and June, late January and March, and parasitize less than 1 % of RGM pupae in in July. Parasitization started at the 4th Octobel' ( the wet season) . The maggots occa­ week of September and reached Hs highest sionally behaved as hyperparnsitoid on pupae level at the last week of November at Raipur of P. or11zcie2G> . in the wet season. In stubble, the parasite population was 8.5 to 15.8%. Then, the data show the role of 177 parasitoids in minimizing pressure32>. In three important species was studied. P. 01·yzae Ranchi, parasitization by Platygaster was as is very common in Java, only females we.te high as 40% in May 1981. The parasitoid found, and the host and the parasitoid were appears late in l{harif, toward the end of synchronised. P. rnirificus was ectoparasitic October•>. In Indonesia, P. oryzae parasitized and deposited an egg near a fulJ -grown 70 to 90 % of RGM pupae in West Java31 >. or a of RGM. A solitary living larva grew rapidly and sucked the host. The dura­ Biology of the parasitoids tion of the total life cycle was about half that of the host. N. Oryzae, an ectoparasitic Surveys on natural enemies of rice insect wasp, laid eggs near the pupa of RGM. The pests were undertaken on the paddy crop in total life cycle was about two thirds of that India for six consecutive years, 1975- 80 of RGM 7 >. In Karawang, J ava Island, the Kharif season. A total of six kinds of parasi­ parasitoids were abundant during the second toids of RGM were identified as follows: P. generation and kept the pest populations at a oryzae, P. rnirificus, Platygaster sp., .P1·0- much lower level at Pusakanegara3•>. Leptacis oryzae, Telenornus is1·aeli and N eanan­ In China, ontogeny and biology of P. oryzae, status sp. Prevalence of P. oryzae was moder­ a gregarious endoparasitoid of RGM were ate, while that of P. rnirificus was high and studied. Development of its eggs newly de­ of others traceaoi. posited into the host egg was clarified based Pan-trapping with a soft vinyl yellow pan on the morphological characteristics. The egg could collect a large number of micro stage lasted 13 to 14 days, while the larval Hymenoptera and the brown colored species stage was only 3 days. The fully developed of Platygaster sp. which appear to be new larva was white and ovoid. The mouth was to rice ecosystem in India10>. a simple transverse orifice. Before pupation Parasitization by Platygaster sp. in Madu­ each larva formed an ovoid cocoon. The female rai was 22.3% during October and reached adult deposited two to three egg groups in a peak of 78% during December. In Melur, one host (a group of 10 to 15 eggs were parasitization gradually increased from Octo­ deposited at each oviposition). Nine to 61 ber and the peak was observed in the second parasitoids emerged from each parasitized week of February. It is indicated that high pupa. The sex ratio was 8 female to 1 male. parasitization is obtained during the late rice P. oryzae hibel'llates in the early embryonic growing season 1•>. stage in the first instar larvae of the host. In Eastern Uttar Pradesh, infested tillers The duration of a generation was 25 to 30 collected in fields were brought to the glass­ days22,. house to observe parasitoid emergence, and In Thailand, developmental periods of two a parasitoid was identified as P. rnirificus parasitoids, P. oryzae and P. foerste1·i were Gi rault (Pteromalidae) 2•>. In Indonesia, investigated and morphological characteristics biology of P. oryzae was studied. The parasi­ of their immature stages were observed as toid is widely distributed in Java and is the follows. Developmental stage consisted of most important parasitoid of RGM. P. oryzae spindle, round, and blastula stages in the egg oviposited in newly hatched host larvae period including the embryo stage. Larva has Reproduction was parthenogenetic. The num­ the 1st to 4th instar stages, prepupa, and ber of ovarian mature eggs was 648, how­ pupa respectively. Duration from egg to adult ever the average number of eggs laid pet· emergence in P. oryzae and P. foersteri was female was 95. The complete life cycle 27.3 and 29.7 days in the average. The pa1·asi­ averaged 30.5 days. The longevity of adult toid took about 5 days longer than the de­ was 4.1 days when honey solution was g iven 28>. velopmental period of the host midge. Newly In Indonesia, six species of parasitoids of emerged adults remained in the host for about RGM were found in Java and biology of four additional days before escaping from 178 JARQ Vol. 22, No. 3, 1988

the gal120>. Interspecific relation of P. oryzae and P. foersteri was studied. The rate of Effect of insecticide application coexistence of the two parasitoids was far lower in the field than in cage; only P. foer­ The toxicity of various insecticide treat­ steri was supposed to complete the develop­ ments to P. oryzae Cameron was determined ment. These facts indicate that there would in field-plot test at Cuttack, India. The be some factors to avoid direct competition parasitoid was not detected absent in the plot between both species in fields21 ,. treated with granules of mephosfolan and fensulfothin at 1.5 kg (a.i.) /ha2 ,. In the labo­ Outbreak ratory condition, a known number of parasi­ toid adults were released in the 15 x 2.5 cm The severe outbreak of RGM in the central glass tube containing a sprayed rice leaf and rice-growing area of Thailand occurred in the mortality was recorded at 15 min interval June 1977 in Chachengsao province. The after placed in the glass tube2>. The endo­ dominant parasitoid was N. grallarius and sulfan caused high mortality of the parasitoid parasitism ranged from 11 to 35%. P. 01·yzae within 30 min. The order of toxicity to and 0. indica were also present3l. In eastern parasitoid was endosulfa.n (200 ppm) , phos­ Thailand, parasitism by N. grallarius was 18 phamidon (500 ppm) , monocrotophos (400 to 24%, followed by 30% in southern areas, ppm) , chlorpyrifos (200 ppm) , and phosalone 68% in northeast, and 2.9% in northern areas. (704 ppm). Phosalone caused mortality That of P. oryzae ranged 3 to 36% and, at the after 4.5 hr, indicating that it is the safest same place, that of P. foersteri 0.8 to 10.2%17>. so far as tested11,. The insecticides effective In Indonesia, parasitism by N. oryzae and P. on RGM were also toxic to the parasitoid, mirificus was low when 12 localities in west however the highest percentage of parasitiza­ and central Java were surveyed in March, tion was recorded with chlorpyrifos 10 G, in­ the wet season, 19794 >. dicating that it is safe for the parasitoid, while the emulsified concentration of the same Predacious mite insecticide recorded the lowest percentage of parasitization, indicating that it is highly In Thailand, a high potential of Amblyseius toxic to the parasitoid23 >. imbricatus as an important predator of RGM egg was preliminarily studied18>. In Indo­ Discussion nesia, A. imbricat1ts, egg predator, was the most important to maintain low population It is highly significant to note that interest­ of RGM in the concecutively planting areas ing relationship between the natural enemies at high land in West Java6 >. (parasitoids and predators) and RGM was clarified in tropical Asia with emphasis on Alternate host of parasitoids biological and ecological studies of the natural enemies in international cooperation of the P. oryzae was found to have an altemate experts of rice entomology. In Indonesia, host, Orseoliella ,iavanicci Kieffer, which oc­ importance of the parasitoids and a predator curred on lmperata cylind1·ica abundantly was found in field condition because these growing around paddy fields. During the natural enemies had a high -potential to con­ fallow season, P. oryzae attacked mainly the trol RGM in a consecutive planting area in alternate host. The parasitoid started to high land of West Java, and the parasitoids attack RGM after transplanting of rice. 0 . population was maintained for their genera­ ,iavanica was considered to have an important tions through the alternate host midge, O. role as an origin of the parasitoid occur­ ,iavanica, which occurs on I. cyl-indrica, alang­ rence5,36 > alang weeds, during the fallow season. The 179

predacious mite, A. irnb?'icat1ts, was important (1982). for feeding on eggs of the host insect. Judg­ 11) Joshi, R. C. & Venugopal, M. S.: Studies on ing from the effectiveness of these natural the toxicity of certain insecticides on Platy­ gasler sp., an egg-lnrval parasitoid of the enemies, natural conservation system must be rice gall midge, Orseolia 01·yzcw (Wood­ established in paddy fields. However, taxo­ Mason). Science ancl Ci1ltn1·e, 49,260 (1983). nomic study is also important to identify 12) Joshi, R. C., Grover, P. & Venugopal, M. S.: species of the natural enemies, then coopera­ The rice gall midge, Orseolia 01·yzae-a brief tion of taxonomists is needed. The parasitic review. Ceci

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