Recent Studies on Natural Enemies of the Rice 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> . Cecidomyiidae, Diptera, is one of the im­ In the present paper, the authors introduce portant insect 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 China, India, 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 species 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 pest 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 larva 70 to 90 % of RGM pupae in West Java31 >. or a pupa 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.