Appl. Entomol. Zool. 40 (3): 483–488 (2005) http://odokon.ac.affrc.go.jp/

Attraction of medinalis (: ) males in Southeast to female sex pheromone traps: Field tests in southernmost China, northern Vietnam and southern Philippines with three synthetic pheromone blends regarding geographic variations

Kei KAWAZU,1,*,† Yoshito SUZUKI,2 Yutaka YOSHIYASU,3 Efieda B. CASTILLON,4 Hiroshi ONO,5 Pham Thi VUONG,6 Feng-Kuan HUANG,7 Taro ADATI,8 Takehiko FUKUMOTO9 and Sadahiro TATSUKI1 1 Graduate School of Agricultural and Life Sciences, The University of Tokyo; Tokyo 113–8657, Japan 2 National Agricultural Research Center; Tsukuba, Ibaraki 305–8666, Japan 3 Graduate School of Agriculture, Kyoto Prefectural University; Kyoto 606–8522, Japan 4 Bohol Agricultural Promotion Center; Dao District, Tagbilaran City, The Philippines 5 Appropriate Agriculture International Co., Ltd.; Machida, Tokyo 194–0013, Japan 6 Ministry of Agriculture and Rural Development, Vietnam National Institute for Plant Protection; Dong Ngac, Tu Liem, Hanoi, Vietnam 7 Institute of Plant Protection Guangxi Academy of Agricultural Sciences; Daxue Road 44, 530007, Nanning, P. R. China 8 International Institute of Tropical Agriculture; Kano Station, Kano, Nigeria 9 Specialty Chemicals Research Center, Shin-Etsu Chemical Industry Co., Ltd.; Joetsu, Niigata 942–8601, Japan (Received 9 August 2004; Accepted 31 March 2005)

Abstract Field tests of three types of synthetic sex pheromone blend (Japanese blend: Z11-18:Ald (55 mg), Z13-18:Ald (500 mg), Z11-18:OH (120 mg) and Z13-18:OH (180 mg), Indian blend: Z11-16:Ac (50 mg) and Z13-18:Ac (500 mg) and Philippine blend: Z11-16:Ac (500 mg) and Z13-18:Ac (10 mg) based on geographic variations in sex pheromones so far reported) for the leaffolder , Cnaphalocrocis medinalis Guenée (Lepidoptera: Crambidae), were per- formed at Nanning, in southernmost China, Hanoi, in northern Vietnam, and on Bohol, an island in the southern Philippines. In all of these tests, only the Japanese blend attracted significant numbers of male C. medinalis, while neither the Indian nor the Philippine blend showed any attractiveness to the males. The results at Nanning and Hanoi, from which the Japanese population may originate from, support the current inference about the migration routes of C. medinalis. On the contrary, the results on Bohol, in the Philippines, were unexpected and showed the presence of a population responding to the Japanese blend, but not to the Philippine blend.

Key words: Rice leaffolder; Cnaphalocrocis medinalis; geographic variation; sex pheromone

China, such as the Fujian and Guangdong INTRODUCTION provinces, as with rice planthoppers (Wada et al., The rice leaffolder, Cnaphalocrocis medinalis, is 1980; Kamiwada et al., 1994). a migratory rice pest widely distributed in humid In the Asian populations of C. medinalis, geo- tropical to temperate countries of Asia, Oceania graphic variations in the female sex pheromone and Africa (Khan et al., 1988). In Japan, C. medi- blend have been reported: Sex pheromone blend of nalis fails to over-winter and the early summer Indian and pheromone-like components of Philip- adults are thought to be overseas migrants, mostly pine populations consist of (Z)-11-hexadecenyl from the rice double-cropping areas of southern acetate (Z11-16:Ac) and (Z)-13-octadecenyl

*To whom correspondence should be addressed at: E-mail: [email protected] † Present address: Department of Electronic Chemistry, Tokyo Institute of Technology, Yokohama, Kanagawa 226–8502, Japan DOI: 10.1303/aez.2005.483

483 484 K. KAWAZU et al. acetate (Z13-18:Ac) at ratios of 1–6:20 (Indian crude extract of Japanese populations (Kawazu et blend) (Ganeswara Rao et al., 1995) and 98:2 al., 2000). (Philippine blend) (Ramachandran et al., 1990). On For the background described above, we exam- the contrary, a blend of a Japanese population con- ined the responsiveness of male C. medinalis to sex sists of different components, (Z)-11-octadecenal pheromone using synthetic Japanese, Philippine (Z11-18:Ald), (Z)-13-octadecenal (Z13-18:Ald), and Indian blends in paddy fields at Nanning, in (Z)-11-octadecen-1-ol (Z11-18:OH) and (Z)-13- southernmost China; Hanoi, in north Vietnam; and octadecen-1-ol (Z13-18:OH) at a ratio of 11 : 100 : on Bohol Island, in the Philippines. 24 : 36 (Kawazu et al., 2000). Field tests in Japan using the above three synthetic blends have shown MATERIALS AND METHODS that only the Japanese blend had significant attrac- tiveness to male C. medinalis (Kawazu et al., 2000, Chemicals. Synthetic monounsaturated alde- 2001, 2002). Also, in field tests at Hangzhou in the hydes, alcohols and acetates were synthesized by lower Yangzhe Valley, China, with the same three Shin-Etsu Chemical Company (Tokyo, Japan). The blends, only the Japanese blend was significantly compounds were purified by column chromatogra- attractive (Kawazu et al., 2002). These results are phy in the same manner as reported in our previous consistent with the inference described earlier, report (Kawazu et al., 2000). Gas chromatographic since the populations in the lower Yangzhe (GC) analyses showed that the purified compounds Valley may also originate from the annual migrants contained 0.1% of the corresponding E-isomers from the rice double-cropping areas of southern (Kawazu et al., 2000). The GC analyses were con- China (National Coordinated Research Team, ducted on a Shimadzu GC-17A gas chromatograph 1981; Chen et al., 1989; Suzuki and Wada, 1994; equipped with an FID and a splitless injector sys- Sogawa, 1995). Furthermore, since C. medinalis in tem. The column used was a chemically bonded, the rice double-cropping areas cannot over-winter, fused silica capillary column coated with DB-23 they also may originate from migrants from south- (30 m0.25 mm ID, J&W Scientific, CA, USA). ernmost China (areas to the south of 22°N latitude) Field tests. Baits were prepared using gray halo- and/or northern Vietnam where C. medinalis can butyl isoprene blend elastomer septa (West Co., breed all year round (National Coordinated Re- Singapore). Each pheromone blend containing the search Team, 1981; Chen et al., 1989). It is there- required amounts and ratios of the synthetic com- fore interesting to examine the responsiveness of pounds mixed with 200 ml hexane was poured onto males to the sex pheromones in populations in the inner surface of a rubber septum. After evapo- southernmost China and northern Vietnam in- ration of the solvent, the baits were placed in alu- cluded in the putative primary emigration area of minum-laminated polyethylene bags and stored C. medinalis populations migrating to Japan. at 20°C until use. The composition and amount On the other hand, it may also be possible that C. of the synthetic pheromone components used for medinalis originating from islands in Southeast each septum were as follows: Japanese blend: Asia, including the Philippines, migrate to Japan Z11-18:Ald (55 mg), Z13-18:Ald (500 mg), with the aid of seasonal southerly and south-west- Z11-18:OH (120 mg) and Z13-18:OH (180 mg); erly winds (Mills et al., 1996). In such a case, male Philippine blend : Z11-16:Ac (500 mg) and responding to the Philippine blend would Z13-18:Ac (10 mg); and Indian blend: Z11-16:Ac appear in Japan. But, until now, no significant at- (50 mg) and Z13-18:Ac (500 mg). traction of C. medinalis males by the Philippine Tests were conducted in paddy fields in Nanning blend has been recorded in Japan (e.g., Kawazu et (22°48N, 108°20E), China (May 31–June 16, al., 2001), suggesting no migration routes of C. 2002), Hanoi (21°02N, 105°51E), Vietnam (Aug. medinalis to Japan from the Philippines. In the re- 29–Sep. 22, 2002) and on Bohol Is. (9°50N, port regarding the identification of the Philippine 124°10E), the Philippines (Aug. 7–Oct. 2, 2001 blend, no behavioral activity has been demon- and Mar. 14–May 2, 2002). Cone traps slightly strated; only EAG activity was reported (Ra- modified from those reported by Kawasaki and machandran et al., 1990). In our analyses, neither Sugie (1990) were used. The traps were arranged Z11-16:Ac nor Z13-18:Ac were detected in the in two blocks, each with traps containing a set of Attraction of the Rice Leaf Folder Moth to the Sex Pheromone Traps 485 baits (Japanese, Indian and Philippine blends, and control). Pheromone traps were set at the bound- aries of the paddy fields and at the height of the top of the rice plants. The distance between traps within a block was greater than 10 m and the dis- tance between blocks was greater than 10 m. When checking the number of trapped moths, the trap lo- cations were moved one position within a block. The number of trapped moths was checked every 3 or 4 d. The captured moths in the Philippines and Vietnam were morphologically identified. For statistical analyses, the total number of trapped males for each treatment on a checking day were transformed to SQRT (X0.5) and differ- ences among means were tested for significance by Tukey’s test. Morphology species identification. The genus Cnaphalocrosis contains about 35 species in the world (Robinson et al., 1994). The species of the genus share similar wing markings and a bifur- cated uncus in the male genitalia. A rice pest, Cnaphalocrosis patralis, described and recorded from the Philippines (Bradley, 1981), is the most closely related species to C. medinalis in terms of wing markings and genitalic character- istics. However, the former species is easily sepa- rated from the latter by a displaced post-medial line in the forewing and the lack of the harpe on the vulva (spur-like projection in Bradley, 1981) seen in C. medinalis in the male genitalia (Kawazu et al., 2000), and other characteristics. C. medinalis is also distinguished from another related species, Cnaphalocrosis pilosa (Warren, 1896), in the ovate and simpler vulva, together with a straight post- medial line in the forewing.

RESULTS In the present tests at Nanning, China, Hanoi, Vietnam and Bohol Is., the Philippines, only the Japanese blend showed significant attractiveness to male C. medinalis moths, while neither the Indian nor the Philippine pheromone blends attracted Fig. 1. Comparison of attractiveness of different synthetic males (Fig. 1). pheromone blends to Cnaphalocrocis medinalis males at three sites in Southeast Asia. a: Nanning, China in 2002, b: Hanoi, At Nanning, despite the short testing periods, the Vietnam in 2002, and c: Bohol Island, the Philippines in 2001 Japanese blend attracted a large number of male and 2002. Values with the same letter at each site were not sig- moths (9.9 moths/trap/d), while the Indian and nificantly different at 5% by Tukey’s test. Philippine blends attracted no moths (Fig. 1a). At Hanoi, the Japanese blend attracted a number of male moths (3.4 moths/trap/d), both the Indian and 486 K. KAWAZU et al.

Philippine blends attracted a small number of males of C. medinalis, yet the number was not sig- nificantly different from the control (Fig. 1b). On Bohol Island, a relatively small number of trap catches (0.3 moths/trap/d in the wet season and 0.4 moths/trap/d in the dry season) were obtained (Fig. 1c). This was probably due to very low popu- lation densities, since almost no moths or injury to rice leaves by the larvae could be observed in the testing field. Each of the Indian and Philippine blends attracted one female of C. patnalis, a closely related species to C. medinalis, in 2002 in the Philippines. Neither the Indian nor Philippine blends attracted Cnaphalocrocis pilosa males in our field test. This may have been due to a low population density of C. pilosa.

DISCUSSION The present results obtained from all of the test sites during the specified periods in southernmost Fig. 2. Schematic diagram of movements of C. medinalis China, north Vietnam and the southern Philippines and the likely source areas in the spring and summer seasons are quite similar to those obtained from various in southeastern and eastern Asia. See text for details. sites in Japan and Hangzhou, China. This suggests that C. medinalis populations, of which males re- the period of moth occurrences. spond to the Japanese blend, are widely distributed C. medinalis may originate from migrants from from eastern Asia through Southeast Asia. southernmost China (areas to the south of 22°N The primary emigration areas of C. medinalis latitude) and/or northern Vietnam to the rice dou- migrating to the east Asian region have been in- ble-cropping areas of southern China from April to ferred to be in southernmost China and/or northern May with the aid of southwesterly monsoons. Vietnam, like the rice planthoppers, Nilaparvata Thereafter, C. medinalis in the rice double-crop- lugens (Stål) and Sogatella furcifera (Horvarth) ping areas of southern China may migrants to (Hemiptera: Delphacidae), of which the seasonal Japan, the middle of China and Korea from June to occurrence pattern in eastern Asia is quite similar July with the aid of the low-level jet streams to that of C. medinalis (National Coordinated Re- (Fig. 2). On the other hand, from the results in the search Team, 1981; Chen et al., 1989; Suzuki and Philippines, it is also possible that C. medinalis Wada, 1994; Sogawa, 1995). The results at Nan- moths originating from the Philippines migrate to ning, China, and Hanoi, Vietnam, in which only Japan in spring and summer with the aid of sea- the Japanese blend among the three blends tested sonal southerly and southwest winds (Fig. 2). was attractive, support the above inference as well The Philippine blend used in the present tests as the validity of the use of the Japanese blend for was prepared based on Ramachandran et al. monitoring C. medinalis in Japan. (1990). It is possible that geographic variations in On the other hand, the results on Bohol were un- the pheromone system are present within the expected. Contrary to our expectations that male Philippines as previously reported with the sex moths would be attracted to the Philippine blend, pheromones of other species such as Agrotis sege- here also only the Japanese blend showed signifi- tum (Tóth et al., 1992), if Ramachandran et al. cant attractiveness, whereas the Philippine blend used a population of another locality in the Philip- did not. Also, the very low number of the trap pines for their pheromone identification. This also catches (Philippine blend) may have been due to a might indicate the occurrence of pheromone-based very low population density and/or differences in assertive mating or random mating as has been Attraction of the Rice Leaf Folder Moth to the Sex Pheromone Traps 487 found with population using different pheromone mology.Agricultural Press, Beijing. 409 pp. (in Chi- blends of Ostrinia scapulalis (Takanashi et al., nese). 2005). Since, however, in their report descriptions Ganeswara Rao, A., D. D. R. Reddy, K. Krishnaiah, P. S. Beevor, A. Cork and D. R. Hall (1995) Identification about the collection locality of the used and and field optimization of the female sex pheromone of the the behavioral activity of the pheromone compo- rice leaffolder, Cnaphalocrocis medinalis in India. En- nents are lacking, verification of the female sex tomol. Exp. Appl. 74: 195–200. pheromone system of this species in the Philip- Kamiwada, H., A. Tanaka and T. Haruguchi (1994) Mass pines may be of interest. immigration and occurrence of the rice leafroller, Cnaphalocrocis medinalis Guenée, in Kagoshima prefec- The EAG-active components of C. patnalis were ture in 1993. Proc. Assoc. Plant Protec. Kyushu 40: reported to be Z13-18:Ac and Z11-16:Ac at a 98–101 (in Japanese). 96 : 4 ratio (Ramachandran et al., 1990), which is Kawasaki, K. and H. Sugie (1990) A simple sex pheromone very close to the Indian pheromone blend. In this cone trap. Jpn. J. Appl. Entomol. Zool. 34: 317–319 (in research, however, the Indian blend attracted no Japanese with English summary). male C. patnalis moths in the Philippines. This Kawazu, K., J. Hasegawa, H. Honda, Y. Ishikawa, S. Waka- mura, H. Sugie, H. Kamiwada, T. Kamimuro, Y. may have been due to a low population density. It Yoshiyasu and S. Tatsuki (2000) Geographical variation will be necessary to conduct pheromonal research in female sex pheromones of the rice leaffolder moth, on the C. patnalis over a wide area of the Philip- Cnaphalocrocis medinalis: identification of pheromone pines. components in Japan. Entomol. Exp. Appl. 96: 103– C. medinalis is regarded as a member of the 109. Kawazu, K., K. Nagata, Z. Zhang, H. Sugie and S. Tatsuki Cnaphalocrocis species, to which many related (2002) Comparison of attractiveness in Japan and China species exist. Various populations of C. medinalis of three synthetic pheromone blends based on geographic depend on the habit. 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