Biosci. Biotechnol. Biochem., 76 (11), 2153–2155, 2012 Note Female Sex Pheromone Secreted by mimosa (: ), a Biological Control Agent for an Invasive Weed in Vietnam

y Le Van VANG,1 Chau Nguyen Quoc KHANH,1 Hiroshi SHIBASAKI,2 and Tetsu ANDO2;

1Department of Plant Protection, College of Agriculture and Applied Biology, Can Tho University, Can Tho City, Vietnam 2Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan

Received June 21, 2012; Accepted July 10, 2012; Online Publication, November 7, 2012 [doi:10.1271/bbb.120483]

Larvae of the clearwing , pheromone. We therefore analyzed the pheromone gland (Lepidoptera: Sesiidae), bore into the trunk of Mimosa extract of the females and examined an optimum pigra L., which is one of the most invasive weeds in synthetic lure to monitor the males. Vietnam. GC-EAD and GC-MS analyses of a phero- M. pigra stems with galls, which included the larvae mone gland extract revealed that the female of C. mimosa, were collected in Can Tho City. After produced (3Z,13Z)-3,13-octadecadienyl acetate. A lure removing the superfluous parts, the stems (about 15 cm baited with the synthetic acetate alone successfully long) were placed in transparent plastic boxes with a attracted C. mimosa males in a field test. While the wetted cotton piece and kept under laboratory conditions addition of a small amount of the corresponding alcohol (27–30 C, 12L:12D) until emergence of the adults. The did not strongly diminish the number of captured males, adults were sexed by inspecting their abdominal tips. a trace of the aldehyde derivative or the (3E,13Z)- The abdominal tips of ten one-d-old virgin females were isomer markedly inhibited the attractiveness of the excised 3 h before the onset of the scotophase and acetate. The diurnal males were mainly attracted from soaked in hexane (100 mL/female) for 15 min to extract 6:00 am to 12:00 am. the pheromone. As the first step, the crude extract was analyzed by gas chromatography with an electroanten- Key words: pheromone; sesiid moth; male attrac- nographic (EAG) detector (GC-EAD). The GC instru- tant; 3,13-diene; ment was equipped with a DB-23 capillary column (0:25 mm 30 m, 0.25-mm film thickness, J&W Scien- The weed called mimosa, Mimosa pigra L., which is a tific), and the oven temperature was programmed to branched prickly bush in the family of Leguminosae and 80 C for 2 min, ramped at 8 C/min to 210 C, and held native to Central and South America, has invaded all for 10 min. The effluent from the column was split into tropical regions of the world. In Vietnam, M. pigra, two lines, which were led to a flame ionization detector which was found first in Long An Province in 1979,1) (FID) and EAD in a ratio of 1:1.6) By injecting aliquots has spread throughout the country and threatened the of the extract (each of 0.2 female equivalence, FE), the biodiversity of seasonally inundated grasslands.2) Many male antennae reproducibly responded to one compo- efforts, including spraying with herbicides, destruction nent (tR 18.43 min), as shown in Fig. 1A. by fire, and mechanical intervention, have been made to The pheromone extract (1.5 FE) was next analyzed by control M. pigra, but the results have not been suffi- GC combined with mass spectrometry (GC-MS) in an ciently successful due to rapid reconstitution of the electron ionization mode (70 eV). Although the same weed. New effective management such as biological GC conditions as those used for GC-EAD measurement control is therefore desired. The clearwing moth, were used, the tR values for the two analyses were Carmenta mimosa Eichlin and Passoa, inhabits Central different. Elution for the GC-MS analysis was always and South America, and the larvae bore into the stem of faster than that for the GC-EAD measurement. M. pigra. This lepidopteran species in the family of Figure 1B shows a total ion chromatogram (TIC) of Sesiidae has been introduced to Australia as a potential the crude extract and mass chromatograms of the ions at biological control agent.3,4) C. mimosa has not been m=z 248, 81, 67, and 61. The mass spectrum of the officially introduced in Vietnam, but it is frequently EAG-active component (tR 16.51 min), which showed found in Can Tho City. We are planning to utilize this Mþ at m=z 308 (0.4%) and [AcOH + 1]þ at m=z 61 species for biological control of the weed in the Mekong (2%), revealed the structure of octadecadienyl acetate. Delta as well. Since monitoring the survival, spread, and Most of the known sesiid pheromones are composed of abundance of agents is indispensable to evaluate a 3,13-octadecadienyl compounds, and some sesiid spe- biological control program,1,4) the sex pheromone is one cies secrete 2,13-octadecadienyl compounds.7,8) Table 1 of the most essential tools. While the attraction of shows GC-MS data for a series of synthetic acetates C. mimosa males by (3Z,13Z)-3,13-octadecadienyl ace- measured with a DB-23 column. The tR and Kovats tate (Z3,Z13-18:OAc) has been reported,5) it is impor- retention index (KI) values for the natural pheromone tant to understand the chemical structure of the natural coincide well with those of a (3Z,13Z)-isomer of the

y To whom correspondence should be addressed. Tel/Fax: +81-42-388-7278; E-mail: [email protected] 2154 L. V. VANG et al. A B Z3,Z13-18:OAc Z3,Z13-18:OAc E3,Z13-18:OAc Z3,E13-18:OAc E3,E13-18:OAc Z3,Z13-18:OH EAD ------

m/z 61 0.1 mV

m/z 67

FID m/z 81

m/z 248 ------16.0 18.0 20.0 15.0 16.0 17.0 tR (min) tR (min)

Fig. 1. Analyses of the Sex Pheromone of Carmenta mimosa Females by GC-EAD (A) and GC-MS (B). A, chromatograms of the pheromone extract (0.2 FE) recorded by EAD and FID; B, TIC of the pheromone extract (1.5 FE) and mass chromatogram of fragment ions at m=z 248 (M 60), 81 (base peak), 67, and 61. Dashed line arrows on TIC indicate tR of some structurally related compounds (authentic standards) which were not detected in the extract.

Table 1. GC-MS Data for a Natural Pheromone Component and at m=z 248 is diagnostic for octadecadienyl acetates Synthetic Standards (½M 60þ) and the corresponding alcohols þ GC data Relative intensity (%) (½M 18 ), and the ions at m=z 81 and 67 are Compound B/A 100 abundantly present in the mass spectra of both types a tR (min) KI 67 (A) 248 (B) of compounds. While the pheromone extract used for the Natural pheromone 16.51 2639a 98 22 22 GC-MS analysis was limited, the mass chromatograms Z3,Z13-18:OAc 16.51 2639b 96 21 22 at m=z 248, 81, and 67 in Fig. 1B indicate a possibility b E3,Z13-18:OAc 16.40 2627 99 17 17 that the C. mimosa females produced no structurally Z3,E13-18:OAc 16.32 2618b 96 21 22 E3,E13-18:OAc 16.23 2606b 100 20 20 related compounds. Z2,Z13-18:OAc 16.52 2640b 87 29 33 Based on the GC-EAD and GC-MS analyses, a field E2,Z13-18:OAc 16.66 2658b 84 28 33 attraction study of C. mimosa males with the synthetic Z2,E13-18:OAc 16.33 2619b 82 30 37 pheromone candidate and related compounds, which had E2,E13-18:OAc 16.47 2636b 84 30 36 been supplied by Shin-etsu Chemical Co. or synthesized 9,12) A crude pheromone extract of Carmenta mimosa and each synthetic isomer in our previous studies, was carried out in Can Tho of 3,13- and 2,13-octadecadienyl acetates were analyzed by GC-MS, using City. Each test compound (>98% purity) was applied to an instrument equipped with a DB-23 capillary column and operated in an a rubber septum (white rubber, 9 mm OD, Sigma- electron ionization mode (70 eV). Aldrich), and the lure was placed at the center of a sticky aColumn temperature: 80 C for 2 min and 8 C/min to 210 C. bPublished data for synthetic standards.9) Column temperature: 100 C for board trap (SE-trap , 30 cm 27 cm bottom plate with 2 min, 20 C/min to 175 C and 6 C/min to 220 C. a roof; Sankei Chemical) which was hung at 1.5 m in height in an area with abundant M. pigra. The field evaluation of the single-component lures baited with one 3,13-diene and a (2Z,13Z)-isomer of the 2,13-diene.9) geometrical isomer of 3,13- and 2,13-octadecadienyl The mass spectra of the two acetates have many aspects acetates indicated that only the traps of Z3,Z13-18:OAc of similarity, but the relative intensity between two ions (1.0 mg) caught the C. mimosa males (5:6 3:2 males/ at m=z 248 and 67 of the 3,13-diene is smaller than that trap/night for two weeks). This result supported the of the 2,13-diene. The value for the natural pheromone experiment on male attraction in Central America,5) and coincides well with that for the 3,13-diene. Since the clarified that Z3,Z13-18:OAc indeed mediated the two positional isomers of octadecadien-1-ol have been mating communication of this diurnal species as an more clearly differentiated by their GC-MS data than the important chemical cue. isomers of the acetate,9) the acetate component in the Lepidopteran species usually secrete a multi-compo- crude extract (5.0 FE) was saponified with K2CO3, and nent pheromone to establish a species-specific commu- the resulting alcohol was analyzed by GC-MS. The nication system.13) The females of many sesiid species chromatographic behavior (KI, 2684) and small relative secrete a mixture of dienyl compounds with a different intensity (1%) of the ion at m=z 248 confirmed the 3,13- functional group and/or geometrical isomers.7,8) While dienyl structure of the natural pheromone. While the no minor pheromone components could be found in the double-bond positions have not been determined by such pheromone gland of C. mimosa, our interest in the other chemical experiments as DMDS derivatiza- activities of the structurally related compounds of tion,10,11) we concluded that the EAG-active component Z3,Z13-18:OAc prompted us to carry out two field in the pheromone extract was Z3,Z13-18:OAc. The ion tests, Test 1 and Test 2, as shown in Table 2. Addition Sex Pheromone of a Clearwing Moth 2155 Table 2. Field Attraction of Carmenta mimosa Males by Lures the structurally related compounds. It might be neces- Baited with 3,13-Octadecadienyl Compound(s) sary for the males to respond to several compounds to Lure component (mg) keep away from other sesiid species in the place of Captured males origin. Z3,Z13-18: E3,Z13-18: /trap/nighta The daily light cycle is nearly 12L:12D in the OAc OH Ald OAc Mekong Delta of Vietnam, the photo phase starting at Test 1 1.0 0 0 0 5:0 3:9 a around 6:00 am throughout the year. Pheromone traps 1.0 0.1 0 0 4:8 1:7 a were examined three times a day (at 6:00 am, 12:00 am, 1.0 0 0.1 0 0:1 0:1 b and 6:00 pm) for one week in order to identify the active 1.0 0 0 0.1 0.0 time of the C. mimosa males. This observation revealed 1.0 0.1 0.1 0 0:1 0:0 b that more than 80% of males were captured during the 1.0 0.1 0.1 0.1 0.0 0 0 0 0 0.0 period from 6:00 am to 12:00 am. We are using pheromone traps to further investigate ecological aspects Test 2 1.0 0 5:4 3:7 a of C. mimosa to apply the species as a biological control : : 0.95 0.05 3 7 1 9 a agent for the M. pigra weed. 0.9 0.1 3:8 2:1 a 0.8 0.2 0:6 0:7 b 0.5 0.5 0:3 0:3 b Acknowledgments 0 1.0 0:3 0:3 b 0 0 0.0 We thank Dr. Yutaka Arita for identifying the insect. Tests were carried out from March 5 to 25 in 2012 (Test 1) and from March The authors are grateful to Drs. Fumiaki Mochizuki and 28 to April 18 in 2012 (Test 2) in Can Tho City (Vietnam), using four traps Takehiko Fukumoto of Shin-etsu Chemical Co., Ltd., for for each lure. supplying Z3,Z13-18:OAc and E3,Z13-18:OAc. This a Mean SE. Values within each test followed by a different letter are study was supported in part by grant-in-aid to JSPS significantly different at p < 0:05 by the Tukey-Kramer test. Fellows (2200097). to the lure of the aldehyde derivative (Z3,Z13-18:Ald) or References (3E,13Z)-isomer (E3,Z13-18:OAc) at a 10% ratio strongly inhibited the attractiveness of Z3,Z13- 1) Triet T, Kiet LC, Thi NTL, and Dan PQ, ‘‘Research and Management of Mimosa pigra,’’ eds. Julien M, Flanagan G, 18:OAc. Since the effect of the alcohol derivative Heard T, Hennecke B, Paynter Q, and Wilson C, CSIRO (Z3,Z13-18:OH) was not clear in Test 1, lures with Entomology, Canberra, pp. 45–51 (2004). 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