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| Country or region name | Japan |
| Organism group | insect |
| Order name | Coleoptera |
| Family name | Curclionidae |
| Species name | Euscepes postfasciatus |
| English common name | West Indian sweetpotato weevil |
| Substantially same species (synonym) | |
| Year of invasion or detection | 1947 |
| Native region | West Indies |
| Situation of establishment | Category 3: Settled before 1950, but not distributed all over the country |
| Taxonomic description | |
| Expansion of distribution area | |
| In Japan, the weevil restricted to the Ryukyu Archipelago and the
Ogasawara Islands, southernmost part of Japan (Yasuda and Kohama, 1990;
Miyaji and Tanaka, 1998). It was first found at Okinawa Island in 1947
(Asato, 1950). The weevil is considered to have been accidentally introduced
into Okinawa Island from Hawaii or Saipan in US military cargo (Takara,
1954) and/or from foreign countries to the south with Japanese repatriates
after the World War II (Kohama, 1990). The current northern limit of the
weevil is the Amami Islands in the Ryukyu Archipelago.
After first appearing in the central part of Okinawa Island in 1947, the weevil expanded rapidly across the entire island in 1952. In 1951, the weevil was also found on Miyako and Yaeyama Islands (Takara, 1954). Its distribution has been northward; it reached Okinoerabu Island in 1966 (Sakae, 1968), Yoron Island in 1968 (Miyake, 1968), and Amami Island (Miyaji and Tanaka, 1998). Although adults of E. postfasciatus possess well-developed hind wings, they do not fly (Sherman and Tamashiro, 1954; Raman and Alleyne, 1991). Therefore, flight is not a means of dissemination of this weevil. Infestation of a field occurs by means of infested cuttings, adults crawling from adjacent infested fields, and by other mechanical means. Infested cuttings or roots of sweet potato carry the weevils to newly planting area. (Tucker, 1937; Sherman and Tamashiro, 1954; Alleyne, 1982). Adults move out from infested fields by crawling, and invade into adjacent newly planted field (Yasuda, 1997a). The dispersal rate of 33m per 5-day period in the cleared field (without host plants) shows high mobility of this flightless beetle under some unsuitable habitat conditions (Kinjo et al., 1995). Shimizu and Moriya (1996) estimated the distance walked in this weevil measured by an actograph in laboratory. The total estimated distance walked for the 7 days were 13.8-426.9m (averaged 218m) in females and 13.8-487.5m (averaged 177.9m) in males. |
|
| Environmental impact | |
| In Japan, the weevil is the most serious pest of sweet potato in the Ryukyu Islands (Kohama, 1990). When a root is heavily infested, the entire root is riddled and filled with fecal matter (Sherman and Tamashiro, 1954). An unpleasant smell is characteristic of such damage and roots so affected taste bitter (Alleyne, 1982). Larval damage is similar to that of Cylas formicarius and caused roots to produce furano-terpenoids and coumarins, making them unpalatable (Uritani et al., 1975). Yasuda (1997b) determined the control threshold on sweet potato damaged by E. postfasciatus. He calculated the regression equation express the relationship between the proportion of damaged storage roots at harvest and the percentage of injured stems on day 75 after planting. Based on this equation, the threshold level of stems injured during the growing period for a tolerable injury level (13.6% of roots damaged at harvest) was estimated to be 5%. The insecticide application for this control threshold was as effective as the conventional application; three applications could be reduced to two. | |
| Economic damage | |
| In Japan, the weevil is the most serious pest of sweet potato in the Ryukyu Islands (Kohama, 1990). When a root is heavily infested, the entire root is riddled and filled with fecal matter (Sherman and Tamashiro, 1954). An unpleasant smell is characteristic of such damage and roots so affected taste bitter (Alleyne, 1982). Larval damage is similar to that of Cylas formicarius and caused roots to produce furano-terpenoids and coumarins, making them unpalatable (Uritani et al., 1975). Yasuda (1997b) determined the control threshold on sweet potato damaged by E. postfasciatus. He calculated the regression equation express the relationship between the proportion of damaged storage roots at harvest and the percentage of injured stems on day 75 after planting. Based on this equation, the threshold level of stems injured during the growing period for a tolerable injury level (13.6% of roots damaged at harvest) was estimated to be 5%. The insecticide application for this control threshold was as effective as the conventional application; three applications could be reduced to two. | |
| Reproduction | |
| Growth | |
| Females lay eggs singly in both root and stem of sweet potato. Larvae grow within the host plants. Pupation occurs within a small chamber prepared by the larva. Adult eclosion also occurs in the pupal chamber. Adults are sexually immature when they emerge from pupae. Most adults stay within host plants for more than 10 days and emerge from the host after sexual maturation. Adults feed on sweet potato tissue and emerge by chewing exit holes (Sherman and Tamashiro, 1954; Kohama and Shimoji, 1998). Adults live for up to 6 months in the laboratory. Females can lay fertile eggs over a period of four to six months. Mated females lay an average of 106 eggs per month. At 24-27 C, the eggs hatch after 7-9 days; larvae develop into pupae after 18-30 days and the pupal stage lasts 7-10 days. The preoviposition period is 9-13 days at 25 C (Kohama and Shimoji, 1998). In the subtropical conditions of Okinawa, southern part of Japan, this weevil remains active throughout the year and completes up to 4 overlapping generations (Yasuda, 1998). Adults move actively during the scotophase in the laboratory (Shimizu and Moriya, 1996). Reproductive activities are also observed during the dark period (Shimoji and Kohama, 1994). | |
| Countermeasure | |
| Yasuda (1991) showed that spot treatment of granulated chemicals around the stem was more effective than the conventional practice of spraying uniformly throughout the field. When 3% carubosurufan granule is applied on the ground around the stems at a dose of 1g per plant, the infestation level and the number of weevil is suppressed in both stems and roots. Transportation of fresh sweet potato from Okinawa to mainland Japan is prohibited under the regulation of the Plant Protection Law of Japan. To solve this problem, an experimental eradication project for the weevil with Sterile Insect Technique (SIT) is currently in progress on Kume Island, Okinawa, Japan (Kuba et al., 2000; Yamagishi and Shimoji, 2000; Kuba, et al., 2003). One larval parasitoid, Bracon sp. (Braconidae) has been reported in Okinawa, Japan (Yasuda, 1998). | |
| Writer's name and affiliation | |
| © Written by Kohama, T. Okinawa Prefectural Government, Fruitfly Control Project Office. (Witten on 30 Oct. 2004) | |
| Organism group | plant |
| Order name | Solanales |
| Family name | Convolvulaceae |
| Species name | Ipomea batatas |
| English common name | sweet potato |
| Substantially same species (synonym) |
| No. | Kind of Photo | Photo | Name of copyright holder and explanation of photo |
| 1 | Alien species |  |
© Kohama, T. Adults of Euscepes postfasciatus |
| 2 | Alien species |  |
© Kohama, T. An larva of Euscepes postfasciatus |
| 3 | Alien species |  |
© Kohama, T. An pupa of Euscepes postfasciatus |
| 4 | Damage |  |
© Kohama, T. Damaged sweet potatoes by Euscepes postfasciatus |
| 1 | Author | Alleyne EH. |
| Year | 1982 | |
| Title | Studies on the biology and behavior of the West Indian sweet potato weevil, Euscepes postfasciatus (Fairmaire) (Coleoptera: Curculionidae). | |
| Magazine | Caribbean Food Crop Society | |
| Volume | 18 | |
| Number | ||
| Page | 236-243 | |
| Summary | ||
| Key Word | Euscepes postfasciatus, West Indian sweet potato weevil, behavior, biology, Coleoptera, Curclionidae | |
| 2 | Author | Asato S. |
| Year | 1950 | |
| Title | The West Indian sweet potato weevil: a new insect pest of sweet potato (Coleoptera: Curculionidae). (In Japanese). | |
| Magazine | Kunigami-noho | |
| Volume | 2 | |
| Number | 8 | |
| Page | 5-11 | |
| Summary | ||
| Key Word | West Indian sweet potato weevil, Euscepes postfasciatus, Coleoptera, Curclionidae, sweet potato | |
| 3 | Author | Kayumi, J., K. Kiritani, T. Shimohata, H. Yasuda, H. Tsuzuki and T. Asayama |
| Year | 1984 | |
| Title | Studies on the Population Dynamics of the Rice Water Weevil, Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curclionidae). (In Japanese with English summary) | |
| Magazine | Jap. J. appl. Ent. Zool. | |
| Volume | 28 | |
| Number | ||
| Page | 274-281 | |
| Summary | ||
| Key Word | rice water weevil | |
| 4 | Author | Kinjo K, Ito Y, Higa Y. |
| Year | 1995 | |
| Title | Estimation of population density, survival and dispersal rates of the West Indian sweet potato weevil, Euscepes postfasciatus Fairmaire (Coleoptera: Curcurionidae). | |
| Magazine | Applied Entomology and Zoology | |
| Volume | 30 | |
| Number | 2 | |
| Page | 313-318 | |
| Summary | ||
| Key Word | West Indian sweet potato weevil, Euscepes postfasciatus, population density, survival rate, sispersa Coleoptera, Curclionidael | |
| 5 | Author | Kohama T, Shimoji Y. |
| Year | 1998 | |
| Title | Reproductive maturity of the female West Indian sweet potato weevil, Euscepes postfasciatus (Fairmaire) (Coleoptera: Curculionidae). | |
| Magazine | Applied Entomology and Zoology | |
| Volume | 33 | |
| Number | 1 | |
| Page | 1-4 | |
| Summary | ||
| Key Word | West Indian sweet potato weevil, Euscepes postfasciatus, Coleoptera, Curclionidae, reproductive maturity | |
| 6 | Author | Kohama T. |
| Year | 1990 | |
| Title | Invasion and colonization of the sweetpotato weevils in Okinawa and current problems for their control. (In Japanese). | |
| Magazine | Plant Protection | |
| Volume | 44 | |
| Number | 3 | |
| Page | 115-117 | |
| Summary | ||
| Key Word | West Indian sweet potato weevil, Euscepes postfasciatus, Coleoptera, Curclionidae, invasion, control, Okinawa | |
| 7 | Author | Kuba H, Teruya T, Sakakibara M. |
| Year | 2000 | |
| Title | Eradication of weevils by Sterile-Insect-Release Methods (9) Experimental eradication project of sweet potato weevils in Kume Island.( In Japanese). | |
| Magazine | Plant Protection | |
| Volume | 54 | |
| Number | 11 | |
| Page | 483-486 | |
| Summary | ||
| Key Word | sweet potato weevil, Euscepes postfasciatus, Cylas formicarius, Coleoptera, Curclionidae, eradication, sterile insect release method | |
| 8 | Author | Kuba, H., T. Kohama and D. Haraguchi |
| Year | 2003 | |
| Title | Eradication projects of exotic sweet potato weevils using SIT in Okinawa. | |
| Magazine | Proceedings of the NIAES-FFTC joint international seminar on biological invasions | |
| Volume | ||
| Number | ||
| Page | 273-287 | |
| Summary | ||
| Key Word | eradication, sweetpotato weevil, West Indian sweet potato weevil, SIT, Okinawa | |
| 9 | Author | Miyaji K, Tanaka T. |
| Year | 1998 | |
| Title | Geographic distribution of the sweet potato weevil, Cylas formicarius Fabricius (Coleoptera; Brentidae) and the small sweet potato weevil, Euscepes postfasciatus Fairmaire (Coleoptera; Curculionidae) in the Amami Islands. (In Japanese). | |
| Magazine | Kyushu Plant Protection Research | |
| Volume | 44 | |
| Number | ||
| Page | 88-92 | |
| Summary | ||
| Key Word | sweetpotato weevil, geographic distribution, Cylas formicarius, small sweet potato weevil, Euscepes postfasciatus, Coleoptera, Amami Islands | |
| 10 | Author | Miyake T. |
| Year | 1968 | |
| Title | Confirmation of occurrence of the West Indian sweetpotato weevil in Yoron. (In Japanese). | |
| Magazine | Kyushu Shokubutu-boeki | |
| Volume | 297 | |
| Number | ||
| Page | 3 | |
| Summary | ||
| Key Word | West Indian sweetpotato weevil, occrrence, Coleoptera, Curclionidae | |
| 11 | Author | Raman KV, Alleyne EH. |
| Year | 1991 | |
| Title | Biology and management of the West Indian sweet potato weevil, Euscepes postfasciatus. In: Jansson RK, Raman KV, eds. Sweet potato pest management, a global perspective. | |
| Magazine | Westview Press | |
| Volume | ||
| Number | ||
| Page | 263-281 | |
| Summary | ||
| Key Word | WEst Indian sweet potato weevil, Euscepes postfasciatus | |
| 12 | Author | Sakae M. |
| Year | 1968 | |
| Title | The West Indian sweet potato weevil. In: Plant Quarantine Insect Pests in Amami Islands. (In Japanese) | |
| Magazine | Report of the Ohshima Branch, Kagoshima Prefectural Agricultural Experiment Station: (in Japanese). | |
| Volume | ||
| Number | ||
| Page | 49-58 | |
| Summary | ||
| Key Word | West Indian sweet potato weevil, Euscepes postfasciatus, Amami Islands | |
| 13 | Author | Sherman M, Tamashiro M. |
| Year | 1954 | |
| Title | The sweetpotato weevils in Hawaii: their biology and control. | |
| Magazine | Hawaii Agricultural Experiment Station Technical Bulletin. | |
| Volume | 23 | |
| Number | ||
| Page | 1-36 | |
| Summary | ||
| Key Word | sweetpotato weevils, Hawaii, biology, control, Euscepes postfasciatus | |
| 14 | Author | Shimizu T, Moriya S. |
| Year | 1996 | |
| Title | Daily locomotor activity in the Indian sweet potato weevil, Euscepes postfasciatus (Fairmaire) (Coleoptera: Curculionidae) and sweet potato weevil, Cylas formicarius (Fabricius) (Coleoptera: Brentidae) monitored by an actograph system. | |
| Magazine | Applied Entomology and Zoology | |
| Volume | 31 | |
| Number | 4 | |
| Page | 626-628 | |
| Summary | ||
| Key Word | West Indian sweet potato weevil, Euscepes postfasciatus, locomotor activity | |
| 15 | Author | Shimoji Y, Kohama T. |
| Year | 1994 | |
| Title | Oviposition behavior of the West Indian sweet potato weevil, Euscepes postfasciatus Fairmaire (Coleoptera: Curculionidae). (In Japanese with English summary) | |
| Magazine | Japanese Journal of Applied Entomology and Zoology | |
| Volume | 38 | |
| Number | ||
| Page | 43-46 | |
| Summary | ||
| Key Word | West Indian sweet potato weevil, Euscepes postfasciatus, oviposition, behavior, Coleoptera, Curclionidae | |
| 16 | Author | Takara T. |
| Year | 1954 | |
| Title | Invasion and control of Omphis anastomosalis (Guenee) (Lepidoptera: Pyralidae) and Euscepes postfasciatus (Fairmaire) (Coleoptera: Curculionidae), in the Ryukyus. (In Japanese). | |
| Magazine | Plant Protection | |
| Volume | 8 | |
| Number | ||
| Page | 436-438 | |
| Summary | ||
| Key Word | Euscepes postfasciatus, Omphis anastomosalis, invasion, control | |
| 17 | Author | Tucker MA. |
| Year | 1937 | |
| Title | The control of scarabee (Euscepes batatae, Waterh.). | |
| Magazine | Barbados Dept. Sci. Agric. J. | |
| Volume | 6 | |
| Number | ||
| Page | 133-154 | |
| Summary | ||
| Key Word | control, Euscepes postfasciatus, Coleoptera, Curclionidae | |
| 18 | Author | Uritani I, Saito T, Honda H, Kim W. |
| Year | 1975 | |
| Title | Induction of furano-terpenoids in sweet potato roots by the larval components of the sweet potato weevils. | |
| Magazine | Agr. Biol. Chem. | |
| Volume | 39 | |
| Number | 9 | |
| Page | 1857-1862 | |
| Summary | ||
| Key Word | sweet potato weevils, sweet potato root, furano-terpenoids | |
| 19 | Author | Yasuda K, Kohama T. |
| Year | 1990 | |
| Title | Distribution of the sweetpotato weevil, Cylas formicarius (Fabricius) and the West Indian sweetpotato weevil, Euscepes postfasciatus (Fairmaire) in Okinawa Prefecture. (In Japanese). | |
| Magazine | Proceedings of the Association for Plant Protection of Kyushu | |
| Volume | 36 | |
| Number | ||
| Page | 123-125 | |
| Summary | ||
| Key Word | Cylas formicarius, Euscepes postfasciatus, distribution, Okinawa | |
| 20 | Author | Yasuda K. |
| Year | 1991 | |
| Title | Chemical control of the sweetpotato weevils, Euscepes postfasciatus (Fairmaire) and Cylas formicarius (Fabricius). (In Japanese). | |
| Magazine | Proceedings of the Association for Plant Protection of Kyushu | |
| Volume | 37 | |
| Number | ||
| Page | 107-110 | |
| Summary | ||
| Key Word | chemical control, sweetpotato weevils, Euscepes postfasciatus, Cylas formicarius | |
| 21 | Author | Yasuda K. |
| Year | 1997 | |
| Title | Dispersion of sweet potato stems damaged by the West Indian sweetpotato weevil, Euscepes postfasciatus (Fairmaire) (Coleoptera: Curculionidae), on sweet potato fields and adult emigration from the field. (In Japanese). | |
| Magazine | Proceedings of the Association for Plant Protection of Kyushu | |
| Volume | 43 | |
| Number | ||
| Page | 86-90 | |
| Summary | ||
| Key Word | West Indian sweet potato weevil, damage, dispersion, emigration | |
| 22 | Author | Yasuda K. |
| Year | 1997 | |
| Title | Control threshold on sweet potato, Ipomoea batatas L., damaged by the West Indian sweet potato weevil, Euscepes postfasciatus (Fairmaire) (Coleoptera: Curculionidae). (In Japanese with English summary). | |
| Magazine | Japanese Journal of Applied Entomology and Zoology | |
| Volume | 41 | |
| Number | 4 | |
| Page | 201-207 | |
| Summary | ||
| Key Word | Euscepes postfasciatus, control threshold, sweet potato, West Indian sweet potato weevil | |
| 23 | Author | Yasuda K. |
| Year | 1998 | |
| Title | Studies on integrated pest management of West Indian sweet potato weevil, Euscepes postfasciatus (Fairmaire) and sweet potato weevil, Cylas formicarius (Fabricius). (In Japanese with English summary). | |
| Magazine | Bulletin of the Okinawa Agricultural Experiment Station | |
| Volume | 21 | |
| Number | ||
| Page | 1-80 | |
| Summary | ||
| Key Word | West Indian sweet potato weevil, Euscepes postfasciatus, sweet potato weevil, Cylas formicarius, IPM | |
| No. | Habitat |
| 1 | upland crop field |
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