@article {13993,
	title = {Evaluation of partial sterility in mating performance and reproduction of the West Indian sweetpotato weevil, Euscepes postfasciatus},
	journal = {Entomologia Experimentalis Et Applicata},
	volume = {136},
	number = {1},
	year = {2010},
	month = {Jul},
	pages = {45-52},
	abstract = {The sterile insect technique (SIT) is based on population and behavioral ecology and is widely used to suppress or eradicate target pest insect populations. The effectiveness of SIT depends on the ability of the released sterile males to mate with and inseminate wild females. The use of gamma-radiation to induce sterility is, however, associated with negative impacts not only on reproductive cells but also on somatic cells. Consequently, irradiation for sterilization diminishes mating performance over time. In this study, we evaluated the balance between the irradiation dose and both fertility and mating propensity in Euscepes postfasciatus (Fairmaire) (Coleoptera: Curculionidae) for 22 days following irradiation. The mating propensity of males irradiated with a 150-Gy dose, as currently used to induce complete sterility of E. postfasciatus in the SIT program in Okinawa Prefecture, was equal to that of non-irradiated weevils for up to 6 days, and the mating propensity of males irradiated with a dose of 125 Gy was equal to that of non-irradiated weevils for twice this period (12 days). The fertilization ability of weevils irradiated with a dose of 125 Gy was reduced by 4.6\% in males and 0.6\% in females, compared to the potential fertilization ability. We also discuss the possibility of the application of partially sterilized insects in eradication programs.},
	keywords = {Euscepes postfasciatus},
	isbn = {0013-8703},
	author = {Kumano, Norikuni and Kuriwada, Takashi and Shiromoto, Keiko and Haraguchi, Dai and Kohama, Tsuguo}
}
@article {13994,
	title = {Effect of body size and sex ratio on male alternative mating tactics of the West Indian sweetpotato weevil, Euscepes postfasciatus},
	journal = {Entomologia Experimentalis Et Applicata},
	volume = {135},
	number = {2},
	year = {2010},
	month = {May},
	pages = {154-161},
	abstract = {Male body size is considered to be one of the major determinants of mating success among many insect species. Because the effectiveness of the sterile insect technique (SIT) depends on the ability of released sterile males to mate with and inseminate wild females, it is indispensable to understand the effect of male body size on the mating behavior of both sexes for the progress of the SIT program. We investigated how male body size and the presence of other rival males affect the guarding and copulatory durations of the West Indian sweetpotato weevil, Euscepes postfasciatus (Fairmaire) (Coleoptera: Curculionidae). In this species, males guard females before and after copulation. By observing the mating behavior under two sex-ratio conditions (male-to-female ratios of 1:1 and 2:1), we found that small males hastened to court females when rival males were present, but the females rejected these small males as mates. Therefore, we consider that female weevils adopt a counter-adaptation for mate preference in response to this male mating strategy. Body size did not affect the durations of copulation and post-copulatory guarding. Although we found a conditional mating strategy for body size in E. postfasciatus, it is unlikely to have a large influence on the weevil-eradication program using SIT.},
	keywords = {Euscepes postfasciatus},
	isbn = {0013-8703},
	author = {Kumano, Norikuni and Kuriwada, Takashi and Shiromoto, Keiko and Haraguchi, Dai and Kohama, Tsuguo}
}
@article {13995,
	title = {Intensive resistance by females before copulation induces insemination failure in the West Indian sweet potato weevil Euscepes postfasciatus},
	journal = {Population Ecology},
	volume = {53},
	number = {1},
	year = {2011},
	month = {January},
	pages = {111-117},
	abstract = {Persistent mating attempts by males (sexual harassment) are frequently observed among animals. For females, resisting persistent males can be costly because vigorous resistance increases both energy expenditure and the possibility of injury. Although one tactic for coping with male harassment is to cease resistance and mate with the persistent partner, the females of several species are able to prevent the fertilization of their egg(s) despite copulation. In this study, we used three different sex ratios to investigate whether a male{\textquoteright}s mating persistence affects his mating success in the West Indian sweet potato weevil Euscepes postfasciatus, in which males mount females both before and after copulation. Consistent with our predictions, we found that female weevils resist and manipulate sperm transfer either before or during copulation according to their preferences. Female weevils were able to reject the sperm of persistent males despite having copu- lated with them. However, neither copulation and/or post-copulatory mounting affected insemination success. We speculate that the intensive resistance shown by females before copulation may induce mechanical sterility in E. postfasciatus.},
	keywords = {Euscepes postfasciatus},
	isbn = {1438-3896},
	author = {Kumano, Norikuni and Kuriwada, Takashi and Shoromoto, Keiko and Haraguchi, Dai and Kohama, Tsuguo}
}
@article {13991,
	title = {Effect of irradiation on dispersal ability of male sweetpotato weevils (Coleoptera: Brentidae) in the field},
	journal = {Journal of Economic Entomology},
	volume = {100},
	number = {3},
	year = {2007},
	month = {June},
	pages = {730-736},
	abstract = {We used the mark-and-recapture method in the field to test the effect of gamma radiation on the dispersal ability of the male sweetpotato weevil, Cylas formicarius elegantulus (Summers) (Coleoptera: Brentidae), a serious sweetpotato pest in Japan. To evaluate the dispersal ability of male sweetpotato weevil, we released 27,218 males (13,302 males irradiated with a dose of 200 Gy and 13,916 nonirradiated males) in two replications (September and October 2005). Each replication lasted 5 d from the release of weevils to the removal of traps, and male weevils were released twice (1 and 3 d before trap setting). Forty pheromone traps were placed in lines corresponding to eight compass directions and five distance classes (20,50,100,200, and 500 m) in each replication. We captured 2,263 irradiated males (17.0\%) and 2,007 nonirradiated males (14.4\%) in the two replications. Six irradiated and eight nonirradiated males were captured in the traps 500 m far from the release point. All parameters to evaluate the dispersal ability of irradiated male sweetpotato weevil (recapture rate, dispersal distance, and dispersal direction) were similar to nonirradiated males in three of the four trials. However, parameters were different between irradiated males and nonirradiated males in one trial. Because the majority of parameters consistently show that the similarity of the dispersal ability, we considered that male sweetpotato weevil irradiated with a dose of 200 Gy possessed equal dispersal ability to that of nonirradiated males in the field.},
	keywords = {Cylas formicarius elegantulus},
	isbn = {0022-0493},
	author = {Kumano, Norikuni and Kohama, Tsuguo and Ohno, Suguru}
}
@article {13990,
	title = {Irradiation does not affect field dispersal ability in the West Indian sweetpotato weevil, Euscepes postfasciatus},
	journal = {Entomologia Experimentalis Et Applicata},
	volume = {130},
	number = {1},
	year = {2009},
	month = {January},
	pages = {63-72},
	abstract = {The effect of irradiation on the dispersal ability of males and females of the flightless West Indian sweetpotato weevil, Euscepes postfasciatus (Fairmaire) (Coleoptera: Curculionidae), a major sweet potato pest, was examined in the field using mark-release-recapture techniques. To evaluate the dispersal ability of the weevil, we released 7 619 weevils in two replicates (July and August 2007). Each replicate lasted 5 days from release to sampling and consisted of one weevil release and two weevil samplings. Thirty-two traps were placed in lines corresponding to eight compass directions and in four distance classes (8, 12, 16, and 20 m) in each replicate. We captured 709 (9.3\%) weevils in the two replicates. Weevils dispersed at least 20 m from the release point in 2 days, regardless of sex or irradiation. Dispersal was strongly affected by wind direction, and in both replicates most weevils were recaptured in upwind directions. The mean dispersal distance for non-irradiated weevils was about 11 m per 2 days. Although there were some differences between sexes in recapture rate and dispersal distance, there was no consistent difference between irradiated and non-irradiated weevils in dispersal distance. We conclude that irradiation does not affect the dispersal ability of flightless E. postfasciatus in the field.},
	keywords = {Euscepes postfasciatus},
	isbn = {0013-8703},
	author = {Kumano, Norikuni and Kawamura, Futoshi and Haraguchi, Dai and Kohama, Tsuguo}
}
@article {13989,
	title = {The neogregarine protozoan Farinocystis sp. reduces longevity and fecundity in the West Indian sweet potato weevil, Euscepes postfasciatus (Fairmaire)},
	journal = {Journal of Invertebrate Pathology},
	volume = {105},
	number = {3},
	year = {2010},
	month = {November},
	pages = {298-304},
	abstract = {The number of West Indian sweet potato weevils, Euscepes postfasciatus, being mass-reared in a facility for use in sterile insect technique (SIT) eradication programs has undergone a drastic reduction. A neogregarine protozoan pathogen Farinocystis sp. (an undescribed species) was detected in vivo in the mass-reared E. postfasciatus. We investigated the effects of this disease on the longevity and fecundity of host weevils and the incubation time of the disease in the host body under mass-rearing conditions. Our results demonstrated that infection by this Farinocystis sp. decreased both longevity and fecundity in E. postfasciatus. In particular, the pathogen severely limited the production of progeny by infected females compared to healthy females. Therefore, we consider this protozoan infection to be the major cause of the decreased E. postfasciatus production in the mass-rearing facility. (C) 2010 Elsevier Inc. All rights reserved.},
	keywords = {Euscepes postfasciatus},
	isbn = {0022-2011},
	author = {Kumano, Norikuni and Iwata, Noriko and Kuriwada, Takashi and Shiromoto, Keiko and Haraguchi, Dai and Yasunaga-Aoki, Chisa and Kohama, Tsuguo}
}
@article {13987,
	title = {Sperm storage and viability within females of Euscepes postfasciatus: effect of irradiation on sperm abundance and viability within female},
	journal = {Journal of Insect Physiology},
	volume = {55},
	number = {9},
	year = {2009},
	month = {September},
	pages = {813-817},
	abstract = {Irradiation has been widely used in suppression or eradication programs that use the sterile insect technique (SIT) or in studying sperm competition. Although it is well known that irradiation has negative impacts on reproductive (sperm) cells, previous studies have assumed that sperm from irradiated males behave identically to normal sperm in the female reproductive tract after mating. In this study, we used the West Indian sweetpotato weevil Euscepes postfasciatus to investigate the effect of irradiation on the abundance and viability of sperm in female spermatheca for 14 days after copulation. The abundance of sperm in females did not change throughout the experimental period, and sperm viability gradually decreased regardless of irradiation. In this weevil, irradiated sperm appear to behave identically to normal sperm in females for 14 days following irradiation/copulation. Therefore, the effect of irradiation on sperm viability within the female spermatheca is considered to be insignificant},
	keywords = {Euscepes postfasciatus},
	isbn = {0022-1910},
	author = {Kumano, Norikuni and Haraguchi, Dai and Kohama, Tsuguo}
}
@article {13988,
	title = {Female mating status does not affect male mating behavior in the West Indian sweetpotato weevil, Euscepes postfasciatus},
	journal = {Entomologia Experimentalis Et Applicata},
	volume = {131},
	number = {1},
	year = {2009},
	month = {April},
	pages = {39-45},
	abstract = {Because multiple mating by females encourages sperm competition, the assessment of female mating status before insemination is important for males in order to avoid the risk of sperm competition or to intensify sperm competition. When interacting with females before sperm transfer, males can alter their mating tactics according to the risk or intensity of sperm competition. Information on how mating systems are associated with sperm competition is essential for sterile insect technique eradication programs, which depend on successful mating of released sterile males with wild females. We tested whether males of the West Indian sweetpotato weevil, Euscepes postfasciatus (Fairmaire) (Coleoptera: Curculionidae), adjusted their mating behavior in response to female mating experience and/or age. As virgin/young female weevils accepted males more easily than non-virgin/old females, assessing females before insemination can be adaptive for male weevils. We found that E. postfasciatus males were unable to adjust their mating tactics in response to female mating status. Although this mating strategy would be costly for individual male weevils, the ability in males to discriminate female mating status can prevent the chance of mating with already-mated females containing the sperm of wild male(s). Therefore, the mating tactics of male E. postfasciatus are advantageous for sterile insect technique eradication programs.},
	keywords = {Euscepes postfasciatus},
	isbn = {0013-8703},
	author = {Kumano, Norikuni and Haraguchi, Dai and Kohama, Tsuguo}
}
@article {13303,
	title = {Geographic variation of elytral color in the sweet potato weevil, Cylas formicarius (Fabricius) (Coleoptera: Brentidae), in Japan},
	journal = {Applied Entomology and Zoology},
	volume = {44},
	number = {4},
	year = {2009},
	month = {Nov},
	pages = {505-513},
	abstract = {To use elytral color morphs of Cylas formicarius as a genetic marker in its eradication using the sterile insect technique, the geographic distribution of the morphs was examined in the three main infested areas of Japan (Central Ryukyus, Southern Ryukyus, and Ogasawara Islands). In addition to the two known color morphs in Japan (bluish elytra (BE) and greenish elytra. (GE)), the piceous elytra (PE) was found mainly in the Southern Ryukyus at low frequency. The color morph frequencies varied between the Central and Southern Ryukyus and between locations within the two areas, while only BE was found in the Ogasawara Islands. PE would be useful for genetically marking sterile weevils to be released. Similarly, GE would be useful in some islands where GE is rarely or not found. BE frequencies on two islands in the Central Ryukyus (Amami and Okinawa) and two islands in the Southern Ryukyus (Miyako and Ishigaki) in 2006-2007 were higher than in 2002-2003.},
	keywords = {Cylas formicarius},
	isbn = {0003-6862},
	author = {Kawamura, Kiyohisa and Ohno, Suguru and Haraguchi, Dai and Kawashima, Shunji and Kohama, Tsuguo}
}
@article {13304,
	title = {PCR-RFLP Discrimination between Okinawa and Ogasawara Strains of the Sweet Potato Weevil, Cylas formicarius (Fabricius)},
	journal = {Japanese Journal of Applied Entomology and Zoology},
	volume = {53},
	number = {2},
	year = {2009},
	month = {2009},
	pages = {60-63},
	abstract = {To establish a simple method for discriminating Okinawa and Ogasawara strains of the sweet potato weevil, Cylas formicarius, about 560 bp of the internal transcribed spacer-1 (ITS-1) region of the ri- bosomal DNA (rDNA) of C. formicarius was collected from several is- lands of Okinawa Prefecture and Ogasawara Islands and analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The 345 weevils collected in Okinawa and Ogasawara were discriminated correctly by the RFLP patterns with the restriction enzyme RsaI. The results suggest that C. formicarius originating from Ogasawara Islands is an effective genetic marking strain for an eradica- tion project using the sterile insect technique implemented by the Oki- nawa prefectural government.},
	keywords = {Cylas formicarius},
	isbn = {0021-4914},
	author = {Kawamura, Kiyohisa and Ohno, Suguru and Haraguchi, Dai and Kohama, Tsuguo}
}
@article {13300,
	title = {Ultraviolet light-emitting diode (UV LED) trap the West Indian sweet potato weevil, Euscepes postfasciatus (Coleoptera: Curculionidae)},
	journal = {Applied Entomology and Zoology},
	volume = {47},
	number = {3},
	year = {2012},
	month = {Aug},
	pages = {285-290},
	abstract = {The West Indian sweet potato weevil Euscepes postfasciatus (Fairmaire) is a troublesome pest insect of sweet potato that originally came from the Caribbean, but is now expanding its distribution into the Pacific Islands. Although sterile insect techniques have been used against this pest in a demonstration experiment on Kume Island (Ohno et al. (2006) Kontyu to Shizen 41:25-30), effective methods of monitoring E. postfasciatus are scarce. It is necessary to detect the weevils at an early stage of invasion in uninvaded areas, and an attractant trap can be used to achieve this. Thus, we developed an ultraviolet (UV) light-emitting diode trap, invented a method for diffusing the light to attract more insects, and investigated the attractiveness of the light trap to E. postfasciatus under laboratory conditions. Our results indicate that diffused UV light has a higher potential to attract E. postfasciatus than direct UV light. Furthermore, sweet potato is an effective bait to use to capture the weevils attracted by UV light. Thus, E. postfasciatus can be trapped using diffused UV light and sweet potato bait.},
	keywords = {Euscepes postfasciatus},
	isbn = {0003-6862},
	author = {Katsuki, Masako and Omae, Yusuke and Okada, Kensuke and Kamura, Toru and Matsuyama, Takashi and Haraguchi, Dai and Kohama, Tsuguo and Miyatake, Takahisa}
}
