@article {14012,
	title = {Pre-exposure to sex pheromone did not affect mating behavior in the sweetpotato weevil Cylas formicarius},
	journal = {Journal of Pest Science},
	volume = {84},
	number = {1},
	year = {2011},
	month = {March},
	pages = {93-97},
	abstract = {In sterile insect technique (SIT) programs, the released sterile males are important for their effectiveness. The use of sex pheromones to collect males is economical; however, pre-exposure to sex pheromones may affect male mating behavior, and would thus reduce the effectiveness of the SIT programs. Males exposed to sex pheromone may become attractive to other males due to pheromone adsorption on their body impregnation, prevent mating and reduce the dispersal of sterile males. We examined the effect of pre-exposure to sex pheromone on the mating behavior of male sweetpotato weevil Cylas formicarius. Pre-exposure to high-dose sex pheromone for 24 h did not affect the male mating behavior of C. formicarius, and the exposed males did not attract other males. These results suggest that male C. formicarius that were collected from a mass-rearing facility using sex pheromone can be effectively used in SIT programs.},
	keywords = {Cylas formicarius},
	isbn = {1612-4758},
	author = {Kuriwada, Takashi and Kumano, Norikuni and Shiromoto, Keiko and Haraguchi, Dai}
}
@article {14013,
	title = {Simplification of the collecting method of adult sweetpotato weevils from artificial diets},
	journal = {Japanese Journal of Applied Entomology and Zoology},
	volume = {55},
	number = {1},
	year = {2011},
	month = {2011},
	pages = {22-24},
	abstract = {The West Indian sweetpotato weevil Euscepes postfasciatus (Fairmaire) (Coleoptera: Curculionidae) is a major pest of the sweet potato Ipomoea batatas (L.) Lam (Solanales: Convolvulaceae) in some countries. In order to improve the mass-rearing systems involved in an eradication program employing the sterile insect technique (SIT), we improved the efficiency of the method used for collecting adult weevils from artificial larval diets; this was done by using the combination of a sieve and Tullgren apparatus. Using this combination, we could collect 95.4\% of weevils from artificial diets. Furthermore, the time spent in collection with this method was approximately one-fifth of that spent with the existing hand-sorting method. These results showed that this new collection method will improve the efficiency of mass rearing of West Indian sweetpotato weevils.},
	keywords = {Euscepes postfasciatus},
	isbn = {0021-4914},
	author = {Kuriwada, Takashi and Kumano, Norikuni and Shiromoto, Keiko and Haraguchi, Dai}
}
@article {14014,
	title = {The effect of an artificial adult diet on the reproductive performance of the West Indian sweetpotato weevil Euscepes postfasciatus},
	journal = {Japanese Journal of Applied Entomology and Zoology},
	volume = {55},
	number = {1},
	year = {2011},
	month = {2011},
	pages = {27-29},
	abstract = {The West Indian sweetpotato weevil Euscepes postfasciatus (Fairmaire) (Coleoptera: Curculionidae) is a major pest of the sweet potato Ipomoea batatas (L.) Lam (Solanales: Convolvulaceae) in some countries. To improve mass rearing systems involved in an eradication program employing the sterile insect technique (SIT), we examined the effect of an artificial adult diet on the reproductive performance of both male and female E. postfasciatus. The artificial diet had a negative effect on female fecundity but no effect on male mating ability. Our results suggest that the artificial diet should be improved to prevent adverse effects on female fecundity.},
	keywords = {Euscepes postfasciatus},
	isbn = {0021-4914},
	author = {Kuriwada, Takashi and Kumano, Norikuni and Shiromoto, Keiko and Haraguchi, Dai}
}
@article {14011,
	title = {Age-dependent investment in death-feigning behaviour in the sweetpotato weevil Cylas formicarius},
	journal = {Physiological Entomology},
	volume = {36},
	number = {2},
	year = {2011},
	month = {Jun},
	pages = {149-154},
	abstract = {Because life-history theory predicts that risky behaviours such as mating should increase as life expectancy decreases, predatory avoidance is expected to decrease with age. However, this prediction has not been examined. In the present study, the effect of age on death-feigning behaviour, a form of predatory avoidance behaviour in the sweetpotato weevil Cylas formicarius (Summers) (Coleoptera: Brentidae), is investigated by performing a longitudinal study. Because the effects of mating history and age usually cannot be distinguished, mating history is controlled. The results show that only female weevils decrease the investment in death-feigning behaviour with age, whereas male weevils do not show any age-related change. In addition, death-feigning behaviour of mated females is longer than that of virgin females, possibly because additional mating partners would be not needed by mated females.},
	keywords = {Cylas formicarius},
	isbn = {0307-6962},
	author = {Kuriwada, Takashi and Kumano, Norikuni and Shiromoto, Keiko and Haraguchi, Dai}
}
@article {14008,
	title = {EFFECT OF IRRADIATION ON DEATH-FEIGNING BEHAVIOR IN THE MALE SWEETPOTATO WEEVIL CYLAS FORMICARIUS (COLEOPTERA: BLENTIDAE)},
	journal = {Florida Entomologist},
	volume = {93},
	number = {1},
	year = {2010},
	month = {March},
	pages = {39-44},
	abstract = {The sterile insect technique (SIT) is widely used to suppress or eradicate target insect pest populations. The effectiveness of SIT depends on the ability of the released sterile males to mate with and inseminate wild females. Irradiation is effective for sterilizing mass-reared insects, and the negative impacts of this procedure are not limited to reproductive cell damage. In this study, we evaluated the death-feigning that is considered as an antipredator behavior of male Cylas formicarius (Summers) (Coleoptera: Blentidae) irradiated with 200 Gy, which is the dose used in the SIT program in Okinawa Prefecture. Irradiated male insects were observed in the laboratory for 10 d after irradiation. On d 0, fewer irradiated males feigned death than nonirradiated males. The number of irradiated and nonirradiated males who feigned death and the duration of their death-feigning were about the same from 2 d after irradiation. On the basis of our results, we discuss the optimal release time of irradiated male C. formicarius.},
	keywords = {Cylas formicarius},
	isbn = {0015-4040},
	author = {Kuriwada, Takashi and Kumano, Norikuni and Shiromoto, Keiko and Haraguchi, Dai}
}
@article {14009,
	title = {The Effect of Inbreeding on Mating Behaviour of West Indian Sweet Potato Weevil Euscepes postfasciatus},
	journal = {Ethology},
	volume = {117},
	number = {9},
	year = {2011},
	month = {September},
	pages = {822-828},
	abstract = {When there is an inbreeding depression, mating with a kin individual is generally considered maladaptive behaviour. However, in some conditions, the inclusive fitness benefits from inbreeding may outweigh the costs of inbreeding depression, and thus, inbreeding tolerance is often adaptive. Inbreeding depression and the effect of relatedness on mating behaviour in the West Indian sweet potato weevil Euscepes postfasciatus were examined. No significant inbreeding depression was detected as indicated by body weight and number of progeny emerging from sweet potato roots. Male mating performance (i.e. number of mating occurrences per night) was adversely affected by inbreeding depression, but the effect was low (fitness loss was 6.3\%). Although there were no significant differences in latency to mounting, pre-copulatory guarding, copulation and post-copulatory guarding duration between full-sib and non-kin pairs, the copulation rate of full-sib pairs was significantly higher than that of non-kin pairs. These results support the theoretical prediction that when inbreeding depression is weak, copulation with close relative individuals is favoured.},
	keywords = {Euscepes postfasciatus},
	isbn = {0179-1613},
	author = {Kuriwada, Takashi and Kumano, Norikuni and Shiromoto, Keiko and Haraguchi, Dai}
}
@article {14010,
	title = {Inbreeding avoidance or tolerance? Comparison of mating behavior between mass-reared and wild strains of the sweet potato weevil},
	journal = {Behavioral Ecology and Sociobiology},
	volume = {65},
	number = {7},
	year = {2011},
	month = {July},
	pages = {1483-1489},
	abstract = {Inadvertent selection is an important genetic process that frequently occurs during laboratory culture. The mass-reared strain of the sweet potato weevil Cylas formicarius exhibits stronger inbreeding depression than the wild strain does. When inbreeding depression occurs in a population, mating with a close relative is often considered maladaptive; however, in some contexts, the inclusive fitness benefits of inbreeding may outweigh the costs, favoring individuals that tolerate a low level of inbreeding depression. Theory predicts that mass-reared strain weevils will avoid inbreeding while wild strain weevils will tolerate inbreeding. To examine this prediction, we compared the effect of relatedness on the mating and insemination successes in mass-reared and wild strains of C. formicarius. While close relative pairs of the wild strain copulated less frequently than non-kin pairs, almost all mass-reared strain pairs copulated irrespective of relatedness. The results showed that the strain with weak inbreeding depression (wild strain) avoided inbreeding, whereas the strain with strong inbreeding depression (mass-reared strain) tolerated inbreeding. The contradiction between the theoretical prediction and our results is discussed from the perspective of laboratory adaptation, mating systems, and life history of C. formicarius.},
	keywords = {Cylas formicarius},
	isbn = {0340-5443},
	author = {Kuriwada, Takashi and Kumano, Norikuni and Shiromoto, Keiko and Haraguchi, Dai}
}
@article {14005,
	title = {High population density and egg cannibalism reduces the efficiency of mass-rearing in Euscepes postfasciatus (Coleoptera: Curculionidae)},
	journal = {Florida Entomologist},
	volume = {92},
	number = {2},
	year = {2009},
	month = {June},
	pages = {221-228},
	abstract = {The West Indian sweetpotato weevil Euscepes postfasciatus (Fairmaire) (Coleoptera: Curculionidae) is a major pest of sweetpotato Ipomoea batatas (L.) Lam (Solanales: Convolvulaceae) in some countries. In order to improve mass-rearing for an eradication program employing the sterile insect technique (SIT), optimal population density of E. postfasciatus in an artificial diet was examined. Six population densities (1000, 4000, 7000, 10000, 13000, and 16000 individuals per container with 200 g of artificial diet) were compared for effect on the number of eggs collected and hatchability. The total number of eggs collected after 24 d increased with an increase in population density and reached a saturation level at 13,000 individuals, whereas hatchability was not affected by population density. The results indicated that optimal population density in mass rearing was 13,000 individuals on 200 g of artificial diet. Furthermore, we examined cannibalism by adult weevils in the presence of other diets . The result suggested that egg cannibalism may be a major reason for the low rate of egg collection in the mass rearing of E. postfasciatus.},
	keywords = {Euscepes postfasciatus},
	isbn = {0015-4040},
	author = {Kuriwada, Takashi and Kumano, Norikuni and Shiromoto, Keiko and Haraguchi, Dai}
}
@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 {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}
}
