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Ichinose K.,Kyushu Okinawa Agricultural Research Center | Yasuda K.,Okinawa Prefectural Agriculture Research Center | Yamashita N.,Kyushu Okinawa Agricultural Research Center | Matsumura M.,Kyushu Okinawa Agricultural Research Center | Okada Y.,Kyushu Okinawa Agricultural Research Center
Agricultural and Forest Entomology | Year: 2016

In southern Japan, sweet potato weevils Euscepes postfasciatus (Fairmaire) are being eradicated using the sterile insect technique because of their damaging effects on sweet potato crops. However, the effect of irradiation on the dispersal and survival of this species needs to be evaluated. We observed the dispersal of normal and irradiated weevils for 21 days after their release in a sweet potato field during all four seasons, and estimated their survival using the Weibull function. Normal weevils generally moved further than irradiated weevils, and all weevils had greater dispersal distances in the summer than in the winter, with spring and autumn intermediate between these two extremes (summer: 0.23 m/day versus 0.29 m/day; winter: 0.15 m/day versus 0.07 m/day; spring: 0.20 m/day versus 0.17 m/day; autumn: 0.20 m/day versus 0.15 m/day, respectively). Normal weevils had low variation in mean life expectancy (approximately 8 days throughout the year), whereas the life expectancy of irradiated weevils was drastically reduced in the summer (2.20 days). The implications of these results for the efficiency of this eradication technique are discussed. © 2016 The Royal Entomological Society. Source

Okada Y.,Kyushu Okinawa Agricultural Research Center | Yasuda K.,Okinawa Prefectural Agriculture Research Center | Sakai T.,Miyakonojo Research Station | Ichinose K.,Kyushu Okinawa Agricultural Research Center
Journal of Economic Entomology | Year: 2014

The preferences of the West Indian sweet potato weevil, Euscepes postfasciatus (Fairmaire), to tubers of sweet potato, Ipomoea batatas (L.), for food and for oviposition were evaluated, and correlated to sweet potato's resistance to immatures. Adults (parent) were released in a plastic box containing tubers of sweet potato cultivars and maintained for 5 d, after which the adults on each tuber were counted. All adults were then removed and each tuber was maintained separately. New adults that emerged from the tubers were counted. Cultivars were grouped by cluster analyses using the number of parent adults on the tubers and the number of new adults emerging from the tubers, adjusted for the weight of each tuber. Cultivars were divided into five groups: average level of preference, preferred, preferred for oviposition but not for food, preferred for food but not for oviposition, and not preferred. New adults from the first two groups took less time to eclose than those from the other groups, and their body size was smaller. In a second experiment, one to five cultivars were selected from each group and inoculated each tuber with 10 weevil eggs on each cultivar. Although the proportion of eclosed adults was not significantly different between cultivars, the time to eclosion was shorter and body size was smaller on preferred cultivars. The selection of tubers by parent adults was not linearly related with larval development, and did not reduce the survival of the immatures. © 2014 Entomological Society of America. Source

Matsumura H.,Shinshu University | Miyagi N.,Okinawa Prefectural Agriculture Research Center | Taniai N.,Okinawa Prefectural Agriculture Research Center | Fukushima M.,Shinshu University | And 3 more authors.
PLoS ONE | Year: 2014

Momordica charantia is a monoecious plant of the Cucurbitaceae family that has both male and female unisexual flowers. Its unique gynoecious line, OHB61-5, is essential as a maternal parent in the production of F1 cultivars. To identify the DNA markers for this gynoecy, a RAD-seq (restriction-associated DNA tag sequencing) analysis was employed to reveal genome-wide DNA polymorphisms and to genotype the F2 progeny from a cross between OHB61-5 and a monoecious line. Based on a RAD-seq analysis of F2 individuals, a linkage map was constructed using 552 co-dominant markers. In addition, after analyzing the pooled genomic DNA from monoecious or gynoecious F2 plants, several SNP loci that are genetically linked to gynoecy were identified. GTFL-1, the closest SNP locus to the putative gynoecious locus, was converted to a conventional DNA marker using invader assay technology, which is applicable to the marker-assisted selection of gynoecy in M. charantia breeding. © 2014 Matsumura et al. Source

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