Evaluation of Beta corolliflora for resistance to curly top in Idaho

Curly top of sugarbeet is caused by Beet severe curly top virus (BSCTV) or closely related curtovirus species which are vectored by the beet leafhopper (Circulifer tenellus). Beta corolliflora, shown in 1969 to impart a very high level of curly top resistance to sugarbeet into the BC2 generation, is a wild relative of cultivated sugarbeet that has not been utilized in breeding programs. The nature of curly top resistance from B. corolliflora seems to be reduced symptoms and resistance to viral accumulation. Field screening of 14 B. corolliflora accessions for resistance to curly top followed by PCR detection of BSCTV did not identify any accessions with phenotypic symptoms of curly top and 9 accessions did not have detectable virus. Clip cage inoculations followed by PCR detection of BSCTV and of related species, Beet mild curly top and Beet curly top viruses, were difficult to interpret due to small sample size but indicated that accessions BETA 408, BETA 414, BETA 528, BETA 690, and BETA 805, from Genebank Gatersleben, Foundation Liebniz Institute of Plant Genetics and Crop Plant Research, Gatersleben, Germany had no visible curly top symptoms or evidence of virus accumulation. Results of a preference test showed that beet leafhoppers did not have a strong aversion to B. corolliflora and likely would have at least sampled the plants in the field. Therefore, field screening for resistance to curly top, at least in the early generations of an introgression program, should be successful

Evaluation of Beta corolliflora for resistance to curly top in Idaho

Curly top of sugarbeet is caused by Beet severe curly top virus (BSCTV) or closely related curtovirus species which are vectored by the beet leafhopper (Circulifer tenellus). Beta corolliflora, shown in 1969 to impart a very high level of curly top resistance to sugarbeet into the BC2 generation, is a wild relative of cultivated sugarbeet that has not been utilized in breeding programs. The nature of curly top resistance from B. corolliflora seems to be reduced symptoms and resistance to viral accumulation. Field screening of 14 B. corolliflora accessions for resistance to curly top followed by PCR detection of BSCTV did not identify any accessions with phenotypic symptoms of curly top and 9 accessions did not have detectable virus. Clip cage inoculations followed by PCR detection of BSCTV and of related species, Beet mild curly top and Beet curly top viruses, were difficult to interpret due to small sample size but indicated that accessions BETA 408, BETA 414, BETA 528, BETA 690, and BETA 805, from Genebank Gatersleben, Foundation Liebniz Institute of Plant Genetics and Crop Plant Research, Gatersleben, Germany had no visible curly top symptoms or evidence of virus accumulation. Results of a preference test showed that beet leafhoppers did not have a strong aversion to B. corolliflora and likely would have at least sampled the plants in the field. Therefore, field screening for resistance to curly top, at least in the early generations of an introgression program, should be successful

Do rice water weevils and rice stem borers compete when sharing a host plant?*

The rice water weevil (RWW) Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae) is an invasive insect pest of rice Oryza sativa L. in China. Little is known about the interactions of this weevil with indigenous herbivores. In the present study, adult feeding and population density of the weevil, injury level of striped stem borer Chilo suppressalis (Walker) (Lepidoptera: Pyralidae) and pink stem borer Sesamia inferens (Walker) (Lepidoptera: Noctuidae) to rice, as well as growth status of their host plants were surveyed in a rice field located in Southeastern Zhejiang, China, in 2004 with the objective to discover interspecific interactions on the rice. At tillering stage, both adult feeding of the weevil and injury of the stem borers tended to occur on larger tillers (bearing 5 leaves) compared with small tillers (bearing 2~4 leaves), but the insects showed no evident competition with each other. At booting stage, the stem borers caused more withering/dead hearts and the weevil reached a higher density on the plants which had more productive tillers and larger root system; the number of weevils per tiller correlated negatively with the percentage of withering/dead hearts of plants in a hill. These observations indicate that interspecific interactions exist between the rice water weevil and the rice stem borers with negative relations occurring at booting or earlier developmental stages of rice