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        검색결과 4

        1.
        2009.05 구독 인증기관·개인회원 무료
        This study was conducted to compare the effectiveness of single and combination use of N. californicus and N. womersleyi for control of Tetranychus urticae. The experiment was conducted with 5 replications in kidney bean leaf disc (2.5cm diameter) at 25℃, 60-70% RH, a photoperiod of 16:8 (L:D) h. The inoculation ratio was 5:1 for T. urticae:pytoseiidae mite and treatments are: a, N. californicus:T. urticae (4 adult female:20 adult female) b, N. womersleyi:T. urticae (4:20) c, (N. californicus+N. womersleyi):T. urticae ((2+2):20) d, Only T. ulticae (20). T. urticae population became significantly lower in the treatment plots than in the control plot but the higher egg number of T. urticae was observed in the treatment "b" plot than in "a" and "c" plots. In the "c" plot, lower number of N. womersleyi was observed than N. californicus. The result indicates that single use of N. californicus and combination use of N. californicus and N. womersleyi were more effective than single use of N. womersleyi but, there was no significantly difference between single use of N. californicus and combination use of N. californicus and N. womersleyi for control of T. urticae. Also, N. californicus appears to interfere or outcompete N. womersleyi.
        2.
        2008.10 구독 인증기관 무료, 개인회원 유료
        Environmental tolerance of three important spider mite predators; Neoseiulus womersleyi, Neoseiulus californicus and Phytoseiulus persimilis (Phytoseiidae) was experimented by treating combination of temperature and relative humidity for egg hatching and immature survival. Egg hatching rate increased at the relative humidity incrased for three species. Temperature effects were only significant to N. californicus and P. persimilis. The lethal humidities for three species were in the range of 56-77, 82.0, 66-94% RH, respectively. Larva does not need to feed for larval development into protonymph in three tested species. No larvae survived at lower than 75% RH for N. womersleyi, but around 80% at 95% RH. N. californicus larvae survived around 50% and 100% at 75 and 95% RH. P. persimilis larve survival was decreased as the temperature increased at 75% RH, but platued around 100% at 95% RH. Cannibalism was higher in N. californicus and lower in P. persimilis. Implementation of the results was discussed relative to biological control of spider mites in open field and greenhouse crops.
        3,000원
        3.
        2008.10 구독 인증기관·개인회원 무료
        Neoseiulus womersleyi (Schicha) (Acari: Phytoseiidae) is one of the most important predators of spider mites in Japan. Various characteristics have been studied in this species. However, because there is a lack of genetic markers, genetic diversity within and among populations has not been well elucidated. Microsatellites, short stretches of tandem-repeated 1- to 5- nucleotide sequences, are ubiquitously present in eukaryotic genomes and are highly polymorphic. Their high polymorphism makes them suitable markers for studying intra-specific variation. In this study, we developed microsatellite markers in N. womersleyi, and then examined genetic diversity in their populations. Microsatellite enriched genomic DNA library was contracted and sequenced from a single female adult. Of the 40 plasmids sequenced, 31 plasmids showed microsatellite sequences and 24 plasmids were unique. Finally, we could design primers on three loci. When tested their diversity on one wild and two laboratory populations, five to 18 alleles were detected. The wild population showed highest genetic diversity, and this divergence decreased in rearing populations. To investigate the effects of different rearing conditions, genetic diversity in two rearing populations, which were different in population size, were compared with those in the original wild populations. The allelic richness and gene diversity were not significantly different between wild and large-size populations, while the values were significantly decreased in small-size populations. Thus, 40 to 60 females per generation was sufficient to conserve the genetic diversity in N. womersleyi populations during laboratory rearing. In conclusion, the microsatellite markers developed were useful to evaluate genetic diversity in wild and laboratory populations of N. womersleyi.
        4.
        2008.05 구독 인증기관·개인회원 무료
        Temperature and humidity are the vital environmental factors influencing the distribution and abundance of ectothermal organisms. Also, these variables often determine the efficacy of biological control of spider mites using phytoseiid mites N. californicus, N. womersleyi and P. persimilis are promising biocontrol agents of spider mites. The combined effects of temperatures (15,20,25,30 & 35oC) and relative humidity (33,51,75 & 95%) on egg hatch, incubation period from single egg and cannibalism from five eggs experiment were tested for three phytoseiid mites. Photoperiod was set to 16L:8D and neither water nor diet was provided. The result showed that higher temperatures (30&35oC) and lower relative humidity (33&51%) caused increased egg mortality by shrinking and desiccation. The egg hatch of N. californicus and P. persimilis were higher than N. womersleyi in all conditions with the exception of 35oC and 95% RH treatment where P. persimilis did not hatch at all. The incubation periods of egg decreased as the humidity level increased even under the same temperature. The cannibalism, habit of feeding the same species was found from protonymphal and deutonymphal stages under higher humidity levels (75&95%) in the three phytoseiid species. This tendency was higher in N. californicus and N. womersleyi than in P. persimilis. The results partially explain the lower predator performance during hot summer by P. persimilis and the possibility to sustain the predator population when the prey population is low.