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Volume 42 (1998)
- Issue 4 Pages 197-
- Issue 3 Pages 107-
- Issue 2 Pages 45-
- Issue 1 Pages 1-
Volume 42, Issue 1
Displaying 1-7 of 7 articles from this issue
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Akira Kondo, Toshihiro Sano, Kenji Chiwaki, Fukusaburo Tanaka1998 Volume 42 Issue 1 Pages 1-5
Published: February 25, 1998
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSTo develop an easier control decision-making system, the control threshold of Tetranychus urticae on chrysanthemum was estimated in terms of proportion of leaves with adult females. The relationship between the proportion of leaves with mites and the mean number of mites per leaf fitted the Kono-Sugino model. The relationship between the injury level of leaves at harvest (30 July) and the mean number of mites per leaf at various census dates was described by the same model. The control threshold in terms of proportion of leaves with mites at various census dates could be estimated by combining the two relationships. For example, the control threshold when assuming the economic injury level to be 50% of the leaf undersurface to be spotted was 0.1%, 15.6%, and 81.8% for 5, 16, and 26 July, respectively. However, the control threshold at more than 1 month before harvest was difficult to establish because of the high marketable quality of chrysanthemum. Wald's sequential likelihood-ratio test seemed useful in control decision-making.View full abstractDownload PDF (716K) -
Kiyohiko Sugiura, Hajimu Takada1998 Volume 42 Issue 1 Pages 7-14
Published: February 25, 1998
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe suitability of seven aphid species: Aphis gossypii, Aphis craccivora, Myzus persicae, Sitobion akebiae, Aulacorthum solani, Aulacorthum nipponicum and Acyrthosiphon pisum, as prey of Cheilomenes sexmaculata was evaluated from five biological and morphological characteristics (15L-9D, 18°C). All first instar larvae fed on A. nipponicum died in a few days. The mean developmental duration from hatching to adult eclosion was significantly shorter in A. craccivora (18.0 days) than in the four other aphid species (20.1-20.9 days) except M. persicae (18.7 days); the survival rate was not significantly different between these six species (70.3%-91.3%). Female pupae were significantly heavier in A. solani and M. persicae (18.4-18.5mg) than in A. pisum (16.0mg) or S. akebiae (15.2mg). The mean preoviposition period was significantly shorter in A. craccivora, A. solani, A. akebiae, and M. persicae (7.3-8.0 days) than in A. gossypii (11.6 days). The mean number of eggs laid in the first 10 days after the start of oviposition was significantly more in A. craccivora (172) than in A. gossypii (99). From these results, A. craccivora and M. persicae are the best prey and A. gossypii is the worst prey of C. sexmaculata, but the difference in suitability was not great. A prey list of C. sexmaculata is given.View full abstractDownload PDF (1046K) -
Minoru Miyasono, Minoru Suzuki, Fujiko Yamashita, Chiyoko Kumagai, Yos ...1998 Volume 42 Issue 1 Pages 15-20
Published: February 25, 1998
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSA highly UV-resistant strain, designated UVR-M, of Bacillus thuringiensis serovar kurstaki was produced by selection using repeated exposure to UV irradiation. The difference in the UV resistance levels between the UVR-M strain and the HD-1 (serovar kurstaki) strain was more than 100 times. This resistance was observed in both spores and vegetative cells. When compared to the HD-1 strain, the UVR-M strain was 1.5 times more prolific in production of spore/crystal complexes, and 1.75 times more active against silkworm (Bombyx mori) larvae. Larvicidal activity tests with six selected lepidopterous pests showed no significant difference between the two strains in activity against Plutella xylostella, Spodoptera litura, Spodoptera exigua, and Homona magnanima. However, the UVR-M strain was five times and 20 times more active against Spodoptera depravata and Adoxophyes sp., respectively, compared to the HD-1 strain. The field persistence of the activity and the spore viability of the UVR-M strain was far greater than that of the HD-1 strain.View full abstractDownload PDF (871K) -
Akira Koike, Hisashi Nemoto, Hiroshi Amano1998 Volume 42 Issue 1 Pages 21-23
Published: February 25, 1998
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSMany predacious phytoseiid mites were found in silk nests of other organisms on Japanese pear trees. A simple physical trap (Cotton trap), modeling a spider's nest, was devised. This trap trapped many phytoseiids when it used on the pear trees.View full abstractDownload PDF (1185K) -
Tomonori Arai1998 Volume 42 Issue 1 Pages 24-27
Published: February 25, 1998
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSSeveral morphological characteristics of each nymphal stage of Pseudococcus cryptus were compared. Antennae of slide-mounted individuals of each stage were observed under a differential interference microscope. The number of antenna segments of the first, second, and third instar, and adult females were 6, 6, 7 and 8, respectively. The length of the second and third antenna segments differentiated the first instar from the second instar nymph. Each instar stage was precisely discriminated by the number and length of antenna segments. To discriminate nymphal stages by external appearance, the body length, dorsal wax covering, and 17 paired marginal wax appendages were compared under a stereoscopic microscope. Nymphal stages could not be identified by body length alone. The first instar had only one pair of wax appendages, and the second instar could be distinguished from other stages by the appearance of 17 paired marginal wax appendages. The third instar could be differentiated from adult females by the combination of body length and dorsal waxy covering. The accuracies of the first, second, third instar nymph, and adult female, discriminated by combined observation of body length, dorsal wax covering and 17 paired marginal wax appendages, were 92.0%, 91.4%, 93.4% and 81.8%, respectively.View full abstractDownload PDF (2845K) -
Akira Kondo, Kenji Chiwaki, Fukusaburo Tanaka1998 Volume 42 Issue 1 Pages 28-30
Published: February 25, 1998
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSDownload PDF (462K) -
Yasuhiko Konno, Kiyoshi Domon1998 Volume 42 Issue 1 Pages 30-32
Published: February 25, 1998
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSWe investigated the LD50 values and acetylcholinesterase (AChE) sensitivity to carbamate insecticides in the rice leaf beetle, Oulema oryzae Kuwayama. Resistant populations showed high levels of resistance to PHC (>28, 000×), BPMC (135×to 151×) and benfuracarb (21×to 29×). The median inhibition concentration (I50) of carbamates to AChE in resistant populations was clearly greater than in susceptible populations. The acetylcholinesterase insensitivity ratio (IR) values ranged from 634×(benfuracarb) to>20, 000×(PHC and BPMC). Therefore, insensitivity to AChE is an important mechanism in carbamate resistance in the rice leaf beetle.View full abstractDownload PDF (501K)
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