Zhang XueKe

Antimicrobial activities of essential oil from Artemisiae argyi leaves

A study was conducted to determine the antimicrobial activities of essential oil from Artemisiae argyi leaves. The sample of the essential oil was analyzed by GC-MS. From 18 compounds representing the oils, Eucalyptole (18.42%), Spathulenol (14.32), 4-Methyl-1-(1-methylethyl)-3-cyclohexen-1-ol (3.10%), 3-Carene (2.64%) appeared as the main components. The screening of antimicrobial activity of the essential oil was evaluated using agar diffusion and broth microdilution methods. Gram-positive bacterial were more sensitive than gram-negative bacterial of the 8 microorganisms, and Staphylococcus aureus ATCC 6538 showed the lowest MIC (0.3125%) and MBC (0.625%). In the disc diffusion assay, Staphylococcus epidermidis ATCC 49134 and Bacillus subtilis ATCC 6633 showed obvious inhibitory activity. Survival curve showed that, 2MIC of Artemisiae argyi essential oil had a lethal effect on Candida albicans within the first 1 h. Results presented here suggest that the essential oil of Artemisiae argyi leaves possesses antimicrobial properties, and provides scientific foundations for exploition of Artemisiae argyi.

Effects of tip-pruning treatment on source-sink regulation of Catharanthus roseus seedlings

Fifty cultivated Catharanthus roseus seedlings were selected for tip-pruning treatment and the effects of tip-pruning on seedling growth and source-sink regulation were investigated for revealing physiological mechanisms of plants. The results showed that tip-pruning treatment resulted in obvious inhibition of apical dominance and enhancement of branching numbers. The contents of soluble sugars, acid sucrose invertase activity (AI) had a great change in differently positional leaves of the seedling. The sink strength in tip leaves of seedlings dramatically declined after tip-pruning treatment, while that in the leaves at the middle and bottom of seedlings had no obvious changes. The inhibition of apical dominance of tip leaves of seedlings was caused by the diminished sink strength due to tip-pruning treatment.

Studies on Bionomics and Occurrence Regulation of Phigalia djakonovi Moltrecht

Investigation and observation were made on bionomics and occurrence regulation ofPhigalia djakonovi Moltrecht, which is a major pest of white birch, in Daxing’an Mountain forest area of Inner Mongolia during 1997 to 1999. The pest has one generation per year and overwinters as pupae in the soil in this area. Development, bionomics and outbreak of the pest are closely related with the food and environment conditions.

Newcone and seed pests collected in Northeastern ChinaBarbara fulgens Kuznetsov (Lepidoptera: Tortricidae) the lustrous spruce cone moth

This paper is the first of a series dealing with morphological characteristics, biological cycle and damage importance of insect species newly identified as cone and seed pests in Northeastern China. The spruce cone mothBarbara fulgens appears to be a serious pest of korean spruce cones in Heilongjiang province.