Cassida vittata Vill. (Coleoptera : Chrysomelidae) is a very important insect pest to sugar beet crop. Its larvae and adults feed upon sugar beet leaves causing significant defoliation, consequently reduce root weight and sugar percent (%) to this crop. Entomopathogenic microorganisms, mainly entomopathogenic bacteria, is a vital factor of the natural mortality against insects. Research on microbial pathogens of insects is increasing to find out environmental friendly alternatives to hazardous chemical insecticides. This investigation was done at the Experimental Farm of Sakha, Agricultural Research Station, Kafr Elsheikh Governorate, Egypt during 2018 and 2019 seasons. Obtained results showed that 11(29.72%) C. vittata larvae out of 37 individuals died naturally with Bacillus aryabhattai. Six (29.72%) C. vittata adults out of 25 individuals died naturally due to exposure to 10 8 cfu/ml suspension, which used for laboratory and field tests. In a laboratory test, the mortalities of larvae were 20.00, 30.00 and 45.00% after 3, 7 and 10 days post-treatment, respectively. Whereas, the mortalities of adults were 10.00, 25.00 and 40.00% after 3, 7 and 10 days post-treatment, respectively. Also, in a field test, the reduction of larvae were 12.86, 29.79 and 43.99% for 3, 7 and 10 days after treatment, respectively. Reduction of adults were 14.06, 27.05 and 39.84% for 3, 7 and 10 days after treatment, respectively. This strain was identified by GATC (biotech sequence company, Germany), for the first time in Egypt. These results conclude that this strain is an effective biocontrol agent against C. vittata larvae and adults in sugar beet fields.

Context: Comparison between a wild type strain Rhizobium spp. (RCA-220) and a genetically modified strain E. coli BL21 in context of growth features.Objective: To observe the comparative growth characteristics of a genetically modified E. coli BL21 and an isolated wild type strain Rhizobium spp. (RCA-220). Materials and Methods:Different kinds of investigations were accomplished in both Luria-Bertani (LB) liquid and semi-solid media to observe the growth and maintenance of these strains. For the isolation of Rhizobium spp. selective Yeast Extract Manitol Agar (YEMA) was used. Colony morphology, pH, temperature, carbon source, salt concentration and light were taken under consideration and optimized for growth characteristics.Results: For the strain E. coli BL21, the maximum growth rate was 1.9 at incubation time 72 h, pH 7.2, temperature 37°C (optimized) while for Rhizobium spp. the growth rate was significantly higher (OD 2) at pH 6.8, temperature 28°C (optimized). Among all used carbon sources, strains grown in the medium supplemented with peptone showed rapid and good performance. So, peptone was proved as the best carbon source for both strains. The maximum growths of these strains were observed at 0g/100ml NaCl salt concentration. RCA-220 strain was comparatively more tolerable to salt than E. coli BL21 strain. In this work, E. coli BL21 showed rapid and good performance in presence of light while Rhizobium spp. showed better performance in absence of light. Statistical analysis showed that the growth rate of Rhizobium spp. was significantly higher than E. coli BL21. Conclusion:From the experimental results, it can be concluded that naturally obtained microbial strains were stable and could tolerate any stress condition where the modified strains lose their growth capability and the overall growth performances were reduced or slowed down than the wild type strain.

Chloroform extracts of the leaf, stem bark, stem wood and roots of Glycosmis pentaphylla (Retz.) were tested against the brine shrimp, Artemia salina nauplii for cytotoxic activity in which the dose-mortality assay revealed LC50 values of 28.579, 28.659, 57.213 and 84.111 ppm respectively, for the plant parts efficacy of which could be arranged in the order of leaf > stem bark > stem wood > root. The same extracts were tested for repellency against Tribolium castaneum (Herbst) adults where the root bark and root wood were separately extracted and used. The F values of the arcsin transformed data were 60.983, 14.177, 19.437, 15.429 and 1.082 respectively for the leaf, stem bark, stem wood, root bark and root wood extracts. Except for the root wood extract, strong repellent activity was observed for the rest of the extracts (P<0.001). Key words: Artemia salina; Tribolium castaneum; Glycosmis pentaphylla; cytotoxic activity; repellent activity. DOI: 10.3329/jles.v3i0.7443 J. Life Earth Sci., Vols. 3-4: 33-36, 2009

DOI: http://dx.doi.org/10.3329/jles.v8i0.20156 J. Life Earth Sci., Vol. 8: 119-122, 2013