Impact of Propolis on Escherichia coli and Bacillus subtilis Based on Total DNA, RNA and Protein Levels.

<b>Background and Objectives:</b> Propolis is a natural product derived from plant resins and collected by honeybees to protect the colony against different pathogens. The antimicrobial properties of an ethanolic extract of propolis (EEP) were investigated in this study. <b>Materials and Methods:</b> In the Egyptian Governorate of Giza, F1 carniolan honeybee (<i>Apis mellifera carnica</i> P.) colonies collected propolis in the autumn, spring and summer of 2019-2020. We investigated the antibacterial activity of EEP against Gram-positive <i>B. subtilis</i> and Gram-negative <i>E. coli</i>. Propolis was evaluated and its effects on the amounts of total DNA, RNA and protein in <i>Bacillus subtilis</i> and <i>Escherichia coli</i> were investigated. <b>Results:</b> Propolis inhibited the growth of <i>B. subtilis</i>. At 5% concentration, the inhibition zones were 8.66, 10.66 and 8.52 mm for autumn, spring and summer propolis, respectively, at 10% concentration, they were 19.66, 21.33 and 18.0 mm, respectively. Propolis also inhibited the growth of <i>E. coli</i> at a 5% concentration. The inhibition zones were 3.660, 4.00 and 4.33 mm for autumn, spring and summer propolis, respectively and at 10% concentration, they were 7.65, 8.33 and 7.33 mm, respectively. The inhibition zones were the largest (10.66 and 21.33 mm) for <i>B. subtilis</i> at 5 and 10% propolis, respectively, whereas slightly low inhibition zones (4.0 and 8.33 mm) were observed for <i>E. coli</i> (5 and 10% propolis, respectively) in spring. In <i>E. coli</i> and <i>B. subtilis</i>, propolis inhibited the replication of DNA-dependent RNA polymerase. <b>Conclusion:</b> The study showed that total DNA, RNA and protein levels in <i>B. subtilis</i> were reduced by 40, 15.52 and 52.6%, respectively, whereas those in <i>E. coli</i> were reduced by 12, 15 and 8%, respectively. Furthermore, propolis activity was less effective against Gram-negative bacteria than Gram-positive bacteria.

Pesticidal Effect of Leaves Extract of Different Plants on the Larvae of Cotton Leaf Worm, Spodoptera littoralis.

<b>Background and Objective:</b> The cotton leafworm, <i>Spodoptera littoralis</i> (Boisd.) (Lepidoptera: Noctuidae), represents the worst lepidopterous pest on most vegetable crops. Moreover, its host range is extensive because it is a polyphagous and cosmopolitan pest that can cause an estimated loss of nearly 25.8 to 100% of crop production. Natural controls have replaced pesticides due to the environmental damage that chemical pesticides cause. Eggplant, tomato, okra and pepper are Egypt's most significant vegetable crops and the leaves of these plants are cheap and can act as botanical and nontoxic pesticides. <b>Materials and Methods:</b> <i>Spodoptera littoralis </i>larvae were reared in the laboratory and plant leaves of eggplant, tomato, okra and pepper were extracted in the laboratory with organic solvents. Then, these extracts were applied to the larvae. Therefore, the histological sectors in larvae bodies were prepared and the changes were observed compared with the control. <b>Results:</b> This study proved the efficiency of all plant leaf extracts, especially those of eggplant and tomato leaves (LC₅₀ of 1191.9 and 1582.7 ppm, respectively). In contrast, okra and pepper leaf extracts had the highest LC₅₀ (3904.8 and 5431.6 ppm, respectively). Also, the abnormalities in the midgut and internal tissues were evident in the larvae treated with eggplant leaf extracts, followed by tomato leaf extracts and okra leaf extracts. Larvae treated with pepper leaf extracts were as normal as the control. <b>Conclusion:</b> The current study opens horizons to new plant extracts that are cheap and unused plant parts and make them helpful as new and good insecticides.