Cytogenotoxicity Assessment of Aqueous Extracts of Rauvolfia vomitoria (Apocynaceae) on the Male Germ Line Cells of the Pest Grasshopper Zonocerus variegatus (Orthoptera: Pyrgomorphidae)

Cytogenotoxic effects of aqueous extracts of Rauvolfia vomitoria Afzel (Apocynaceae) stem bark were assessed on male germ line cells of the grasshopper Zonocerus variegatus. Concentrations of 0, 10, 15 and 20 µg/ml of infused and macerated aqueous extracts of R. vomitoria were prepared and administered through injection to the grasshoppers. Grasshoppers were dissected after 72 hours of incubation and the different parameters were then evaluated. Results revealed significant (p < 0.05) reduction of the length and the width of testis follicles with increasing concentrations of the two aqueous plant extracts. Meiosis analysis revealed a significant (p < 0.05) increase in meiotic abnormalities with increasing concentrations of the two aqueous plant extracts. Infused and macerated aqueous extracts of R. vomitoria at different concentrations did not modify the karyotype of Z. variegatus. Cyclophosphamide (CP) induced chromosomes aberrations and significantly (p < 0.05) reduced the mean chromosomes complement number which ranged from 2n= 19.00 ± 0.00 (controlled individuals) to 2n= 17.60 ± 1.82 (CP treated individuals). These observations indicate that infused and macerated aqueous extracts of R. vomitoria stem bark could induced cytogenotoxicity on the germ line cells of the grasshopper Z. variegatus. These results also confirm the utilization of CP as positive control in chromosomes aberration assays on grasshoppers.

Insecticidal Activity of Ageratum conyzoides (Asteraceae) Aqueous Extracts against the Grasshopper Zonocerus variegatus (Orthoptera: Pyrgomorphidae)

Ageratum conyzoides (Asteraceae) is an annual plant with insecticidal activity against some insect pests. The present study was designed to evaluate the insecticidal activity of aqueous extracts (infusion and maceration) of A. conyzoides against the pest grasshopper Zonocerus variegatus (Orthoptera, Pyrgomorphidae). Concentrations of 0, 10, 30, 100 & 300 µg/ml were prepared and administrated through injection to grasshoppers. Mortality rate was recorded for adult grasshoppers each day until the 9th day of treatment. Results revealed a significant increase (p < 0.05) of mortality rate with increasing concentrations of the two plant extracts. Plant extracts at 300 µg/ml induced 100.00 ± 0.00 percent mortality of adults Z. variegatus after 4 and 5 days for A. conyzoides infusion and maceration respectively. No mortality was registered after treatment with 0 & 10 µg/ml of the two plant extracts. Male mortality rate tended to be higher than that of female at the same concentration. Also, infusion tended to significantly increase (p < 0.05) mortality rate than maceration at the same concentration. Phytochemicals screening have shown that the presence of saponins, tannins, triterpenoids and alkaloids in the A. conyzoides aqueous extracts may be responsible for the insecticidal activity of this plant. These phytochemicals may therefore be exploited and serve as suitable alternatives to synthetic insecticides against the grasshopper Z. variegatus.

In-Vitro Effects of Ricinus Communis Seed Kernel Extract On Some Antioxidant And Hydrolytic Enzymes In Nymph And Adult Zonocerus Variegatus (Grasshopper)

Background: Many plants have been identified for their insecticidal properties as alternatives to synthetic ones, which are toxic to untargeted organisms and environment. Ricinus communis (Castor) has been re-ported to exhibit insecticidal properties against insect pests. Zonocerus variegatus (Grasshopper) is a notable pest of several crops, and has been linked with great economic losses to farmers. The present study investigates the in-vitro toxicity of R. communis seed kernel extract (RCSKE) on the activities of selected antioxidant and hydrolytic enzymes in nymph and adult Zonocerus variegatus (Grasshopper), using cypermethrin (CYPER-M) and chlorpyrifos (CPF) as standard conventional pesticides. Methods: Seed kernel of Ricinus communis (Castor) was subjected to acidified aqueous extraction to obtain the extract (RCSKE). Crude enzyme preparations were obtained from nymph and adult Z. variegatus grass-hoppers. The in-vitro effects of different concentrations (15, 30, 45, 60, 75, 90 and 105μg/ml) each of RCSKE, CYPER-M and CPF on the activities of superoxide dismutase (SOD), catalase (CAT), acetylcholinesterase (AChE) and carboxylesterase (CES) in crude enzyme preparations were estimated spectrophotometrically. The level of statistical significance was 0.05. Results: The RCSKE significantly reduced the in-vitro SOD activity (p < 0.05) in nymph Z. variegatus at all the concentrations, whereas both CYPER-M and CPF significantly reduced the activity only at certain concentrations. The CAT activity in the nymph was significantly decreased by RCSKE and CPF at all the concentrations, but CYPER-M decreased it only at certain concentrations. In adult Z. variegatus, SOD activity was not significantly affected (p > 0.05), while CAT activity was significantly increased (p < 0.05) by the three agents at all the concentrations. The AChE and CES activities in the nymph were significantly reduced by RCSKE, CYPER-M and CPF at all the concentrations. The RCSKE and CPF significantly increased the CES activity, while CYPER-M caused a significant decrease in the activity in adult Z. variegatus. Conclusion: The seed kernel extract of Ricinus communis is an effective pesticidal agent and hence, it could be a source of biopesticide alternative with greater potential than cypermethrin and chlorpyrifos. In addition, the antioxidant, acetylcholinesterase and carboxylesterase enzymes in the nymphs of Z. variegatus grasshoppers are more susceptible to the effect of the extract than in the adult grasshoppers.

Sanitary Diagnosis of Cotton Cultivation in the West Central Region of Cote D'ivoire

In order to contribute to cotton cultivation sustainability in west central Côte d'Ivoire, a phytosanitary diagnostic study was conducted in 11 plots. It consisted of monitoring the sanitary condition of 10 rural plots and an experiment plot set up at the Research Farm of University Jean Lorougnon Guédé of Daloa according to the regular and careful inspection of cotton seed germination, seedling health and cotton plants throughout the growing season. The results obtained indicated that the cotton varieties used by farmers had very low germination with maximum number of healthy seedlings of 43.75 % in an experiment condition. Highest number of infected seedlings (24-51%) showing characteristic symptoms of seedling blight leading to their death was observed. Under cultivation, a variety of pests was identified on cotton plants. The most important were Bemisia tabaci, Jacobiella fasciali, Helicoverpa armigera, Dysdercus sp, Earias sp, Zonocerus Variegatus, Haritalodes derogata. The Species Zonocerus Variegatus and Haritalodes derogata proved to be devastating on the experimental plot where 100% loss was recorded. The main disease observed at flowering stages in cotton plants was cotton virescence disease. Although lowly infection were observed (0.11 -0.35%) cotton cultivation monitoring and management must be set up so as to prevent its expansion in the west central. Theses finding gives useful information to farmers to reduce cotton yield losses in west central Côte d'Ivoire.Int. J. Appl. Sci. Biotechnol. Vol 6(2): 152-157

Crystal structure of pyrrolizidine alkaloid N-oxygenase from the grasshopper Zonocerus variegatus

The high-resolution crystal structure of the flavin-dependent monooxygenase (FMO) from the African locust Zonocerus variegatus is presented and the kinetics of structure-based protein variants are discussed. Z. variegatus expresses three flavin-dependent monooxygenase (ZvFMO) isoforms which contribute to a counterstrategy against pyrrolizidine alkaloids (PAs). PAs are protoxic compounds produced by some angiosperm lineages as a chemical defence against herbivores. N-Oxygenation of PAs and the accumulation of PA N-oxides within their haemolymph result in two evolutionary advantages for these insects: (i) they circumvent the defence mechanism of their food plants and (ii) they can use PA N-oxides to protect themselves against predators, which cannot cope with the toxic PAs. Despite a high degree of sequence identity and a similar substrate spectrum, the three ZvFMO isoforms differ greatly in enzyme activity. Here, the crystal structure of the Z. variegatus PA N-oxygenase (ZvPNO), the most active ZvFMO isoform, is reported at 1.6 Å resolution together with kinetic studies of a second isoform, ZvFMOa. This is the first available crystal structure of an FMO from class B (of six different FMO subclasses, A–F) within the family of flavin-dependent monooxygenases that originates from a more highly developed organism than yeast. Despite the differences in sequence between family members, their overall structure is very similar. This indicates the need for high conservation of the three-dimensional structure for this type of reaction throughout all kingdoms of life. Nevertheless, this structure provides the closest relative to the human enzyme that is currently available for modelling studies. Of note, the crystal structure of ZvPNO reveals a unique dimeric arrangement as well as small conformational changes within the active site that have not been observed before. A newly observed kink within helix α8 close to the substrate-binding path might indicate a potential mechanism for product release. The data show that even single amino-acid exchanges in the substrate-entry path, rather than the binding site, have a significant impact on the specific enzyme activity of the isoforms.