Olive Leaf Extracts Toxicity to the Migratory Locust, Locusta migratoria: Histopathological Effects on the Alimentary Canal and Acetylcholinesterase and Glutathione S-Transferases Activity.

The migratory locust, Locusta migratoria (Linnaeus), is the most widespread locust species. Frequent applications of insecticides have inevitably resulted in environmental pollution and development of resistance in some natural populations of the locust. To find a new and safe alternative to conventional insecticides, experiments were conducted to assess the effect of olive leaf extracts on L. migratoria fifth instar larvae. The methanolic extracts were prepared from the leaves sampled during four phenological growth stages of olive tree which are as follows: Cluster formation (Cf), Swelling inflorescence buds (Sib), Full flowering (Ff), and Endocarp hardening (Eh). The most relevant result was noted with the extract prepared from the leaves collected at the Sib-stage. Results showed that treatment of newly emerged larvae resulted in a significant mortality with a dose-response relationship. The olive leaf extracts toxicity was also demonstrated by histopathological changes in the alimentary canal resulting in a considerable disorganization and serious damage of the midgut, ceca, and proventriculus structure. Epithelial cells alterations, less dense and degraded striated border, disintegrated regeneration crypts, vacuolarized cells, extrusion of cytoplasmic contents, and rupture of muscular layer were evident in the midgut and ceca of treated larvae. Data of biochemical analyzes showed that olive leaf extracts induced a significant decrease of the hemolymph metabolites (proteins, carbohydrates, and lipids). In a second series of experiments, we showed that the olive leaf extracts reduced the activity of acetylcholinesterase and induced the glutathione S-transferases with a dose-response relationship.

First observation of HO˙ reactivity in water under high energy ions at elevated temperature.

This communication reports the first observation of the formation of HO˙ produced under two different High energy ion beams, (18)O(8+) and (36)Ar(18+) having Linear Energy Transfers (LET) of 65 and 350 eV nm(-1) respectively, at temperatures up to 411 K. Both scavenging with various concentrations of SCN(-) and heavy-ion pulse radiolysis methods are used with an original temperature and pressure regulated optical cell. Deconvolution of kinetics is used to analyze the evolution of HO˙ track segment yields as a function of time and temperature. It takes care of involving the ionic strength effect and Arrhenius expression in the rate constants correction. The results show a fast decay of HO˙ yields in the 10(-10)-10(-8) s range which denotes an efficient reactivity of this species in the track structure of the ion beam. This effect is enhanced with the lowest LET of O(8+). Increasing the temperature also accelerates the decays for both ions. These observations are discussed in terms of temperature activation of reactions and the track structure exhibiting the formation of HO˙ in a "low LET" penumbra around the ionization tracks. HO˙ track segment yields at 100 ns, of 0.4 × 10(-7) and 0.6 × 10(-7) mol J(-1), respectively for 350 and 65 eV nm(-1), are not affected by temperature.