Two mitochondrial haplotypes in Pterochloroides persicae (Hemiptera: Aphididae: Lachninae) associated with different feeding sites.

Pterochloroides persicae (Cholodkovsky) is an aphid species belonging to the subfamily Lachninae that uses different members of Rosaceae (specially Prunus spp.) as hosts. Partial sequences from the mitochondrial cytochrome c oxidase 1 (COI) and the nuclear long-wave opsin genes were obtained for approximately 100 P. persicae aphid individuals sampled from 34 colonies collected mainly in Tunisia and other Mediterranean locations. The variability found at the mitochondrial locus revealed the presence of two maternal haplotypes in the studied area that differed in a single nucleotide. The nuclear gene analyzed, however, failed to reveal any variability in this species. The variability found at the COI locus was related to the season of aphid sampling and with the site of feeding, with haplotype I mostly detected in samples collected in spring and summer on trunks and branches and haplotype II only detected in aphids collected in autumn on roots. The observed pattern of molecular variation suggests the presence of two clonal races of P. persicae coexisting in the studied area differentially adapted to conditions prevalent in the alternative seasons and/or to different feeding sites.

Purification of a natural insecticidal substance from Cestrum parqui (Solanaceae).

Cestrum parqui is a shrub originating from Chile used in Tunisia as an ornamental plant. The toxicity of this plant was observed for the first time on the Desert Locust Schistocerca gregaria. It was shown that the toxicity of the plant is concentrated in the Crude Saponic Extract (CSE). In the present research we try to study chemically this fraction to isolate the active substances. The CSE was separated by column chromatography and the obtained fractions were biologically tested on Schistocerca larvae. We observed that only the fraction F9 was active, the separation of this fraction on preparative plates permits to isolate the active compound called S1. The tentative of structure elucidation of the natural substance S1 using 1H and 13C NMR shows that S1 is an heterosidic saponin. Structural modification of S1 structure provoke its activity lose.