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Comparative study of the biological activities of the aqueous extracts of two spontaneous plants harvested in the Algerian Sahara

The present study investigates the insecticidal and herbicidal effects of leaf extracts from two plants were harvested in the Northern Algerian Sahara. These are Cleome arabica (Capparaceae) and Pergularia tomentosa (Asclepiadaceae). The efficacy of the extracts from the plants was evaluated by the reflux extraction method. The phytochemical screening of the aqueous extracts of C. arabica shows a remarkable richness in active principles in comparison with the extract of P. tomentosa; including flavonoids, saponosides, glycosides, terpenes, sterols, deoxyose, polyphenols and total alkaloids. The imago of Tribolium confusum treated with aqueous extracts of C. arabica and P. tomentosa at doses of 80% to 100% respectively have mortality rates of 73.33% to 96.67%, and 36.67% to 86.67%. The lethal time 50 (TL50%) of the aqueous extract of C. arabica was estimated about 6.41 days, and 6.94 days for the extract P. tomentosa for the imago of T. confusum. The extracts of P. tomentosa is less toxic than the extracts of C. arabica. The allelopathic potentials of C. arabica and P. tomentosa tested on germination of the seeds of a weed Dactyloctenium aegyptium (Poaceae) and two cultivated species, including Hordeumvulgare and Triticumdurum (Poaceae), show that the inhibitory effect of extracts of C. arabica is very highly significant. It manifests itself in the growth of the aerial and underground part of the H. vulgar and T. durum. The inhibition rate is more than 84.44% for D. aegyptium seeds treated with the different concentrations. The inhibition rates range from 75.56% to 91.11% for T. durum wheat irrigate at 80% to 100%, but are only 55.56% to 77.78% for barley seeds treated with the same concentrations (80% to 100%).