  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%).
