الفهرس 
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Abstract
Development of natural pesticide agents from plant secondary metabolites is one of the major steps towards reduction of the negative effects associated with synthetic chemical pesticides.
The present study aimed investigating the pesticidal activity of extracted root exudates and aqueous leaf extracts of three desert plants namely Artemisia judaica, Asphodelus microcarpus and Solanum nigrum against some pests such as root-knot nematode Meloidogyne incognita, plant pathogenic bacteria ( Erwinia carotovora, Xanthomonas campestris, and Ralestonia solanacearum), the greater wax moth Galleria mellonella and two weed plants (purslane and phalaris).
7.1. Evaluation of the nematicidal activity of allelochemicals and leaf extracts of A. judaica, A. microcarpus and S. nigrum.
7.1.1. Root exudates
This study indicated that A. microcarpus root exudate was the most effective at all concentrations as it needs only a concentration of 26.87 µg/ml to prevent the hatching of 50% of the treated eggs of M. incognita followed by A. judaica with LC50 of 40.02 µg/ml. Black nightshade, S. nigrum root exudate, gave the least effect. For larval mortality, A. judaica and A. microcarpus root exudate were almost equally potent against the J2 nematode larvae. Solanum nigrum root exudate, was the least effective.
7.1.2. Leaf extracts
Artemisia judaica aqueous leaf extract was the most potent as it needs only a concentration of 19.28 µg/ml to prevent the hatching of 50% of the treated eggs, and killed 100% of J2 larvae at a concentration of 100 µg/ml.
7.2. Evaluation of the bactericidal activity of allelochemicals and leaf extracts of A. judaica, A. microcarpus and S. nigrum.
7.2.1. Root exudates
The crude root exudates of A. microcarpus had remarkable effect on the bacterial growth of the three tested bacteria species namely E. carotovora, X. campestris, and R. solanacearum while A. judaica and S. nigrum showed no antibacterial action on these tested gram- negative bacteria.
7.2.2. Leaf extracts
The crude leaf extract of A. judaica exhibited the highest antibacterial activity against the three studied bacterial species where it showed the lowest minimum inhibition concentration values (0.25 mg/ml to 0.45 mg/ml). The highest MIC values were achieved from S. nigrum leaf extract (3.5 mg/ml to 4.5mg/ml) which represented the weakest antibacterial activity.
7.3. Evaluation of the insecticidal activity of root exudate and leaf extracts of A. judaica, A. microcarpus and S. nigrum.
7.3.1. Root exudates
Root exudate of A. judaica had the highest total mortality percent in addition to causing some deformations in adult moths compared with the control ones. In addition, A. microcarpus root exudate caused the maximum mortality in larval stage; caused maximum larval longevity and reduced larval weight as compared with the control ones. Root exudates of S. nigrum showed the least biological activity against G. mellonella larvae.
7.3.2. Leaf extracts
Asphodelus microcarpus aqueous leaf extract showed maximum larval longevity and reduced larval weight compared with control, where S. nigrum aqueous leaf extract caused the maximum larval mortality. In addition to A. judaica aqueous leaf extract caused some deformations in adult moths.
7.4. Evaluation of the herbicidal activity of root exudates and leaf extracts of A. judaica, A. microcarpus and S. nigrum.
7.4.1. Root exudates
Artemisia judaica was the most effective root exudate that can be used against purslane while A. microcarpus was the most effective one against phalaris compared to the other examined root exudates.
7.4.2. Leaf extracts
Asphodelus microcarpus aqueous leaf extract showed almost similar results to A. judaica on the detected growth parameters, and chlorophyll content in case of P. minor but ranked the second after A. judaica in case of P. oleracea.
The previous results showed that the A. microcarpus root exudate and A. judaica aqueous leaf extract had the most effective pesticidal activity and it is recommended to be used for pest management.