Najah Mohamad Tonp1*, Ibrahem Aziz Saker1 and Angham Mohamad Boubou 1

1 Department of Plant Protection, Faculty of Agricultural Engineering, Lattakia University, Syria.

(*Corresponding author: Najah Mohamad Tonp, Email:  tonpnajah@gmail.com)

Received: 15/ 6/ 2025     Accepted: 14/ 9/ 2025

Abstract: 

A preliminary laboratory study was conducted to evaluate the biological effects of the aqueous extracts of four local plant species: oleander (Nerium oleander L.), common myrtle (Myrtus communis L.), sticky fleabane (Inula viscosa L.), and pink pepper (Schinus molle L.) against the red tomato spider mite, Tetranychus evansi, at its three developmental stages (eggs, first-instar nymphs, and adult females) on black nightshade (Solanum nigrum) under controlled laboratory conditions (temperature: 24 ± 4 °C, relative humidity: 65 ± 5%, photoperiod: 16:8 h light/dark). The acaricide azocyclotin was used as a standard reference treatment, in addition to a water-treated control. The results showed that the leaf extract of oleander (Nerium oleander) exhibited the highest efficacy in killing individuals, inhibiting egg hatching, and reducing female fertility, significantly outperforming the other plant extracts. The mean egg hatching rate was recorded at 4.4%, while the average mortality rates of both nymphs and adult females reached 78% and 72%, respectively, compared with the control. Regarding the evaluation of the fertility of newly matured females after treatment with aqueous extracts, oleander extract demonstrated the strongest effect, causing the death of all females in all replicates before oviposition. These findings indicate the potential use of local plant extracts as effective natural sources in Integrated Pest Management (IPM) programs, thereby contributing to the protection of economically important crops from harmful mites in an environmentally safe manner.

Keywords: Plant extracts, T.evansi, Biological efficacy, Bioassays.

 Full paper in Arabic: PDF