Abstract
The negative effects of nematicides on humans and the environment directed our attention to look for alternatives that are safer, active, and eco-friendly. Therefore, alternative safe methods have high attention to control plant pests such as insects and plant parasitic nematodes. The current research was conducted to study the chemical compositions of different ethanolic plant extracts (basil, peppermint, and horsemint) collected from a high altitude of 2000 meters above the level sea from Ranyah, Saudi Arabia, and toxic effects of each at concentrations of (100, 200, and 400ppm) on survival of Nieloidogyne incognita in vitro and its reproductivity on eggplant cv. Melana in vivo. All treatments of the tested plant species were toxic to the nematode. Basil extract at the rates (200 and 400 ppm) achieved the highest J2 mortality compared to the other extracts and concentrations. The reproduction of M. incognita was highly suppressed and the degree of toxicity varied greatly according to concentration and plant species. The toxicity positively correlated with the increase in concentration. Basil and horsemint at the concentration of 400 ppm seemed to be the most effective in controlling M. incognita and improving the growth of eggplant than the other concentrations. HPLC analysis showed 21 active compounds in the extracts that play a toxic role against the nematode and the chemical compound contents of basil extract were about 28 times higher than horsemint and 13 times more than peppermint which reflects the efficiency of basil in the control process.