Can aromatic and medicinal plants effectively control Tylenchulus semipenetrans? Evidence from in vitro and in vivo studies

Tylenchulus semipenetrans is a highly damaging obligate plant parasitic nematode (PPN) that poses a significant threat to citrus crops. The use of chemical nematicides has proven effective in reducing T. semipenetrans populations; however, repeated use can have negative environmental impacts, necessitating the adoption of more ecological strategies. The current study aimed to evaluate the nematicidal effect of three aromatic and medicinal plants (AMPs), Rosmarinus officinalis, Laurus nobilis and Verbena officinalis against T. semipenetrans in terms of juvenile J2 mortality and eggs hatch inhibition under greenhouse and laboratory conditions. The results showed that all AMPs aqueous extracts exhibited toxicity against T. semipenetrans, with J2 mortality ranging between 25.85 % and 75.17 %, compared to 1.0 to 13.6 % in the control treatment. Egg hatching varied between 0 % and 66 %, compared to 73 to 95 % in control treatment. Toxicity increased with increasing AMPs aqueous extract concentration and incubation period, reaching more than 55.44 % mortality after 96 h and complete egg hatching inhibition after 144 h of incubation at an R. officinalis aqueous extract concentration of 10 %. In the greenhouse experiment, the aqueous extract of R. officinalis was highly active against T. semipenetrans, resulting in a substantial reduction in nematode populations, with counts ranging from 475 nematodes/100 g of soil and 122 nematodes/10 g of roots, compared to populations of 997.30 nematodes/100 g of soil and 185 nematodes/10 g of roots in the control treatment. The results of this study suggest that AMPs studied, could be used as a bionematicide product for managing T. semipenetrans.