Bioactivity of essential oils of Dizygostemon riparius (Plantaginaceae) on Tetranychus neocaledonicus (Acari: Tetranychidae)

Abstract

The red mite, Tetranychus neocaledonicus (Acari: Tetranychidae) is one of the most important agricultural pests that cause significant damage to crop productivity from family farmers to large rural producers, and chemical control, via pesticides, is widely employed. However, their continuous and exacerbated use presents numerous health and environmental risks. In this context, the secondary metabolites present in the essential oils of aromatic plant species have been gaining prominence as eco-efficient alternatives. For example, the terpene profile of the essential oil (EO) of the recently described species Dizygostemon riparius (Plantaginaceae) has gained attention. Initially, D. riparius was collected from the banks of the Rio Preto in São Benedito do Rio Preto, Maranhão, Brazil. The EOs were extracted using the hydrodistillation method and contained terpene classes, which, according to the literature, have shown significant biological activity. The EOs were then tested against T. neocaledonicus mites (Acari: Tetranychidae), demonstrating their toxic potential, with lethal concentrations (LC50) of 2.52 µL/mL and 4.17 µL/mL for the white and lilac floral morphotypes, respectively. The white morphotype showed 62% repellency at the two sublethal concentrations tested, whereas the lilac morphotype showed percentages of 76% and 66% for the LC20 and LC30, respectively. The present study is the first to report the acaricidal potential of the EO chemical constituents of the white and lilac morphotypes of D. riparius against T. neocaledonicus.