Lethal and Sublethal Effects of an Essential Oil-Based Emulsion of Patchouli, <i>Pogostemon cablin</i> (Lamiaceae), on the Tomato Leafminer

Abstract

There has been an excitement toward novel eco-friendly alternatives to pest management, particularly formulations based on essential oils (EOs). Here, the biological activity of an EO-based emulsion derived from patchouli, Pogostemon cablin, was assessed against Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), a devastating and invasive pest in tomato crops worldwide. Laboratory bioassays were carried out to determine and compare lethal doses, lethal times, oviposition of treated individuals, and oviposition of T. absoluta on treated leaves of tomato to pure patchouli essential oil or its emulsion containing 18% of oil. The LD50 were 10.06 and 2.57 µg of patchouli per mg of insect for the EO and emulsion, respectively. Oviposition was reduced in adults derived from the second instar treated with LD10 by 78.5% (EO) and 85.4% (emulsion). The EO and its emulsion conferred similar avoidance to adults when sprayed on tomato leaves. Therefore, both formulations present similar lethal and sublethal effects against T. absoluta. This study demonstrated a remarkable potential of an emulsion containing 18% of P. cablin oil to be employed for T. absoluta management on tomato crops. Further studies are needed to assess and guarantee open field applications.

Keywords

• acute toxicity
• biorational insecticide
• integrated pest management
• plant-based pesticide