Phytochemical Characterization, Fumigant and Contact Toxicity Activities of Four Essential Oils Against Eriophyid Gall Mite, Aceria pongamiae Keifer (Acarina: Eriophyidae).

ABSTRACT

Plant-derived essential oils (EO) offer a natural alternative to chemical pesticides for eco-friendly pest control approaches. Aceria pongamiae Keifer, a notorious pest that affects Pongamia pinnata (L.) Pierre has mainly been controlled using synthetic acaricides leading to resistance development and environmental issues. EOs provide a natural and biodegradable option for pest control, with a unique mode of action. This study evaluates the acaricidal efficacy of EOs-eucalyptus Eucalyptus maculata Hook (EEO), lavender Lavandula angustifola L. (LEO), peppermint Mentha piperita L. (PEO), and black pepper Piper nigrum L. (BPEO) against A. pongamiae for the first time. We investigated the biological activity of EOs using fumigation and contact toxicity assays at concentrations ranging from 0.1 to 1 % and 0.6 to 0.9 % respectively, overexposure periods of 24, 48 and 72 h. Chemical characterization of EOs was performed using GC-MS analysis. Eucalyptol (62.88 %), linalyl acetate (39.11 %), menthol (44.35 %), and caryophyllene (32.77 %) were the main components of EEO, LEO, PEO and BPEO respectively. After 24 h of observation, EEO (LC50=1.01 %) and after 48 and 72 h, PEO had the highest fumigant toxicity (LC50=0.71 and 0.29 % respectively). The BPEO showed the most contact toxicity after 24, 48 and 72 h (LC50=0.92, 0.68 and 0.46 % respectively). This work reinforces the selection of adequate essential oils for implementation in future pest control strategies.