Castor Seed Oil: A Promising Biomitecide for Sustainable Management of the Red Coffee Mite (Oligonychus ilicis) (McGregor, 1917) (Prostigmata: Tetranychidae)

The coffee red mite [Oligonychus ilicis (McGregor, 1917)] (Prostigmata: Tetranychidae) is one of the main causes of conilon coffee (Coffea canephora Pierre & Froehn) crop damage due to its phytophagous habit. Nowadays, environment and human harmful synthetic pesticides are used to control this pest. In this context, plant-derived bioactive compounds have been studied as a sustainable alternative for the pest mite management in crops. The aim of this study was to evaluate the castor (Ricinus communis) seed oil action on eggs, larvae, nymph (protonymph and deutonymph) and adults of O. ilicis. Coffee leaf discs (4 cm in diameter) containing 12 individuals of O. ilicis were sprayed with castor seed oil at concentrations of 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0% (v/v) using airbrush. The ovicidal and mortality activity of this extract were evaluated against O. ilicis. The effective concentration of castor oil to cause 50% inhibition of O. ilicis larvae hatching (LC 50) was 1.26% (v/v). Oligonychus ilicis treated with this oil at a concentration of 3.0% presented a larvae hatching percentage of 29.3%, lower than that obtained for the control treatment (79.1%). Castor seed oil 3.0% (v/v) was highly toxic to nymphs and adults of O. ilicis with mortality of 96 and 88%, respectively. Castor seed oil was effective for larvae hatching inhibition and nymphs and adults mortality of O. ilicis, being promising for the coffee red mite sustainable biocontrol.