ACARICIDAL AND REPELLENT ACTIVITY OF THREE ESSENTIAL OILS AGAINST TETRANYCHUS URTICAE KOCH (ACARI: TETRANYCHIDAE)

Abstract

The contact toxicity and repellent effects of three essential plant oils viz., Swietenia macrophylla (Mahogany), Azadirachta indica (Neem) and Eucalyptus camaldulensis (Eucalyptus) were evaluated against female adults of Tetranychus urticae Koch (Acari: Tetranychidae) under laboratory conditions. The selected essential oils were tested at 0.5, 1.0, 1.5, 2.0 and 3% concentration. Mahogany oil (S. macrophylla) was the most toxic essential oil to T. urticae females and eggs, while eucalyptus (E. camaldulensis) was the least toxic one (LC50 = 0.887 and 2.146% for adults and 1.230 and 6.980 for eggs), respectively. Leaf discs treated with increasing concentrations of S. macrophylla and E. camaldulensis oils showed a high percentage of repellency (92-100%), respectively. The oviposition deterrent indexes (ODI) of eucalyptus and mahogany oils were ranged (24-100) for T. urticae at a concentration (0.5-3.0%), while this value was between (7-60) in the case of neem oil at the same above concentration. In the persistence test, the mites were exposed to 1, 24, 48 and 72 h old residue and it was found that the lethal concentration effects of the plant oils fade within two or three days. The results suggest that oils of mahogany, neem and eucalyptus can potentially be used to manage T. urticae.