Insecticidal effects of essential oils from two medicinal plants against Aleuroclava jasmini (Hemiptera: Aleyrodidae)

Abstract

The whitefly, Aleuroclava jasmini Takahashi (Hemiptera: Aleyrodidae) is an important pest on paper mulberry Brousson etiapapyrifera (L.) Vent. (Moraceae) plants in the green space of Tehran, Iran. Considering the importance of essential oils in the integrated management program of pests, the present survey were carried out to assess the insecticidal effects of essential oils extracted from garden thyme, Thymus vulgaris L. (Lamiaceae), and neem seed, Azadirachta indica A. Juss (Meliaceae) on mortality of immature stages of A. jasmini including eggs, first-instar nymphs, and pupae, and adult repellency. Three doses of the above mentioned essential oils consisting of 0.125%, 0.25% and 0.5% (v/v), were tested in contact toxicity assays. Separately, various essential oils (0.5%), as well as Tween-20 (0.5%) were applied as treated and control for adult repellency. Responses differed according to the type and concentration of oils, as well as growth stage of A. jasmini. The highest mortality was detected with increasing concentration of assayed essential oils. The results showed that younger nymphs were more sensitive to treatments than other growth stages. Essential oil derived from T. vulgaris was the most effective, decreasing the survival rate of eggs, nymphs and pupae 64%, 76% and 50%, respectively, as compared with controls. In free-choice assays, the mean numbers of eggs laid on 0.5% A. indica and T. vulgaris oil-treated plants were 80.98% and 58.57% lower than on control plants, respectively. In conclusion, extracted oils from T. vulgaris and A. indica represented the highest contact toxicity, and repellency to A. jasmini respectively. Finally, the assayed essential oils show promise for inclusion in integrated A. jasmini management programs in green space of Tehran, Iran.

Keywords

• insecticide
• repellency
• essential oil
• paper mulberry
• whitefly