D3114: Selected essential oils as an alternative to control Bemisia tabaci MED in Brazil

The introduction of Bemisia tabaci Mediterranean (MED) (Gennadius) (Hemiptera: Aleyrodidae) (Biotype Q) in Brazil, has attracted the attention of farmers and the scientific community, since this species has a high capacity for infestation and high tolerance to conventional insecticides. As an alternative to chemical control, botanical derivatives stand out as a valuable tool for integrated pest management. In this sense, this work evaluated for the first time the bioactivity of essential oils of Piper marginatum Jacq. (Piperaceae) (PM-EO) and Mansoa alliaceae (Lam.) A.ww H. Gentry (Bignoniaceae) (MA- EO) on B. tabaci MED. First, concentration-mortality bioassays were performed to estimate the lethal concentrations (LCs) on nymphs of B. tabaci MED. The LC₅₀s and LC₉₀s were tested in multi-choice assays (repellency and oviposition deterrrence) and no-choice assays (ovicidal effects and infestation ability). Finally, assays were carried out in a greenhouse to check the efficiency of essential oils under semi-field conditions. The major constituents of MA-EO were diallyl trisulphide (52.8%) and diallyl disulphide (33.9%), while (E)-methyl eugenol (34.7%) and (Z)-methyl eugenol (27.5%) were the major components of the PM-EO. The EOs were toxic against nymphs in laboratory and semi-field, besides to present ovicidal potential, repellence, oviposition deterrence and colonization inhibition by B. tabaci MED. Our results reveal two promising sources of botanical pesticides to control B. tabaci MED. These compounds can act causing lethal and sublethal effects in all insect life stages, increasing the control efficiency. However, further studies must be carried out to make the use of these oils feasible in fields.