New challenges demand new solutions: Selected essential oils as an alternative to control Bemisia tabaci MED in Brazil

Abstract

The introduction of Bemisia tabaci Mediterranean (MED) (Gennadius) (Hemiptera: Aleyrodidae) (Biotype Q) into Brazil has attracted the attention of farmers and the scientific community as 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 (IPM). In this context, 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) against 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 deterrence) and no-choice assays (ovicidal effects and infestation ability). Finally, assays were carried out in a greenhouse to check the efficiency of the essential oils under semifield conditions. The major compounds identified in PM-EO were (E)-methyl eugenol (34.7%) and (Z)-methyl eugenol (27.5%), while diallyl trisulfide (52.8%) and diallyl disulfide (33.9%) were the major compounds in MA-EO. The EOs were toxic against nymphs in the laboratory and greenhouse and showed ovicidal effect and repellent action. The EOs also reduced oviposition and inhibited the colonization by B. tabaci MED. Our results reveal two promising sources of botanical pesticides to control B. tabaci MED. These compounds can cause lethal and sublethal effects in all insect life stages, increasing the control efficiency.