Parâmetros toxicológicos de óleos essenciais utilizados no combate as pragas da cultura do cajueiro (Anacardium Occidentale) para o seu polinizador, a abelha Apis mellifera L.

Abstract

The use of essential oils as a natural insecticide has been an alternative to pesticides, which have been implicated as a cause of human, animal, and environmental contamination, as well as a factor in the decline in the diversity and abundance of agricultural pollinators. However, the effects of this natural product on pollinators, especially bees, remain under-researched. The present study aimed to determine the toxicological parameters of essential oils used to combat pests of cashew (Anacardium occidentale) crop for its main pollinator, the honeybee (Apis mellifera). The study followed the international standards established by the Organization for Economic Co-operation and Development (OECD) to test toxicity level by determining the topical average lethal dose (LD50) and the average oral lethal concentration (LC50) at 24 and 48 hours, using the bee A. mellifera as surrogate. Thus, essential oils of 10 plant species were tested: Cymbopogon citratus, C. winterianus, Foeniculum vulgare, Lippia alba, L. sidoides, Mentha arvensis, Ocimum basilicum, O. gratissimum, O. micranthum and O. selloi, in concentrations 0.125, 0.25, 0.5, 1.0, 2.0, 4.0 and 8.0%. Results showed that all the essential oils tested were toxic to A. mellifera, but mortality varied according to the essential oil of the tested plant species and concentrations used. The LD50 ranged from 0.254% at 48 hours for C. winterianus to 3.780% at 24 hours for O. micrantum, while the LC50 ranged from 0.398% at 48 hours for M. arvensis to 2.135% at 24 hours for L. alba. It is concluded that the essential oils studied are not safe for use in the presence of pollinating insects, unless management measures are taken to avoid their contact or oral exposure with the product.