Essential oils as active ingredients of botanical insecticides against aphids
2019
Ikbal, Chaieb | Pavela, Roman
Aphids are significant pests of almost all current cultivated plants. Protection against aphids is based predominantly on the application of synthetic insecticides; however, these insecticides have a negative impact on nontarget organisms, including humans. Therefore, new plant protection alternatives have been sought. Essential oils (EOs) isolated from plants are among the substances generally considered safe for the environment and health and can thus be used as active substances in new botanical insecticides. This is why the efficacy of EOs has also been studied using laboratory methods against some aphid species in contact and fumigation tests. This review summaries the present knowledge of acute toxicity of EOs against aphids. Despite the methodological non-uniformity of published papers, it was possible to select 25 plant species whose EOs have shown LD₅₀ below 1 µl (µg) ml⁻¹ in contact tests and 16 plant species whose EOs have shown LC₅₀ below 1 µl l⁻¹ in fumigation tests or have resulted in aphid mortality over 90% upon application of 2 µl l⁻¹. EOs from only five plant species (Foeniculum vulgare, Mentha piperita, M. pulegium, Ocimum basilicum, and Pimpinella anisum) have shown excellent efficacy in both contact and fumigation tests and can thus be considered an optimal source of active substances for the development of botanical insecticides against aphids. At the same time, methodological principles for primary screening of acute toxicity of the EOs against aphids were critically discussed, including potential directions of further research in this field of knowledge.
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