Repellence and fumigant toxicity of essential oils of Ocimum gratissimum and Ocimum kilimandscharicum on Tuta absoluta (
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RESEARCH ARTICLE
Repellence and fumigant toxicity of essential oils of Ocimum gratissimum and Ocimum kilimandscharicum on Tuta absoluta (Lepidoptera: Gelechiidae) Flaure Rosette Ehawa Essoung 1 & Alain Tcho Tadjong 2 & Sumesh Chander Chhabra 3 & Samira Abuelgasim Mohamed 4 & Ahmed Hassanali 3 Received: 5 April 2020 / Accepted: 16 June 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Tuta absoluta Meyrick originates in South America and is now one of the most important insect pests of Solanaceae in different parts of the world, including Africa. Its control has relied primarily on chemical insecticides, which are associated with negative ecological effects. In the present study, essential oils of Ocimum gratissimum and O. kilimandscharicum were tested for repellence and fumigant toxicity on the adult stages under laboratory conditions. The oil of O. gratissimum was more repellent, but its toxicity was comparable with that of O. kilimandscharicum. The major constituents of O. gratissimum were methyl eugenol (39.5%) and eugenol (29.7%). Those of O. kilimandscharicum were camphor (47.1%) and 1.8-cineole (19.3%). Eugenol (LC50 of 0.24 μl/ml, 83.3%, RI50 = 0.15) and camphor (LC50 of 0.23 μl/ml, 89.5%, RI50 = 0.13) were more toxic (at 1 μl/ml for 24 h) and repellent than the other constituents. The results show potential of the essential oils for use in integrated management of the tomato pest. Keywords Tomato leaf-miner . Essential oil . Ocimum species . Botanical insecticides . Repellence . Fumigant toxicity
Introduction The tomato borer, Tuta absoluta Meyrick (Lepidoptera: Gelechiidae), is an oligophagous and very harmful leafmining moth which feeds on Solanaceae crops, particularly tomato (Lycopersicon esculentum Mill.), but also on eggplant (Solanum melongena L.), potato (Solanum tuberosum L.), common bean (Phaseolus vulgaris L.), sweet pepper (Solanum muricatum L.) and Datura spp. (Garcia and Espul
1982). The moth was first known as a plant pest in many South American countries (Korycinska and Moran 2009). Now, it has spread rapidly throughout Afro-Eurasia and Middle Eastern countries (Sylla et al. 2017; Xian 2017; Biondi et al. 2018) and is considered as a global economic pest on tomato and other Solanaceae plants (Desneux et al. 2011). This high speed of colonisation is associated with the ability of the pest to adapt to varying climatic conditions and its high biotic potential. Each adult female of T. absoluta may
Responsible editor: Giovanni Benelli * Flaure Rosette Ehawa Essoung [email protected]; [email protected] Alain Tcho Tadjong [email protected] Sumesh Chander Chhabra [email protected] Samira Abuelgasim Mohamed [email protected] Ahmed Hassanali [email protected]
1
University Institute of Technology, University of Ngaoundere, P.O. Box 455, Ngaoundere, Cameroon
2
Department of Chemistry, Faculty of Science, University of Buea, P.O. Box 63, Buea, Cameroon
3
Chemistry Department, School of Pure and Applied Sciences, Kenyatta University, P.O. Box 43
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