Effect of extracts from methanolicine plants on certain Moroccan plants on Tuta absoluta (Lepidoptera, Gelechiidae )

After the introduction of Tuta absoluta (Meyrick) in 2008, this pest caused serious damage to tomato production in Morocco. Chemical control is a quick and simple method to prevent the development of this pest. However, the widespread use of pesticides poses potential risks to human health and the environment. This study is an attempt to provide alternatives based on the use of natural products to be used as biopesticides of plant origin. Seven Moroccan plants (Thymus vulgaris, Ononis natrix, Lawsonia inermis, Ricinus communis, Argania spinosa, Urtica dioica and Peganum harmala) were collected from different areas of the Souss Valley. The active ingredients were extracted using a rotary evaporator (40 degree C) with methanol as a solvent. The toxicity of the plant extracts against L2 larvae of T. absoluta was evaluated using the 'Leaf dip bioassay' method. POLO-PC software was used to determine the lethal dose to 90% of larvae (LD90). The extract of T. vulgaris gave the highest rate of mortality (97%), followed by R. communis, P. harmala and U. dioica, which gave mortality rates of around 80%, 65% and 55% respectively. The lowest LD90 was obtained with the extract of T. vulgaris (156 023 ppm).Original Abstract: Apres son introduction en 2008, Tuta absoluta (Meyrick) a cause des graves dommages a la production de tomates au Maroc. La lutte chimique est une methode rapide et simple pour empecher le developpement de ce ravageur. Cependant, l'utilisation massive de ces produits chimiques presente des risques potentiels pour la sante et l'environnement. Afin de prevenir cet inconvenient, cette etude est un essai pour fournir des alternatives basees sur l'utilisation des bioinsecticides d'origine vegetale qui sont des produits naturels. Sept plantes marocaines (Thymus vulgaris, Ononis natrix, Lawsonia inermis, Ricinus communis, Argania spinosa, Urtica dioica et Peganum harmala) ont ete collectes dans differentes zones de la vallee du Souss. Les matieres actives ont ete extraites en utilisant un evaporateur rotatif (40 degree C) et du methanol comme solvant. La methode du > a ete adoptee pour evaluer la toxicite in vitro de ces extraits vegetaux contre les larves L2 de T. absoluta. Le logiciel POLO-PC a ete utilise pour determiner la dose letale pour 90% des larves (DL90). L'extrait de T. vulgaris a affiche le taux de mortalite le plus important (97%), suivi par R. communis, P. harmala et U. dioica e qui affichaient respectivement des taux d