Résumé:
Plant extracts are of great interest as a potential source of biologically active
molecules. It is in this context that the present study, which focuses on the
valorization of extracts of botanical origins in the field of plant protection, is included.
Two plants are used to prepare the extracts; the medicinal plant thyme and the toxic
plant stramony. The extracts are obtained by the superheated water technique, an
innovative technique based on the physicochemical properties of water that are
modified by the increase in temperature and pressure. The efficacy of the extracts is
assessed against Tuta absoluta (Meyrick) the tomato leafminer, which is considered a
serious threat for tomato production in Algeria. The toxicity of plant extracts is
estimated in vitro and in vivo on Nada F1 variety tomato plants. The biological tests
showed that D. stramonium extract had a remarkable mortality rate exceeding 85%
and 58% for T. vulgarisL extract. three days after treatment. A gradual decrease of the
rates of infestation by the leafminer is observed after spraying of these extracts, the
rates recorded one week after treatment are of the order of 10% for the plants treated
with the Datura extract and 6.66% for the plants. treated with thyme extract.
