Chemical Composition and Insecticidal Activity of Thymus algeriensis Boiss and Reut. Essential Oil against Aphis fabae Scopoli1763

Abstract

Background: The aim of the present work was to study the chemical composition and evaluate the insecticidal activity of Thymus algeriensis Boiss and Reut. essential oil (TAEO) against Aphis fabae Scopoli is a polyphafous which desap many cultivated plants, under shelter and in the open field. Methods: The extraction of essential oil from the aerial parts of T. algeriensis was performed by hydro-distillation (yield: 2.7% w/w). The extracted essential oil was analyzed by gas chromatography coupled with mass spectrometry (GC/MS) and by gas chromatography (GC). Result: From this essential oil 22 compounds representing 92.27% of the oil were identified. The main constituents were carvacrol (61.5%), g-terpinene (8.81%) and p-cymene (10.83%). The experiment was carried out in random blocks (05), to study the behavior of Aphis fabae and its host, namely Vicia fabae. Thus, twenty-five bean plants infested with black aphids were chosen and distributed at random. The plants were treated by spraying at different doses of (HETA) (control, acetone; 0.1; 0.05 and 0.01%). The results obtained showed that TAEO at 0.1% results in a decrease of infestation rate of A. fabae, leading a mortality rate of 75.51%.The results of the treatment carried out at the beginning of spring are very promising; oil could thus be used as bio-insecticide.