Comparison of the insecticidal effects of water extracted and intact aromatic plants on Acanthoscelides obtectus, a bruchid beetle pest of kidney beans
Résumé
Acanthoscelides obtectus (Say) is one of the most damaging pests of kidney beans, Phaseolus vulgaris L. worldwide. However, aromatic plants from the families Lamiaceae, Lauraceae, Myrtaceae and Poaceae can protect kidney beans by direct or delayed insecticidal effect, through increased adult mortality and inhibition of beetle reproduction (both oviposition and adult emergence). The efficiency of hydrodistillated and intact plants from Thymus vulgaris and T. serpyllum, Mentha piperata, Rosmarinus officinalis, Satureia hortensis, Eucalyptus globulus, Laurus nobilis, Origanum vulgare, and Cymbopogon nardus was compared. For both extracts, Origanum vulgare had the best effect. The insecticidal effect was induced by more than the essential oils because no significant difference was noticed between distilled and intact plants extract. Inhibition of reproduction was particularly important. These results suggest that lipidic as well as non lipidic, allelochemicals, such as phenolics, or non-protein amino-acids, or flavonoids may be involved in the toxicity of aromatic plants to this beetle. © 1995 Birkhäuser Verlag.