Fumigant and repellent activity of Rutaceae and Lamiaceae essential oils against Acanthoscelides obtectus Say

Acanthoscelides obtectus Say, a principal pest of kidney beans Phaseolus vulgaris L. in the Mediterranean area, is a multivoltine and oligophagous bruchid that damages not only host plant (kidney bean) but also other Leguminosae species. Essential oils of Rutaceae: Citrus reticulata L. and Citrus limonum L. and of Lamiaceae Mentha piperita L. and Lavandula angustifolia L. were evaluated by fumigation upon A. obtectus adults using concentrations of 13.33, 40, 80 and 106.66 µl/L air. Their vapours have a toxic increasing effect depending upon concentrations and time exposure. Lamiaceae essential oils exhibited the higher fumigant activity inducing mortality of about 37.5 to 100% and 45.25 to 95% for, respectively lavender and peppermint essential oils after 24 h only. Mortality percentages of 85 and 72.5%, respectively for C. limonum and C. reticulata were recorded after exposure time of 96 h at the highest dose. Repellency activity studied at 0.105, 0.315, 0.631 and 0.842 µl/cm2 concentrations showed a higher repellency percentage of 71.25% for peppermint essential oil on A. obtectus adults. Our results suggest that Lamiaceae essential oils more than Rutaceae ones may be useful as a seed protecting tool with fumigation effects against A. obtectus and could replace synthetic insecticides which are harmful to the environment. Key words: Acanthoscelides obtectus, Phaseolus vulgaris, essential oils, repellency, fumigant toxicity.