Comparative toxicity of essential oils, their emulsifiable concentrates and nanoemulsion formulations against the bean aphid, Aphis fabae

Abstract

The present study aims to prepare emulsifiable concentrate (EC) and nanoemulsion formulations from the plant essential oils of Lavandula angustifolia (Mill.), Ambrosia maritima (L.), Commiphora myrrha (Nees) Engl., Juniperus virginiana (L.), Rheum palmatum (L.) and Tagetes minuta (L.). The efficiency of these essential oils along with their formulations were compared against the bean aphid, Aphis fabae (Scopoli). Results disclosed that all EC preparations passed the emulsion stability and foam formation tests. The particle droplet size of the nanoemulsions varied from 64.3 to 264.7 nm. The toxicity of EC formulations was slightly higher than the corresponding nanoemulsion formulations. Both EC and nanoemulsion of R. palmatum were the most efficient (LC50 = 1003.60 and 1105.34 mg L−1, respectively). EC preparations had no adverse effects on seed beans. The absence of organic solvents and the high aphicidal activity of EC formulations might make these preparations suitable for controlling A. fabae.