K. Zarred - Institut Supérieur Agronomique of Chott Mariem (ISA), University of Sousse, Tunisia.
A. Laarif - UR۱۳AGR۰۹, Regional Center for Research in Horticulture and Biological Agriculture (CRRHAB), University of Sousse, Tunisia.
A. Ben Hamouda - UR۱۳AGR۰۹, Regional Center for Research in Horticulture and Biological Agriculture (CRRHAB), University of Sousse, Tunisia.
I. Chaieb - Laboratory of Plant Protection, National Institute of Agronomic Research of Tunisia (INRAT), University of Carthage, Tunisia.
J. Mediouni-Ben Jemaa - Laboratory of Biotechnology Applied to Agriculture, National Institute of Agronomic Research of Tunisia (INRAT), Tunisia.

B-biotype Bemisia tabaci is a severe insect pest worldwide in many ornamental, agricultural, and horticultural crops. Control of this insect is obstructed by resistance to many AcetylCholinEsterase (AChE)-inhibiting insecticides, such as organophosphates and carbamates. In the present work, we evaluated the acetylcholinesterase inhibitory activity of six monoterpenoids namely α-pinene, terpineol, linalool, ß-myrcene, nerol and geraniol in vitro and in vivo. Inhibition of AChE of B. tabaci was measured by colorimetric method. The results showed that all of the monoterpenoids produced AChE inhibitory activity, with IC۵۰ values ranging from ۰.۹۶ to ۲۶.۸۵ mM. Alpha-pinene showed the most potent inhibitory activity (IC۵۰= ۰.۹۶ mM). Kinetic analysis showed reversible non-competitive type inhibition, revealing that these components might bind both the enzyme alone and the enzyme-substrate. Results demonstrate the AChE inhibitory activity as mode of action of these monoterpenoids at relatively high concentrations. Thus, this could be useful for investigation of new ecofriendly natural insecticidal compounds.

Acetylcholinesterase, Bemisia tabaci, IPM, Monoterpenoids, Non-competitive inhibition