Michela Panini1,2, Francesco Tozzi3, Christoph T Zimmer4,5, Chris Bass4,5, Linda Field5, Valerio Borzatta3, Emanuele Mazzoni2, Graham Moores1. 1. ApresLabs Ltd, Harpenden, Herts, UK. 2. Dipartimento di Scienze delle Produzioni Vegetali Sostenibili, Università Cattolica del Sacro Cuore, Piacenza, Italy. 3. Endura SpA, Ravenna, Italy. 4. College of Life and Environmental Sciences, University of Exeter, Penryn, Cornwall, UK. 5. Department of Biological Chemistry and Crop Protection, Rothamsted Research, Harpenden, Herts, UK.
Abstract
BACKGROUND: Metabolic resistance is an important consideration in the whitefly Bemisia tabaci, where an esterase-based mechanism has been attributed to pyrethroid resistance and over-expression of the cytochrome P450, CYP6CM1, has been correlated to resistance to imidacloprid and other neonicotinoids. RESULTS: In vitro interactions between putative synergists and CYP6CM1, B and Q-type esterases were investigated, and structure-activity relationship analyses allowed the identification of chemical structures capable of acting as inhibitors of esterase and oxidase activities. Specifically, methylenedioxyphenyl (MDP) moieties with a polyether chain were preferable for optimum inhibition of B-type esterase, whilst corresponding dihydrobenzofuran structures were potent for the Q-esterase variation. Potent inhibition of CYP6CM1 resulted from structures which contained an alkynyl chain with a terminal methyl group. CONCLUSIONS: Synergist candidates could be considered for field control of B. tabaci, especially to abrogate neonicotinoid resistance.
BACKGROUND: Metabolic resistance is an important consideration in the whitefly Bemisia tabaci, where an esterase-based mechanism has been attributed to pyrethroid resistance and over-expression of the cytochrome P450, CYP6CM1, has been correlated to resistance to imidacloprid and other neonicotinoids. RESULTS: In vitro interactions between putative synergists and CYP6CM1, B and Q-type esterases were investigated, and structure-activity relationship analyses allowed the identification of chemical structures capable of acting as inhibitors of esterase and oxidase activities. Specifically, methylenedioxyphenyl (MDP) moieties with a polyether chain were preferable for optimum inhibition of B-type esterase, whilst corresponding dihydrobenzofuran structures were potent for the Q-esterase variation. Potent inhibition of CYP6CM1 resulted from structures which contained an alkynyl chain with a terminal methyl group. CONCLUSIONS: Synergist candidates could be considered for field control of B. tabaci, especially to abrogate neonicotinoid resistance.