Biochemical evaluation of interactions between synergistic molecules and phase I enzymes involved in insecticide resistance in B- and Q-type Bemisia tabaci (Hemiptera: Aleyrodidae)

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. © 2017 Society of Chemical Industry