Identification of Biochemical Markers Linked to Neonicotinoid Cross Resistance in Bemisia tabaci (Hemiptera:Aleyrodidae)

摘要

The whitefly,Bemisia tabaci (Hemiptera:Aleyrodidae),is a serious pest in many cropping systems world-wide and occurs in different biotypes.The most widespread one is the B-type,whereas the Q-biotype is nowadays still mostly restricted to Southern Spain.Neonicotinoid cross-resistance is known at a high level in Q-types from Spain and individual samples col-lected in Italy and Germany.Now we detected for the first time high neonicotinoid cross-resistance in a B-type from Israel.Target site resistance to imidacloprid using [~3H]imidacloprid in icotinic acetylcholine receptor (nAChR) binding assays could not be detected in any of these highly resistant strains.The impact of metabolizing enzymes such as esrterases,glutathione S-transferases,and cytochrome P450-dependent monooxygenases in neonicotinoid resistance was studied biochemically with artificial substrates.Monooxygenase activity was increased 2-3 fold in moderately resistant strains (RF approx 30) and even 5-6-fold in highly resistance nad,therefore,monooxygenases seem to be the only enzyme system responsible for neonicotinoid resistance in B.tabaci Q-and B-types.The oxidative degradation of imidacloprid in resistant Q-type strains could be confirmed by metabolism studies of [~14C]imidacloprid in vivo.Five-hydroxy-imidacloprid could be detected as the only main metabolite.The insecticidal activity and binding affinity to nAChR of this compound was 10 times lower than imidacloprid itself in B.tabaci.Arch.Insect Biochem.