Characterisation of abamectin resistance in a field-evolved multiresistant population of Plutella xylostella.
BACKGROUND
Plutella xylostella (L.) has evolved resistance to various kinds of insecticide in the field. Reversion and selection, cross-resistance, inheritance and mechanisms of abamectin resistance were characterised in a field-derived multiresistant population of P. xylostella from China.


RESULTS
Compared with a susceptible Roth strain, the field-derived TH population showed approximately 5000-fold resistance to abamectin. Rapid reversion of abamectin resistance was observed in the TH population when kept without insecticide selection. The TH-Abm strain, selected from the TH population with abamectin, developed 23 670-fold resistance to abamectin, a high level of cross-resistance to emamectin benzoate and low levels of cross-resistance to spinosad and fipronil. Genetic analyses indicated that abamectin resistance in the TH-Abm strain was autosomal, incompletely dominant and polygenic. P450 monooxygenase activities in the TH-Abm strain were significantly elevated compared with the TH strain. Piperonyl butoxide (PBO) inhibited a small part of abamectin resistance in the TH-Abm strain.


CONCLUSIONS
Field-evolved high-level resistance to abamectin in the TH population was not stable. Selection of the TH population with abamectin resulted in an extremely high level of cross-resistance to emamectin benzoate and low levels of cross-resistance to spinosad and fipronil. Enhanced oxidative metabolism was involved in, but may not be the major mechanism of, polygenic abamectin resistance in the TH-Abm strain.
Pu
Xin
X
College of Plant Protection, Nanjing Agricultural University, Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects (Ministry of Agriculture), Nanjing, PR China.
Yang
Yihua
Y
Wu
Shuwen
S
Wu
Yidong
Y
D000818:Animals; D018432:Drug Resistance, Multiple / Q000187:drug effects* / Q000235:genetics; D004357:Drug Synergism; D019143:Evolution, Molecular; D005260:Female; D007305:Insecticide Resistance / Q000187:drug effects* / Q000235:genetics; D007306:Insecticides / Q000494:pharmacology*; D007559:Ivermectin / Q000031:analogs & derivatives* / Q000494:pharmacology; D007915:Lepidoptera / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D008297:Male
D007306:Insecticides; C048324:abamectin; D007559:Ivermectin