MANUJUM, KITIYAPORN., SOMBOON, SUNGWARL.,
Insecticide Toxicology and Environmental Laboratory,
Faculty of Agriculture, Khon Kaen University, Thailand
diamondback moth, Plutella xylostella Linnaeus (Plutellidae :
Lepidoptera) is a serious pest of cruciferous crops where various classes of
insecticides were used intensively. Field strains of the diamondback moth collected
from seven cruciferous vegetable plantations from four provinces ; Khon Kaen,
Nakhon Ratchasima, Petchaboon and Udon Thani ; were examined for levels of insecticide
resistance to abamectin, Bacillus thuringiensis subspecies aizawi
(Bta), Bacillus thuringiensis subspecies kurstaki
(Btk), chlorfenapyr and profenofos when compared with a susceptible strain.
Insecticide bioassays were carried out by leaf dip feeding method using third
instar, generation 2 and generation 10, larvae. Median lethal concentrations
(LC50) were determined by probit analysis from which resistance ratios were
calculated. Resistance to abamectin, Bta, Btk and profenofos were observed with
the resistance ratios of 2- to 84- fold, 1- to 15- fold, 1- to 15- fold and
1- to 9- fold, respectively. No resistance to chlorfenapyr was found from all
collected field strains.
activities were assayed by a spectrophotometric method using microplate reader.
Activities of general esterase, glutathione S-transferase and oxygenase were
significantly higher (P < 0.05) in resistance strains compared with those
in a susceptible strain. No significant different (P > 0.05) was found in
activity of aetylcholinesterase.
The levels of detoxification enzyme activity,
general esterase and oxygenase, were correlate with varying levels of resistance
in different strains suggesting that both enzymes may play an important role
in diamondback moth resistance. Moreover, biochemical microassays proved to
be an alternating method for monitoring insecticide resistance in field populations
of the diamondback moth.
ที่มา : การประชุมวิชาการสมาคมพิษวิทยาแห่งประเทศไทย ประจำปี
2548 Food & Chemical Safety วันที่ 17-18 พฤศจิกายน 2548 โรงแรมแกรนด์ ทาวเวอร์อินน์