논문 상세보기
Monocrotophos resistance in the two-spotted spider mite, Tetranychus urticae Koch, mediated by point mutation of acetylcholinesterase
Molecular mechanisms of monocrotophos resistance in the two-spotted spider mite (TSSM), Tetranychus urticae Koch, were investigated. The resistant (AD) strain showed ca. 3,565-fold resistance compared to a susceptible (UD) strain. No significant differences in the esterase and gluthathion-S-transferase activities were found between two strains whereas AD showed a 1.9-fold higher mixed function oxidase activity. Acetylcholinesterase (AChE) inhibition assay revealed that the AChE from AD strain is 91-fold less sensitive to monocrotophos, suggestive of the target site insensitivity mechanism. Three point mutations (G228S, A391T and F439W/Y) in the AChE gene (tssmace) appeared to primarily contribute to the reduced sensitivity of AChE as judged by the correlation study of mutation frequency versus resistance levels (LC50) of several field populations. The resulting correlation coefficients of the G228S and F439W mutations were 0.711 and 0.300, respectively, suggesting that G228S mutation may play a more significant role in resistance. The A391T mutation, saturated in all field populations examined, appears to provide a base line resistance.
