Relationship of esterase,acetylcholinesterase and propoxur-resistance to Culex pipiens pallens

Objective To study the activity of relationship between esterase, acetylcholinesterase and the resistance to propoxur in the larva of Culex pipiens pallens. Methods WHO bioassay and spectrophotometric method were used. Results A strain from field selected using propoxur in lab for generations with 12.07-fold resistance ratio was abtained, which the parent was 4.77-fold. The difference of esterase activity between sensitive and resistant strain was not significant. Otherwise, the acetylcholinesterase activity between two strains existed significant difference at high concentration (100×10-6, 10×10-6 and 1×10-6) propoxur. The inhibiting rate was (93.92±0.65)%, (91.69±0.54)% and (87.03±1.14)% respectively in sensitive strain, and (89.81±0.92)%, (87.41±1.66)% and (83.84±0.36)% respectively in resistant strain. Conclusion Metabolic detoxification induced by esterase play a minor role in propoxur-resistant strain. The insensitive AChE may be the main factor in related to the propoxur resistance.