The use of polyacrylamide gel electrophoresis for the investigation and detection of fenitrothion and chlorpyrifos-methyl resistance in Oryzaephilus surinamensis (Coleoptera : Silvanidae)

Esterase activity in 16 strains of Oryzaephilus surinamensis (L.) with diff erent degrees of resistance to chlorpyrifos-methyl and fenitrothion were in vestigated quantitatively and qualitatively. Chlorpyrifos-methyl resistance strongly and positively correlated with total esterase activity, whereas t here was a moderate relationship between fenitrothion resistance and estera se activity. Polyacrylamide gel electrophoresis (PAGE) provided visual conf irmation of these relationships and identified qualitative differences in e sterase activity between the two highly chlorpyrifos-methyl strains. Both m ethods revealed that the elevated esterase activity was not acetylcholinest erase based. The involvement of elevated esterase activity in resistance wa s confirmed through its inhibition by chlorpyrifos and chlorpyrifos oxon. P AGE was identified as an effective tool for the simple and rapid detection of resistance due to the activity of esterases and is more powerful than qu antitative total esterase assays due to its ability to identify both quanti tative and qualitative differences. (C) 2001 Academic Press.