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Altered acetylcholinesterase associated with organophosphate resistance in Rhyzopertha dominica (F.) (Col., Bostrichidae) populations from Brazil and the United States
Author(s) -
Guedes R. N. C.,
Zhu K. Y.,
Kambhampati S.
Publication year - 1998
Publication title -
journal of applied entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.795
H-Index - 60
eISSN - 1439-0418
pISSN - 0931-2048
DOI - 10.1111/j.1439-0418.1998.tb01495.x
Subject(s) - bostrichidae , oxon , organophosphate , biology , acetylcholinesterase , chlorpyrifos , aché , population , pesticide resistance , cholinesterase , toxicology , cross resistance , pesticide , botany , pest analysis , microbiology and biotechnology , ecology , enzyme , biochemistry , pharmacology , demography , neuroscience , sociology
Microplate assay format was used to examine the susceptibility of acetylcholinesterase (AChE) to inhibition by malaoxon and chlorpyrifos‐methyl oxon in individual adult insects of an organophosphate susceptible and two resistant populations (Marshall and Uberlândia) of Rhyzopertha dominica (F.). AChE from these resistant populations was significantly less sensitive to inhibition by malaoxon, but not by chlorpyrifos‐methyl oxon. suggesting that other resistance mechanisms might also contribute to the overall resistance, at least to chlorpyrifos‐methyl. The remaining AChE activities in the presence of 10 −4 m malaoxon were 22.8 and 20.3% in the Marshall and Uberlândia populations, respectively, whereas the remaining activity in the susceptible population was 18.9%. Both resistant populations showed about 27% of remaining activity in the presence of 10 −6 m chlorpyrifos‐methyl oxon, whereas the remaining activity in the susceptible population was 26.1%. One cycle of selection of the resistant populations with chlorpyrifos‐methyl decreased the sensitivity to chlorpyrifos‐methyl oxon (≅ 3%), but increased their sensitivity to malaoxon (3–7%), suggesting that selection with chlorpyrifos‐methyl might result in deselection for resistance to malaoxon in these populations. Such effects on the sensitivity of AChE by different organophosphate selections suggest that different modifications in AChE structure might have occurred in these resistant populations of R. dominica.