Bulletin of Entomological Research (1997) 87, 581-586

R.N.C. Guedes, S. Kambhampati, B.A. Dover and K.Y. Zhu (1997)
Biochemical mechanisms of organophosphate resistance in Rhyzopertha dominica (Coleoptera: Bostrichidae) populations from the United States and Brazil
Bulletin of Entomological Research 87 (6), 581-586
Abstract: Four possible biochemical mechanisms of organophosphate resistance were examined in populations of Rhyzopertha dominica (Fabricius) collected from eight locations in the states of Minas Gerais and Sao Paulo in Brazil and from seven locations in northeast Kansas, United States. Results from insecticide bioassays with synergists (triphenyl phosphate, diethylmaleate, and piperonyl butoxide) suggested that metabolic detoxification mechanisms might be involved in organophosphate resistance in some of the populations of R. dominica. However, overall low synergism, non-synergism or even antagonism presented by these synergists in all 15 resistant populations suggested that carboxylesterases, cytochrome P450 monooxygenases and glutathione S-transferases were not likely to play a major role conferring organophosphate resistance in R. dominica. This hypothesis was strongly supported by our biochemical studies showing no significant difference in these enzyme activities, as well as cytochrome b₅, P420, and P450 levels between the susceptible and resistant populations. In contrast, all resistant populations of R. dominica showed higher acetylcholinesterase activity than the susceptible population both in the presence and absence of malaoxon. Furthermore, acetylcholinesterase from the resistant populations was less sensitive to inhibition by malaoxon than that from the susceptible. These results suggested that quantitative and qualitative changes in acetylcholinesterase might contribute to organophosphate resistance in these populations of R. dominica.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Raul Narciso C. Guedes

Research topic(s) for pests/diseases/weeds:
pesticide resistance of pest
molecular biology - genes

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Rhyzopertha dominica	Stored grain	Brazil (south)
	Rhyzopertha dominica	Stored grain	U.S.A. (mid S)