| 8980024 |
Thomas JD, Ottea JA, Boethel DJ, Ibrahim S: Factors Influencing Pyrethroid Resistance in a Permethrin-Selected Strain of the Soybean Looper, Pseudoplusia includens (Walker). Pestic Biochem Physiol. 1996 May;55(1):1-9.
Cytochrome P450 monooxgenase activity toward p-nitroanisole was measured in larvae of three strains of soybean looper, Pseudoplusia includens (Walker), including a laboratory susceptible (S) strain, a resistant (R) strain selected for several generations with permethrin, and a nonselected (NS) strain from the same field collections as the R strain. Activity was significantly higher in R strain larvae than in the S and NS strains (1.8- and 1.4-fold, respectively), and there was no significant difference between activity in the S and NS strains. Resistance to the alpha-cyano pyrethroids deltamethrin and cypermethrin was similar to or higher than that observed with permethrin (RR = 70.0, 62.4, 145.3 and 12.1, 32.3, and 27.0 for permethrin, deltamethrin, and cypermethrin in R and NS strains, respectively). The R strain was less resistant (RR = 4.3) to tefluthrin, a pyrethroid with a fluorinated-phenyl alcohol moiety, and a nonester (ether) pyrethroid, BRC 429 (RR = 17.7). Piperonyl butoxide (PB) significantly increased the toxicity of each insecticide tested in the R and NS strains. In addition, penetration of 14C-cypermethrin was decreased significantly at 24 hr after treatment when R strain larvae were pretreated with PB, with 21.1% of the applied dose unpenetrated in PB-treated larvae and 7.6% unpenetrated in larvae not treated with PB. |
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