DEF sensitive esterases in homogenates of larval and adult Helicoverpa zea, Spodoptera frugiperda, and Agrotis ipsilon (Lepidoptera: Noctuidae).
Homogenates of Helicoverpa zea (Boddie), Agrotis ipsilon (Hufnagle), and Spodoptera frugiperda (J. E. Smith) third instars and adults contained S,S,S-tri-n-butyl phosphorotrithioate (DEF)-sensitive enzymes that hydrolyzed trans-cypermethrin and two known esterase substrates, alpha-naphthyl acetate and beta-naphthyl acetate. Except for H. zea with alpha-naphthyl acetate, larval preparations were more active than those of adults, and no marked sex differences were apparent. The hydrolysis of trans-cypermethrin in noctuid preparations were inhibited by DEF, with pI50 values ranging from 4.5 to 6.7. DEF was a potent inhibitor of the degradation of general carboxylesterase substrates alpha-naphthyl acetate and beta-naphthyl acetate in some cases. Electrophoretic studies confirmed the presence in noctuid gut homogenates of one or more DEF-sensitive esterases that hydrolyzed alpha-naphthyl acetate and beta-naphthyl acetate and that were completely inhibited by dichtorvos.
Usmani
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Department of Entomology, University of Missouri, Columbia 65211, USA. kusmani@mailcity.com
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D000818:Animals; D004950:Esterases / Q000037:antagonists & inhibitors* / Q000302:isolation & purification / Q000378:metabolism; D005260:Female; D007306:Insecticides / Q000378:metabolism; D007814:Larva / Q000201:enzymology; D008297:Male; D009036:Moths / Q000201:enzymology*; D009284:Naphthols / Q000378:metabolism; D063086:Organothiophosphates / Q000494:pharmacology*; D010574:Pesticide Synergists / Q000494:pharmacology*; D011722:Pyrethrins / Q000378:metabolism; D018411:Spodoptera / Q000201:enzymology*
D007306:Insecticides; D009284:Naphthols; D063086:Organothiophosphates; D010574:Pesticide Synergists; D011722:Pyrethrins; C017160:cypermethrin; C005366:naphthyl acetate; C006863:butyl phosphorotrithioate; C027876:alpha-naphthyl acetate; D004950:Esterases