Activity of 0-Ethyl S-Propyl Organophosphoros Compounds Against Tobacco Budworms and Boll Weevils1234

Abstract

In the laboratory, sprays of organophosphorus compounds with the O -ethyl S -propyl moieties were 5–100X more active against a susceptible strain of the tobacco budworm, Heliothis virescens (F.), and all except ER-9700, 9362, 9306, and NTN-9306 were 2–3X more active against the boll weevil, Anthanomus grandis Boheman, than certain alkyl or aryl O, O -dialkyl organophosphorus compounds. LD50’S for topical applications of Bay NTN-9306, ( O -ethyl 0 -[4-(methylthio)phenyl] S -propyl phosphorodithioate) to a susceptible and a field-collected strain of the tobacco budworm differed ca. 8X (0.024 and 0.19 mg/g after 48 h, respectively); this might indicate a potential for resistance to this new class of organophosphorus compounds. In the field, NTN-9306, Rohm & Haas RH-218 ( O -ethyl S -propyl O -(2,4,6-trichlorophenyl) phosphorothioate), and Ciba-Geigy CGA-15324 ( O -(4-bromo-2-chlorophenyl) O -ethyl S -propyl phosphorothioate), each applied at a rate of 1 lb/acre, reduced damage to bolls by Heliothis spp. (predominately the tobacco budworms) 81–85% compared with bolls in untreated plots.