Cross Resistance in a Diazinon-Resistant Strain of Musca domestica (L.)1

Abstract

Laboratory selection of a Diazinon^® (0,0-diethyl 0-(2-iso- propyl-4-methyl-6-pyrimidinyl phosphorathioate )-resistant field strain of house fly, Musca domestica( (L,), for nine generations on Diazinon-treated panels increased resistance not only to Diazinon but to a wide variety of insecticides. The levels of resistance to the various materials, as determined by topical application, were: Diazinon (38-fold), parathion (16), ronnel (18), Chlorthion^® (O-(3-chloro-4-nitrophenyl0,0-dimethyl phosphorothioate) (23), malathion (5), Sevin^® (1-naphthyl-N-methyl carbamate) (more than 37-fold), Isolan^®(dimethyl 5-(I-isopropyl-3-methyl-pyrazolyl) carbamate) (14), Pyrolan^® (dimethyl 5-(3-methyl-I-phenylpyrazolyl) carbamate) (10), chlordane (400), dieldrin (220), lindane (250), DDT (more than 6,400-fold), TDE (more than 1,300), methoxychlor (more than 3,600), Dilan^® (1 part 1,1-his(p-chlorophenyl)-2-nitropropane and 2 parts (I,I-bis(p-chlorophenyl)-2-nitrobutane) (10) allethrins (5), pyrethrins (4), and Lethane 384^® (2-(2-butoxyethoxy) ethyl thiocyanate) (2-fold). These increases in tolerance, except to Lethane, pyrethrins, allethrins, and malathion (which may be simply instances of vigor tolerance), are considered true resistances. The extent of cross-resistance indicates that most of the contemporary materials will be ineffective against Diazinon- resistant flies. It is suggested that phosphorodithioates, more stable carbamates, or more toxic thiocyanates may offer promise for control. Tests on resistant flies collected from the field without further selection on Diazinon in the laboratory indicate that the pattern of resistance determined in this study is very similar to that which occurs under completely natural conditions of selection.