Synthesis and structure activity relationships in diphenylureas against Culex quinouefasciatus

Substituted diphenylureas 1-23 have been synthesised from isocyanates gener ated from azides of benzoic acid and 4-chlorobenzoic acid with aniline, and 4-chloro-, 2-trifluoromethyl-, 3-trifluoromethyl, 4-phenoxy-, 2,4-dichloro -, 2,5-dichloro-, 3,4-dichloro-, 3-chloro-4-methoxy-, 3-chloro-2-methyl-, 3 -chloro-4-methyl- and 4-nitro-anilines. All the compounds have been tested for insect growth regulating (IGR) activity against early third instar larv ae of Culex quinquefasciatus, the human filariasis vector. Compounds 15 and 19 [1-(4-chlorophenyl)-3-(3-trifluoromethylphenyl) urea and 1-(4-chlorophe nyl)-3-(3,4-dichlorophenyl)urea] exhibit 100% emergence inhibition at 1 ppm concentration against Cx quinquefasciatus larvae. These compounds may play a useful role in mosquito control by maintaining the vector populations at a minimum level.