Biocidal and Biostatic Activity of Aliphatic Amines Against Southern House Mosquito Larvae and Pupae1

Abstract

About 120 aliphatic, fatty, and alkyl amines were evaluated against larvae and pupae of the southern house mosquito, Culex pipiens quinquefasciatus Say. The lower alkyl amines and their salts showed low level of activity. In the homologous series of primary long chain alkyl amines (R-NH2), the activity generally increased as the length of the alkyl chain increased. Against larvae, oleyl, tall oil, coco oil and tallow amines showed considerable activity. In the secondary amines (R2 NH), dicoco (mostly dilauryl) amine was more effective against larvae than dilauryl and dioleyl-linoleyl amine. They were not effective against pupae. Two tertiary amines (trilauryl and tricapryl) showed little activity. Fatty imidazolines and diethanol amides generally were ineffective against larvae, but they showed some activity. against pupae. The former group, however, was more active than the latter. Three fatty propylene diamines showed considerable activity against both larvae and pupae. These were com and tallow propylene diamines. In the homologous series of primary beta-amines, the biological activity was correlated with the length of the alkyl chain. Maximum activity was obtained when the alkyl side chain contained 15 carbon atoms. This was true for both the larvae and the pupae. Their salts were less effective. In the homologous monoquarternaries, high larvicidal activity was manifested by dimethyl-dilauryl, and dimethyl dicoco ammonium salts. In general the dimethyl dialkyl ammonium chlorides were more effective against pupae than larvae. One compound, namely dimethyl dialkyl ammonium bromide, also was quite effective against larvae and pupae. The remaining quaternaries showed slight to moderate activity. Alkyl imidazolinium and isoquinolinium bromides showed slight to moderate activity. The imidazolinium halides were generally more effective. Ethoxylated adducts of aliphatic amines showed slight to moderate activity. Among these the ethoxylated adducts of β-mono amines and β-diamines were more effective. The overall level of activity of these compounds was lower than that of the parent compounds.