Mosquito larvicidal activities of oil solutions and emulsifiable formulations containing lipophilic N-alkyl and N,N'-dialkylalkylenediamines.

Abstract

Alkyl halides with various chain lengths were reacted with alkylenediamines such as propylenediamine (1,3-diaminopropane), putrescine, 1, 1, 4, 4-tetramethylputrescine, 1, 4-cyclohexane bis methylamine, and Duomeen® L-11 (N-(2-undecyl)propylenediamine) to provide effective larvicides against Anopheles albimanus Wiedemann, Culex pipiens quinquefasciatus Say, and Aedes aegypti (L.). Many of the amines were good surfactants with high solubilities in oil. They were conveniently formulated in emulsions with oil. The test emulsion was applied to the surface of 1 liter of water containing larvae in a pan. At the water surface the emulsion broke to form an oil film. Against 3rd instars of A. aegypti, the 48-h LD50 value was 860 μl of emulsion containing 5% Richfield Larvicide oil applied to the 465-cm2 surface of the water. Much lower LD50 values were obtained with emulsions containing amine in addition to oil. With emulsions containing 1% of various amines and 4% oil, the LD50 values in μl emulsion/465 cm2 were: 17 μl with N,N′-didecyl-1,4-cyclohexane bis methylamine; 20 μl with N-decyl Duomeen L-11; 23 μl with N-tetradecylpropylenediamine; 33 μl with N,N′-dinonyl-1,1,4,4-tetramethylputrescine; and 37 μl with oleylamine. By contrast, the LD50 value was 4.6 μl of emulsion containing only 0.04% Abate® (0, 0′-(thiodi-p-phenylene)0,0,-0′,0′-tetramethyl phosphorothioate) and 0.16% oil. Abate was 92 times as potent as the most active diamine, but this difference in potencies was reduced to 29-fold when larval exposure to the oil film during the 48-h test period was reduced to 2 h.