Abstract: Nepetalactone, the primary component of catnip oil, were extracted by the using method of simultaneous distillation extraction and separated by using silica gel chromatography column. To compare the repellency of nepetalactone and DEET on mosquitoes, topical bioassay method on the skin and a cage olfactometer were employed to assess the effective protection time and the spatial repellency. The results showed that essential oil of catnip was comprised of 55% nepetalactone, with the constitution of 32% Z, E-nepetalactone and 23% E, Z-nepetalactone. Evaluated by using laboratory efficacy criterions and bioassay method of public health insecticides for pesticide registration, the results showed that the protection time for DEET and nepetalactone against Aedes albopictus was 9.6±0.2 h, and 2.2±0.2 h respectively, and against Culex pipiens pallens was 11.5±1.5 h and 4.3±0.8 h respectively. When used alone, nepetalactone attracted mosquitoes to the trap of the olfactometer, however, when mixed with human odor or a L-lactic acid dichloromethane solution, nepetalactone inhibited the attractiveness obviously. Nepetalactone exhibited a spatial repellency, but was not an ideal topical repellent. DEET did not have the attractiveness to mosquitoes, and did not exhibit inhibition on L-lactic acid dichloromethane solution too, but enhanced the attractivity of human odor to mosquitoes.

Key words: Catnip, nepetalactone, DEET, mosquitoes, repellent activity