关键词: 甜菜夜蛾, 抗药性, 氯氟氰菊酯, 表皮穿透率

Abstract: Resistance to lambda-cyhalothrin in the beet armyworm, Spodoptera exigua (Hübner), collected from Jiangpu County, Nanjing, Jiangsu Province was determined by three bioassay methods. The results indicate that the sequence of resistance levels was topical application for 3rd instar larvae (5 499.5-fold) and 5th instar larvae (3 973.2-fold)＞leaf-dip method for 3rd instar larvae (1 041.6-fold)＞leafsandwich method for 5th instar larvae (24.7-fold). Therefore, the resistant strain of S. exigua has a resistance level obtained by way of contact toxicity at least 160 times than that of stomach toxicity. After 8 h treatment the results indicate that the rate of uticular penetration of ¹⁴C lambda-cyhalothrin in 5th instar larvae of the resistant strain was only about 55.5% of that in the susceptible strain. It is safe to say that delayed cuticular penetration is an important mechanism responsible for this resistance.

Key words: Spodoptera exigua, insecticide resistance, lambdacyhalothrin, cuticular penetration