甜菜夜蛾对虫酰肼的抗性选育、风险评估及交互抗性

Selection,risk assessment and cross-resistance of resistance to tebufenozide in the beet armyworm,Spodoptera exigua (Hübner) (Lepidoptera:Noctuidae)

虫酰肼是目前防治甜菜夜蛾Spodoptera exigua（Hübner）的一种主要杀虫剂,为评估其抗性风险,在室内进行了抗性筛选和交互抗性的研究。采用饲料感染法,在甜菜夜蛾饲养75代期间用虫酰肼筛选62代,与起始种群相比抗性上升39.2倍,与室内敏感品系相比抗性上升141.3倍。在筛选的早、中、后期,现实遗传力h^2分别为0.1075（F0-F25）、0.2780（F26-F50）和0.0538（F51-F75）,整个筛选62代现实遗传力为0.1556。抗性种群筛选43次（F55）后停止用药筛选,饲养21代后,与敏感品系相比,抗性水平由63.5倍下降到21倍,抗性下降3倍。说明甜菜夜蛾具有对虫酰肼产生抗性的风险,且抗性衰退缓慢,短期内很难恢复到敏感水平。交互抗性测定结果表明,上述室内选育的抗性品系对甲氧虫酰肼具有71.4倍的高水平交互抗性,对阿维菌素具有13.1倍的中等水平交互抗性,对甲维盐、茚虫威和呋喃虫酰肼分别具有7.0、8.4和4.7倍的低水平交互抗性,但对溴虫腈交互抗性不明显（1.9倍）。结果提示：间断交替使用虫酰肼可以延缓抗性的发展,但除溴虫腈外,虫酰肼和其他几种新型杀虫剂之间的轮用可能不是甜菜夜蛾抗性治理的有效策略。

Tebufenozide, the first commercial non-steroidal ecdysteroid agonist, is used as a key insecticide to control the beet armyworm, Spodoptera exigua （Hübner） at present. To evaluate the risk of resistance, a field population of the beet armyworm from Shenzhen, Guangdong province was used to select for resistance to tebufenozide by dietary exposure in the laboratory. After selection with tebufenozide 62 times during 75 generations, a resistant strain was achieved with resistance ratio of 39.2 to tebufenozide compared with the original reference strain （141.3 compared with a susceptible laboratory strain）. Estimation of realized heritability （ h^2 ） of resistance in different selection stages was based on the method described by Tabashnik ＆ McGaughey. The results showed that the h^2 to tebufenozide in the early, middle and latter selection stages was 0.1075 （F0 - F25）, 0.2780 （F26 - F50） and 0.0538（F51 - F75）, respectively. The h^2 for the entire selection experiment was 0. 1556. The susceptibility to tebufenozide increased 3 times when the culture was kept for 21 generations without exposure to the chemical pressure after 43 rounds of selection. This suggested that the beet armyworm has the capability of developing resistance to tubufenozide, and it is difficult for the beet armyworm to recover the sensitivity to tebufenozide during a short period. Bioassay revealed that this resistant strain had high cross-resistance to methoxyfenozide （RR = 71.4）, moderate cross-resistance to abamectin （13.1）, low cross-resistance to emamectin benzoate （7.0）, indoxacarb （8.4） and JSll8 （4.7）, and a little crossresistance to chlorfenapy （1.9）. The results of resistance risk assessment suggest when tebufenozie is applied by interruption and/or alternation with other insecticides possessing a different mode of action, the resistance development rate in the beet armyworm would be delayed. However, cross-resistance between tebufenozide and other insecticides except chlorfenapy indicates that a resistance management strategy for the beet armyworm involving the rotation of these new insecticides is not likely to be effective.