Miles M, Lysandrou M
Dow AgroSciences, Wantage, OX12 9JT, U.K.
Meded Rijksuniv Gent Fak Landbouwkd Toegep Biol Wet. 2002;67(3):665-9.
A sample of Spodoptera littoralis pupae were field collected from in Lebanon in November 1999. Approximately 50 healthy pupae were used to initiate a laboratory colony (stain code LEB). As a benchmark for sensitivity to insecticides the susceptible laboratory strain (LET) was used for comparison. The LET stain has been held in laboratory culture for over 10 years and originated from Israel. Three test chemicals were investigated; Spinosad (Tracer, 480 g/L SC), chlorpyrifos (Dursban 480 g/L EC) and cypermethrin (Ambush C 100 g/L EC) representing a range of different modes of actions. To estimate the sensitivity of the LEB strain relative to the LET stain laboratory bioassays, conducted on second instar larvae exposed treated tomato leaves for two days. The method used was based on IRAC (Insecticide Resistance Action Committee) insecticide susceptibly test number 7. Larvae from the LEB strain were tested in both the F1 and F2 laboratory generations. LC50 values were calculated using a Log-Probit model allowing the susceptibly of each strain to each test item to be compared. The LEB (field) strain were approximately twice as sensitive to spinosad compared with the LET (laboratory) strain. The LEB strain was 6-10 times less sensitive to chlorpyrifos which was within the range expected. However the LEB stain was 250-360 times less sensitive to cypermethrin compared with the LET strain, indicating a high level of resistance to pyrethroids in the field population. This kind of relationship gave a strong indication for negative cross resistance between spinosad and cypermethrin. It was concluded that spinosad had potential as a resistance management tool due to its novel mode of action and negative cross resistance with pyrethroids.
1999年11月，从黎巴嫩野外采集了一批埃及棉铃虫蛹。大约50只健康蛹被用于建立一个实验室种群（品系代码LEB）。作为对杀虫剂敏感性的基准，使用敏感的实验室品系（LET）进行比较。LET品系已在实验室培养超过10年，源自以色列。研究了三种测试化学品；多杀菌素（催杀，480克/升悬浮剂）、毒死蜱（敌百虫480克/升乳油）和氯氰菊酯（安打C 100克/升乳油），它们代表了一系列不同的作用方式。为了评估LEB品系相对于LET品系的敏感性，对暴露于经处理番茄叶两天的二龄幼虫进行了实验室生物测定。所使用的方法基于IRAC（杀虫剂抗性行动委员会）杀虫剂敏感性测试编号7。LEB品系的幼虫在F1和F2实验室世代中均进行了测试。使用对数概率模型计算LC50值，以便比较每个品系对每个测试项目的敏感性。LEB（野外）品系对多杀菌素的敏感性约为LET（实验室）品系的两倍。LEB品系对毒死蜱的敏感性低6 - 10倍，这在预期范围内。然而，与LET品系相比，LEB品系对氯氰菊酯的敏感性低250 - 360倍，表明田间种群对拟除虫菊酯具有高水平抗性。这种关系强烈表明多杀菌素和氯氰菊酯之间存在负交互抗性。得出的结论是，由于其新颖的作用方式以及与拟除虫菊酯的负交互抗性，多杀菌素具有作为抗性管理工具的潜力。
