Prabhaker Nilima, Castle S J, Buckelew L, Toscano Nick C
Department of Entomology, University of California, Riverside, CA 92521, USA.
J Econ Entomol. 2008 Feb;101(1):174-81. doi: 10.1603/0022-0493(2008)101[174:bsobtb]2.0.co;2.
Susceptibility to spiromesifen, a tetronic acid derivative, was determined for three imidacloprid-resistant strains and 12 geographically discrete natural populations of Bemisia tabaci (Gennadius) (=Bemisia argentifolii Bellows & Perring) (Hemiptera: Aleyrodidae) from California and Arizona by laboratory bioassays. Newly emerged first instars were sprayed with aqueous serial dilutions of spiromesifen and evaluated for toxicity to establish baseline susceptibility data. Interpopulation variability in susceptibility to spiromesifen was observed among the natural populations of whiteflies up to 29-fold; however, there was only 30-fold difference in susceptibility among natural and resistant populations tested. In general, spiromesifen was quite toxic to first instars across most of their geographic range, with LC50 values ranging from 0.210 to 6.08 microg (AI)/ml. The magnitude of variation was smaller among the three-resistant strains. These results suggest that the observed variability reflect natural variation in spiromesifen susceptibility among all the test populations, possibly due to previous exposure to insecticides at each location. The effectiveness of spiromesifen also was evaluated against all immature stages of whiteflies from three field and two resistant strains. Spiromesifen was significantly more active against early instars of whiteflies based on lower LC50 values recorded compared with the fourth instars. Spiromesifen was effective against the resistant strains including a Q-biotype of B. tabaci from Spain, which is highly resistant to neonicotinoids. Results of this study indicate absence of cross-resistance between spiromesifen and more commonly used neonicotinoids. Our findings suggest that spiromesifen should be considered an ideal candidate for whitefly resistance management programs in rotation with other effective chemistries.
通过实验室生物测定，测定了三种对吡虫啉具有抗性的烟粉虱品系以及来自加利福尼亚州和亚利桑那州的12个地理上离散的烟粉虱[烟粉虱（Gennadius）=银叶粉虱（Bellows & Perring）]（半翅目：粉虱科）自然种群对四元酸衍生物螺虫乙酯的敏感性。将新羽化的一龄若虫用螺虫乙酯的系列水稀释液进行喷雾处理，并评估其毒性以建立基线敏感性数据。在粉虱的自然种群中，观察到对螺虫乙酯的敏感性存在种群间差异，差异高达29倍；然而，在测试的自然种群和抗性种群之间，敏感性差异仅为30倍。一般来说，在其大部分地理分布范围内，螺虫乙酯对一龄若虫毒性相当大，LC50值范围为0.210至6.08微克（有效成分）/毫升。在三个抗性品系中，变异幅度较小。这些结果表明，观察到的变异性反映了所有测试种群对螺虫乙酯敏感性的自然变异，这可能是由于每个地点之前接触过杀虫剂所致。还评估了螺虫乙酯对来自三个田间种群和两个抗性品系的粉虱所有未成熟阶段的效果。基于记录的较低LC50值，螺虫乙酯对粉虱早期若虫的活性明显更高，与四龄若虫相比。螺虫乙酯对包括来自西班牙的对新烟碱类高度抗性的Q型烟粉虱在内的抗性品系有效。本研究结果表明螺虫乙酯与更常用的新烟碱类之间不存在交叉抗性。我们的研究结果表明，螺虫乙酯应被视为与其他有效化学药剂轮换用于粉虱抗性治理计划的理想候选药剂。
