Plant Research International, Wageningen UR, P.O. Box 619, 6700 AP, Wageningen, The Netherlands.
J Chem Ecol. 2012 Apr;38(4):370-7. doi: 10.1007/s10886-012-0097-7. Epub 2012 Mar 29.
Pyrethrins are active ingredients extracted from pyrethrum flowers (Tanacetum cinerariifolium), and are the most widely used botanical insecticide. However, several thrips species are commonly found on pyrethrum flowers in the field, and are the dominant insects found inside the flowers. Up to 80% of western flower thrips (WFT, Frankliniella occidentalis) adults died within 3 days of initiating feeding on leaves of pyrethrum, leading us to evaluate the role of pyrethrins in the defense of pyrethrum leaves against WFT. The effects of pyrethrins on WFT survival, feeding behavior, and reproduction were measured both in vitro and in planta (infiltrated leaves). The lethal concentration value (LC50) for pyrethrins against WFT adults was 12.9 mg/ml, and pyrethrins at 0.1% (w/v) and 1% (w/v) had significantly negative effects on feeding, embryo development, and oviposition. About 20-70% of WFT were killed within 2 days when they were fed chrysanthemum leaves containing 0.01-1% pyrethrins. Chrysanthemum leaves containing 0.1% or 1% pyrethrins were significantly deterrent to WFT. In a no-choice assay, the reproduction of WFT was reduced significantly when the insects were fed leaves containing 0.1% pyrethrins, and no eggs were found in leaves containing 1% pyrethrins. Our results suggest that the natural concentrations of pyrethrins in the leaves may be responsible for the observed high mortality of WFT on pyrethrum.
除虫菊素是从除虫菊花（菊科飞蓬属）中提取的活性成分，是应用最广泛的植物性杀虫剂。然而，田间除虫菊花朵上通常存在几种蓟马，且是花朵内的优势昆虫。有 80%的西花蓟马（Frankliniella occidentalis）成虫在开始取食除虫菊叶片后 3 天内死亡，这促使我们评估除虫菊素在除虫菊叶片抵御西花蓟马中的作用。我们在体外和体内（渗透叶片）测量了除虫菊素对西花蓟马存活、取食行为和繁殖的影响。除虫菊素对西花蓟马成虫的致死中浓度值（LC50）为 12.9mg/ml，0.1%（w/v）和 1%（w/v）的除虫菊素对取食、胚胎发育和产卵有显著的负面影响。当取食含有 0.01-1%除虫菊素的菊花叶片时，2 天内约有 20-70%的西花蓟马死亡。含有 0.1%或 1%除虫菊素的菊花叶片对西花蓟马有显著的驱避作用。在无选择试验中，当昆虫取食含有 0.1%除虫菊素的叶片时，西花蓟马的繁殖显著减少，而在含有 1%除虫菊素的叶片中则未发现卵。我们的结果表明，叶片中除虫菊素的自然浓度可能是导致西花蓟马在除虫菊上高死亡率的原因。
