泽兰实蝇（Procecidochares utilis）作为天敌控制紫茎泽兰（Eupatorium adenophorum）已经在国内外得到广泛的应用，但关于它对紫茎泽兰控制的有效性和防治现状的研究尚不深入。该文通过对攀西地区紫茎泽兰入侵危害严重的路域生态系统中泽兰实蝇寄生状况的抽样调查，初步研究了泽兰实蝇对紫茎泽兰生长，特别是生殖能力的影响。寄生率的调查采用随机取样法，分别从植株寄生率和枝条寄生率两方面进行，并比较不同生境下及不同年龄植株枝条寄生率的差异；选取相同数量、相同部位的各年龄植株寄生和非寄生枝条（对照），分别调查其花枝量、头状花序数及结实量，进行分析比较。研究结果表明：1）植株寄生率与枝条寄生率有显著差异（p<0.05），分别为71.67%和17.30%，前者显著高于后者；样方调查结果，成熟群落中枝条寄生率为17.48枝·m-2；1虫瘿·枝条-1的枝条占所有寄生枝条的92.30%；2）湿润生境下紫茎泽兰的枝条寄生率为20.27%，显著高于干旱生境下的枝条寄生率（9.33%）（p<0.05）；3）不同年龄植株枝条寄生率有差异，0～1年生植株枝条寄生率分别为36.36%和21.56%，显著高于2～4年生的植株枝条寄生率，分别为13.50%、 8.82 %和12.16%（p<0.05）；4）在目前的寄生强度下，泽兰实蝇对紫茎泽兰枝条的直径、花枝量、头状花序数及结实量均无显著影响（p>0.05）。
Crofton weed gall fly (Procecidochares utilis) has been used widely as a natural enemy to control the invasive plant, crofton weed (Eupatorium adenophorum), but the effectiveness and mechanisms of crofton weed gall fly in controlling and preventing the weed have not well been studied. In this paper, we surveyed parasitism of gall fly on crofton weed in ecosystems that had been damaged by crofton weed in the western Panzhihua Prefecture, Sichuan Province, Southwest China. We studied the effects of the gall fly on the growth and reproduction of crofton weed by comparing the parasitism rates of individuals and branches with different ages in different habitats. The diameter, quantity of blossom branches, capitula and seeds between parasitized and normal branches also were compared. The results showed that: 1) there were significant differences (p<0 .05) in the parasitism rates based on individuals (71.67%) and branches (17.30%). There were, on average, 17.48 parasitized branches per square meter in the adult population; branches with one insect gall accounted for 92.30% of the total parasitized branches. 2) The parasitism rate of branches (20.27%) in the humid habitat was markedly higher than that in the drought habitat (p<0.05). 3) The parasitization rate of branches differed significantly among individuals of different ages. Parasitism rates of seedlings (36.36%) and one-year-old individuals (21.56 %) were significantly higher (p<0.05) than older individuals (13.50%, 8.82%, and 12.16% for two-year, three-year, and four-year old individuals). 4) Crofton weed gall fly had no significant effect on the diameter of branches, quantity of blossom branches, capitula or seeds of crofton weed, suggesting that parasitism of crofton-weed gall fly would not impact the growth and reproduction of crofton weed.