Blossey B, Eberts D, Morrison E, Hunt T R
Department of Natural Resources, Cornell University, Ithaca, NY 14853, USA.
J Econ Entomol. 2000 Dec;93(6):1644-56. doi: 10.1603/0022-0493-93.6.1644.
Lythrum salicaria L., purple loosestrife, an invasive Eurasian perennial, is degrading wetlands across temperate North America. Chemical, physical, and mechanical methods failed to provide long-term control. Therefore, four host-specific insect species (two leaf feeders, a root feeder, and a flower feeder) were introduced as biological control agents. To increase the availability of adults of the root feeding weevil Hylobius transversovittatus Goeze for field releases, we developed a semiartificial diet. Suitability of different diet formulations (varying vitamin mixes, salt mixes, antimicrobials, water content, root content) and temperatures for larval development were evaluated. We also monitored how rearing on artificial diet and the number of larvae per container affected larval development time, larval survival, adult weight, and incidences of deformities. Rearing larvae on artificial diet reduced development time from 1-2 yr to 2-3 mo. Larval development was fastest and survival rates highest under constant temperatures of 25 degrees C. Hatch rate and larval survival decreased if eggs were surface sterilized. Using FABCO antimicrobials could not prevent fungal contamination; use of methyl paraben and sorbic acid was successful in suppressing fungal and bacterial growth throughout larval development time to <10%. The moisture content of the diet did not significantly affect larval survival, development, or adult weight. Decreasing the proportion of purple loosestrife roots in the diet reduced adult weight and the proportion of larvae completing development, and increased development time; no larvae were able to complete development in root-free diet. With an increase in the number of larvae per cup, survival rates were reduced. The experiments revealed a female biased sex ratio: females consistently developed faster and were heavier than males. Incidence of adult deformities was consistently below 5%. Increased availability of adults for field release as a result of mass production using the semiartificial diet will accelerate the biocontrol program targeting purple loosestrife. We are able to produce several hundred weevils per week and have adapted the diet to rear other root-feeding weevils.
千屈菜（Lythrum salicaria L.），即紫千屈菜，是一种入侵性的欧亚多年生植物，正在使北美洲温带地区的湿地退化。化学、物理和机械方法都未能实现长期控制。因此，引入了四种寄主专一性昆虫物种（两种食叶昆虫、一种食根昆虫和一种食花昆虫）作为生物防治剂。为了增加用于田间释放的食根象甲Hylobius transversovittatus Goeze成虫的数量，我们开发了一种半人工饲料。评估了不同饲料配方（不同的维生素混合物、盐混合物、抗菌剂、含水量、紫千屈菜根含量）和温度对幼虫发育的适宜性。我们还监测了在人工饲料上饲养以及每个容器中的幼虫数量如何影响幼虫发育时间、幼虫存活率、成虫体重和畸形发生率。在人工饲料上饲养幼虫将发育时间从1 - 2年缩短至2 - 3个月。在25摄氏度的恒温下，幼虫发育最快且存活率最高。如果卵进行表面消毒，孵化率和幼虫存活率会降低。使用FABCO抗菌剂无法防止真菌污染；使用对羟基苯甲酸甲酯和山梨酸成功地将整个幼虫发育期间的真菌和细菌生长抑制到<10%。饲料的含水量对幼虫存活率、发育或成虫体重没有显著影响。降低饲料中紫千屈菜根的比例会降低成虫体重和完成发育的幼虫比例，并延长发育时间；在无紫千屈菜根的饲料中没有幼虫能够完成发育。随着每个杯子中幼虫数量的增加，存活率降低。实验揭示了雌性偏向的性别比例：雌性始终比雄性发育得更快且更重。成虫畸形发生率始终低于5%。由于使用半人工饲料进行大规模生产而增加了用于田间释放的成虫数量，这将加速针对紫千屈菜的生物防治计划。我们每周能够生产数百只象甲，并且已经调整了饲料以饲养其他食根象甲。
