Jones Douglas B, Giles Kristopher L, Chen Yi, Shufran Kevin A
Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078-3033, USA.
J Econ Entomol. 2005 Feb;98(1):217-21. doi: 10.1603/0022-0493-98.1.217.
Polymerase chain reaction (PCR) primers were designed and tested for identification of immature parasitoids in small grain cereal aphids and for estimation of parasitism rates. PCR technique was evaluated for 1) greenhouse-reared greenbugs, Schizaphis graminum (Rondani), parasitized by Lysiphlebus testaceipes Cresson and 2) aphids collected from winter wheat fields in Caddo County, Oklahoma. For greenhouse samples, parasitism frequencies for greenbugs examined by PCR at 0, 24, and 48 h after removal of L. testaceipes parasitoids were compared with parasitism frequencies as determined by greenbug dissection. PCR was unable to detect parasitism in greenbugs at 0 and 24 h postparasitism, but it was able to detect parasitoids 48 h after parasitoid removal at frequencies that were not significantly different from dissected samples. Field-collected samples were analyzed by rearing 25 aphids from each sample and by comparing parasitoid frequencies of mummies developed and PCR performed on another 50 aphids. Aphid samples included corn leaf aphids, Rhopalosiphum maidis (Fitch); bird cherry-oat aphids, Rhopalosiphum padi (L.); English grain aphids, Sitobion avenae (F.); and greenbugs. Mummies were isolated until adult emergence, whereupon each parasitoid was identified to species (L. testaceipes was the only parasitoid species found). Parasitism detection frequencies for PCR also were not statistically different from parasitism frequencies of reared aphids. These results indicate that PCR is a useful tool for providing accurate estimates of parasitism rates and especially for identification of immature parasitoids to species.
设计并测试了聚合酶链式反应（PCR）引物，用于鉴定小粒谷物蚜虫体内的未成熟寄生蜂以及估计寄生率。对PCR技术进行了评估，对象为：1）温室饲养的被淡黄蚜小蜂寄生的麦二叉蚜；2）从俄克拉何马州卡多县冬小麦田采集的蚜虫。对于温室样本，将去除淡黄蚜小蜂寄生蜂后0、24和48小时通过PCR检测的麦二叉蚜寄生频率与通过解剖麦二叉蚜确定的寄生频率进行了比较。PCR无法在寄生后0和24小时检测到麦二叉蚜体内的寄生情况，但在去除寄生蜂48小时后能够检测到寄生蜂，其频率与解剖样本无显著差异。对田间采集的样本进行分析时，从每个样本中饲养25只蚜虫，并比较发育成的僵蚜的寄生蜂频率，同时对另外50只蚜虫进行PCR检测。蚜虫样本包括玉米叶蚜、禾谷缢管蚜、麦长管蚜和麦二叉蚜。将僵蚜分离直至成虫羽化，然后将每只寄生蜂鉴定到物种（淡黄蚜小蜂是唯一发现的寄生蜂物种）。PCR的寄生检测频率与饲养蚜虫的寄生频率在统计学上也没有差异。这些结果表明，PCR是一种有用的工具，可用于准确估计寄生率，特别是用于将未成熟寄生蜂鉴定到物种。
