Shrestha Govinda, Skovgård Henrik, Reddy Gadi V P, Steenberg Tove, Enkegaard Annie
Western Triangle Ag Research Center, Montana State University, Conrad, MT, United States of America.
Department of Agroecology, Science and Technology, Aarhus University, Research Centre Flakkebjerg, Forsøgsvej 1, Slagelse, Denmark.
PLoS One. 2017 Aug 30;12(8):e0184080. doi: 10.1371/journal.pone.0184080. eCollection 2017.
Aphid species feeding on lettuce occupy distinct feeding sites: the lettuce aphid Nasonovia ribisnigri prefers to feed on heart leaves, whereas the potato aphid Macrosiphum euphorbiae feeds only on outer leaves. The aphid parasitoid Aphelinus abdominalis, known to be able to regulate M. euphorbiae on many crops, has recently been indicated as a promising biocontrol candidate also for use against N. ribisnigri, a major pest of lettuce. This study therefore examined A. abdominalis parasitization preference between N. ribisnigri and M. euphorbiae and its ability to parasitize aphids feeding on different parts of lettuce plants. In addition, life history traits of A. abdominalis on these aphid species were investigated. In no-choice laboratory experiments on leaf discs and 24 h exposure, A. abdominalis successfully parasitized 54% and 60% of the offered N. ribisnigri and M. euphorbiae, respectively, with no significant difference. In the corresponding choice experiment, however, A. abdominalis had a tendency for a significantly higher preference for M. euphorbiae (38%) compared to N. ribisnigri (30%). Growth chamber experiments on whole plants demonstrated that A. abdominalis was able to parasitize aphids, regardless of their feeding locations on lettuce plants. However, aphid feeding behavior had a significant effect on the parasitization rate. A. abdominalis parasitized significantly higher percentages of M. euphorbiae or N. ribisnigri when aphids were exposed separately to parasitoids on whole lettuce plants as compared with N. ribisnigri exposed only on heart leaf. A significant preference of A. abdominalis for M. euphorbiae compared to N. ribisnigri was also observed in the growth chamber choice experiment. A high percentage of adult emergence (> 84%) and female-biased sex ratio (> 83%) were found irrespective of the aphid species.
生菜蚜Nasonovia ribisnigri更喜欢在心叶上取食，而马铃薯长管蚜Macrosiphum euphorbiae只在外叶上取食。蚜虫寄生蜂黄腹蚜小蜂Aphelinus abdominalis已知能够在许多作物上控制马铃薯长管蚜，最近它也被认为是防治生菜主要害虫生菜蚜的一种有前景的生物防治候选物。因此，本研究考察了黄腹蚜小蜂对生菜蚜和马铃薯长管蚜的寄生偏好及其寄生取食生菜植株不同部位蚜虫的能力。此外，还研究了黄腹蚜小蜂在这些蚜虫种类上的生活史特征。在叶盘上进行的无选择实验室实验和24小时暴露实验中，黄腹蚜小蜂分别成功寄生了54%和60%的供试生菜蚜和马铃薯长管蚜，差异不显著。然而，在相应的选择实验中，黄腹蚜小蜂对马铃薯长管蚜（38%）的偏好显著高于生菜蚜（30%）。在整株植物上进行的生长室实验表明，无论蚜虫在生菜植株上的取食位置如何，黄腹蚜小蜂都能够寄生它们。然而，蚜虫的取食行为对寄生率有显著影响。与仅在心叶上暴露的生菜蚜相比，当蚜虫在整株生菜上单独暴露于寄生蜂时，黄腹蚜小蜂寄生马铃薯长管蚜或生菜蚜的比例显著更高。在生长室选择实验中也观察到，黄腹蚜小蜂对马铃薯长管蚜的偏好显著高于生菜蚜。无论蚜虫种类如何，都发现成虫羽化率很高（>84%）且性别比偏向雌性（>83%）。
