Parma Research and Extension Center, Department of Entomology, Plant Pathology, and Nematology, University of Idaho, Parma, Idaho, United States of America.
Research and Education Center, Department of Entomology, University of Kentucky, Princeton, Kentucky, United States of America.
PLoS One. 2024 Sep 30;19(9):e0311220. doi: 10.1371/journal.pone.0311220. eCollection 2024.
Pest management on hemp is still in its infancy, and biological control options are limited. Helicoverpa zea (corn earworm) is one of the key pests of hemp cultivated outdoors, especially on cultivars grown for cannabinoids and grain. In a three-year study, we assessed the effect of diet on the performance of H. zea and its tachinid parasitoids. Parasitized (bearing fly eggs) and unparasitized (without eggs) H. zea larvae were fed on hemp flowers or an artificial diet. Five tachinid species parasitized H. zea larvae, but the most abundant species were Winthemia rufopicta (68.8%) and Lespesia aletiae (28.3%). Overall, 55.2% of H. zea larvae bearing tachinid eggs died, while the mortality of unparasitized larvae reached 24.7%. The success of tachinids increased by 2-fold when the host larvae were fed on an artificial diet. Our results demonstrated that high protein food (artificial diet), intensity of parasitism, and caterpillar size play a role in the fitness of both the herbivores (H. zea) and its tachinid parasitoids. These findings have important implications for understanding biological control mechanisms and open new insights into the impact of landscape variation on plant-herbivore-parasitoid interactions. This study contains supporting evidence that makes both Winthemia rufopicta and Lespesia aletiae excellent candidates for biological control programs against H. zea, a key pest of hemp in the United States.
麻类作物的害虫管理仍处于起步阶段，生物防治选择有限。玉米穗夜蛾（Helicoverpa zea）是户外种植麻类作物（尤其是用于大麻素和谷物种植的品种）的主要害虫之一。在一项为期三年的研究中，我们评估了饮食对玉米穗夜蛾及其潜蝇科寄生蜂表现的影响。已寄生（携带蝇卵）和未寄生（无卵）的玉米穗夜蛾幼虫分别以麻类花卉或人工饲料为食。有五种潜蝇科寄生蜂寄生玉米穗夜蛾幼虫，但最丰富的物种是红腹幽蝇（Winthemia rufopicta）（68.8%）和细足幽蝇（Lespesia aletiae）（28.3%）。总体而言，携带潜蝇科寄生蜂卵的玉米穗夜蛾幼虫死亡率为 55.2%，而未寄生幼虫的死亡率达到 24.7%。当宿主幼虫以人工饲料为食时，潜蝇科寄生蜂的成功率增加了两倍。我们的研究结果表明，高蛋白食物（人工饲料）、寄生强度和毛毛虫大小对食草动物（玉米穗夜蛾）及其潜蝇科寄生蜂的适应性都起着作用。这些发现对理解生物防治机制具有重要意义，并为景观变化对植物-食草动物-寄生蜂相互作用的影响提供了新的见解。本研究提供了支持证据，表明红腹幽蝇和细足幽蝇是防治美国麻类作物主要害虫玉米穗夜蛾的生物防治计划的优秀候选者。
