Mediation of Tritrophic Interactions by Oxidative Stress in a Model Plant-Insect-Entomopathogen System

杆状病毒是一组感染昆虫的病毒。然而，这些病毒对昆虫的影响似乎因昆虫消耗的寄主植物的化学成分而异。例如，与以番茄或生菜等其他寄主植物为食的烟草芽孢虫相比，杆状病毒在以棉花为食时杀死烟草芽孢虫的能力较差。在这项研究中，PI试图确定导致一些寄主植物使它们的食草性昆虫对杆状病毒感染更具抵抗力的化学相互作用。初步研究表明，活性氧物种(ROS)的产生是此类疾病抑制的主要原因，但尚不清楚这种情况是如何发生的，也不清楚这些活性产物改变了感染途径中的哪些步骤。ROS的产生是正常细胞过程的结果，但可以通过摄入饮食化学物质来改变。高水平的ROS会导致一种被称为氧化应激的情况，这种情况会损害细胞物质，并与衰老和癌症的发展有关。ROS还可以摧毁许多微生物，并似乎干扰杆状病毒杀死寄主昆虫的能力。这项研究将研究与饮食有关的ROS是否通过破坏病毒或改变昆虫的免疫反应来干扰昆虫的病毒感染。这些研究应该对理解多个营养水平之间复杂相互作用的化学基础具有广泛的意义。此外，研究结果将有助于全面了解氧化应激对疾病过程和疾病生态学的影响。最后，由于杆状病毒目前被用作化学杀虫剂的环境友好替代品，这些结果可能有助于改善农业中的生物防治做法。

Baculoviruses are a group of viruses that infect insects. The effect of these viruses on insects, however, appears to vary with the chemical composition of the host plant that the insect consumes. For example, baculoviruses are less able to kill tobacco budworm (Heliothis virescens) when the insect feeds on cotton, than when it feeds on its other host plants such as tomato or lettuce. In this study, the PIs seek to determine the chemical interactions that cause some host plants to render their insect herbivores more resistant to infection by baculoviruses. Preliminary studies have suggested that the generation of reactive oxygen species (ROS) is a major cause of such disease inhibition, but it is unclear how this occurs or what steps in the pathway of infection are being altered by these reactive products. Generation of ROS occurs as a consequence of normal cellular processes but can be altered by ingestion of dietary chemicals. High levels of ROS lead to a condition known as oxidative stress which can damage cellular substances and has been associated with aging and cancer development. ROS can also destroy many microorganisms and appear to interfere with the ability of baculoviruses to kill their host insects. This study will examine whether diet-related ROS interfere with viral infection of insects by damaging the virus or by altering insect immune responses. These investigations should have broad implications for understanding the chemical basis of complex interactions among multiple trophic levels. Additionally, results will contribute to a general understanding of the effects of oxidative stress on disease processes and disease ecology. Finally, because baculoviruses are currently being used as an environmentally-friendly alternative to chemical pesticides, these results may help improve biological control practices in agriculture.