**2. ROS Generation and Oxidative Stress in Arthropods**

ROS are free radicals that are highly unstable and reactive and contain one or more unpaired electrons. They are naturally produced in all cells and organisms and are crucial in several metabolic processes including cell signaling, cellular proliferation, and transcription regulation [15,16]. A tight balance between ROS production and its neutralization supports healthy life and vector potentials and ameliorates the effects of insecticides/acaricides. However, an imbalance between ROS production and antioxidant activities results in cellular damage, a phenomenon known as oxidative stress, which is highly detrimental to the life of any organism, including hematophagous vectors.
