Impacts of Ionizing Radiation on Life History and Immunity in the Cricket, Acheta domesticus L.

Abstract

Oxidative stress from high-dose ionizing radiation can contribute to accumulating cellular damage, affecting various fitness related traits. However, studies on low-dose ionizing radiation (LDIR) have shown hormetic effects on growth, longevity, and immunity. Comprehensive lifetime studies assessing LDIR effects and studies investigating LDIR immune stimulation in insects are limited. We utilized 137Cs gamma radiation with a dose rate of 0.25 Gy/min. We examined the impacts of early-life exposure (doses: 0, 0.2, 0.5, 1, 2, 4, 7, and 10 Gy) on life history and immunity in Acheta domesticus. Moderate doses (above 4 Gy) increased mean longevity but decreased growth rate, adult body mass and innate immunity. We also performed a time course study in male A. domesticus to assess the acute effects of radiation (doses: 0, 0.2, 0.5, 0.75, 1, 5, and 15 Gy) on innate immunity and redox status. LDIR (below 1 Gy) generally achieved immune stimulation and improved the encapsulation response but effects were time dependent. Benefits could extend to improved immune responses and protection against infection. Our results provide evidence of immune stimulation with LDIR in insects but with potential trade- offs with life history traits when assessing early-life exposure. With increasing concern of radiation exposure in the environment, more comprehensive studies utilizing a multi- discipline approach will help to elucidate the full mechanism of hormesis.