Feeding can increase thermal adaptation of herbivorous insect: a case study with corn leaf aphid under acclimation temperature

Climate change is predicted to increase the frequency and magnitude of extreme heat events, which will involve great challenges for most of the ectotherm organisms, such as insects. In this study, we address the thermal tolerance of corn leaf aphid, Rhopalosiphum maidis (Hemiptera: Aphididae) under extreme high temperatures across differential life stages. Immature instars and adults of R. maidis were exposed to brief events of increasing temperatures (0.5 °C min-1), starting at 22 °C and reaching one of the 14 maximal temperature selected (from 38.5 to 44.5 °C). In each temperature regime, the mortality of R. maidis was compared with and without barley seedlings. Results showed that the critical high temperature (CTh) of R. maidis was between 39.0 to 39.5 °C in no feeding treatments, while it was between 39.5 to 40.0 °C in feeding treatments. The upper lethal temperatures (ULTs) of R. maidis were significantly different between feeding and no feeding treatments. In addition, the ULTs varied significantly across life stages with highest ULTs values for 4th instars. Feeding significantly increased the thermal tolerance of phytophagous insect. Variable balances in plant-herbivore interactions will be induced according to the insect feeding diet status and particular instar during the time of extreme temperature as illustration of global warming as part of climate changes. Our findings could be valuable in developing a reliable phenological model for the prediction of population dynamics of R. maidis.