High temperatures reduce nutrients and defense compounds against generalist Spodoptera litura F. in Rorippa dubia

Abstract

Global warming not only alters phenology but also nutritional quality and defense compounds in plants, which consequently hinders their defense against herbivorous insects. In this study, the performance of Spodoptera litura was analyzed to observe the effects of high temperatures on chemical-based defense in plants in the context of insect–plant interaction. Results show that high temperature reduced the nutritional value and content of defense compounds in the foliage of yellow cress (Rorippa dubia). These alterations negatively affected the performance of second instar S. litura larvae feeding on plants grown at high temperature. Low quality of the food source is likely the key cause of slow development of larvae. Adaptation of herbivorous insects known as compensatory feeding is projected resulting in more crop losses under global warming. Our data reveal temperature-induced reduction in the content of defensive compounds (in constitutive resistance) along with lower response capability against herbivore attacks (in induced resistance), which indicate a decrease in plant fitness. High temperatures caused by global warming negatively affect crop production and are expected to increase the burden on plant protection practices.