Changes in Aphid—Plant Interactions under Increased Temperature

SIMPLE SUMMARY: The changing climate, particularly the temperature increase, can affect both herbivorous insects and plants. Aphids, being poikilothermal organisms, are directly exposed to an increase in temperature that, in turn, affects their biology. An increase in temperature can also indirectly affect aphids by changing the quality of the host plant tissues. This work focused on investigating the effects of climate change on plant–insect interaction. In particular, it was analyzed how an increase in ambient temperature can affect the condition of Macrosiphum rosae and its host Rosa rugosa, and how it correlates with the activity of oxidative stress-related enzymes (SOD, CAT, POD, β-glucosidase, GST, and PPO) both in insect and plant tissues. Thermal stress ranging from 25 to 28 °C has a significant impact on M. rosae–R. rugosa interaction, affecting aphid fitness and the activity of enzymes related to oxidative stress in both insect and plant. ABSTRACT: Thermal stress in living organisms causes an imbalance between the processes of creating and neutralizing reactive oxygen species (ROS). The work aims to explain changes in the aphid–host plant interaction due to an increase in temperature. Tests were carried out at three constant temperatures (20, 25, or 28 °C). Firstly, changes in development of Macrosiphum rosae were determined. Secondly, the activity of enzymatic markers (superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), β-glucosidase, polyphenol oxidase (PPO), and peroxidase (POD)) in aphid M. rosae tissues and host plant were analyzed at all temperatures. An increase in temperature to 28 °C had a negative effect on the biology of M. rosae by shortening the period of reproduction and longevity, thus reducing the demographic parameters and fecundity. Two stages of the aphid’s defensive response to short-term (24–96 h) and long-term (2 weeks) thermal stress were observed. Aphid defense responses varied considerably with temperature and were highest at 28 °C. In turn, for the plants, which were exposed to both abiotic stress caused by elevated temperature and biotic stress caused by aphid feeding, their enzymatic defense was more effective at 20 °C, when enzyme activities at their highest were observed.