Role of temperature on the interaction between Japanese quince Chaenomeles japonica and herbivorous insect Aphis pomi (Hemiptera: Aphidoidea)

Observations in recent years have shown that climate change can affect plants and herbivorous insects. An increase in temperature can indirectly affect insects by changing quality of host plant tissues or directly affecting their biology. So far, little research has addressed the problem of the interactive impact of abiotic and biotic stress on defence mechanisms, and effectivity of plant defence mechanisms. The work is aimed at explaining how the plant reacts to abiotic stress caused by elevated temperature and additional biotic stress caused by feeding Aphis pomi aphids. Experiments in a climatic chamber at three temperatures: 20, 25 and 28 degrees C were carried out to detect changes in developmental stages, demographic parameters and insect fecundity. The activity of enzymatic markers (superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), beta-glucosidase, polyphenol oxidase (PPO), peroxidase (POD)) in the tissues of the host plant was determined. An increase in temperature to 28 degrees C had significant negative effects on the biology of A. pomi, with a shortening of the reproduction period, total lifespan, a reduction in population demographic parameters and fecundity, by half. The temperature and foraging of sucking insects, act additively, causing a synergistic defence effect in the plant. The plant defence responses differed significantly depending on the temperature and were highest at 20 degrees C. Due to the flexible activity of enzymes, which played a role as adaptive mechanisms and ran more effectively at lower temperatures, the Ch. japonica protected itself against ROS excessive induction and the plants were able to respond quickly to the combined effect of both stress factors.