Abstract: 【Aim】The codling moth, Cydia pomonella, is a quarantine pest in the world and one of the important fruit-boring pests on fruit trees. The purpose of this study is to explore the effects of host switching on the growth, development and reproduction of C. pomonella under high temperature stress, and to clarify its adaptation mechanism to hosts. 【Methods】 The apple population and walnut population of C. pomonella reared on the original hosts and the switched hosts, respectively, at the temperature gradient of 26, 32, 35 and 38 ℃, and designated as apple population reared on apples, walnut population reared on walnuts, apple population reared on walnuts and walnut population reared on apples. The survival rates and duration of different developmental stages and adult fecundity of the experimental population of C. pomonella were analyzed, and the life tables of various treatments were constructed and the population parameters were analyzed. 【Results】 The apple and walnut populations of C. pomonella reared on the original hosts and the switched hosts at 26 and 32 ℃ could grow and develop normally, and the developmental duration was shortened with the increase of temperature. At 26 ℃, larval duration of the apple population of C. pomonella reared on walnuts was the longest (31.76 d), and the pupal duration of the walnut population of C. pomonella reared on walnuts was the longest (11.36 d). At 32 ℃, the egg and larval duration of the apple population of C. pomonella reared on apples were 4.88 and 26.98 d, respectively, and the pupal duration of the walnut populations of C. pomonella reared on apples was the shortest (8.54 d). The adult longevity of C. pomonella at the temperature ranging from 26 to 35 ℃ exhibited significant difference. At 35 and 38 ℃, the development process of C. pomonella was blocked and the developmental duration was prolonged. The female adults could not lay eggs at 35 ℃, and the larval survival was significantly inhibited at 38 ℃. The survival rates of C. pomonella at various developmental stage and the average numbers of eggs laid per female decreased with the increase of temperature. The average number of eggs laid per female of the apple population of C. pomonella reared on apples was the highest (up to 109.20 grains) at 26 ℃. The fitness indexes (egg hatching rate, larval survival rate, pupation rate, eclosion rate and number of eggs laid per female) and population parameters (intrinsic growth rate, finite rate of increase and net reproductive rate) of the apple population of C. pomonella reared on apples were the largest, and those of C. pomonella reared on walnuts were the lowest. 【Conclusion】 Under high temperature stress, host switching has a significant effect on the growth, development and reproduction of C. pomonella, and too high temperature is not conducive to its growth and reproduction. It still has the ability to feed and damage hosts after host switching, and apples are more conducive to improving the fitness and population growth of C. pomonella than walnuts. In general, C. pomonella has the highest fitness to apple hosts, with the strongest fecundity and high adaptability on apples.

Key words:  Cydia pomonella, high temperature, host switch, growth and development, fitness, life table