Abstract: 【Aim】 Peach fruit moth (Carposina sasakii) and oriental fruit moth (Grapholita molesta) are two kinds of fruit tree pests worldwide. Climate warming has many important impacts on their geographical populations. The objective of this research is to identify the differences in the rapid heat tolerance and heat tolerance plasticity among the geographical populations of C. sasakii and G. molesta, so as to provide a basis for their forecast and integrated management. 【Methods】 By measuring the knockdown time (KDT) at the constant temperature 42.5 ℃ and the critical thermal maximum (CTMax) under basal (non-subjected to pretreatment) or heat hardening (subjected to pretreatment at 35 ℃ for 2 h) conditions, we systematically compared the similartities and differences in the rapid heat tolerance and heat tolerance plasticity of adults among different geographical populations of C. sasakii (Jilin population, Zhengzhou population and laboratory population) and G. molesta (Jilin population, Zhengzhou population, Nanchang population and laboratory population). 【Results】 The changes of KDT of adults in different geographical populations of C. sasakii and G. molesta were consistent. There was no significant difference in KDT among geographical populations and between genders of the adults of C. sasakii and G. molesta. Heat hardening significantly increased the KDT of C. sasakii and G. molesta by 14.63 and 55.12 s, respectively. There was no significant interaction between or among populations, genders and heat hardening factors as for KDT of the both two fruit moth species. The responses of the adults of C. sasakii and G. molesta populations to CTMax were different. There were significant differences in the CTMax among the adult populations of C. sasakii, which was ranked in a descending order of Jilin population ［(38.57±1.61) ℃］, Zhengzhou population ［(37.60±1.32) ℃］ and laboratory population ［(37.24±1.46) ℃］. Heat hardening had a significant effect on the CTMax of C. sasakii adults, and there was an interaction between the adult populations and heat hardening factors as for C. sasakii. It was mainly reflected that heat hardening significantly enhanced the CTMax of Jilin population and Zhengzhou populations by 2.05 and 1.34 ℃, respectively, while there was no significant difference in the CTMax between the basal and heat-hardened laboratory populations. There were significant differences in the CTMax among the adult populations of G. molesta, which was ranked in a descending order of Nanchang population (39.20±1.81) ℃, Jilin population (38.63±1.42) ℃, Zhengzhou population (38.27±1.32) ℃, and laboratory population (38.15±1.51) ℃. Heat hardening had a significant effect on the CTMax of G. molesta adults, and there was an interaction between the adult population and heat hardening factors as for G. molesta. It was mainly reflected that heat hardening significantly increased the CTMax of the Zhengzhou population ［basal： (38.18±1.34) ℃; heat-hardened: (39.17±0.60) ℃］, but not significantly increased the CTMax of the Jilin population, Nanchang population and laboratory population. Gender factor, and its interaction with population or heat hardening, and the interaction of the three factors showed no significant effects on the CTMax of the adults of C. sasakii and G. molesta. 【Conclusion】 The northern population of C. sasakii had a stronger rapid heat tolerance than the central population, but the southern population of G. molesta had the strongest rapid heat tolerance compared with the central population and northern population. Laboratory acclimation could reduce the rapid heat tolerance of both species, and heat hardening could improve the rapid heat tolerance of the both two fruit moth species, but the heat tolerance plasticity was not consistent among different populations between the two fruit moth species. The above conclusions may be due to the different evolutionary mechanisms of thermal adaptation between the two fruit moth species and the differences in living environment among geographical populations. It is of great significance to clarify the similarities and differences of rapid heat tolerance and its plasticity among geographical populations of C. sekakii and G. molesta for insect heat adaptation research and fruit safety production in the condition of climate warming.

Key words:  Carposina sasakii, Grapholita molesta, geographical populations, heat tolerance, heat tolerance plasticity, knockdown time, critical thermal maximum