Abstract:

Objective: This study aims to explore the tolerance of emerald ash borer to a hot and humid environment and the possibility of colonization under high temperature and humidity conditions in southern China. Method: In this study, the survival rate of adults, the number of mature eggs per adult female, and the hatchability of fresh eggs were measured under different conditions of high temperature and humidity. Result: 1) Adults of emerald ash borer were relatively tolerant to constant high temperature and humidity. At 80% RH, both male and female adults were able to survive for more than 3 days at 38℃ when the relative humidity was 80%. The survival rate of males started to decrease on the third day at 41℃, while the mortality of females occurred only at constant temperatures above 42℃. Female adults were more tolerant than male adults, and females could survive for 24 hours at 43℃, while all males died within 12 hours. 2) Eggs of emerald ash borer could develop to maturity at 28℃, 38-43℃, 80% RH. The number of mature eggs per female at 38℃ and 41℃ were significantly more than that at 28℃. The number of mature eggs declined gradually with the increase of temperature when constant temperature was over 41℃, and no mature egg was observed at 44℃. 3) At 80% RH, eggs were easy to be infested by pathogens. However, some eggs still hatched at 28℃ and 38℃, but not at over 41℃. The egg hatchability decreased significantly under high temperature and humidity compared to the hatchability at 28℃. Conclusion: The results demonstrate that emerald ash borer has strong tolerance to high temperature and humidity, so that it is possible to survive and establish populations after being spread to some regions in central or southern China.

Key words: Agrilus planipennis, extreme environment, tolerability, temperature and humidity effects, time-dose-mortality model