Abstract:

Objective: This study aims to determine the population dynamics of Monochamus alternatus adults in Guangxi and its correlation with pine stand and meteorological factors, which could provide information for its forecast and prevention. Method: Based on the data collected with APF-I lure cores and ZM-80B traps, the population dynamics of M. alternatus adults occurred in eastern, northern, western, southern and central regions of Guangxi were studied through dynamic monitoring method from 2019 to 2020. Subsequently, the correlations of population dynamics in M. alternatus with stand factors, including latitude, inner/edge, altitude, canopy density, tree age, slope and epidemic area and non-epidemic area of pine wood nematode (Bursaphelenchus xylophilus), and meteorological factors, including monthly average temperature, monthly average maximum temperature, monthly average minimum temperature, monthly average humidity, monthly average minimum relative humidity, monthly average rainfall and monthly average sunshine hours were analyzed. Result: One to three peak periods of M. alternatus adults appeared in eastern, western, southern and central regions of Guangxi in one year, adults were able to be trapped from January to February that usually are the coldest months. However, only one peak period of M. alternatus adult appeared in northern Guangxi in one year, and no adult was trapped from January to February. The inception period of M. alternatus adults occurred in eastern, northern, western, southern and central Guangxi was early January, early April, early February, early January and late February, respectively. The annual occurrence peak period was from mid March to mid-late September, from mid April to late July, from late March to early August, from late March to mid-late August, and from early April to mid-late August, respectively. The end of peak period was mid-late September, late July, early August, mid-late August and mid-late August, respectively. The end period was late December, early November, late December, late December and late November, respectively. The amount of female adults trapped in central Guangxi was significantly higher than that in other four regions, and the amount of male adults trapped in eastern, western and central regions of Guangxi was significantly higher than that in northern and southern regions of Guangxi. The amount of female adults trapped was significantly higher than that of males in Guangxi, except for western regions. The amount of male and female adults trapped in the forest was significantly higher than that in the forest edge, however the trapping number had no correlation with latitude, altitude, tree age and epidemic area and non-epidemic area of B. xylophilus. There were significant negative correlations between canopy density and number of captured male adults, and slope and annual trapping amount of females. Occurrence regulation of M. alternatus in the five regions of Guangxi had significant positively correlation with monthly average temperature, monthly average maximum temperature, monthly average minimum temperature and monthly average rainfall. Conclusion: There are 1-3 peak periods of M. alternatus adult occurrence per year in Guangxi, i.e., 2 peak periods in the eastern regions, 1 peak period in the northern, southern and central regions, 3 peak periods in the western regions. Adults are active in the forest for a longer time; air temperature has significant effect on the their population dynamics among all meteorological factors, while the effect of stand factors is little.

Key words: Monochamus alternatus, population dynamics, stand factors, meteorological factors