Objective The seasonal phenological characteristics and population dynamics of Japanese pine sawyer beetle, Monochamus alternatus Hope (Coleoptera: Cerambycidae), in different regions of Jiangxi province were analyzed to provide the basic data and scientific basis for improving the local population monitoring level and formulating accurate control strategies of this beetle.

Method The initial and terminal occurrence periods, activity peak period and the sex ratio of adult M. alternatus were monitored through setting up monitoring plots and installing the attractant traps in pure stands of Masson pine forest in Quannan, Nankang, Wan'an, Nancheng, Wanli and Fuliang along the latitude gradient of about 1° in Jiangxi province.

ResultsThe initial occurrence periods of M. alternatus in Jiangxi were from late March to early May, and were obviously delayed from south to north regions. The final appearance periods of this beetle were from early October to early December, and were obviously shorten from south to north regions. The occurrence period of adults M. alternatus lasted for 5-9 months and decreased significantly from south to north regions. Adult activity peak period gradually postponed and the peaks transited from 2 to 1 from south to north regions. The population density of M. alternatus in central Jiangxi were larger than that in southern or northern Jiangxi. The sex ratio of this beetle was 1: 0.74-0.87, showing biased female and no difference was found in different regions of Jiangxi province. There was an obviously positive correlation between trapping amounts of this beetle and the mortality of Masson pine.

Conclusion Geographical latitude and local climatic conditions significantly affect the seasonal occurrence and adult activity peak of M. alternatus, and the population density of M. alternatus is positively related with the mortality of their host plant.