Abstract:

To clarify the occurrence pattern and seasonal dynamics of dominant pest insects, a five-point sampling method was used to investigate the dominant pests on chrysanthemum seedlings in greenhouse from 2018 to 2020 by using sticky board. The main occurrence periods of chrysanthemum pest insects were divided by quartile method. Meanwhile, the occurrence pattern, seasonal dynamics and temporal niche of the dominant pest insects were also analyzed. The results showed that Frankliniella occidentalis damaged chrysanthemum seedlings for most of the year. The main occurrence period was from April to August and peaked in May, June and July. Population size of  F. occidentalis  was 636, 1411, and 256 individuals per sticky board  in main occurrence period, respectively. The niche width of F. occidentalis decreased with the year. The ecological niche width of Phytomyza syngenesiae was relatively small, the damage mainly occurred from January to June, and the main occurrence period was from March to June. The occurrence peaked in March during the three years, with the population size of P. syngenesiae being 256, 239, and 124 individuals per sticky board, respectively. The niche width of Myzus persicae and Trialeurodes vaporariorum was larger than that of F. occidentalis and P. syngenesiae in the three years, indicating that M. persicae and T. vaporariorum could hold longer occurrence time than other pests; the main occurrence period was from February to April, and the peak occurrence date was not fixed throughout the year. The similarity of niche overlap indices among the four species of pests indicated that they were similar and competitive in the temporal dimension of their occurrence. Therefore, the control of dominant pest insects on chrysanthemum seedlings should be focused on F. occidentalis from March to October and P. syngenesiae from January to June.

Key words: chrysanthemum seedling, main occurrence period, population dynamics, niche width, quartile method.