西花蓟马与烟蓟马在紫甘蓝上的种间竞争

 【目的】研究外来入侵物种西花蓟马与本地物种烟蓟马的种间竞争。【方法】在实验室条件下，将西花蓟马与烟蓟马的紫甘蓝种群作为研究对象，以不同的种群数量混合或单独饲养，繁殖1代或多代后检查并比较2种蓟马的产卵数量、种群数量及后代性比的变化情况，分析2种蓟马的种群增长竞争和生殖能力竞争。【结果】当烟蓟马与西花蓟马个体数分别以40﹕20、30﹕30、20﹕40的种群比例在紫甘蓝上共存竞争时，西花蓟马分别在4代、4代和5代后被烟蓟马完全取代，并且在竞争过程中伴随着西花蓟马种群雌虫比例的逐代下降。生殖能力竞争的结果表明烟蓟马可以显著降低西花蓟马的产卵量和后代的雌雄比例。当1对西花蓟马分别与1、2、3头烟蓟马雌虫共存时，西花蓟马的日均产卵量由5.7粒分别下降到2.6、1.9和0.8粒；1头西花蓟马雌虫分别与1、2、3头烟蓟马雌虫共存时，西花蓟马的日均产卵量由7.6粒分别下降到3.6、2.5和1.4 粒；而当1对西花蓟马分别与3头和5头烟蓟马雌虫共存时，西花蓟马后代的雌雄比例由3.1分别下降到2.4和1.3。【结论】在以紫甘蓝为寄主植物的竞争体系中，烟蓟马试验种群在短时间内取代了西花蓟马试验种群。烟蓟马除自身具有更强的繁殖力，其对西花蓟马生殖的抑制作用也是产生这一现象的重要原因。

Interspecific Competition Between Frankliniella occidentalis and Thrips tabaci on Purple Cabbage

【Objective】 The objective of this study is to investigate the interspecific competition between invasive Frankliniella occidentalis and native Thrips tabaci on purple cabbage under laboratory conditions. 【Method】 The fecundity, population, sex ratios of offspring of F. occidentalis and T. tabaci were evaluated after one or more generations in the mixed population or single population at different initial population rates on purple cabbage, and population growth competition and reproductive competition between F. occidentalis and T. tabaci were studied based on the above results. 【Result】 When both species co-existed at the initial population rates of 40:20, 30:30 and 20:40, T. tabaci completely displaced F. occidentalis after 4, 4 and 5 generations, respectively. In addition, the female ratio of F. occidentalis decreased during the process of competition. Further studies indicated that the reproductive capacity and ratio of females to males of F. occidentalis decreased significantly because of the presence of T. tabaci. When 1, 2 and 3 females of T. tabaci was added into a pair of F. occidentalis, the number of eggs laid per day per female by F. occidentalis decreased from 5.7 to 2.6, 1.9 and 0.8, respectively. When the same treatment was done in a female of F. occidentalis, the number of eggs laid per day per female by F. occidentalis decreased from 7.6 to 3.6, 2.5 and 1.4, respectively. When 3 and 5 females of T. tabaci was added into a pair of F. occidentalis, the ratio of females to males of offspring of F. occidentalis decreased from 3.1 to 2.4 and 1.3, respectively. 【Conclusion】 The competitive displacement of F. occidentalis by T. tabaci was observed in a short time in the ecological system on purple cabbage. According to this research, the mechanisms responsible for competitive displacement may include the difference in fecundity and reproduction suppression between the two thrips.