不同农业生态系统对夏番茄田中烟粉虱及其自然天敌种群动态的影响

Effects of different agroecosystems on population dynamics of Bemisia tabaci and its natural enemies in summer tomato fields

为明确烟粉虱及其优势天敌在不同农业生态系统番茄田中的发生规律,于云南省昆明市选取花卉、河流和山地3种不同类型的主要农业生态系统,采取五点取样法进行系统调查,使用四分位法对烟粉虱的种群动态进行分析,利用生态位相关指数分析烟粉虱及其优势天敌在时间生态位上的关系。结果表明:在烟粉虱主要发生时期,花卉农业生态系统番茄田中烟粉虱若虫和成虫的种群密度最低,分别为44.66和36.25头·株^(-1),河流农业生态系统番茄田中烟粉虱若虫和成虫的种群密度最高,分别为645.79和449.04头·株^(-1);花卉农业生态系统中优势天敌的种类最多,分别为烟盲蝽、六斑月瓢虫、异色瓢虫、丽蚜小蜂和海氏桨角蚜小蜂5种,其中烟盲蝽、六斑月瓢虫、异色瓢虫和丽蚜小蜂在主要发生时期的种群密度分别是河流农业生态系统的1.90、1.66、1.79、2.19倍,分别是山地农业生态系统的1.61、1.16、1.24、1.43倍;在花卉、河流和山地农业生态系统中六斑月瓢虫与烟粉虱生态位重叠指数均最大,并且其与烟粉虱在空间上跟随关系最密切,灰色关联度值分别为0.32、0.38、0.35;优势天敌与烟粉虱的生态位重叠指数均在花卉农业生态系统中最大,表明在农田周围增加显花植物种植面积的比例,可以增加天敌昆虫的多样性,抑制烟粉虱种群的暴发。

We examined the dynamics of Bemisia tabaci and its dominant natural enemies in tomato fields from three major types of agroecosystems in Kunming,Yunnan Province,including flower,river,and mountain.Five-point sampling method was used to systematically quantify the numbers of B.tabaci and its natural enemies.The population dynamics of B.tabaci were analyzed by quartile method.The niche correlation index was used to analyze the relationship between B.tabaci and its dominant natural enemies in temporal niche.The results showed that tomato field in flower agroecosystem held the lowest densities of nymphs and adults B.tabaci during main activity period,which were 44.66 and 36.25 individuals per plant,respectively.The nymphs and adults B.tabaci in tomato field of river agroecosystem had the highest densities,which were 645.79 and 449.04 individuals per plant,respectively.Tomato field in flower agroecosystem had the maximum natural enemy species,including Nesidiocoris tenuis,Menochilus sexmaculatus,Harmonia axyridis,Encarsia formosa and Eretmocerus hayati.The population densities of N.tenuis,M.sexmaculatus,H.axyridis and E.formosa in tomato field of flower agroecosystem were 1.90,1.66,1.79,2.19 fold to river agroecosystem,and 1.61,1.16,1.24,1.43 fold to mountain agroecosystem during in main activity period,respectively.M.sexmaculatus had the largest temporal niche overlap with B.tabaci in tomato field of the three agroecosystems.Moreover,M.sexmaculatus had the closest spatial-following relationship with B.tabaci,with the gray correlation degrees with B.tabaci in flower,river and mountain agroecosystems being 0.32,0.38 and 0.35,respectively.The largest temporal niche overlap index of dominant natural enemies and B tabaci presented in flower fields of agroecosystem tomato,indicating that increasing the proportion of flowering plants around cropland can increase the diversity of natural enemies and thus inhibit the outbreak of B.tabaci population.