双斑长跗萤叶甲越冬卵在玉米田的空间分布型

The spatial distribution pattern of overwintering egg of Monolepta hieroglyphica (Motschulsky) in corn field

为明确双斑长跗萤叶甲越冬卵的空间分布型,2011年10月采用分层随机抽样法在山西省晋中市的玉米田对土壤中的越冬卵进行调查。通过频次分布检验、聚集度指标的测定、改进的Iwao m*-m回归分析法和Taylor幂法则对越冬卵在土壤中的空间分布型进行了分析,并对聚集均数(λ)进行检验,分析越冬卵聚集的原因。结果表明:双斑长跗萤叶甲越冬卵在土壤中的理论分布型符合负二项分布,各项聚集度指标均满足C>1、CA>0、I>0、k>0、m*/m>1,空间分布图式在低密度下为聚集分布,基本成分为单个个体,个体间相互排斥。基本成分的相对聚集度随越冬卵种群密度而变化的速率为3.52m-15.61。种群密度越大,相对聚集度的变化速率也越大,而且聚集的程度随着卵密度的增大而增高。聚集均数(λ)的测定表明,聚集是成虫的产卵习性和田间植被的生长情况、土壤性质、温湿度等环境因子综合作用的结果。双斑长跗萤叶甲成虫主要在近土表的土壤中产卵,在距土表15 cm以上的土壤中,有94.2%的越冬卵分布在距土表0—10 cm的土层中,其中以距土表2—5 cm的土层中的卵量最多,平均每个样点有卵25.56粒,占总数的64.7%,显著高于其他深度土层的卵量。

The objectives of this work were to clarify the spatial distribution pattern of the overwintering eggs of M.hieroglyphica（Motschulsky）.An investigation with stratified random sampling was conducted on the egg number in corn field of Jinzhong,Shanxi province in October 2011.The spatial distribution pattern of the overwintering eggs of M.hieroglyphica in soil was studied by determination of frequency distribution,aggregated indices,the improved Iwao′s regression equation and Taylor′s power law.The reasons for the aggregation of the overwintering eggs of M.hieroglyphica was analyzed according to estimation by aggregation mean（λ）.Results indicated that the overwintering eggs of M.hieroglyphica belong to negative binomial distribution and the aggregated indices of overwintering eggs met C＆gt;1,CA＆gt;0,I＆gt;0,k＆gt;0,m＊/m＆gt;1,so M.Hieroglyphica eggs in soil presented pattern of aggregation distribution in low population density,and its fundamental component was the individual that was mutually exclusive.The rate of relative aggregation change of fundamental component was 3.52m-15.61,which changed with the population density of overwintering egg of M.hieroglyphica.The greater the population density of overwintering eggs,the greater the change rate of relative aggregation degree.The degree of aggregation increased with the population density of overwintering eggs.Aggregation mean λ value indicated that the aggregation might be due to the combined actions of the oviposition habits of adults and other environmental factors,including the growth of vegetation,soil features,temperature and humidity,etc.Female of M.hieroglyphica usually deposited the overwintering eggs below the soil surface.It was observed that the 94.2% of the eggs were laid in the top 10 cm between 0 and 15 cm of the soil surface.In addition,the number of M.hieroglyphica eggs between 2 and 5 cm below the soil surface was significantly more than others with an average value of 25.56 in every sample,which is 64.7% of the total.