白背飞虱不同虫态的空间分布型及变动规律

Study on Spatial Distribution Pattern of Various Stages of Whitebacked Planthopper, Sogatella Furcifera (Horvath)

经过对白背飞虱不同虫态在同一生境内空间格局进行连续测定，表明其仅在田间初始低密度情况下呈现随机或均匀分布，一般均为聚集分布．分布参数显示白背飞虱种群为负二项分布，基本成分是个体群；低龄若虫有较高的聚集度；高龄若虫及成虫活动能力强，空间分布图式趋于个体；不同虫态平均密度（Ｘ）与方差（Ｓ２）用负二项分布曲线公式Ｓ２＝Ｘ＋Ｘ２／Ｋｃ配合良好；采用种群聚集均数（λ）测定，平均密度２．５５头／丛是判定聚集原因的临界值．采用Ｉｗａｏ理论抽样模式，得出不同密度下的理论抽样数，并建立序贯抽样模式，可应用于田间抽样．

The results of successive determination on spatial distribution pattern of Sogatella furcifera in the same habitat showed that the spatial distribution of various stages of this plant hopper in field belonged to an aggregated one, while it was random or uniform distribution at initial low density. Distribution parameters indicated that population of S.furcifera was negative binomial servise and basic component was individual group. Low instar nymphs of S.furcifera had a higher aggregate degree, spatial distribution pattern of high instar nymphs and adults trended to individuals. The relationship between average density of different stages (X) and variance (S 2) could be expressed using the equation of the negative binomial distribution curve, S 2=X+X/K c. Average 2.55 insects per clump was a critical value to evaluate aggregation causes. The Iwao theoretical sampling model was used to calculate the theoretical sampling number under various densities and build up a sequential sampling model, which will be applied to field sampling of the insect.