褐飞虱、白背飞虱种间、种内密度制约效应研究

以高感品种TN1为材料．研究了褐飞虱、白背飞虱成、若虫密度对种群的制约效应。实验表明，单虫种一龄善虫密度15头／株和30头／株相比．褐飞虱成虫的羽化率、短翘率、体长和若虫历期均无明显差异，但成虫雌性比率前高；白背飞虱成虫羽化率前比后高21．22％．短翘率高15.25％。在两种飞虱一龄若虫密度30、45、60头／株等虫量混合组配下，褐飞虱成虫羽化率60头／株比30头／株下降28％，白背飞虱若虫历期以30头／株最长。在总虫量为30头／株时，种内(30头／株)和种间(15：15头／株)比．白背飞虱种内处理成虫羽化率高36．83％．昔虫历期短；褐飞虱以种内处理成虫短翘率高。从产卵位点来看．褐飞虱喜产在稻株叶鞘中下部厚肉组织上，白背飞虱以叶脉基部产卵为主．成虫密度2、4、8对／株3处理，其叶鞘、叶脉上的平均卵块变小；10天内的平均卵量亦减步。同密度下，种间组合比种内组合的产卵量多。从各指标对密度反应来看，褐飞虱比白背飞虱更耐拥挤。

THE DENSITY-DEPENDENT EFFECTS OF NILAPARVATA LUGENS(STAL)AND SOGATELLA FURCIFERA HORVATH (HOMOPTERA:DELPHACIOAE)ONTHEIR POPULATION PERFORMANCES

The density-dependent effects of Nilaparvata lugens Stal and Sog atellafurciferaHorvath(Homoptera:Delphacidae)in TN 1. a high susceptive rice variety to bothinsects. on thelr ponulation performances were studied.The results showed that at theinterspecific 1 st- instar nymph densities of 1 5 and 30 per titler. there were not significantdifference among emergence rate. short- wing rate. female body- length of adult andnymph developmental period from ist- instar to adult for N. lugens. but female ratio offormer density was higher than that of latter one. for S. furcifera. adult emergence rate andshort- wing rate of formerdensity were 21.22% and 15.25% higher than those of latterone. respectively. Among the intraspecific lst- instar nymph densities of 30. 45 and 60 pertiller in the same proportion. adult emergence rate of 60 per tiller for N. lugens was 28.00% lower than that of 30 per tiller. nymph period of 30 per tiller for S. furctferalasted longest. At the total density of 30 per tiller. adult emergence rate of interspecific nymph density for S. furcifera. was 36.83% higher compared with intraspecitic one in the same proportion. N. lugens adult would like to lay eggs on the lower positions of rice sheath. while S. furciferaon the lower positions of leaf vein. As the adult density increased from 2 to 8 per tiller. either interor intraspecific density. reductions in the average size of egg- mass and eggs laidby per female within 10 d were observed for both N. iugens and S. furcifera. however. compared with the interspecific adult density. mixed one was higher in average egg numbers. The experiment indicated N. lugens is more tolerable to density than S. furcifera.