Study On Biology And Ecology Of Alsophila Spinulosa Main Pests

In view of the serious pest damage of Alsophila spinulosa plants in Guizhou Chishui Alsophila National Nature Reserve in recent years,and the lack of related pest research data,in order to find out the situation of related pests of A.spinulosa plants in this reserve,in this paper,the community diversity indexes of arthropod community,species richness and dominant populations on A.spinulosa plants were analyzed,and the main pest groups of A.spinulosa plants in this area were identified.The biological and ecological studies on the dominant species were carried out,which provided a scientific reference for the monitoring and control of A.spinulosa pests in the reserve.The specific results are as follows:1.According to the investigation of the main pests and natural enemies of A.spinulosa.it was found that the arthropod communities on A.spinulosa plants in Chishui Alsophila spinulosa National Nature Reserve belonged to 6 orders,14 families and 15 species.Among them,there are 3 orders,6 families and 6 species of herbivorous pests,of which Rhoptroceros cyatheae(Wei et Wang,1995)and Phthonolba viridifasciata(Inoue,1963)are the main pests,and the species richness of natural enemy community is higher than that of pest community,including 9 natural enemy resources,6 predator species and 3 parasitic species.Parasitic groups are the main natural enemies of A.spinulosa pests.2.Studies on the biology of main pests.R.cyatheae occurs four generations a year in Guizhou Chishui Alsophila spinulosa National Nature Reserve,the development period of each generation is about 45 days,the peak period of R.cyatheae is from April to June,the number of insects is larger in the middle and last ten days of May,two generations occur from April to June,the number of insects is less from July to August,and the overwintering generation occurs in late October.It is clear that the parasitic natural enemy is Vibrissina turrita.Parasites mostly appeared in May to June.P.viridifasciata is a newly discovered pest,which has five generations a year.When the weather warms up in late March,the pupae begin to Eclosion,the first generation eggs begin to hatch in early April,and the larvae feed on fresh Alsophila spinulosa leaves.The second generation occurs in late May,and the larvae concentrate in June.The third generation occurs in July and August.The development period of the previous three generations is about 45 days,and the fourth generation occurs in October.The larval development period and pupal period are longer than those of the previous three generations.The overwintering generation occurs from mid-December to mid-January.It is clear that the parasitic natural enemies are Endasys sp.and Charops sp.the number of larvae parasitized in June and August is more than in other months.P.viridifasciata is not a newly introduced pest and may exist at the same as R.cyatheae.3.Spatial distribution pattern of R.cyatheae and P.viridifasciata larval population.All the indexes of R.cyatheae and P.viridifasciata larvae showed aggregated distribution.Because the mean of population aggregation ? > 2,it shows that the aggregation of R.cyatheae larvae and P.viridifasciata larvae is caused by both insect habits and environment,and is determined by both of them.Both R.cyatheae larvae and P.viridifasciata larvae showed aggregated distribution,and the individuals of the larvae were attracted to each other,and the basic component of the distribution was individual groups.And R.cyatheae larvae and P.viridifasciata populations are aggregated distribution under all densities,and the aggregation intensity increases with the increase of population density.The optimal sampling number under different population density was also determined by the optimal theoretical sampling model.