| The larvae of P.viridifasciata and R.Cyathea mainly feed on the you ng leaves of A.spinulosa and A.metteniana,which jeopardizes the growth and reproduction of both plants,resulting in reduction of the number of s pores.Therefore,P.viridifasciata and R.Cyathea were as studied objects i n this experiment,the population dynamics of both on A.spinulosa in Gui zhou Chishui Alsophila National Nature Reserve were further investigate d,which can provide theoretical support for the pest monitoring and contr ol work in the reserve.At the same time,study on the choice selection of t he larvae of P.viridifasciata to different leaf discs,olfactory response and oviposition options of R.Cyathea was conducted to gain a preliminary un derstanding of the relationship between the two phytophagous insects and their host plants.The chemical compounds of the young leaves of A.spin ulosa and A.metteniana were analyzed by gas chromatography-mass spec trometry,which can provide some scientific references for the developme nt of attractants.The main results are as follows.（1）Population dynamics of two phytophagous insects of A.spinulosa.Acc ording to the results of sampling and analysis in April-December 2020 a nd May-December 2021,there was no significant variation（P>0.05）in p opulation quantity of P.viridifasciata larvae,while population quantity of R.Cyathea changed significantly（P<0.05）.Meanwhile,the populations o f P.viridifasciata and R.Cyathea larvae were differed significantly（P<0.05）from different sample points,probably because the different distributio n of A.spinulosa,microclimate environment and the degree of human inte rference in different sample points made the population quantity of the tw o phytophagous insects different.In addition,the larvae of P.viridifasciat a was mainly emerged in July and December,and that of R.Cyathea did i n June and October.（2）Study on adult emergence observation,olfactory response and oviposit ion selection of R.Cyathea.（1）In the adult emergence experiment,of whic h 91 were successfully emerged,with a eclosion rate of 30.3%,47 female s and 44 males,with a male to female ratio of 1:0.94.The adult emerged f rom 07:00 to 00:00,and the peak emergence was from 11:00 to 13:00.（2）I n the olfactory response experiment,The females of R.Cyathea showed si gnificant response to A.spinulosa（P<0.05）,while males and larvaee show ed no significant response（P>0.05）,probably because R.Cyathea mainly relied on oviposition of females for dispersal and the difference of sex and olfactory organs with male and larvae.The females showed more obvious tendency to A.spinulosa than the males and larvae.（3）In oviposition choi ce experiment,In the pairing of A.spinulosa and A.metteniana,there was no significant difference（P>0.05）in the oviposition quantity of R.Cyath ea on A.spinulosa and A.metteniana,and the oviposition quantity was（28.0±7.4）eggs on A.spinulosa and（23.0±7.8）eggs on A.metteniana.In th e pairing of A.metteniana and Arachniodes chinensis,the oviposition qua ntity was（26.0±4.5）eggs on A.metteniana,but none were observed on A.chinensis,indicating that R.Cyathea could accurately identify host and n on-host plants for oviposition.In the non-selective experiment,ovipositio n quantity on A.spinulosa was significantly higher than that on A.metteni ana（P<0.05）,indicating that R.Cyathea preferred to choose A.spinulosa as their oviposition host.Oviposition quantity on the abaxial side of the le aves of both plants was significantly higher than that on the adaxial side o f the leaves（P<0.05）,indicating that R.Cyathea preferred to choose on th e abaxial side of the leaves as their oviposition position,thus reducing the risk of being parasitized or predated by natural enemies.（3）Study on the tendency selection of P.viridifasciata larvae towards different plant leaves.（1）Under both light and darkness,the selection frequency towards A.spinulosa and A.metteniana were significantly higher than that towards green leaf discs（P<0.01）,indicating that larvae have a clear tendency to host plant odor.（2）under darkness,the selection frequency towards A.spinulosa and A.metteniana were significantly higher than those of A.chinensis and Nephrolepis auriculata（P<0.01）,which indicates that the larvae are better at discriminating between host plants and non-hosts.（3）Under darkness,its selection frequency towards A.spinulosa was significantly higher than that of the other three ferns（P<0.05）,in which A.spinulosa was selected 46 times during our study.It accounted for 38.3% of the total frequency,showing that the larvae can precisely judge the most adapted host plant A.spinulosa and show stronger tendency to it.（4）Analysis of the chemical compounds of the young leaves of A.spinulo sa and A.metteniana.GC-MS analysis showed that 34 compounds were d etected,including 23 compounds from A.spinulosa and 19 compounds fro m A.metteniana.The main group is hydrocarbons,with a relative content in A.spinulosa（43.9±4.07%）and A.metteniana（58.4±7.72%）,followed by alcohols,with a relative content in A.spinulosa（13.0±3.72%）and A.m etteniana（13.5±1.25%）,and the rest of aldehydes,acids,lipids and amine s,with a relative content in A.spinulosa（8.47±4.36%）and A.metteniana（4.19±1.63%）.There were 8 components in both plants;γ-sitosterol,doust anol,octyl p-methoxycinnamate,nonanal,and four other alkanes,respecti vely.In this regard,there are some similarities and differences in the comp osition of the compounds between the two plants. |
