Endangered Mechanism And Its Conservation Of Butterfly Bhutanitis Thaidina(Blanchard) In Taibai Mountain

Bhutanitis thaidina(Blanchard)belongs to the order Lepidoptera,family Papilionidae and genus Bhutanitis.There is little information about this rare and threatened species of butterfly in China.This study defines specific conservation methods to guarantee the long-term survival of B.thaidina(Blanchard)in the town of Houzhenzi on the south slope of Taibai Mountain based on describing its biology and behaviors,establishing its life-tables and habitat requirements,and analyzing threats to its survival.In this research area,B.thaidina(Blanchard)is univoltine,overwintering as pupae in the gaps of rocks and under deciduous leaf litter.Adults start eclosion in late May and males emerge 4～7 days earlier than females.The females lay eggs as a mass on the underside of the host plant leaf from early June to early July.The egg period lasts for 14～16d.The larval stage lasts for almost 40 days with five instars,all feeding on Aristolochia manshuriensis.Duration of the pupal stage is about 300 days.Life-tables show that the L1-L3 larvae are the key stages revealing a high mortality of 81.6%in 2011 and 90.5%in 2012.The heavy and long-duration rains,natural enemies and diffusion are the main causes of high mortality.The mortality in the egg period,2.2%in 2011 and 51.85%in 2012,occurs from failure to hatch,heavy rains and natural enemies.The high mortality in 2012 was mainly caused by steady and heavy rains and natural enemies.The experimental population life table demonstrated that heavy rains resulted in the pupae dying from mildew with a mortality rate of 44.4%.The host plant A.manshuriensis mainly survives in the broadleaf forests and broadleaf-coniferous mixed forests at altitudes from 1755m to 2280m and with a canopy density of 0.4～0.95.Occupied habitats are defined by the presence of the host plant and eggs or larvae within the transect samples,while unoccupied habitats are defined by the presence of the host plant only.Occupied and unoccupied habitats show significant differences in elevation(t=2.918 p=0.009)and canopy density(t=-5.529 p<0.001).There is no difference in host plant density between occupied habitats and unoccupied habitats.Pearson correlation coefficients show the larval density is highly correlated with the canopy density and also with altitude,while larval density is not correlated with the density of the host plant.The decrease in larval density is related to increasing canopy density.An analysis of habitat requirements shows suitable habitats for B.thaidina(Blanchard)are located at the open glades in the forests with an elevation range between 1928～2280m and with a canopy cover of 0.4～0.75.Based on the results of life-tables and an analysis of habitat requirements,we propose that B.thaidina(Blanchard)lives in small extinction-prone populations in the forests on the south slope of Taibai Mountain.This shortage of suitable habitats is the main cause of B.thaidina(Blanchard)being endangered.Natural enemies(including spiders,ants and birds),unfavorable climatic conditions and dispersal are important threats among the larval stages and limit population increase and rehabilitation.Moreover,interspecific competition is also a potential threat for B.thaidina(Blanchard).The corresponding conservation measures proposed are:① increasing the suitable patches and improving the quality of the patches,② constructing corridor patches or"stepping stone" patches to reduce the isolation of populations and increase inter-communication,③ human assistance in their reproduction under dense mesh netting in the local area,which will reduce the impact of natural enemies and poor weather conditions,and ④ supervision and patrol should be beefed up in the forests in order to prevent illegal collection of B.thaidina(Blanchard)as well as destruction of A.manshuriensis.