Phylogeny And Prediction Of Potential Geographic Distribution Of Sirex(Hymenoptera:Siricidae) In China

Sirex woodwasps(Hymenoptera: Siricidae),the sorts of major woodborers in coniferous timberland,can weaken or kill their host plants by co-infesting with its obligate mutualistic fungus and mucus.S.noctilio Fabricius,a devastating international forestry quarantine pest,originates from Eurasia and North Africa.In 2013,S.noctilio was found in the Pinus sylvestris L.var.mongolica Litv.plantation in Heilongjiang Province.S.noctilio has spread to other provinces in northeastern China.Sirex woodwasps have not been paid enough consideration and there is a research gap for Chinese researchers.Due to S.noctilio established in China,there is a critical need to study the biodiversity,phylogenetic relationship,and the potential geographic distribution of Sirex woodwasps.The main results are as follow:1.Revised the list of Sirex woodwasps in China,by identifying through external morphological characteristics,the pits on ovipositor,etc.There are 8 species of Sirex woodwasps distributed in China,including S.noctilio,S.dux(Semenov),S.ermak(Semenov),S.juvencus(L.),S.nitobei Matsumura,S.piceus G.R.Xiao & Wu,S.tianshanicus(Semenov),and S.vates Mocsáry.The highest biodiversity of Sirex woodwasps in China is in the Meng Xin Region.Commonly,several species of woodwasps co-infest the same host plant in the habitat.2.The specimens,identified as S.imperialis W.F.Kirby,are S.nitobei according to morphological identification.S.imperialis has not been found in China yet.According to morphological and molecular identification,both S.sinicus Maa and S.rufiabdominis G.R.Xiao & Wu are the synonym of S.nitobei.The revised checklist of Sirex woodwasps contains 27 species.3.The neighbor-joining tree,maximum likelihood tree,and Bayesian inference tree of the Sirex genus were constructed,based on the CO Ⅰ gene.The interspecific phylogenetic relationship of the Sirex genus shows the Sirex woodwasps originate from Western North America,and are differentiated into different species in North America,Western Eurasia,Central Asia,and East Asia.The early period differentiated species mainly infest the Pinaceae and Cupressaceae species.And the later period differentiated species mainly infest the Pinaceae species.4.Under near current and future climate conditions,the potential geographic distribution of four species of Sirex woodwasps was predicted by the maximum entropy model.The predicted area of the suitable area of S.nitobei in China is 13.64×106 km2,under the near current climate conditions.And the predicted area of the suitable area of S.juvencus,S.dux,and S.cyaneus around the world except for Antarctica is 4.56×107 km2,3.17×107 km2,and 3.97×107 km2,respectively.Under the future climate conditions,the predicted area of the suitable area of all these four Sirex woodwasps species showed an upward trend.And the variation tendency of these four Sirex woodwasps might be close to the predicted results of ssp585,ssp126,ssp245,and ssp245,respectively.The distribution pattern of the Sirex woodwasps is mainly driven by summer rainfall,the temperatures in summer and winter.In this study,Sirex woodwasps distributed in China were identified by morphological and molecular identification and revised the checklist.The phylogenetic relationships of the Sirex genus were analyzed.Under current and future climate conditions,the potential geographic distribution of four Sirex woodwasps species was predicted,and the environmental factors which could restrict their distribution were expounded.The results of this study will provide a scientific reference for the control,monitoring,and early warning of Sirex woodwasps.