| From the beginning of the 20th century to the present,Sirex noctilio(Hymenoptera: Siricidae)has invaded more than a dozen countries in Oceania,Africa,South America and North America,and is highly dangerous invasive pest in the world.In 2013,woodwasps collected from Xindian Forest Farm,Dulbert Mongolian Autonomous County,Daqing City,Heilongjiang Province,China,were identified as Sirex noctilio.In 2014,the State Forestry Administration added Sirex noctilio to the national forestry dangerous pest list.Sirex noctilio is a newly discovered dangerous pest in forestry in China.The first-hand research result based on its domestic occurrence is almost blank,which is not conducive to the control of Sirex noctilio.In order to learn more about this insect,and in order to reduce the loss caused by it,this paper studies the biological characteristics of Sirex noctilio in Heilongjiang Province,Inner Mongolia Autonomous Region and Jilin Province by lab feeding,fine anatomy and spatial distribution.At the same time,the ecological characteristics of Sirex noctilio were studied in the aspects of bait wood monitoring,host volatile matter screening,silvicultural control technology.The main results are as follows:1.The adults of Sirex noctilio have obvious morphological characteristics,but it is difficult to identify the eggs,larvae and pupae.The morphological characteristics of female adults of Sirex noctilio are as follows:each foot is reddish brown,only the last tarsal node is black;the length of the accessory segment pad of the second tarsal node of the hind foot is 0.3-0.4 times the length of the second tarsal node;the ventral surface of the ovipositor is carved,and the distance between the central carved points is nearly the same as the diameter of the carved point itself.The morphological characteristics of male adults of Sirex noctilio were as follows: the base and end of abdomen were black,and the middle part was orange.There is only one-color type of Sirex noctilio in China,that is,the legs of male and female adults are reddish brown,which is consistent with the color types of each invasion site of Sirex noctilio.Different from the native of southern Europe,it can basically exclude the possibility that the invasion source of Sirex noctilio in China from southern Europe.2.The harm characteristics of Sirex noctilio host are "Needle,Middle,Dying,Trunk,Tear,Hole"."Needle" refers to harmful coniferous trees,especially Pinus,and In China,it is the Pinus sylvestris var.mongolica Litv.;"Middle" refers to harmful middle-aged forest of Pinus sylvestris var.mongolica,and about 40 years old is the most seriously affected;"Dying" refers to harmful dying trees,rarely harmful to healthy trees;"Drunk" refers to the harmful parts concentrated in the trunk;"Tear" refers to resin outflow from the trunk after the Sirex noctilio lays eggs,which looks like tears;"Hole" refers to a round emergence hole on the trunk of a harmful host.At present,Pinus sylvestris var.mongolica is the only host of Sirex noctilio found in the field of our country,however,the experiment of tree species selection in the laboratory showed that Sirex noctilio were more likely to harm Pinus tabulaeformis and complete their growth and development.3.The results revealed that Sirex noctilio were sexually mature upon emergence,they could mate and/or lay egg immediately.The ovipositing process of Sirex noctilio was divided into four stages: drilling into the bark;drilling into the xylem;laying eggs(injection of poisonous mucus and symbiotic fungi Amylosereum areolatum),and withdrawing the ovipositor.The most frequent oviposition time-duration was between 360 to 540 s,which accounted for 41.40% of the total oviposition time-duration.During those four stages,time-duration of drilling into the xylem was the longest,taking at least 90% of the total duration.Sirex noctilio would carry out 1 to 4 drillings once confirmed at one position.The oviposition time duration showed a significantly positive correlation with the number of oviposition cycles: 1 cycle at t<360 s;2 cycles at 360 s≤t<540 s;3 cycles at 540 s≤t<780 s;and 4 or more cycles at t≥780 s.The rates of 1,2,3 and 4 cycles of oviposition at one oviposition hole were 21.66%,41.40%,27.39% and 9.55%,respectively.4.In Hegang,Heilongjiang Province,the spatial pattern of Sirex noctilio is aggregation distribution.Sirex noctilio gather in the forest to damage the dying Pinus sylvestris var.mongolica,and the trunk of 0-600 cm above the ground is the main damage area.Compared with Tongliao(Inner Mongolia Autonomous Region),Liaoyuan(Jilin Province),Yushu(Jilin Province),Hegang(Heilongjiang Province),the galleries drilled by Sirex noctilio in Qiqihar(Heilongjiang Province)and Daqing(Heilongjiang Province)are longer in horizontal direction,deeper in xylem and more harmful.The characteristics of Sirex noctilio gallery: except that 20% of gallery in Qiqihar are in the shape of "Z",Tongliao,Liaoyuan,Yushu,Hegang and Daqing are in the shape of "U" or "L".5.In Hegang,Heilongjiang Province,most Sirex noctilio completes one generation a year.Adult emergence began in mid-July and ended in early September,and the peak period of emergence was concentrated in the middle and late August.The eggs were laid at about 1cm under the bark,and the egg period was about 2 weeks.The larvae overwintering in the trunk.The larvae are generally 6 instars.The mature larvae pupated at the distance of 2-3cm from the bark,and the pupal stage was 3-4 weeks.6.The bait wood treated by ring cutting method has a good attraction effect on Sirex noctilio,and can be used as a method to monitor Sirex noctilio in forest.The main reason for the seductive effect is related to the mixture of camphene,tricyclene,trans-β-Ocimene,terpinolene,α-pinene oxide,longifolene and β-pinene,which are volatiles in the trunk.7.Clearing of the oviposition tree has obvious management effect on the prevention and control of Sirex noctilio in the early stage of occurrence,which can significantly reduce the occurrence of Sirex noctilio and slow down its diffusion rate.After the control measures were taken,the percentage of pests in Pinus sylvestris var.mongolica was 0.87±0.26%-1.54±0.41%.Compared with the control plot,the rate of insect bearing plants decreased significantly after the measures of removing the source and planting forest were carried out. |
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