| Euwallacea interjectus(Blandford,1894)is one of the ambrosia beetle.It is a native species and widely distributed in China.It is also a trunk pest with a wide range of hosts.It was first reported to harm Firmiana simplex in Guizhou in 1984,and it has caused a lot of damage on poplar plantation in China in recent years.Because of its hidden living habit,the traditional prevention and control methods can not effectively control the occurrence and damage of E.interjectus.To control the ambrosia beetle effectively,the biological characteristics,occurrence rules and population dynamics of E.interjectus were studied.The main objectives of this study are the morphological characteristics,life history,development period,instars division,harm characteristics,host selection,population dynamics of E.interjectus and species identification of other ambrosia beetles in poplar forest.The following results have been achieved:1.The morphological characteristics of female,male and other stages of E.interjectus were recorded.The eggs were 0.76–0.94 mm in length,0.41–0.49 mm in width,oval,milky white and translucent,with smooth surface.The body length of the newly hatched larvae is 1.63–2.55 mm,and the head-capsule width is 0.41–0.49 mm,which is milky white and translucent,growing with the deepening of the color,the body length of the old mature larvae is 4.70–7.02 mm,and the head-capsule width is0.81–1.09 mm.The length of female pupa is 4.65–5.25 mm and its width is 2.07–2.57 mm.The length of male pupa is 3.50–3.95 mm and its width is 1.65–1.72 mm.In the early stage,the pupa is milky white.Female adult is 3.50–3.91 mm long,1.31–1.62 mm wide,length to width ratio 2.4–2.6;body is black,antennae and feet is brown yellow,eye is kidney type,antennae is stick segment flat and enlarged,anterior thoracic midplane in front of the tumor area scaly,accounting for the first two–thirds,notched area reticulate,accounting for the last third;Microshield triangles flush with elytra;Anterior full pit adjacent close,anterior foot tibial lateral circular arc;The wing discs of elytra are bright,the notches are rounded,shallow and large notches,not invagination,and the internotches have a single row of long,vertical setae nodules.Elytra inclined plane has a gentle incline and a smooth and bright surface.The grooves of elytra have obvious round shallow and large grooves,and the intergrooves have a single row of sparse tubercles covered with vertical long hair.The second intersulci has a continuous tuberculate process from base to end,and the posterior margin of the inclined plane has a distinct marginal process.The body length of male adult is 2.40–2.87 mm,about 2.18 times the body width,and the body color is yellowish brown.The lateral view of the anterosternal backplane was flatter than that of the female,the apex was not prominent,the tuberculate of the tumor area was shorter and sparser than that of the female,and the engraved spots were sparse and shallow.Elytra slopes downward from the base 1/4 of the way down at a gentle gradient.It provided more detailed information for the identification and identification of the pilonothorax.2.The life history from 2021 to 2022,developmental period and biological characteristics of the E.interjectus were systematically studied.There are 4generations of E.interjectus per year in Yancheng area and the pest overwintered in the form of adult.The overwintering adult laid eggs in early-April.The first generation larvae began to hatch in early-May,began to pupate from late-May till early-June,and pupae began to emerge from mid-June,and a peak of adult emergence was from late-June till early-July.The larvae of the second generation began to pupate in late July,and pupae began to emerge in early-August with a peak of adult emergence in mid-August.The larvae of the third generation began to pupate in lateAugust,and pupae began to emerge in early-September with a peak of adult emergence in early-September.The larvae of the fourth generation pupate from midSeptember to late-September.The pupate began to emerge in late-September with a peak of adult emergence in October and end in late-October.The larval instars was divided into three instars by the head-capsule.In this paper,the development period of E.interjectus in wild was determined.3.The results showed that the average number of holes was proportional to DBH.The damage rate of poplars with DBH(diameter measured at breast height)larger than 35 cm reached 100%,and the average number of holes was 242.57.The average number of holes was proportional to the height of the tree.The damage rate of poplars taller than 20 m reached 100%,and the average number of holes was 169.71.The average number of holes of poplars with different planting spacing was significantly different.The average number of holes of poplars with 6m×7m planting spacing was176.15.There was no significant difference in the number of holes of silverfish in poplar at different distance from water source(P>0.05);The number of newly added holes was 392 in live trees and 5 in wood segments in the same period of time.The peak of new holes in poplar corresponded to the peak of adult emergence,which was in late June.The number of newly added holes was significantly positively correlated with the number of original wormholes(P<0.01),and the orientation of newly added holes was significantly correlated with the orientation of original wormholes(P<0.01).The newly added holes were mainly concentrated in the height range of 1m–1.5m,accounting for 42.86%.The holes in the whole poplar were mainly distributed in the range of 1–2m,accounting for 41.76%.With the increase of height,the holes decreased,and there were no holes above 7m.The number of progeny was positively correlated with the total length of gallery(P<0.001).4.Five species of ambrosia beetle were identified by means of morphological and molecular identification through two years of trapping monitoring and investigation: Anisandrus maiche Kurentzov;Cnestus mutilatus Blandford;Xyleborinus saxesenii Ratzeburg.Xylosandrus amputates Blandford and Xylosandrus crassiusculus Motschulsky were the new recorded species in Jiangsu Province.The morphological characteristics of the species identification of five ambrosia beetles were provided,and the population dynamics of five ambrosia beetles species in Huanghai National Forest Park were determined.E.interjectus has three peak of adult occurrence a year.It was determined that the correlation between temperature and population dynamics was the strongest among meteorological factors,and the peak of adult occurrence was from June to August when the temperature was high. |
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