Study On The Function Characteristics Of Semiochemicals And The Evaluation Of Trapping Efficacy Of Monochamus Alternatus

Monochamus alternatus is the main trunk borer of pine trees and the vector of transmission pine wood nematode disease in China.A large number of Bursaphelenchus xylophilus are carry of M.alternatus,which are transmitted at the adult feeding and oviposition period.In this paper,we studied the function mechanism and features of plant volatiles and aggregation pheromones by many experiments.Further it was elucidated the variation of lures of plant volatiles and the aggregation pheromone in the field and its influence on the trapping efficacy of lures by gas chromatography-mass spectrometry(GC-MS).By field trapping and monitoring experiments,the influence of spatial height and the circadian rhythm on trapping efficacy of longhorn beetles were studied.The development of reproductive system of different day age adult longhorned beetles and adult M.alternatus ensnared by traps was investigated.The research results show that:1 The attraction distance of plant volatiles is more than 150 m that M.alternatus could be trapped by plant volatilesis at 50 m,100m and 150 m.This suggests that plant volatile was a long-distance semiochemical.Aggregation pheromones only attracted a small amount of longhorn beetles in 50 m,which was a short-distance semiochemical.The trapping effect of mixed lure of plant volatiles and aggregation pheromones that was significantly higher than that of using plant volatiles and aggregation pheromones alone had synergistic effects.2 The plant volatiles are mainly composed of ?-pinene and ethanol(total volume: 160 ml,?-pinene 120 ml,ethanol 40ml).The aggregation pheromone is 2-undecanoxy-1-ethanol with an initial content of 35 ul.The species and content of plant volatiles changed with time.On the 15 th day,the content of ethanol was zero,and the original proportion of plant volatiles changed.Another three new impurities including verbenol,campholenal and verbenylethylether were present during the 15th-45 th day.The proportion of ?-pinene decreased to 73.34% and the contents of the original impurities,i.e.,pinocarveol,pinocarvone,myrtenal and verbenone,were significantly increased on the 60 th day.The aggregation pheromone content was zero at day 45.The results of field trapping showed that the field trapping effect of the new lures(the lures were suspended for 20d)was significantly higher than that of the old lures(the lures were suspended for 50d)at the 50 th day.The trapping effect of the new lures(the lures were suspended for 30d)and the old lures(the lures were suspended for 60d)was extremely significantly different after the 60 th day(P<0.01).In conclusion,The results show that the release rate of attractants for M.alternatus shows the variation tendency of being fast first and then slow in the field.The decrease of lures-trapping effect is related to the premature volatilization of ethanol,the rapid volatilization of active components in the early and the less volatilization in the later.The high-efficiency duration of the self-made attractants for M.alternatus for field trapping is not less than 45 d,and the validity duration is not less than 60 d.3 The trapping amount of male and female adult is correlated with the height of trap suspension.The higher the trapping height,the more the trapping amount was: 3m>1.5m>0m,4m>2m>0m,the trapping amount was significantly more in 1.5m,3m,2m and 4m than 0m.There was no significant difference in the amount of male and female adult trapping at the same height.The traps only trapped longhorn beetles from 19:00 PM to 5:00 AM.The peak time of longhorned beetle was 20:00 PM to 3:00 AM by trapped,and the trapping amount in this stage is 91.89% of the total trapping amount.This suggests that the longhorns are nocturnal insects that move in the upper and middle layers of the forest.4 The ovary color of female adult longhorn beetles feeding on 0d was transparent,then turned into milky white on 3d-10 d,then into light yellow on 15 d,and finally turned yellow on 20d;The diameter of female adult longhorn beetles increased with the number of feeding days,and the average diameter of mature ovarian tube was 4.016 um.The female's internal reproductive system was mature about 20 d.The male adult's testicles were transparent at the beginning of emergence.After feeding for 3 days,the testicles turn pale yellow,and the testicles were slightly enlarged.The male reproductive system was mature at about 6d.Plant volatiles and aggregation pheromones could induce 20.68% female and 24.32% male adults at feeding stage.