| Sound,as one of the environment factors,has significant effect on the life of insects.Monochamus alternatus Hope(Coleoptera:Cerambycidae)is an important forest pest.Not only they can directly damage pine trees but also cause a wilt disease of pine by releasing carried pinewood nematode into pine trees.In order to explore new control methods of M.alternatus,we investigated the effect of acoustic stimulation on M.alternatus.In present study,a commercial device LHC20 was used to investigate the stress effects of ultrasound on the juvenile hormone ?(JH?)of M.alternates and the changes of the activities of acetylcholinesterase(AChE),feeding behavior was also investigated.The results obtained in the experiment are as following:1.In the absence of ultrasound,the JH? titers of M.alternatus adults are low in the first three days after emergence,in the following two days the JH? titers increased gradually.Entering day 6,the JH? titers began to decrease in female adults and in the following days kept stable.For male adults,the JH? titers decreased during entering day 6 and then increased sharply in the following days.Entering day 9,JH? titers of M.alternatus adults yielded significant difference between sexes(p<0.01).After exposure to ultrasound,JH? titers of M.alternatus adults decreased significantly to a lower level than the control group(p<0.05).After exposure to ultrasound of 1,12 and 24 h,the JH? titers existed significant difference(p<0.05)between M.alternatus with different ages.For 1-,3-,and 5-day-old adults groups,the largest,larger and smallest changes of JH? titers were after 12-,24-and 1-h exposure to ultrasound,respectively.The change rate of JH? titers of M.alternatus is significant difference(p<0.01)after 12-h exposure to ultrasound.When exposed to second harmonic(-60 kHz)of CF-FM bats-like ultrasound,the change rate of JH? titers of M.alternatus is 63.6%±2.2%.When exposed to the first harmonic(?30 kHz)of CF-FM bats-like ultrsound,the change rate of JHIII titers of M.alternatus is 16.8%±1.8%.When exposed to ultrasound generated by the commercial device(LHC20),the change rate of JHIII titers is 48%±4.5%.Under ultrasound exposure condition,the JH? titers of M.alternatus adults without or with antennae is significantly lower than the control group(p<0.05).The change rate of JH? titers of female adults without antennae is 18.2%± 1.3%,significantly lower than the with antennae group(44.6%± 3.2%)(p<0.001),moreover,the change rate of JH? titers of male adults without antennae is 18.0%±1.1%,significantly lower than the with antennae group(45.2%±4.1%)(p<0.001).2.Because exposure-time to ultrasound was different,the acetylcholinesterase(AChE)activityof M.alternatus is also different.After 15-,30-,45-,and 60-min-exposure to ultrasound,the AChE activity of 1-day-old M.alternatus was 0.83-,1.39-,1.11-and 1.09-fold of the control,respectively.Moreover,after long-time-,i.e.after 6-h-exposure to ultrasound,the AChE activity of 1-day-old M.alternatus was 1.14-fold of the control and did not yield significant difference.12-h-exposure to ultrasound,the AChE activity was 1.22-fold of the control(p<0.05),the AChE activity of 1-day-old M.alternatus was 1.16-fold of the control(p<0.05)after 24-h-exposure to ultrasound(p<0.05).M.alternatus with different ages generated different stress response to ultrasound.The AChE activity of 5-day-old M.alternatus was decreased significantly(p<0.05)after ultrasound exposure for 30 min,but increased significantly of 1-day-old adults(p<0.05).The AChE activities in 1-day-old and 5-day-old adults without antennae decreased significantly(p<0.05).AChE activity in adult males with antennae varied from 0.0800 ± 0.0191 to 0.1317±0.0090 U/mg protein while AChE activity in adult females with antennae varied from from 0.0803 ± 0.0042 to 0.1383±0.0101 U/mg protein.However,these results showed that the changes of AChE activity induced by ultrasound exposure did not have significant difference between sexes.3.In the absence of ultrasound,M.alternatus stayed randomly in the cage.In the presence of ultrasound,M.alternatus appeared to stay far from the ultrasound source placed in the cage.In addition,after exposure to ultrasound,the feeding areas of M.alternatus adults decreased significantly(p<0.05).In conclusion,ultrasound act as one of the environment factors,has significant effect on the JHIII titers,the changes of the activities of AChE and feeding behavior of M.alternates.It could be used as a potential method to control M.alternatus. |
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