| Semanotus bifasciatus (Motschulsky) is an important pest to Platycladus orientlis, also lead to heavy damage on P. orientlis, S. bifasciatus is one of the major stem borers of cypress, primarily by larva. Larva hazarded phloem heavily, after the fourth stage, they begin to endanger the xylem and block the tunnel connected with outside world with frass, which could cause difficulty for the entrance of small predators. Article focuses on the biological characteristics of beetles and basing on research which was carried out in order to provid a reasonable and effective control method of S. bifasciatus by releasing P. zhonghuajia.By comparing the research to find suitable time and releasence of P. zhonghuajia to provide a theoretical foundation for continuous control, and focousing on the control effect of P. zhonghuajia. to S. bifasciatus,we make a preliminary study and the article main results are as follows:1. Most of S. bifasciatus are 1 year per generation, just a small perception is 2 yearl generation. And test showed that in the newly hatched adults, the females slightly more than adult males. In early March there will be a beetle eggs lied on P. orientalis wood which were placed indoor and outdoor and this treatment had a obvious impact.2. P. zhonghuajia has control action on S. bifasciatus larvae, and can achieve good effection.The trials dates are from the middle of April to the end of May; we set two P. zhonghuajia releasing amounts and one blank as contrasting. The results showed that in Beijing the best time keep out the pest by making use of P. zhonghuajia is the early and middle days in May, when the average temperature of the day was over 20℃.3. In the trials of using P. zhonghuajia to control the S. bifasciatus, comparing two natural enemies releasence, although when P. zhonghuajia put a large amount,the control effect would be better, the following resuilts were not variously differ from the small dose. Releasing more beetles could get better control effect on larva from the third to the fourth stage. But from the perspective of cost-effective prevention,the method of taking use of one tube of each wood to control the beetle larva from the first to the second stage is more efficient. The experiment result also shows that P. zhonghuajia had more tropism to S. bifasciatus larvae while the length of Semanotus bifasciatus ranging from 1cm to 2 cm.4. P. zhonghuajia could kill the adult pest, P. zhonghuajia with submerged dose can lead to the death of S. bifasciatus, and adult beetles died within 48 hours, the adult mortality rate was 100%. The results of P. zhonghuajia controlling the S. bifasciatus adult are different, which died on the ability of the adult male is stronger than the weak died on the female, The reason for further study. As the role of time, the effect of adult female beetles changed. Within started 24 hours of the effect on female adult, S. bifasciatus had no death results; after 48 hours, part of the female deaths; 72 hours later,the Group 3 and Group 5 mortality rate 100%. This showed that the number of P. zhonghuajia had a proportional death effect of Semanotus bifasciatus adult.5. This study found under room temperature that P. zhonghuajia stop movement about half an hour on wood segment which carried worms,and the moving curve, near the spiral, Linear distance of movement between 50-70cm; average line distance between the 80-90. So that the moving distance on wood segment which carried worms of P. zhonghuajia is about 1m range. |
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