Study On Adaptability Of Monochamus Alternatus To The Different Host Plants And The Characteristic Of Harm Of Bursaphelenchus Xylophilus

Monochamus alternatus Hope is a pest that damages many forest trees seriously.Its adult is also an important spreading medium of Bursaphelenchus xylophilus.In recent years, the spreading speed of this pest is very fast,and the correlated economic loss is serious.The biological,ecological characteristic and integrated management of the pest were studied systematically in China,and the integrated management based on these researches was applied to control the pest,and the pest's population was controlled effectively.But the B. xylophilus has spread rapidly in recent years.Nowadays,selecting resistant pine species is the basis of controlling pine wilt disease,and controlling insect vector M.alternatus is the main way to control pine wilt disease.In this research,the interrelation among host plants,M.alternatus and B.xylophilus was studied.And on this foundation,the effects of five host plants on physiological metabolism and the activity of enzymes of M.alternatus were studied,and the inclusions of host plants and the relations between them and adult M.alternatus were analyzed.Furthermore,by inoculating 4 or 5 years old P.thunbergii and P.massoniana seedling with pine wood nematode,the changes of inclusions in the pine phloem were studied,which can help to discover the host selection behavior of M.alternatus,and offer some advice in preventing adults M.alternatus and B.xylophilus.The main results as follows:1.The effects of host plants on survival,boring behavior,activity of cellulase,esterase and carboxylesterase of larvae of M.alternatus were investigated after the larvae were inoculated under the bark of five plants respectively.The results showed that the survival of the larvae fed with P.massoniana was 100%,whereas it was 55.56%which fed with C. deodara.The activity of Cx of M.alternatus fed on P.teada was the highest,which was 4.5754μmol·g^-1(FW)·min^-1,the activity of C₁ andβ-1,4- glucosidase of larvae fed on P. massoniana were the highest,which were 2.8199±0.0510μmol·g^-1(FW)·min^-1 and 3.0793±0.1733μmol·g^-1(FW)·min^-1,respectively.The activities of esterase and carboxylesterase of the larvae fed on P.thunbergii and P.massoniana were the highest, which were 1372.74mmoD/min·μg and 744.82mmoD/min·μg,respectively.2.The results of the effect of physiological metabolism and enzyme activities of M. alternatus fed on five host plants showed that,the testing insects fed with P.massoniana and C.deodara gain weights from the fifth day after eclosion,and others fed on the other there plants gain weights from the seventh day.The relative consumption rate,relative metabolic rate and efficiency of conversion of ingested food of the adult M.alternatus fed on P.massoniana were highest than those fed on the other four plants.The activity of Cx and C₁ of M.alternatus fed on P.massoniana was the highest,and the activity ofβ-1,4-glucosidase which fed on P.teada was the highest.Furthermore,enzyme activity of esterase and carboxylesterase of the M.alternatus fed with P.massoniana was significant higher than those fed on the other four plants.3.In this research,the inclusions of five M.alternatus host plants were determined,the results showed that the total sugar content of the five hosts were given in the order:C. deodara＞P.massoniana＞P.thunbergii＞P.teada＞P.elliottii.Except for C.deodara,the more the total sugar content in phloem,the faster the weights enhance of the M.alternatus. The reducing sugar content of the five host plants in the order:P.elliottii＞P.massoniana＞C.deodara＞P.teada＞P.thunbergii.The reducing,sugar content had no significant effect on feeding and the conversion of digested food and ingested food of M.alternatus.The soluble sugar content of the five host plants in the order:P.massoniana＞P.thunbergii＞C. deodara＞P.teada＞P.elliottii.The higher the soluble sugar content,the better for M. alternatus feeding on,and the higher the relative consumption rate,the poorer of the insect-resistance of the plants.The soluble protein content of the five host plants in the order:P.elliottii＞P. massoniana＞C.deodara＞P.thunbergii＞P.teada.The soluble protein content had no significant effect on feeding of M.alternatus.M.alternatus preferred feeding on the tree bark with low content of tannin.In this condition,its relative consumption rate and the food utilization rate increased,and the insect-resistance of tree species was poor,whereas strong.The content of total phenol decreased in the order of P.elliottii＞P.thunbergii＞P.teada＞C.deodara＞P. massoniana.P.massoniana with low content of total phenol was the preferred object for M. alternatus.4.Inoculated with Bursaphelenchus xylophilus,the content of some materials in the P thunbergii and P massoniana changed.The results showed that after inoculating,the total sugar content of P.thunbergii and P.massoniana both decreased.The reducing sugar content and the soluble protein content of P.thunbergii first increased and then decreased, but its tannin content was opposite and its total phenol content continued to decrease.The reducing sugar content of P.massoniana after inoculating was no significant difference in the first 7days but decreased in the following days,its soluble protein content and tannin content continued to increase and its total phenol content first decreased and then increased.The soluble sugar content of the two species first reduced,then increased and then reduced again.