Effects Of Pest-induced Volatiles From Masson Pine On The Oviposition Selection Of Cnidium Rubru

As one of the most important tree species in Guizhou Province,the Pinus massoniana pine has entered its fruiting peak.However,due to the increasing seriousness of pests,the yield of P.massoniana pine improved varieties has been greatly reduced year after year.Dioryctria rubella is one of the main pests.D.rubella is a feeding pest.which mainly harms the main and side shoots of Masson’s pine,causing multiple branches of the side shoots,malformed crown,and unable to bear fruit.It can also bore pine cones,,seriously harming the seed yield and quality of Masson’s pine.At present,chemical control is the main control method,but this method is not only ineffective,and adverse to environmental protection.Therefore,how to prevent and control D.rubella has become the main technical difficulty.In this study,based on the composition changes of the volatiles of P.massoniana before and after the infestation of D.rubella,this study discussed the effect of volatile of P.massoniana on the oviposition behavior of D.rubella,in order to provide basic research for the development of green control and attractant of D.rubella.The main results are as follows:(1)Study on infestation and oviposition selection behavior of D.rubellaThe selection tendency of D.Rubella on P.massoniana shoot and cone extract,and the oviposition selection on shoot and cone were studied by indoor bioassay.The results showed that D.Rubella had significant selection tendency to the extracts of infested shoots and cones,and the selection rate of extracts from infested shoots was the highest,reaching 70%.In the selection of laying eggs,79.4±17.0 eggs were laid on infested shoot,33.2±9.2 eggs were laid on healthy shoot.62.4±9.2 eggs were laid on infested cone and 19.4±6.8 eggs were laid on healthy cone.The results showed that the D.rubella tended to lay eggs on shoot and cone after infestation.(2)Changes of volatile components of P.massoniana induced by D.rubellaDynamic headspace adsorption method and GC-MS technology were used to collect infested and healthy shoot and cone volatiles,and analyze the changes of their composition and content.The results showed that compared with the healthy shoots,the terpenoid volatiles in the infested shoots were significantly up-regulated,while the other volatiles were downregulated or had no significant change.Ten kinds of specific components were detected in infested shoots,such as α-fenchene,α-terpinene and β-caryophyllene.Compared with healthy cones,the terpenoids in the infested cones were significantly up-regulated,and the aldehydes and amides were significantly down-regulated;7 kinds of specific α-fenchene,2-carene and(+)-sativene were produced.(3)The olfactory behavioral responses of D.rubella to 10 compoundsTen compounds with significant changes in volatile content of infested P.massoniana were screened out,and the olfactory behavior responses of D.rubella to five concentration gradients of 10 compounds were measured by "Y" olfactometer.The results showed that among the 10 compounds tested,α-pinene,β-pinene,α-terpinene,Limonene,α-terpinolene and Benzaldehyde had attractant effects on D.rubella.In benzaldehyde,only 0.1μL/μL concentration of benzaldehyde has a trend reaction.Repellent selection of nonanal by D.rubella,Caryophyllene,p-xylene and o-xylene have no selective taxis.The response rate and selection rate of D.rubella to 10 tested compounds were analyzed by one-way ANOVA and multiple comparisons,the results showed that different concentrations of the same compound and different concentrations of the same compound had significant effects on the olfactory behavior tendency of D.rubella.(4)Effects of 4 kinds of plant volatiles on the egg-laying behavior of D.rubella.Four compounds were screened out from olfactory behavior experiments,and the oviposition selection experiment of D.Rubella was carried out at three concentration gradients.The results showed that α-pinene and limonene had very significant attraction to oviposition,but different concentrations of α-pinene and limonene had no significant effect on egg laying quantity.β-pinene had no significant effect on the oviposition selection of D.rubella.The average number of eggs laid by D.rubella ranged from 40 to 50,but only a few eggs were found in α-terpinene oviposition behavior,and very few eggs or no eggs were laid.Therefore,α-terpinene may be repellent or not selected during oviposition selection.