Behavioural And Electrophysiological Responses Of Dendroctonus Armandi To Volatiles From Pinus Armandi And Dendroctonus Armandi

Dendroctonus armandi is an endemic species of our country. It is a destructive insect of Pinus armandi. In recent years, Dendroctonus armandi caused great damage to Pinus armandi in Qinling and Bashan mountains. It caused extensive massive death of natural pinus armandi forest, seriously affect Sustainable development of ecological and economic environment. At present the main method of controlling Dendroctonus armandi is using chemical pesticide, but there is a lack of research of its effective and no pollution controlling technology. Recently a new way of using chemical ecology to control pest was raised at home and abroad. Better result has been achieved by using the new method to control the other polyphagous woodworm pest, such as Dendroctonus valens and Dendroctonus ponderosae. Based on the rudimentary understanding of biological characteristics and occurrence rule of D. armandi, this research we studied the behavioural and electrophysiological responses of Dendroctonus armandi to Volatiles from pinus armandi and Dendroctonus armandi. The results are summarized as follows:(1) In order to understand how the Dendroctonus armandi find ther victims and whether there is allusion between the male and female, their responses to five kinds of worm body and to the volatile substance of the host plant which after different treatment, were tested using Y-tube olfactometer.The results showed that the volatile substance of the Pinus armandi has higher lure activity to the female. The volatile substance of the female has higher lure activity to the male while both the female and female do not have clear response to the volatile substance of the male. The behavior responses of adult female and male worm to the smell combined worm body and bamboo shoot are obviously higher than that to the corresponding volatile substance of worm body.The results suggest that the pheromone exists in.The pheromone from the female has great allure to the male of the same type. The host plant could strengthen the allure between the female and the male.This may provide useful information of studying new methods to control adults of Dendroctonus armandi.(2)Y-tube olfactometer was used to test the behavioral selectivity of Dendroctonus armandi to volatiles, which extracted by different organic solvent. The data showed that the attractability of three volatiles to the female adults are different: Hexane> pentane>aether;the attracability of three volatiles to the male adults are different too:Hexane> aether> pentane.The results showed that hexane is better than aether and pentane as organic solvent.(3)GC-MS(Gas Chromatography-Mass Spectrometer) is used to analyse the analyse the compounds and relative contents of volatiles extracted from the organic solvent of the phloem of pinus armandi.The results showed that the relative content of the chemical composition of volatile from high to low is:β-Caryophylene(56.86%),a-pinene(6.93%),1,6-Cyclodecadiene(6.18%),β-pinene(5. 57%),β-Ocimene(4.47%),Cycloheptane(4.12%),a-Copaene(2.69%),a-Caryophyllene( 2.63%),Dioctyl o-phthalate(1.18%),Cyclohexene(0.66%).The content of these kinds of compounds is 91.29% of the total content.(4) In order to screen attractive chemicals for trapping males and females of Dendroctonus armandi, several plant volatiles of Pinus armandii were used to test the electroantennogram value and the taxis behavior of Dendroctonus armandi adults. The results showed that among the 7 test chemicals at dosages of 0.01,0.1,1,10 and 100μg,7 chemicals all induced clear EAG responses in proper dosage. Myrcene, (+)-3-carene andβ-caryophyllene all elicited the highest value when using them to irritae both female and male at the dosage of 10μg. The taxis behavior of the beetle to the volatiles was assayed at dosages of 1,10 and 100μg with Y-tube olfactometer. Corrected response percentages of females to (+)-α-pinene,β-pinene and (+)-3-carene were significantly different from that of the hexane control (>72%) at the dosage of 10μg. At the dosage of 1μg, only (+)-3-carene was attractive to males. (-)-α-pinene was somehow repellent to the beetle at the dosage of 100μg. The study will provide the foundation for developing attractive chemicals for D. armandi in fields.(5)Five non-host plant volatiles, Salicylaldehyde,1-Nonanal, Trichloroethylene, Dichlorodim-ethyl ether and cis-3-Hexen-l-ol were used to test the electroantennogram value and the taxis behavior of Dendroctonus armandi adults. The results showed that Trichloroethylene, (+)-3-Carene and P-Caryophylene induced a clear EAG response from the females while 1-Nonanal, Dichlorodim-ethyl ether, (+)-3-Carene and (+)-α-pinene induced a strong EAG response from the males. The attractive effect ofβ-pinene, (+)-3-Carene and (+)-α-pinene was strong to female while Trichloroethylene attracted more male than female. The study would provide reference for developing attractive chemicals for D. armandi in fields.(6) In order to screen the composite components of the plant volatiles which can effectively attract Dendroctonus armandi,we chose six compounds() to make ten composite components according to the composition of the components of Pinus armandi. The results showed that:composite componentsⅢandⅦinduced no EAG response to female,Ⅵinduced weak response, the other 7 composite components induced clear response.Ⅷcaused the strongest EAG responses to female adults; exceptⅣandⅥ,the other 8 composite components all induced clear response to male adults and X caused the strongest response. The attracability ofⅡto female adults is the highest,the value is 81.11%.ⅥⅦandⅤalso exhibited high attracability to females. The attracability of X is the highest, the value is 78.89%, while that ofⅢis the lowest. The composite components ofⅡ,Ⅳ,Ⅴ,Ⅶ,ⅧandⅩcan be used in fields.