| Spodoptera litura is an important agricultural pest in tobacco field,and the damage caused by S.litura come up to economic losses in agricultural production of China every year.S.litura can be found wildly in every place of China,evenly around the world.It has the characteristics of wide distribution,many hosts and strong migration ability.Attract-and-kill strategies as a biological control to manage the S.litura based on sex attractant have been applied constantly.Sex attractant is an important chemical substance for male and female insects to transmit information.Using it to forecast and control pests has the advantages of low dosage,good selectivity and environmental friendliness,but it also has the disadvantages of low efficiency and poor sustainability.Plant volatiles are widely distributed in plant leaves,and insects search the host position by identifying the volatiles.As a synergist,plant volatiles can effectively improve the efficiency of sex pheromone.Plant volatiles as a kind of synergists may provide more efficient services to avoid the limitation of sex attractant in comprehensive trapping pests.In this paper,the effects of environmental factors on the growth and development of S.litura were studied.Electroantennogram(EAG)and six-arm olfactometer were used to measure the response of S.litura to different volatiles and sex pheromones.Through the indoor trapping experiment,the better trapping formula were selected.The main results are as follows:1 The research of the influence of environmental factors on growth and development of S.lituraUnder 16 L : 8 D,the duration of larval development was the shortest(24.66 d),the survival rate at 14 L : 10 D was the highest,and the average pupal weight at 6 L: 18 D was the highest(0.3411 g).With the decrease of light time,the developmental duration and survival rate of S.litura larvae first increased and then decreased.In the temperature range of 18 ℃ to 30 ℃,S.litura could complete its growth and development,and the developmental duration of each stage shortened with the increase of temperature.At 30 ℃,each developmental period was the shortest.The hatching rate of eggs is closely related to the humidity in the environment.The hatching rate of eggs with 80% relative humidity is the highest.2 Electrophysiological responses of S.litura to different volatilesThe electrophysiological responses of S.litura to 21 plant volatiles were tested using EAG technique.The EAG responses of S.litura to different volatiles had significant different.The single volatiles with good activity were screened from 21 kinds of volatiles.In female moths,the order of EAG response values from small to large were as follows: Heptanoic acid < Dibutyl phthalate < Beta-Pinene < Methyl salicylate < 2-(2-Bromophenyl)-1,3-dioxolane < 3-(Trifluoromethyl)phenethyl alcohol < Ocimene < Phenylacetaldehyde < Ethyl salicylate < 1-Hexanol < Myrcene< Eugenol < cis-3-Hexen-1-ol < 2-Methylcyclohexanone < cis-3-Hexenyl hexanoate< Benzyl alcohol < Benzyl acetate < Salicylaldehyde < Ethyl benzoate <Heptaldehyde < Benzaldehyde;In male moths,the order of EAG response value from small to large were as follows: 3-(Trifluoromethyl)phenethyl alcohol < Dibutyl phthalate < Heptanoic acid < Ethyl salicylate < Beta-Pinene <2-(2-Bromophenyl)-1,3-dioxolane < Methyl salicylate < Salicylaldehyde <2-Methylcyclohexanone < Ocimene < Benzyl acetate < Phenylacetaldehyde <Eugenol < 1-Hexanol < Benzyl alcohol < Myrcene < cis-3-Hexenyl hexanoate <cis-3-Hexen-1-ol < Ethyl benzoate < Heptaldehyde < Benzaldehyde.At the same concentration,the EAG responses of males and females were strongly to Benzaldhyde,Heptadhyde and Ethyl benzoate.Benzyl acetate,Salicylaldehyde and Benzyl alcohol had strong stimulation on female antennae.Cis-3-hexenyl hexanoat,Myrcene and Benzyl alcohol had strong stimulation on male antennae.The EAG responses of females to 6 volatiles increased with the increase of concentration,while the EAG responses of males to cis-3-Hexene-1-alcohol and Benzaldehyde increased with the increase of concentration,and then decreased.When two or three volatiles were mixed,the combinations of strong EAG responses to females were excited by Heptadhyde and Benzyl alcohol,cis-3-Hexenyl hexanoate and Myrcene,Myrcene and Heptadhyde,Myrcene and Ethyl benzoate,Heptadhyde and Myrcene.The combinations of strong EAG responses to males were were excited by Heptadhyde and Myrcene,Heptadhyde and Benzyl alcohol,Myrcene and cis-3-Hexenyl hexanoate.When the ratio of cis-3-Hexen-1-ol and Heptadhyde was 9 : 1,the female had the highest responses,and when the ratio was 8 : 2,the male had the highest responses.When the ratio of cis-3-hexen-1-ol and myrcene was 1:1,the female had the highest responses,and when the ratio was 3 : 7,the male had the highest responses.When the ratio of Heptadhyde and benzyl alcohol was 1:9,the female had the highest responses,and when the ratio was 6 : 4,the male had a highest response.In summary,plant volatiles with Heptadhyde had higher EAG response values,which provided the theoretical basis and hypothesis for the further research.3 Behavioral responses of S.litura to different volatilesSix-armed olfactometer was used to measure the behavior of S.litura.Males and Females had significantly different behavioral responses to these volatiles in the number and time spent of S.litura entering the treatment area of Benzaldehyde,Ethyl benzoate and Heptadhyde were significantly more than those of other compounds.There were significant differences in the behavioral responses of males and females S.litura to different concentrations of volatiles.In the experiment of cis-3-Hexen-1-ol treatment,the number entries of males and females in 0.1 mol/L and0.01 mol/L treatment areas were significantly higher than those in other areas.With the increase of the concentration,the number entries increased gradually,while the number entries of males increased first and then decreased.In the experiment of Heptadhyde,Benzaldehyde and Ethyl benzoate treatment,with the increase of concentration,the number entries of males and females increased first and then decreased.In the experiment of Benzyl alcohol and Myrcene treatment,with the increase of concentration,the number entries of females increased first increased and then decreased,while the number entries of males gradually increased.4 Different volatiles synergize the response of S.litura to female sex pheromoneThe EAG responses of males induced by single and multi-component volatiles mixed with sex pheromones were determined.The EAG response values of all mixed combinations were significantly higher than those of single sex pheromone.The EAG response values of adding Heptadhyde to sex pheromone was the highest,and the EAG response values of enhancing sex pheromone were also very obvious.The results of trapping moths in laboratory showed that the rate of S.litura trapped was the highest when Heptadhyde was added to the sex pheromone,which was extremely significant difference from that of sex pheromone;secondly,Benzaldehyde,Ethyl benzoate and Benzyl alcohol were added to the sex pheromone,which were significant difference from that of sex pheromone.Different concentrations of volatiles were added to sex pheromone to induce different effects on males.With the increase of the concentration of Benzaldehyde and Ethyl benzoate,the rate of S.litura trapped first increased and then decreased.The rate was the highest at 0.01 mol/L,which was significantly different from that of sex pheromone.With the increase of Heptadhyde concentration,the rate of S.litura trapped increased,and the rate was the highest at 0.1 mol/L.Two or three volatiles were added to sex pheromone to induce insects,the results showed that only the combination of the two groups had significant synergistic effect on sex pheromone,that the mixture of Heptadhyde and Ethyl benzoate,the mixture of Heptadhyde and Benzaldehyde had the high trapping rate.This study proved that Heptadhyde,as an ideal sex pheromone inducer synergist,can be used to establish a more ideal sex pheromone trapping technology for S.litura,and has application value for the control and forecast of sex pheromone pests.In this thesis,the synergetic odorant volatiles against sex pheromone of S.litura were successfully obtained through electroantennogram response,behavioral response and trapping experiment,which can provide reference for further development of efficient trapping formula and improvement of low efficiency of sex pheromone. |
PDF Full Text Request