Optimization Of Sex Attractant And Preliminary Study Of Food Attractant On Mythimna Separata(Walker)

The oriental armyworm,Mythimna separata(Lepidoptera: Noctuidae),is a typical,gluttonous,and seasonal long-distance migratory pest.Except for Xinjiang,M.separata occurs in other provinces(cities,districts)of China.The adult of M.separata has 4-5 times large-scale migration processes between northern and southern China in a year.The larvae prefer eating leaves of maize,wheat,and rice,which seriously threaten the safety of food crop production in China.Due to the changes of climatic conditions,crop planting structure and the adaptability of the pest,the frequency of the M.separata outbreak increased in recent years.On the one hand,this study optimized the formula of the armyworm attractant and in order to utilize the sex attractant to monitor the dynamics of its population migration.On the other hand,according to the habit of moth preferentially feeds on the nectar of Astragalus sinicus,the attraction of the floral scent from A.sinensis to M.separata was explored and the attracting effect of floral odor on the sexual attractant was also discussed.Our study provided a foundation for the highly trapping technique of this pest.The main results of the study were as follows:1.Identification with GC-MS on female M.separata sex gland extracts with the retention time and mass spectrometry characteristics of synthetic standards indicated that three sex pheromone components,including cis-9-hexadecenal(Z9-16: Ald),cis-11-hexadecenal(Z11-16: Ald)and cis-11-hexadecene acetate(Z11-16: Ac),existed in sex gland.In addition,Z11-16: Ald had a higher proportion and lower contents of Z11-16: Ac and Z9-16: Ald.The electrophysiological tests,including GC-EAD and EAG,showed that Z11-16: Ald,Z11-16: Ac,and Z9-16: Ald caused the antennal potential response to male moth of M.separata.The antennae of male moth produced a strong EAG response to Z11-16: Ald,and the effect increased significantly along with enhancing concentration.While EAG response to Z11-16: Ac and Z9-16: Ald were relatively weak.The indoor wind tunnel test suggested that the single component Z11-16: Ald elicited a few males to complete the comprehensive behavior response,from excitement to pre-mating.Adding greater than 3% component of Z11-16: Ac to Z11-16: Ald significantly increased the pre-matting ratio.When a several amount of Z9-16: Ald component was added to Z11-16: Ald: Z11-16: Ac optimal ratio increased the pre-matting ratio to 57.9%.The field trapping test conducted in three locations showed that the ternary component Z11-16: Ald,Z11-16: Ac,Z9-16: Ald with a ratio of 95: 5: 1and the total dose at 1 mg have a higher trapping effect.2.GC-MS was used to identify the floral components of A.sinicus at bloom period.The results showed that α-farnesene,β-myrcene,D-limonene,β-Ocimene and β-Caryophyllene are the characteristic aroma of the flower odors of A.sinicus.The EAG test indicated that all 12 plant volatiles from A.vulgaris caused various degrees of EAG reaction of male and female moths.Wind tunnel test of single component of plant volatiles documented that plant volatiles,including Z-3-hexenyl acetate,Phenylacetaldehyde,Decanal,Octanal,β-Caryophyllene,and Dodecane showed certain attraction for both male and female M.separata.However,Nonanal and Ocimene have a certain repellent effect.The wind tunnel behavior test with different plant volatiles showed that the male moth had the highest proportion of formula 2(Phenylacetaldehyde: β-caryophyllene: Z-3-hexenyl acetate=1:1:1)and formula 11(Phenylacetaldehyde: Decanal: Octanal: β-Ocimene =1:1:1:1)to oriental flight,which reached 59.61% and 56.02%,respectively,which was significantly higher than other combinations(P<0.05).In the formula where the moth reached the vicinity of the odor source,the formula 10(Phenylacetaldehyde: Decanal: β-Caryophyllene: β-Ocimene=1:1:1:1)had the strongest attracting effect,and 26.81% of the male moths landed near the odor source,significantly higher than the other formulas.Formulation 11 caused several female moths to reverse oriental flight,suggesting significantly higher than others(P<0.05).The highest proportion of female moths reached the vicinity of the odor source,and 30.41% of female moths landed near the source of odor,substantially higher than other combinations with formulation 2(P<0.05).The field experiments showed that attractive effect of the plant volatiles combinations was weak,the trapping amount was less than 20 within one month.The combination of phenylacetaldehyde,β-Caryophyllene,Z-3-hexenyl acetate(1:1:1)with sex attractant of M.separata(pheromone)had the best attractive effect in all formulas and the ratio of insect number largely attracted pheromone alone(P<0.05),indicating that the specific ratio of plant volatiles had a synergistic effect on the sex attractant.