Identification Of Male Pheromone Components Of The Oriental Armyworm Mythimna Separata (Walker) And Its Effect Of Reproduction

Mythimna separata belongs to Noctuidae in Lepidoptera.The larvae can endanger many food crops such as wheat,corn and rice,which are harmful to a wide area and cause serious damage.Therefore,it has become an important agricultural pest in China.Previous studies showed that the male pheromone of M.separata was involved in the exchange of information related to both sexes and had some influence on the reproduction of female and male moths,but the specific function of male pheromone is unclear.Therefore,the subject identified and quantitatively analyzed the extract of male hair-pencils by gas chromatograph electroantennogram spectrometer(GC-EAD)and gas chromatography-mass spectrometry(GC-MS).Through the observation of mating behavior,we can realize the releasing manner of male pheromone.Finally,the specific function of the male moth pheromone was determined through the wind tunnel test and the indoor courtship and mating test.The main results are as follows:1 Extraction and identification of male pheromoneThrough the identification of male pheromone,found benzaldehyde and benzyl alcohol in these two kinds of substances on the EAD response of male and female moths were significantly.Quantitative determination of the two substances by interna l standard method revealed that the single male of 4 days old contained benzaldehyde 19.63 ?g and benzyl alcohol 1.89 ?g.2 Generation and release of male pheromoneHair-pencils(HPs)located in the anterior abdominal cavity is the pheromone release organ.Eight hours after male eclosion,HPs began to retract from the second internodes of the abdomen to 3-4 segments of pockets proportion of the HPs,and vast majority of males' HPs retracted within the pouches after 24 hours when male eclosion.Using GC-MS to detect HPs at different time and different positions,we know that male pheromone is synthesized when HPs begin to retract,and it is generated after retracting pouches.By experimental observation on courtship and copulation behavior,we found that male moths would not turn out HPs during the whole process,but male moth will release the pheromone at unilateral pouches in genital contact process.3 Effects of male worm moth pheromones on electrophysiological response to adult and reproductionThe results of EAG test showed that with the increase of the extract concentratio n of HPs(0.1ME-2ME),the response of the male and female moths increased,and the response value of the female was higher than that of male moths at high concentratio ns.The winner test results showed that the extract of HPs had not effect to attract the female,but inhibited males to approach females in the courtship status.Male pheromones advanced the females courtship and increased the courtship ratio.Cutting male HPs or female antennas compared with the control group,the mating proportion did not decrease significantly,but mating proportion of males lacking antennas dropped to 0.Females copulated with males of cutting off HPs on 1-day-old can increase the amount of eggs.Male cutting off HPs had the same ability as normal male moths to compete with female moths.Male pheromones or n-hexane were applied to posterior abdomen of females,the mating rate of females in the treatment group was 17.24% and that of females in the control group was 52.72%,the result demonstrated that male pheromone can significantly inhibit males mating with females.