| Sitobion avenae(Fabricius)(Homoptera: Polygonaceae)is a major pest on grass crops and a dominant species on wheat crops.When the aphids are attacked by predatory or parasitic natural enemies,they will secrete a viscous liquid from their abdominal tubes,which contains a volatile substance,the alarm pheromone.Like most other aphids,S.avenae alarm pheromone main component is farnesene(EβF,E-β-farnesene),and the nearby aphids sense the alarm signal and respond immediately,and even protect the aphids population by changing the offspring wing type to cope with the external adverse environment.In this study,the effects of different concentrations of EβF on the behavior of the grain aphids S.avenae and wing dimorphism of offspring were determined,and the six mi RNAs related to S.avenae wing dimorphism were cloned and expressed.Mainly got the following results:(1)Effects of different concentrations of EβF release on the behavior of Sitobion avenaeBehavioral assays were used to release EβF from S.avenae.The results showed that for 1~4 instar nymphs,the concentration of EβF increased,and the number of aphids with behavioral responses gradually reduced.EβF was released to adults,along with EβF,as the concentration increased,the ratio of aphids with behavioral responses gradually increased and tended to be stable.(2)Effect of EβF on Sitobion avenae wing dimorphismDifferent concentrations of EβF were used to treat the 3rdinstar nymphs,and the effect on the wing dimorphism of the offspring was observed.The results showed that the proportion of winged aphids in the offspring increased first and then decreased with the increase of EβF concentration.when the concentration of EβF was 200 ng/μL,the offspring had the highest rate of wing aphids.EβF was released in different degrees of crowding,and the wing rate of the offspring did not increase significantly with the maternal crowding degree;when EβF treated of lower density 3rdinstar nymphs,with the increased density of offspring,the generation of wings has increased significantly.(3)Cloning and expression of six micro RNA related to wing dimorphismThe expression proliling of six mi RNAs were assessed between winged andwingless in S.avenae by cloning and q RT-PCR in different developmental stages.The results showed that the six mi RNAs were expressed in S.avenae winged and wingless and different developmental stages.And the relative expression levels was different.sav-mi R-927-5p(t=-3.394,p=0.072),sav-mi R-29(t=-2.427,p=0.04)and sav-mi R-3037(t=-3.641,p=0.022)relative expression levels of the two wing morphs1 stinstar nymphs were significantly different;sav-mi R-3040(t=-3.611,p=0.024)and sav-mi R-3050(t=2.922,p=0.043),sav-mi R-3016(t=4.908,p=0.008)were significantly different at the 2ndinstar nymphs of the two wing morphs,and sav-mi R-3050(t=3.74,p=0.02)was also significantly different at the 3rd instar nymphs of the two wing morphs.sav-mi R-927-5p had a significantly increased expression of pterin in the 1st and 2ndinstar nymphs of the winged scorpion,and sav-mi R-3050 has a similar expression pattern;the expression of sav-mi R-3016 was lower than that of wingless morph except for the 2ndinstar nymphs,however,the expression of winged morph was higher than that of wingless morph in other periods,and the expression of winged morph was significantly increased at 2ndand 3rdinstar nymphs;the relative expression sav-mi R-3037 and sav-mi R-3040 were significantly increased in 1st instar nymphs of winged.The results showed that these six mi RNAs might play a very vital role in the wing-type dimorphism of S.avenae. |
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