Studies On Orientation Behaviors And Regulatory Genes Of Long-distance Migration In Agrotis Pests

Agrotisis a genus of moths of the Noctuidae family,and many of species are the most important crop pests.In the genus Agrotis,Agrotis ipsilon(Rottemberg)and A.segetum Denis and Schiffermaller,which damaged many important crops and vegetables,and distribute widely in China,and cause great yield losses.Migration is one of the most reason for the outbreaks of pests.A.ipsilon and A.segetum undertake a seasonal migration in China,and migration might be the for the outbreaks of it.Study on the molecular biology of A.ipsilon and A.segetum during their long-distance migration,it will provide effective information for the forecasting and management of A.ipsilon and A.segetum.In the study,we evaluated the possibility measuring insect orientations of trapped migratory moths of A.ipsilon using a novel flight simulator;we combined conventional analytical approaches with DNA meta-barcoding to identify pollen grains attached to migrating adults of the turnip moth;we compared the expression levels ofthe cry genes and MagR gene in A.ipsilon and A.segetum;we studied the expression rule of cry genes and MagR gene in A.ipsilon and A.segetum.These studies showed that cry genes and MagR gene have an important function of long-distance migration in A.ipsilon and A.segetum.The main results were summarized as follows:(1)To explore the possibility measuring insect orientations of trapped migratory moths of A.ipsilon,a novel flight simulator was carried out and the direction selectivity of migration A.ipsilon moths during different migration periods were determined.The results showed that A.ipsilon mainly migrated to the north in the first migratory stage;black moths migrated to the north and south in the second migratory stage;and black moths migrated to the south in the third migratory stage.(2)In the present study,combination of DNA sequences and pollen morphology were used to identify the pollen attached to A.segetum during their long-distance migration.Forty pollen species from at least 26 families were detected on A.segetum moths.28 species of pollens were found in first migratory stage including of Citrus sinensis,Robinia pseudoacacia,Melia azedarach,Castanea henryi,Olea europaea,Castanopsis echinocarpa,Ligustrum lucidum,Amorpha fruticosa,Elaeagnus umbellate,Pterocarya rhoifolia,Brassica,Dendromecon,Pinaceae and Rosaceae;11 species of pollens were found in second migratory stage including of Chenopodium album,Adenophora trachelioides,Helianthus,Gnaphalium,Galium,Gaura,Artemisia and Cercidium;8 species of pollens were found in third migratory stage including of Chenopodium album,Chrysanthemum,Pilea,Asteraceae and Lauraceae The turnip moth prefer to attack more on Angiosperm and Dicotyledoneae than those on Gymnosperm and Monocotyledon plant,moreover,they are found to attack on herbaceous plants more than woody plants.(3)Campare to the carrier rates among A.segetum female and male moths,the results showed that 10.86%and 11.46%of the female and male moths were contaminated with various plant pollens,and the carrier rates of pollen were no significantly difference among A.segetum female and male moths.During the different migratoy season,the turnip mothprefer to attack Pinus,Brassicaceae and Asteraceae,respectively.Meanwhile,the taxa and carrier rate of pollen contaminated A.segetum in the early part of the migration period was significantly higher than that in the middle period and the late period of the migration season during 2014-2017.(4)The natal origin of the A.segetum in the first migratory stage may be in central or southern China according to the carried pollen,because the district distribution of Citrus sinensis,Olea europaea,Ligustrum lucidum,Robinia pseudoacacia,Castanopsis echinocarpa,Melia azedarach and Castanea henryi mainly in central and southern China.The natal origin of the A.segetum in the second migratory stage may be in northern or northeast China,because the district distribution of Helianthus annuus,Adenophora and trachelioides mainly in northern and northeast China.(5)In this study,quantitative polymerase chain reaction showed that theCry and MagR genes were present in all tested organs with higher expression in adults during developmental stages of the black and turnip moths.The expression of Cry genes and MagR gene followed a circadian rhythm under normal photoperiods,and constant light or dark disturbed this rhythm.The expression levels of Cry genes and MagR gene were higher in the migratory population than in the reared population and higher in the southward migratory population than in the northward.Moreover,the results showed that the expression levels of those genes under the different treatment groups on Agrotis ipsilon were similar to that of on A.segetum.These findings suggest that the two cryptochrome genes and MagR gene characterized in the black and turnip moth might be associated with migration.