The Study On The Mandible Structure And Feeding Habits Of Dominant Grasshopper In Xinjiang Grassland

Xinjiang autonomous region is one of the most prominent and typical regions in China.It is one of most severely regions in China where affect by locust plague yet.The locust plague has seriously affected Xinjiang’s development in economy,sociality and ecology.We focus on the the dominant grasshoppers in Xinjiang grasslands.The structural and numerical characteristics of mandible of twenty species of grasshoppers in Xinjiang grassland are studied comparatively by our investigated in 2018-2019.And we divided their mandibular types into three types,proposed the new numerical indicator.Moreover,we studied the seven species of grasshoppers in feeding plants through crop content.The last,we systematically studied feeding plants and mandibular structures in different stages of Italian locust,Calliptamus italicus(L.).We studied the dynamic changes and habitat selection of Italian locust in Mount Yamalic.The results show in below:The mandibular structure of twenty species of grasshoppers in Xinjiang grassland are divided into three categories,e.g.graminivorous,forbivorous and herbivorous types.Among them,Oedaleus decorus(Germar),Dociostaurus kraussi(Ingenitskii),D.brevicollis(Eversmann),Pararcyptera microptera(F.-W.),Notostaurus albicornis(Evcrsmann),Gomphocerus sibiricus(L.)and Myrmeleotettix palpalis(Zubovski)are graminivorous-type mandibles whose characteristics are obtuse incisors,parallel ridges and grooves,length/width of molar(female,left mandible:1.17-1.44,right mandible 1.39-1.69;male,left mandible:1.12-1.56,right mandible 1.27-1.65);C.italicus(L.),C.coelesyriensis(Giglio-Tos),Dericorys tibialis(Pallas)and De.annulata(Fieber)are forbivorous-type mandibles whose characteristics are elongated sharp incisors and molar with a deep central concavity surrounded by sharp teeth,length/width of molar(female,left mandible:1.37-1.83,right mandible 2.02-2.48;male,left mandible:1.71-2.02,right mandible 1.98-2.41);Bryodema gebleri(F.-W.),Oedipoda caerulescens(L.),O.miniata(Pallas),Helioscirtus moseri(Saussure),Sphingonotus savignyi(Saussure),S.salinus(Pallas),S.eurasius(Mistshenko),S.nebulosus(F.-W.)and C.barbarus(Costa)are herbivorous-type mandibles whose characteristics are intermediate structure between graminivorous and forbivorous types.C.barbarus(Costa)preferred feed in Krascheninnikovia ceratoides(L.);C.coelesyriensis(Giglio-Tos)preferred feed in Seriphidium borotalense(Poljak.)and K.ceratoides(L.).;N.albicornis(Eversmann)preferred feed in Ceratoides latens(J.F.Gmel.)and Stipa capillata L.;N.albicornis(Eversmann)preferred feed in Ceratoides latens(J.F.Gmel.)and Nanophyton erinaceum(Pall.);O.caerulescens(L.)preferred feed in Inula rhizocephala Schrenk;Gomphocerus sibiricus preferred feed in Stipa capillata L;Bryodema gebleri(F.-W.)and Oedaleus decorus(Germar)are both preferred feed in Stipa capillata L.The different grasshoppers have different breadth of ecological niches,among them the least breadth of ecological niches in Oedaleus decorus(Germar)was one,it could feed 1 species plant in 1 family;the most breadth of ecological niches in Oedipoda caerulescens(Linnaeus,1758)was 7.759,it could feed 9 species plant in 4 families.The remaining species of grasshoppers is intermediate in former species,such as C.barbarus(Costa),N.albicornis(Eversmann),Gomphocerus sibiricus,Calliptamus barbarus(Costa)and Bryodema gebleri(F.-W.)whose breadth of ecological niches are 4.491、3.034、5.734、4.167 and 3.252,respectively.The overlapping breadth of ecological inches Oedaleus decorus(Germar)and Bryodema gebleri(F.-W.)is 0.84,of Calliptamus barbarus(Costa)and N.albicornis(Eversmann)is 0.6.The mandible of C.Italicus(L.)gradually increased in size with development,while the length/width of mandible,incisor and molar are not significantly difference in stages of it(P>0.05).However,median molar teeth of left mandible are obvious in increasing stages;median molar teeth of right mandible are gradually larger and deeper in increasing stages.The Italian locust could feed sixteen species plants in 6 families in Mount Yamalik.The different stages of the Italian locust referred feed in different plants,e.g.,the 1st instar nymph preferred feed in Chondrilla piptocoma and Artemisia sieversiana;the 2nd instar nymph preferred feed in Ceratoides latens;the 3rd instar nymph preferred feed in Ch.piptocoma;the 4th instar nymph preferred feed in Artemisia;the 5th instar nymph preferred feed in Acroptilon repens;male adults prefers to Ar.sieversiana,while female adults prefers to Ar.sieversiana.The breadth of ecological niches of different stage are high-to-low male adults(8.96),the 2nd instar nymph(8.33),the 4th instar nymph(4.57),the 4th instar nymph(4.57),the 1st instar nymph(3.57),the female adults(3.52),the 3rd instar nymph(2.57)and the 5th instar nymph(2),respectively.The life history of the Italian locust in Mount Yamalik:the 1st instar nymph begins in mid-May and reached the peak in early June;at this time,the 2rd instar nymph began to appear and reached their peak in mid-June.The 3th instar nymph appeared in mid-June and reached its peak in late June;at this time,the 4th instar nymph began to appear and reached its peak in early July.Since early July,the adults have appeared and reached their peak in mid-July.The coverage of vegetation show a positive effect on the habitat nymph of the Italian locust.The most suitable vegetation of coverage of nymph of the Italian locust is 25-35%.