| Alfalfa is the most widely cultivated excellent legume forage in the world,known as the "king of forage".Spiders are an important group in the alfalfa fields,with many characteristics,such as species diversity,large predation,wide range of prey and strong adaptability.Spiders are one of the key natural predatory groups of various alfalfa pests.In order to clarify the species diversity and dominant species of spiders in alfalfa fields,this paper conducted a comprehensive investitation of spiders in alfalfa fields of Yuzhong County(Lanzhou City,Gansu Province)and Xifeng District(Qingyang City,Gansu Province)by using net catching and trapping methods.Based on morphological characteristcis and DNA barcoding technology,we carried out species identification for all spider samples collected from the two localities.We established spider catalog of alfalfa fields and investigated temporal dynamics for each of dominant spider species.Also,we comparasively analyzed how alfalfa planting ages influence on the speices diversity of spiders.The results will provide a theoretical guide to better protect and utilize spiders of alfalfa fields.The main results are as follows:1.A total of 55 species in 39 genera of 15 families were identified in alfalfa fields of Yuzhong and Qingyang.Spiders collected from the alfalfa field in Yuzhong county were identified as 48 species,belonging to 34 genera and 15 families(spider samples collected from 8-year-old alfalfa fields were identified as 47 species belonging to 34 genera in 15 families;spider samples of 1-year-old alfalfa field were identified as 42 species belonging to 31 genera and 12 families);In the alfalfa field in Qingyang city,the collected spider samples were identified as 49 species,belonging to 37 genera in 13 families(spider samples of 17-year-old alfalfa field were identified as 48 species belonging to 35 genera in 13 families;and the spider samples of 2-year-old alfalfa field were identified as 45 species belonging to 33 genera in 12 families).In alfalfa fields of Yuzhong and Qingyang,the common dominant families are Lycosidae(3 species in 2 genera in Yuzhong,5 species in 2 genera in Qingyang),Thomisidae(10 species in 8 genera in Yuzhong,11 species in 9 genera in Qingyang),and Philodromidae(5 species in 2 genera in Yuzhong,6 species in 3 genera in Qingyang).In addition,Oxyopidae(2 species in 1 genera in both Yuzhong and Qingyang)is a unique dominant family in Qingyang.Common families in the two places are Araneidae(7 species in 6 genera in Yuzhong,6 species in 6 genera in of Qingyang),Gnaphosidae(3 species in 1 genera in Yuzhong,2 species in 1 genera in Qingyang),Tetragnathidae(1 species in 1 genera in both Yuzhong and Qingyang)Species),Salticidae(8 species in 4 genera in both Yuzhong and Qingyang),Theridiidae(3 species in 3 genera in both Yuzhong and Qingyang),Miturgidae(1 species in 1 genera in both Yuzhong and Qingyang),Clubionidae(1 species in 1 genera in both Yuzhong and Qingyang),Linyphiidae(1 species in 1 genera in Yuzhong,3 species in 3 genera in Qingyang);the rare family in both places is Agelenidae(1 species in 1 genera in Qingyang and Yuzhong),while the unique and rare families in Yuzhong are Amaurobiidae(1 species in 1 genera)and Eresidae(1 species in 1 genera).In these two areas,the common dominant species are Pardosa astrigera,Ebrechtella tricuspidata,Philodromus cespitum,Xysticus ephippiatus.In addition,Xysticus striatipes is a unique dominant specie in Yuzhong,also,Synema globosum and Oxyopes licenti are unique dominant species in Qingyang.2.In the alfalfa field in Yuzhong,the population dynamics of the dominant species are as follows: the peak period of Pardosa astrigera was in May,and then gradually decreased.In September,the number rebounded but the difference was not significant;Xysticus striatipes,Ebrechtella tricuspidata,and Philodromus cespitum all showed an increasing in population density and then decreasing trend,with a peak in July.The number of Xysticus ephippiatus continues to increase,peaking in September.During the same period,the number of dominant species of spiders in alfalfa fields with different ages was significantly different(P <0.05).In late May and mid-June,the number of Pardosa astrigera was significantly higher in the 1-year-old alfalfa field than 1-year-old alfalfa field(P <0.05).At the beginning of July,the number of Ebrechtella tricuspidata in 7-year-old alfalfa fields was significantly higher than 1-year-old alfalfa fields(P <0.05).During the same period,there was no significan difference in the number of other dominant groups.In the alfalfa field in Qingyang,the number of Oxyopes licenti and Xysticus ephippiatus increased at the end of July,and reached a peak in September,which was significantly different from other dominant species(P <0.05);the number of Synema globosum,Pardosa astrigera and Ebrechtella tricuspidata decreased first and then increased at the peak of September,the number of Philodromus cespitum showed a decreasing trend.After August,except for Oxyopes licenti and Xysticus ephippiatus,the number of dominant species in both alfalfa fields with different ages was significantly different(P <0.05).3.A total of 84 insects in 80 genera of 52 families in 10 orders were identified in alfalfa fields of Yuzhong and Qingyang.Insects collected from the alfalfa field in Yuzhong county were identified as 76 species,belonging to 72 genera of 49 families in 10 orders,and insects collected from the alfalfa field in Qingyang county were identified as 75 species,belonging to 73 genera of 46 families in 10 orders.The dominant groups in both places are Hemiptera,Coleoptera and Orthoptera.The dominant pests in common are Adelphocoris lineolatus,Apolygus lucorum,Dolycoris baccarum and Tychius medicaginis.In addition,Pyrrhocoris tibialis,Nabis stenoferus and Locusta migratoria manilensis are also the dominant species in the alfalfa field in Yuzhong;and there are Lygus pratensis and Eurydema gebleri in Qingyang.The dominant predators are Propylaea japonica and Hippodamia variegata.The population dynamics of the dominant groups of insects and the dominant groups of spiders in alfalfa fields are related,and the numbers of the two groups follow each other.In the alfalfa field in Yuzhong,the peak occurrence periods of both two are July and August,however,in Qingyang alfalfa field,the peak period of insects is July and August,while the dominant spider group shows an increasing trend,and the number of dominant spider group reaches its peak in September. |
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