Population Characterization Of Stem-boring Pests Of Artemisia Ordosica In Different Habitats

Artemisia ordosica is one of the dominant community species widely present in the desert areas of Northwest China,which plays an important ecological value in promoting plant community succession,maintaining regional ecosystem stability and improving desert environmental conditions,and also has important economic value.At present,the main stem-boring pests found to damage Artemisia ordosica are Holcocerus artemisiae,Sphenoptera canescens,and Adosomus sp.Etc.Habitat heterogeneity provides diverse resources and habitats for organisms,which has important impacts on species diversity and spatial distribution of species.In this experiment,according to the natural growth of Artemisia ordosica from May to September 2021 to 2022,seven plots of Liujiazhai(LJZ),Guyaozi(GYZ),Changliushui(CLS),Yuanjiao Lake(YGDH),Gaosha Wo(GSW)in Yanchi County,Jingcheng Park(JCGY)and Crescent Lake Airport(YYHJC)in Xingqing District of Yinchuan City were selected,and the stem-boring pests of Artemisia ordosica worm were systematically investigated by checkerboard sampling.Holcocerus artemisiae and Sphenoptera canescens occur in all plots.Therefore,in this study,the effects of biological factors and abiotic factors on the population density and damage rate of stem-boring pests of Artemisia ordosica in different plots were discussed,and their spatial distribution characteristics in different plots,their utilization of spatial resources and interspecific competition were analyzed.The main findings and conclusions are as follows:(1)Among different plots,there were significant differences in population density and damage rate of Holcocerus artemisiae and Sphenoptera canescens(P<0.05).Holcocerus artemisiae was the highest population density(average 1.13 per plant)and the highest rate of insects(60.00%)in LJZ plot,and the GSW plot is the least damaged(average 0.05 per plant.5.00%);Sphenoptera canescens had the highest population density(average 3.50 per plant)in YYHJC plot,the highest rate of insects in CLS plot(80.00%).the GSW plot is the least damaged(average 0.15 per plant,12.50%).Multiple stepwise regression analysis showed that plant richness index and diversity index were the main factors affecting the population density of stem-boring pests of Artemisia ordosica,and plant diversity index and evenness index were the main factors affecting the rate of insects.The population density of the two stem-boring pests was significantly correlated with the plant height,ground path and root length of Artemisia ordosica(P<0.05).Person correlation analysis showed that soil water content and soil organic matter were significantly correlated with the population density and damage rate of Holcocerus artemisiae(P<0.05),and soil pH was significantly correlated with the population density and s amage rate of Sphenoptera canescens(P<0.05).(2)The spatial distribution of Holcocerus artemisiae and Sphenoptera canescens in different plots were clustered,which were mainly caused by environmental factors and the insect’s own behavioral habits.The vertical distribution of Holcocerus artemisiae and Sphenoptera canescens on Artemisia ordosica was uneven,and there were significant differences in their numbers(P<0.05),with the highest distribution ratio of underground stems(roots).Holcocerus artemisiae is distributed aboveground,surface and underground stems in LJZ,YGDH,CLS and YYHJC plots,while only underground stems(roots)are distributed in GYZ,GSW and JCGY plots.Sphenoptera canescens is distributed aboveground,surface and underground stems in GYZ,YGDH,CLS and YYHJC plots,while only underground stems(roots)are distributed in LJZ,GSW and JCGY plots.(3)Among the different plots,Holcocerus artemisiae and Sphenoptera canescens had different degrees of competition.The coexistence rate of the two pests in LJZ plot was as high as 35.00%,followed by YYHJC(15.00%),CLS(12.50%),GYZ(10.00%),YGDH(5.00%)and JCGY(5.00%),and no coexistence in GSW plot.The niche width of Holcocerus artemisiae in LJZ and YGDH plots was large,while the niche width of Sphenoptera canescens was larger in the remaining five plots.The niche overlap index(0.9173),similarity coefficient(1.0258)and interspecific competition coefficient(0.9608)were the highest in LJZ plot,followed by CLS and YYHJC plots,which were the lowest among GSW plot.