Han, Jianguo

Lu, Hui

English

University of Kentucky

University of Kentucky UKnowledge International Grassland Congress Proceedings XXI International Grassland Congress / VIII International Rangeland Congress Determination of Damage Yield Loss Relationships and Economic Injury Levels of Oedaleus asiaticus (Orthoptera: Acrididae) in Steppe of China Hui Lu China Agricultural University, China Jianguo Han China Agricultural University, China Follow this and additional works at: https://uknowledge.uky.edu/igc  Part of the Plant Sciences Commons, and the Soil Science Commons This document is available at https://uknowledge.uky.edu/igc/21/16-1/25 The XXI International Grassland Congress / VIII International Rangeland Congress took place in Hohhot, China from June 29 through July 5, 2008. Proceedings edited by Organizing Committee of 2008 IGC/IRC Conference Published by Guangdong People's Publishing House This Event is brought to you for free and open access by the Plant and Soil Sciences at UKnowledge. It has been accepted for inclusion in International Grassland Congress Proceedings by an authorized administrator of UKnowledge. For more information, please contact UKnowledge@lsv.uky.edu. 　 Multifunctional Grasslands in a Changing World 　 Volume Ⅱ 　 瞯 ]823　 瞯Grasslands/Rangelands Production Systems——— Integrated Management of Harmful Organisms of Grasslands/RangelandsDetermination of damage yield loss relationships and economic injury levels of Oedaleus asiaticus(Orthoptera :Acrididae) in steppe of ChinaHui L and Jian‐Guo HInstitute o f G rassland Science , College o f A nimal Science and Technology , China A gricultural University , 2 YuanMingY uan X ilu , H aidian , Bei j ing , 100094 , E‐mail : aaaluhui＠ 163 .comKey words : oedaleus asiaticus ,grass yields ,action thresholds ,economic injury levels ( EILs)Introduction Previous studies reported that Oedaleus asiaticus is the common and dominant grasshopper of Xilingol grassland ,in Inner Mongolia , China . ( Lu et al . , ２００５ ) . O . asiaticu occurs every growing season and results in yield losses throughpremature dropping of grass . Grain yield losses have also been reported for grasshoppers on grassland from different areas ofChina ( Qiu et al . , ２００４ ) . Study was to establish the relationship between Oedaleus asiaticus populations and yield loss ofgrass , and determine EILs for Oedaleus asiaticus in steppe .Materials and methods The site was on the Xilingol grassland ( ４３°２６′‐４４°３９′ N , １１６°２５′‐１１７°３９′E) in Inner Mongolia duringthe June‐September of ２００５ and ２００６ . The vegetation is dominated by Leymus chinensis and Stipa grandis . The trial was doneusing cages (１ × １ × １m３ ) made from nylon gauze , and O . asiaticus was released into the cages at densities of ０ , ４ , ８ , １６ , ２４grasshoppers/ cage . Typical densities range from ０‐３０ grasshoppers/m２ （Davis et al . , １９９２ ) . T reatments were assigned atrandom within each replicate ( n ＝ ４) . Equal numbers of males and females were introduced into each cage . At forage maturity ,grain yields of all plants in each plot were recorded . EILs were calculated based on the procedures by Pedigo (１９８６) as EIL ＝C/ VIDK .Where C is cost of management , I is injury units per insect , V is market value per unit produce , D is damage per unitinjury , K is proportionate reduction in injury ( K ＝ １ ) . D and I were obtained from the slope of the yield function ( Y ＝ a ＋ bx ) ,where Y ＝ yield ; a ＝ a constant ( intercept) ; b ＝ loss per insect insect ; and x ＝ number of insects per cage , so EIL ＝ C/Vbk .Results The yield loss and O . asiaticus relationship gave a positive linear yield function as presented in Table １ . The yield lossranged from ０ .００３９ to ０ .００４２ kg per insect . The EIL as influenced by different O . asiaticus infestation levels during the ２growing years averaged ９ .５ grasshoppers per meter square ( Table １ ) .Table 1 O . asiaticu y ield loss f unction and EILs on grass .Years Equation R２  Loss ( kg ) per insect EIL per insect２００５２００６ �Y ＝ ０ 噰.０００３x ＋ ０ .００７３Y ＝ ０ .０００２x ＋ ０ .００３５０ 墘.９３倡倡０ .８９倡倡０ Ζ.００３９０ .００４２９ $.２９ .８倡倡 p ＜ ０ .０１Conclusions The determination of the EIL of O . asiaticu is warranted in this study . A density of O . asiaticus ９ .５ per metersquare causes economic injury damage . The action threshold was set at ９ .５ per meter square , a population density at whichinsecticide application is justified so as to prevent further increasing density from causing economic damage . Furtherinvestigations should be done to validate these threshold levels at farmer level . These EILs also should be examined on differentvarieties of grass to minimize the cost of control to the farmer .ReferencesLu , H . , Yu , M . , Zhang , L .S . , et al . , ２００５ . Effects of foraging by different instar and density of Oedaleus asiaticus B .Bienko on forage yield . Plant Protection , ３１ , ５５‐５８ .Qiu , X .H . , Kang , L . , Li , H .C . , ２００４ . The economic threshold for control of the major species of grasshoppers on InnerMongolian rangeland . Entomologia Sinica , ４７ , ３５３‐３６４ .

Determination of Damage Yield Loss Relationships and Economic Injury Levels of \u3ci\u3eOedaleus asiaticus\u3c/i\u3e (Orthoptera: Acrididae) in Steppe of China

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Determination of Damage Yield Loss Relationships and Economic Injury Levels of \u3ci\u3eOedaleus asiaticus\u3c/i\u3e (Orthoptera: Acrididae) in Steppe of China

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