Metapopulationapproachforlandscapelevelmanagementofwesterntarnishedplantbug,Lygushesperus,inTexas(Hemiptera,Miridae)

Insectsource-sinkdynamicsarevitaltoecologicallyintensivepestmanagement.Maintainingsinkplanthosts,or"trapcrops",anddestroyingalternatehostsorbreedingplacesadjacenttothefieldcropareeffectivepestmanagementstrategiesforsomearthropods.However,determiningwhetherahostactsasasourceorasinkischallenging,especiallywhenthepestspeciesishighlymobileandpolyphagous.Thewesterntarnishedplantbug,Lygushesperus,ishighlypolyphagous,andcanutilize>300hosts.Itspresencehasbeendocumentedin26roadsideweedhostsintheTexasHighPlains.PreviousstudiesdemonstratedthatL.hesperuspreferalfalfaovercottonandseveralalternateweedhosts.Afour-yearprojectinvolvedsurveyingandsamplingforL.hesperusintheagriculturallandscapesofseveralsub-regionsofthesouthwesternUnitedStates,includingtheTexasHighPlains.InTexas,geographicinformationofthelandscapevegetationcomplexwascompiledfroma150kmradiusintheTexasHighPlains.Inonestudy,fiftyirrigatedcottonfieldsrepresentingthecropdiversitywithinthisregionweresampledviasweep-netfor10weeks.Thiseffortalsoincludedsamplingofuptosixnon-cottoninsecthabitatswithina3kmradiusofeachfield.SeasonalaverageL.hesperusabundancedatawereregressedwith27fieldcharacteristics(variables),includinghabitat-specificlandcover,distancebetweenfocalcottonfieldsandnon-cottonhabitats,longitude,latitude,elevation,habitatheterogeneityindex,andseveralenvironmental/ecologicalvariables.Significantvariableswereselectedusingastepwiseregressionat15%probabilityrate.A10-parameterlinearmodelexplained93%ofthevariationinthedata.MajorparameterscontributingsignificantlytovariationinL.hesperusabundanceincottonwerecornandsunfloweracreages,focalcottonfielddistancesfromseveralnon-cottonhosts,andhabitatheterogeneityindex.Inaddition,fieldmarking-and-capturestudieswereconductedusingproteinmarkersandenzyme-linkedimmunosorbentassaystocharacterizeL.hesperusintercropmovementbehavior.Thefieldmarking-and-captureapproachcanbeusedtostudytheeffectsofvariouscropmanagementpracticesonL.hesperusintercropmovementandcanpotentiallybeappliedtootherpestsandcroppingsystems.