Range of host plants, spatial distribution, and insect predator of Phenacoccus manihoti (Hemiptera, Pseudococcidae) as an emerging pest of cassava plants in Bali, Indonesia

Abstract.SuparthaIW,WidaningsihD,SusilaIW,YudhaIKW,UtamaIWEK,WiradanaPA.2022.Rangeofhostplants,spatial distribution,andinsectpredatorofPhenacoccus manihoti (Hemiptera:Pseudococcidae)asanemergingpestofcassavaplantsinBali.Biodiversitas23:3022-3030. ThecassavamealybugPhenacoccusmanihoti(Hemiptera:Pseudococcidae)isaverydestructivepestincassavafarminginIndonesia.TheinsecthasalreadymadeitswayintoIndonesia,whereithasattackedcassavaplantswithindicationsofabunchytop,whichmaycauseplantdeath.Theobjectivesofthisstudywereto1)discoverandidentifyaninvasivepestofcassavamealybugpest, P.manihoti,thatattackscassavaplantsinBali; 2)mapthedistributionandabundanceofthesepestspeciespopulationsoncassavaplantsinBali; 3)describethestructureofthepestpopulationincassavaplantationsinBali; 4)identifythedominantfactorsthatinfluencethepopulationstructureofP.manihotiinBali,and5)evaluatethepredatorfaunainregulatingthepopulation.ThefindingsrevealedthatthemealybugspeciesthatattackedcassavainBaliwasP.manihoti,anexoticspeciesthathadneverbeenpublishedearlier.Withahighpopulationabundance,thepesthasspreadfarandeffectivelyoverallinregencies/citiesinBaliProvince.Inallregency/cityregions,thepopulationstructureofP.manihotiwasdominatedbyagegroupsofinstar-1andtwonymphs,withtheexceptionoftheBulelengRegency,whichwasdominatedbyagegroupsofnymphsinstar 3and4.Thenatureofpolyphagyandcosmopolitefeaturesthatarereadilyadaptabletotheenvironmentandhostplantvariables,farmingpattern,temperatureandrainfallfactorswerethekeyfactorsimpactingthepopulationstructureofP.manihotiinthefield.Cryptolaemusmontrouzieri,Chrysoperlacarnea,andScymnussp.werediscoveredtohavearoleinmanagingP.manihotipopulationsinthefield.Thepredatorfaunacommunityisstructurallydiverse,abundant,andhasalowdominance.Cryptolaemus montrouzieriwasthemostdominantofthethreeproducerspeciesinthefield.Theseresultsindicatethatthereisapositivepotentialshownbypredatorymealybugsinthefieldandcanbeusedasaninitialmodelbyrelatedpartiesinformulatingpoliciesrelatedtocontrollinginsect pests of cassava plants.Keywords:Biocontrol,biologicalparameters, insectpredator, integratedpestmanagement,invasivepestINTRODUCTIONIndonesiaisthefourthlargestcassava(Manihotesculenta)producer in the world after Brazil, Nigeria and Thailand (Supatmi 2017; Yi etal.2019).CassavaproductioninIndonesiahasfluctuated,whichdecreasedfrom2010to2015(BPS 2018).One of the factors that caused the fluctuation and decline in production was the disturbance of pests and diseases (Velásquez et al. 2018; Armengot et al. 2020; Skendži? et al. 2021). Several types of diseases that attack cassava in Asia are bacterial blight or cassava bacterial blight (CBB) caused by Xanthomonas campestrispv. manihoti, cassava mosaic disease (CMD) virus, and cassava brown streakdisease (CBSD) (Amer 2017). Meanwhile, the main types of pests, which being the problem in cassava cultivation in Asia are whiteflies (Bemisia tabaci), mealybugs (Phenacoccus manihoti) and red spider mites (Tetranychus urticae) (Parsa et al. 2012; Graziosi et al. 2018). The presenceofmealybugasanimportantpestoncassavaisfurtherreportedtodamagecassavainseveralAfricanandSouthAmericancountries(Adegbite et al. 2021; Eni et al. 2021). The mealybug Phenacoccus sp. (Hemiptera: Pseudococcidae) is the most frequent insect that causes damage to cassava in both countries (Sartiami et al. 2015).Phenacoccus manihotiMatile-Ferreroisthemostharmful pest on cassava in many countries in the world (Yonow et al. 2017; Joshi et al. 2020; Venkatesan et al. 2021). This pest can damage plants directly by sucking the fluids and poisoningtheplantswiththeirsaliva (Bellotti et al. 1999; Barilli et al. 2014). As a result,thecassavadevelopsbunchytopoftheleavesandthiscanresultinthedeathoftheplants (Maruthi et al. 2019; Shirima et al. 2019). This insect is an invasive pest that has entered Indonesia and spread in several areas, especially in Bali Province (Supartha et al.2020).TheentryofthispestintoBaliprovinceisstronglysuspectedthroughthedistributionofornamentalplantsfromotherprovincesorabroad(Hamid et al. 2018; Supartha et al.2022).Theobservationalresultsshowthatasimilarsymptomhasbeen