Native And Exotic Insect Borers Are Important Crop Pests .
ENY-730Native and Exotic Insect Borers Are Important CropPests in the U.S.1Daniel L. Frank and Russell F. Mizell, III2IntroductionInsect borers attack a wide range of agricultural, ornamental, landscape, and forest trees. Concerns are growingthroughout the United States for the economic and aesthetic damages caused by these insects. Woodboring insectsare particularly problematic because injury is not generallynoticed until extensive damage has occurred, which makeseffective management of these pests difficult. Relatively littleis known about the general biology and behavior of manyspecies of insect borers. In addition, comparatively littleresearch has been conducted on the relationships betweenwoodborers and host plants.While a few very destructive exotic species (Table 1) arereceiving a great deal of national attention, hundreds ofnative woodboring insects that are responsible for millionsof dollars of damage and cost of controls each year arereceiving little attention (Table 2). This can be partiallyattributed to the cryptic nature of most insect borer pests.Infestations are usually overlooked until sizeable damagehas occurred. Once damage has been assessed, chemical ormechanical means of control are most often used to manageborer problems. As the amount of damage from theseinsects increases, so must our knowledge of the ecologicalinteractions between insect borers and their hosts. Effectivecontrol can usually only be achieved if management occursbefore significant damage has taken place.DiversityWoodborers are a diverse and important group. Thediversity of these insects spans four taxonomic orders, andover 20 families. In order of importance, Coleoptera, Lepidoptera, Hymenoptera, and Diptera are the insect orderscontaining most borers. Important families include themetallic woodboring beetles, longhorned beetles, bark, andambrosia beetles (Coleoptera), and the clearwing moths(Lepidoptera), to name only a few. The sheer taxomonic,ecological, and morphological diversity of woodboringinsects is astounding. Thousands of North Americanspecies have been named. An wide variety of host plants aresusceptible to their attack.BuprestidaeMetallic wood borers, or flat-headed borers, get theirname from the distinctive metallic colors shown by adults(Figure 1). Adult beetles have a flattened appearance andare generally hard-bodied with short antennae. Larvae arelegless with flattened body segments just behind the head.Important species within this family include the nativebronze birch borer, Agrilus anxius Gory. An invasive speciesthat has spread through most of the continental UnitedStates where ash is present, the emerald ash borer, Agrilusplanipennis Fairmaire.1. This document is ENY-730, one of a series of the Entomology and Nematology Department, UF/IFAS Extension. Original publication date April 2006.Revised August 2006. Reviewed July 2020. Visit the EDIS website at https://edis.ifas.ufl.edu for the currently supported version of this publication. Thisdocument is also available on the Featured Creatures website at http://entnemdept.ifas.ufl.edu/creatures/.2. Daniel L. Frank, graduate student; and Russell F. Mizell, III, professor, Entomology and Nematology Department, North Florida Research and EducationCenter; UF/IFAS Extension, Gainesville, FL 32611.The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other servicesonly to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status,national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county’s UF/IFAS Extension office.U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of CountyCommissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.
landscape pests. Some scolytids transmit fungal diseases toplants. For example, the European elm bark beetle, Scolytusmultistriatus (Marsham), is the carrier of the fungal pathogen that causes Dutch elm disease. Other important speciesinclude the native southern pine beetle, Dendroctonusfrontalis Zimmermann, the shothole borer, Scolytus rugulosus (Mueller), and the exotic granulate ambrosia beetle,Xylosandrus crassiusculus (Motschulsky).Figure 1. Buprestidae adult, Buprestis lineata.CerambycidaeLonghorned beetles, or round-headed borers, are a largeand diverse family of insect borers. Adult beetles get theirname from the characteristically long antennae found onmost species (Figure 2). Larvae generally have three pairsof small thoracic legs. Important species within this familyinclude the redheaded ash borer, Neoclytus acuminatus(Fabricius), the twig girdlers, Oncideres species, and theexotic Asian longhorned beetle, Anoplophora glabripennis(Motschulsky).Figure 3. Scolytidae adult, Ips. spp.SesiidaeClearwing moths are easily recognized by the transparentareas that make up the wings (Figure 4). Most adultmoths are day fliers and wasp-like in appearance. Larvaehave three pairs of thoracic legs in addition to abdominalpro-legs. Important species include the peach tree borer,Synanthedon exitiosa (Say), lesser peach tree borer, Synanthedon pictipes (Grote and Robinson), and the dogwoodborer, Synanthedon scitula (Harris).Figure 2. Cerambycidae adult, locust borer, Megacyllene robiniae.Curculionidae, ScolytinaeThe subfamily Scolytinae within the Curculionidae cangenerally be broken down into two groups, the bark beetlesand ambrosia beetles. Members of both groups are smallreddish-brown to black insects (Figure 3). Larvae are leglessand very small. Bark beetles are important forest pests,while ambrosia beetles are predominantly nursery andNative and Exotic Insect Borers Are Important Crop Pests in the U.S.Figure 4. The peachtree borer, Synnanthedon exitiosa.2
DamageWoodborers can be broken down into two generalcategories based on the condition of the larval host plant atthe time of colonization. These categories include primaryinvaders, which attack apparently healthy trees, andsecondary invaders, which attack stressed, dying, or deadtrees. Many woodboring insects feed on subcortical tissues,which consist primarily of the inner bark, phloem, andimmature xylem of host trees (Figure 5). In addition, thebark, sapwood, heartwood, and pith may also be fed uponto a lesser extent. Fungal hyphae in the plant and cellulosedigesting enzymes in the insect may also be utilized to assistin nutrient assimilation of nutrient-poor host tissue.holes. Noticeable, also, may be vertically split bark createdby larval feeding galleries. Over time, foliage may wiltand the tree canopy may become increasingly sparse asbranches die. Epicormic shoots, adventitious branches onthe lower trunk, may also arise on the trunk of trees at themargin of living and dead tissue. Under intense pressure,the tree will eventually die.Economic damage associated with insect borers remainsan important issue of concern to many growers throughoutthe country. The damage caused by these pests can includedrastic decreases in the number of fruit and nut bearingbranches in orchards and groves, stunted and deformedtrees within hardwood plantations, and aesthetic damage toornamental and landscape trees and shrubs. In some cases,these pests have destroyed entire forests, urban landscapes,plantations, and orchards. Current research involvingthese insects has focused predominantly on forest andexotic woodboring species. Comparatively little researchis conducted on woodboring pests that affect fruit and nutcrops, which are multi-billion dollar industries. Rising costsassociated with preventing insect borer related problems,combined with cheaper imports, have threatened theproduction and value of many US fruit and nut crops.Unfortunately, the cryptic habits of insect borers havehindered efforts to document their activity and develop appropriate management methods. Much of the informationon insect borers is widely scattered and found in older, lessaccessible literature. In addition, research on insect borersis commonly restricted to very few pest species.Figure 5. Damage of the pechtree borer larvae, S. exitiosa.Plant Defenses and Borer InfestationsThe larvae of insect borers cause extensive galleries, ortunnels, that can run throughout the vascular tissue ofhost trees. These galleries grow larger as the larvae mature.Woodborer damage can consist of the girdling and destruction of vascular plant tissue, weakening of trunks andbranches as well as the creation of wounds that allow entryof diseases. Many adult borers will also feed on foliage,needles, stems and shoots, floral resources, or seeping sapof host trees creating further damage.Healthy, vigorously-growing trees often have very efficientmechanisms to prevent woodborer infestations. Forinstance, proper sap flow can be a good deterrent to manyborer pests by preventing them from tunneling into thevascular tissue. Wound induced callus tissue, or periderm,can also act as a mechanism for borer resistance. Callustissue is produced by a plant as developing larvae tunnelthrough the vascular tissue. The tissue encapsulates larvaeand prevents borer development by starving or crushingthem. In addition, the high moisture content of bark andsecondary plant chemicals such as resins may also play arole in host plant resistance.It is often difficult to detect woodborers in newly infestedtrees. Damage is usually not seen until after at least a year,when exit holes created by adults are visible on the branchesand trunks of host trees. Holes are generally round, oval,or semicircular and are found in a random pattern on theplant. Gum will often form as the sap exudes and hardensover the entrance to the gallery while in other plant speciessawdust-like frass is associated with the entrance or exitNative and Exotic Insect Borers Are Important Crop Pests in the U.S.Stressed trees are generally thought to be more susceptibleto woodborer attack because their defense mechanismsare weakened. Research has shown that resistance to larvalborers vanishes as callus formation slows. If the borerlarvae move faster through the vascular tissue than callus3
formation, then the larvae may live to complete development. Strong defense responses are dependant on propercarbon translocation from the tree canopy to the trunk.If severe drought or defoliation stress occurs, it can limitthe amount of carbon translocation and have detrimentaleffects on plant defense responses.These include the Japanese beetle, pine shoot beetle, Asianlonghorned beetle, emerald ash borer, and gypsy moth.Unfortunately, despite quarantine efforts, damage fromthese pests and other insect borers remains high. Exoticinsect borers, along with native North American borers, arechanging the landscape across the country.Although tree stress caused by factors such as drought,poor soil quality, or reduced light can reduce or weakenplant responses to insect borers, evidence has shown thateven unstressed host trees can be susceptible to certainwoodboring insects. Stress may have no effect on resistanceif trees are inherently susceptible to a particular insect borerspecies. Tree species with no co-evolutionary history withan associated insect borer can be extremely susceptibleto attack, as no host resistance genes exist. In some cases,cultural practices such as pruning, fertilizer, soil compaction and improper irrigation regimes increase susceptibilityby making trees more attractive to borers.Major sources for exotic borer introductions includepallets, spools, crating, and dunnage that enter the countrydaily. To a lesser extent, the transportation of seeds andplant cuttings, in addition to the nursery trade, have alsobeen important pathways. Millions of containers are usedin transporting these commodities to the United Statesevery year. Potential for introduction arises because thesecontainers are typically not opened until they reach theirfinal destinations. This problem is further compounded bythe fact that only 2–4 percent of these containers enteringthe country are ever inspected.Despite our current knowledge of woodborer behavior, it isoften difficult to identify the initial condition of larval hostplants because researchers rarely have the opportunity toassess plant conditions prior to discovering that the planthas come under attack. The diversity in the condition oflarval host plants at the time of colonization has led Hanks(1999) to categorize woodboring insects according tospecific aggression levels. These categories include speciesthat attack healthy hosts, weakened hosts, stressed hosts, ordead hosts.Unfortunately, general patterns between borer species andhosts remain unresolved, the function of resistance genesis unclear, and the mechanisms by which one borer speciessucceeds and another fails requires further investigation.In addition, many species initially considered to attackhost trees in any state of health have been found to restricttheir attacks to hosts of a particular condition. Onlywith a greater understanding of the complexities of theinteractions between borer and host can efficient control beaccomplished.Exotic Borer PestsAs our economy and current trade practices becomeincreasingly global, so does the potential for more damageby these insects. By conservative estimates, over 2,000exotic insects are now in the United States, with over 400 ofthem feeding on woody plants. Almost every tree genus inthe United States has at least one exotic insect, with somehaving more than 40. Currently, only five of the 400 exoticwoody plant pests are now regulated by federal quarantine.Native and Exotic Insect Borers Are Important Crop Pests in the U.S.Since 1992, at least fourteen new exotic woodborers havebecome established in the United States. These insects firstappeared in 12 states located throughout the country, andsince 2004 have spread to 37 states. Despite preventivemeasures, these insects have continued to enter the countryand cause damage. These pests only add to managementproblems related to native woodborers that continue tocause serious losses in a variety of crops.ManagementInsect Borer Management Practices insect borer management practices involve several tactics and strategies that areused collectively as an integrated approach to pest management (IPM). Insect borer IPM practices are multifold andinvolve several techniques that may be used depending onthe type of borer pest and the host plant. Although thesemanagement practices can be effective when used alone,collectively they are much more efficient in combatingmany borer species.Monitoring. The first step in managing any pest speciesbegins with a proper monitoring program. Efficientmonitoring tools are essential for accurate and cost effectivemanagement programs. A number of methods have beendeveloped to monitor woodboring pest species. Commonmonitoring tools include sticky traps, funnel traps, pyramidtraps, and circle traps. Traps capture borers by exploitingtheir behavioral and physiological responses to color, trapplacement and design, and pheromones. Pheromone luresare often the best method for attracting woodborer speciesbecause they are species and sex specific. However, research4
involving these lures has been restricted to only a few majorwoodboring pest species.Mechanical Control. Removing and destroying infested,dying, or dead plants and plant parts can often be the bestdefense for current and future infestations. If infestationnumbers are low, direct removal of larvae from trees using aknife or metal hook can be a potential option for control.Chemical Control. Chemical control is the most commonpreventative measure for insect borer infestations. However,very few effective pesticides have been registered for useagainst woodborers, and many of the older chemicals havebeen discontinued. Often only newly transplanted trees andshrubs or high value ornamental and landscape trees justifythe cost of using chemical management. Most insecticidesregistered for woodborer control are residual insecticides,which are applied as sprays to trunks and branches of hosttrees. These insecticides work by killing adult and earlylarval stages that tunnel through the treated bark layer.Another chemical control method is trunk injection, whichdelivers insecticide into the cambium and phloem tissueswhere insect borers feed. However, research has shown thatthe damage caused by inserting the injection devices intotrunks can significantly harm the host tree, and in somecases have even attracted pest species to the treated area.Biological Control. Biological control is currently alittle-used management practice for insect borers. Naturalenemies have often been overlooked as a suitable controlmethod because very little is known about these organismsin relation to insect borers. In addition, borer damage tendsto occur before most natural enemies can effectively suppress these pests. However, entomopathogenic nematodeshave been used with some success. Continuing researchinvolving these organisms has shown promise for futureborer management.Prevention. Borer populations are often limited byenvironmental conditions and food (i.e., host plants inthe proper condition). Environmental factors that causeperiodic outbreaks, such as adverse weather conditions,are often uncontrollable. However, recognizing tree, stand,and landscape factors that predispose a plant to woodborerinfestations is the first step in a prevention program.The vast majority of woodboring insects are consideredsecondary invaders. Good horticultural and/or silviculturalpractices that keep trees healthy are often the best defenseagainst these pests. Appropriate care of trees and shrubscan discourage many borer pests, and can even helpinfested plants survive. Any activity that can reduce treeNative and Exotic Insect Borers Are Important Crop Pests in the U.S.stress can potentially be an effective measure for control.These activities can include: avoiding injury to trunks andbranches, proper site selection of host plants, selection ofwell-adapted host species to a given area, proper wateringand fertilization regimes, and proper care of injuredplants. Other activities such as trunk wrapping to preventmechanical injury have shown mixed results, and in somecases have actually promoted infestation. For instance,damage from outbreaks of southern pine beetle, a severepest of conifers in the southeast, can be minimized ifproper silvicultural practices are conducted. Research andexperience have shown that pine forests that are eitherovercrowded, overmature, or located on poorly drainedbottomland soils are more likely to suffer from southernpine beetle infestations.ConclusionRelative to other better-known insect pests, very fewtools are available for management of woodborers. Manysuppression tactics used for managing insect borers can betime consuming, expensive, or environmentally unfriendly.In many cases there is no guarantee that these tactics willbe effective against woodborer attack. Unfortunately, ourknowledge of the basic biology of many insect borers islimited. In addition, monitoring and sampling of manyborer pests is inefficient, or simply not conducted forpreventative management to take place. Current controltactics are useful to limit the damage that occurs frominsect borer infestations. However, continued research anda greater understanding of the biology of these pests is vitalbefore effective management can occur.Preventative measures such as proper horticulturalpractices and removal of infested, dying, or dead plants andplant parts are a simple but effective step for controllingmany borer pests. Although chemical methods of controlcan be expensive and environmentally unfriendly, propersteps can be taken to reduce their costs and damage tothe environment. Proper timing of chemical treatmentsto match the phenology of insect borers and their hosts aswell as minimizing the amount of drift that occurs duringspraying are both key factors that should be consideredbefore insecticide application occurs. Further researchinvolving reduced-risk insecticides and biological controlmust also be investigated as a means for reducing environmental concern and management costs. Additionally,simple actions such as restricting firewood transport acrosspotential infestation sites, or identifying and reportingborer species of concern, can be successful to reduce thespread and severity of insect borer damage.5
Once the mechanisms accounting for insect borer and hostresponses are known, their responses will become morepredictable allowing current management strategies to berefined and integrated to enhance their effectiveness andacceptance in future management programs. Currently,very little research has been done on many important insectborers and their relationships with their hosts. Withoutfurther research and information, future infestations anddamage will occur and may change our landscape forever.Further ReadingAllison, J., J. Borden and S. Seybold. A review of thechemical ecology of the Cerambycidae (Coleoptera).Chemoecology 14:123-150.Brown, L. N. and R. F. Mizell, III. 1993. The clearwingborers of Florida. Trop. Lepid. 4. Supplement 4. 21 pp.Drooz, A. T. 1985. Insects of eastern forests. USDA For.Serv. Misc. Pub. 1426. Washington, D.C.Hanks, L. M. 1999. Influence of the larval host plant onreproductive strategies of cerambycid beetles. Annu. Rev.Entomol. 44: 483-505.Solomon, J. 1995. Guide to insect borers in north Americanbroadleaf trees and shrubs. USDA-FS Agric. HandbookAH-706. 735 pp.Native and Exotic Insect Borers Are Important Crop Pests in the U.S.6
Table 1. Some exotic woodborers of economic importance.FamilySpeciesHost or Crop InfestedBuprestidaeAgrilus planipennisAshCerambycidaeAnoplophora glabripennisHardwoodsScolytidaeXylosandrus crassiusculusHardwoodsX. mutilatusHardwoodsTomicus piniperdaConifersTable 2. Some native woodborers of economic SesiidaeSpeciesHost or Crop InfestedAgrilus anxiusBirchAgrilus politusWillow, MapleAgrilus sayiBayberry, SweetfernAgrilus vittaticolllisApple, Pear, Cranberry, Serviceberry, HawthornChrysobothris femorataApple, Apricot, Beech, Boxelder, Cherry, Chestnut, Currant, Elm, Hawthorn,Hackberry, Hickory, Horsechestnut, Linden, Maple, Mountain-ash, Oak, Pecan, Pear,Peach, Persimmon, Plum, Poplar, Quince, Redbud, Serviceberry, Sycamore, Walnut,WillowTexania campestrisBasswood, Beech, Maple, Oak, Sycamore, Willow, Yellow-poplarGoes pulverulentusBeech, Elm, Nuttall, Willow, Black oak, Cherrybark oak, Water oak, SycamoreGoes tigrinusOakNeoclytus acuminatusAsh, Hickory, Oak, Walnut, Birch, Beech, Maple, Eastern hophornbeam, Dogwood,Persimmon, Redbud, Holly, Hackberry, Black locust, Honeylocust, Yellow-poplar,Chestnut, Osage-orange, Sassafras, Lilac, Mountain-mahogany, Pear, Cherry, Plum,Peach, Apple, Elm, Basswood, SweetgumNeoptychodes trilineatusFig, Alder, Mulberry, Willow, Netleaf hackberryOberea ocellataSumac, Apple, Peach, Plum, Pear, Currant, BlackberryOberea tripunctataDogwood, Viburnum, Elm, Sourwood, Blueberry, Rhododendron, Azalea, Laurel,Poplar, Willow, MulberryOncideres cingulataHickory, Pecan, Persimmon, Elm, Sourwood, Basswood, Honeylocust, Dogwood,Eucalyptus, Oak, Hackberry, Maple, Fruit treesSaperda calcarataPoplarStrophiona nitensChestnut, Oak, Hickory, Walnut, Beech, MapleCorthylus columbianusMaple, Oak, Yellow-poplar, Beech, Boxelder, Sycamore, Birch, Basswood, Chestnut,ElmDendroctonus frontalisPineDryocoetes betulaeBirch, Sweetgum, Wild cherry, Beech, PearMonarthrum fasciatumOak, Maple, Birch, Chestnut, Sweetgum, Blackgum, Poplar, Hickory, Mimosa, Apple,Peach, PinePhloeotribus liminarisPeach, Cherry, Plum, Black cherry, Elm, Mulberry, Mountain-ashPseudopityophthorus pruinosusOak, American beech, Black cherry, Chickasaw plum, Chestnut, Maple, Hickory,Hornbeam, HophornbeamParanthrene simulansOak, American chestnutSannina uroceriformisPersimmonSynanthedon exitiosaPeach, Plum, Nectarine, Cherry, Apricot, Almond, Black cherrySynanthedon pictipesPeach, Plum, Cherry, Beach, Black CherrySynanthedon rubrofasciaTupeloSynanthedon scitulaDogwood, Pecan, Hickory, Oak, Chestnut, Beech, Birch, Black cherry, Elm,Mountain-ash, Viburnum, Willow, Apple, Loquat, Ninebark, BayberryVitacea polistiformisGrapeNative and Exotic Insect Borers Are Important Crop Pests in the U.S.7
borers vanishes as callus formation slows. If the borer larvae move faster through the vascular tissue than callus Figure 5. Damage of the pechtree borer larvae, S. exitiosa. Native and Exotic Insect Borers Are Important Crop Pests in the U.S. 4 formation, then the larvae may live to complete develop-
ofTrees and Shrubs B-5086 01-08 Bastiaan M. Drees, John A. Jackman and Michael E. Merchant* M any insects feed and make their homes in the bark, trunks and branches of shade trees and shrubs in Texas. Insect borers belong to several different insect groups including a variety of beetles, moths and horntail wasps. Most insect borers are .
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IP-13 IPM for Home Gardens—Insect ID and Control CTAHR — July 2003 . Insect identification . If you have an insect problem, you need to know what insect pest you are dealing with and what stage of the insect’s life cycle is the most likely to cause damage, as well as the stage most susceptible to control measures. General insect information
Increment Borer ’SUUNTO’ Extraction of core samples SUUNTO Increment Borers are used for measuring the growth rate of a standing tree and for checking the quality of wood. Increment Borers are made of special steel (teflon coated). This Increment Borer consists of three parts: 1. Handle 2. Bit 3. Extracteur Increments Borers are used for
Insect orders are groups of insects with a common descent that are similar in body structure, type of wings, type of mouthparts, etc., and to some extent, in habits. With approximately 1,000,000 different insect species, it is impossible to become familiar with more than a small percentage of them. A fundamental step in insect identification is
Invasive Exotic Plant - An aggressive plant that is known to displace native plant species. Invasive exotic species are unwanted plants which are harmful or destructive to man or other organisms (Holmes, 1979; Webster). State Listed Noxious Weeds – Invasive exotic plants prohibited or restricted by Colorado Law.
QUICK FACTS Provides 12-Month Insect Protection Will Not Harm Trees & Shrubs Easy-to-Use . . . Mix in Water and Pour Around Tree/Shrub Adelgids, Aphids, Bronze Birch Borers, Emerald Ash Borers, Leafminers, Scale and other listed pests Trees: 1/2 ounce per inch of distance around trunk Shrubs: 11/2 ounces per foot of height Once a .
I am My Brother’s Keeper (2004) As our New Year’s celebration draws near, I once again find myself pondering the enigmatic story that our tradition places before us at this time—the story of the Binding of Isaac. Once again, I walk for those three long days with father Abraham and ponder the meaning of his journey with his son to the mountain. And once again, I find fresh meaning in the .
