RELATIVE SUSCEPTIBILITY OF WOODY LANDSCAPE PLANTS TO JAPANESE BEETLE (COLEOPTERA: SCARABAEIDAE)

RELATIVE SUSCEPTIBILITY OF WOODY LANDSCAPE PLANTS TO JAPANESE BEETLE (COLEOPTERA: SCARABAEIDAE)

By David W. Held

Abstract. The Japanese beetle (Popillia japonica Newman) was introduced to a New Jersey nursery in 1916 and continues to spread across the United States and Canada. Adults attack foliage, flowers, and fruit of more than 300 species of plants; however, some plants are notably resistant. This paper summarizes data on plant susceptibility of woody plants to Japanese beetles collected from observations and controlled experiments. Resistance to Japanese beetle has been documented among species of maples (Acer) and birch (Betula) and among cultivars of crabapple (Malus), crapemyrtle (Lagerstroemia), and linden (Tilia). Production of certain plant odors, presence of secondary compounds in leaves, and leaf pubescence are factors affecting resistance to this insect. Host plant resistance is the most sustainable means of managing feeding damage or plant losses resulting from Japanese beetle adults. When suitable, incorporating Japanese beetle­resistant plants into new landscapes can reduce or eliminate the expense of replacing damaged plants or frequent insecticide applications.

Key Words. Popillia japonica; Japanese beetle; integrated pest management; host plant resistance.

The Japanese beetle (Popillia japonica Newman) is one of the most damaging pests of urban landscapes in the eastern United States. Yearly costs for management and mitigation of damage are estimated at US$500 million (USDA/APHIS 2002). This scarab was introduced in 1916 to the eastern United States in infested nursery stock (Fleming 1972). At that time, entomologists were unaware of the pernicious nature of this species as evidenced from this quote, "While inspecting a nursery in southern New Jersey during August 1916, our attention was attracted by a scarabaeid feeding on the tips of Crataegus. Inasmuch as it was assumed to be a southern species, no particular attention to it was paid at that time" (Dickerson and Weiss 1918). In the presence of abundant grass and pasture land, and the apparent absence of natural enemies, the Japanese beetle flourished. Currently, this immigrant species partially infests or is established in all states east of the Mississippi River except Florida, and its range extends north into Canada (NAPIS 2003).

Adult Japanese beetles are broadly oval, 8 to 11 mm (about 0.5 in.) long, metallic green in color and have coppery-brown wing covers. Larvae are typical white grubs, C-shaped and cream colored, with three pairs of legs and a light-brown head capsule (Fleming 1972). Japanese beetle has a 1-year life cycle, spending most of its life underground as a grub. A small grub, about 1.5 mm (0.06 in.) long, emerges from an egg laid 3 to 5 cm (1 to 2 in.) deep into moist soil, typically under turfgrass. Females alternate between periods of feeding and mating on host plants and oviposition. During her lifetime, a female will have 12 or more egg-laying bouts and produce 40 to 60 eggs. Once hatched, grubs feed on roots and will reach full size, about 32 mm (1.25 in.) long, by late summer (Fleming 1972). Management of grubs is accomplished with soil insecticides applied preventively (e.g., Merit or Mach2) before egg hatch, or curatively (e.g., Dylox or Sevin) after small grubs are present. Presence of grubs or grub damage may be associated with nearby plants infested with adults; however, females will disperse to find a suitable site for oviposition (Fleming 1972; Potter and Held 2002).

Japanese beetle adults are active from June through August in most of its geographic range. These beetles are day active and mate and feed concurrently on host plants. They can defoliate more than 300 species of woody and herbaceous plants in 79 plant families (Fleming 1972; Potter and Held 2002). Because of their mobility and gregarious habits, swarms of Japanese beetle continually infest and defoliate new plants during the growing season. These factors can complicate control of adults, especially when using short-residual insecticides such as pyrethroids. Certain systemic products delivered through soil or trunk injection are available for control of Japanese beetles on mature, established street and residential trees; however, that treatment may not be an option for newly installed landscape plantings.

Use of insecticides to manage Japanese beetle can be reduced if resistant plants are substituted for more susceptible ones in commercial and residential landscapes. Observations and controlled experiments indicate that certain plant species, and even cultivars of the same species, vary in susceptibility. For example, moderate or complete resistance to Japanese beetle feeding is documented for most evergreens, certain crabapples (Malus), lindens (Tilia), maples (Acer), birch (Betula), and crapemyrtles (Lagerstroemia) (Fleming 1972; Ranney and Walgenbach 1992; Spicer et al. 1995; Potter et al. 1998; Miller and Ware 1999; Pettis et al. 2004). There is no resistance to Japanese beetle among species or cultivars of rose (Rosa) (Potter et al. 1998; Held and Potter 2004).

Most of the information on host susceptibility to Japanese beetle originated from a landmark survey summarized by W.E. Fleming (1972). This publication has since gone out of print; however, the information remains relevant to urban horticulture because of the continued spread of Japanese beetles into the United States and Canada. In his review, Fleming (1972) established a damage rating system based on observations of plant damage noted for each plant species in his listing. This rating system is qualitative and assigns a relative rank to each species based on written and oral accounts of Japanese beetle feeding damage noted from 1920 through 1963, primarily in the New England area (Fleming 1972).

Additional laboratory and field evaluations of Japanese beetle susceptibility for certain horticulturally important taxa have been further investigated by contemporaries of Fleming. These subsequent studies compared the percentage of defoliation of field- or container-grown plants in a common garden type of experiment (e.g., Potter et al. 1998). Blocks of woody plants representing replicates of each cultivar or species were subject to defoliation by natural beetle populations during one or more years. Additional laboratory or controlled field experiments were also used to verify the results of field tests for crabapple (Ranney and Walgenbach 1992; Spicer et al. 1995), crapemyrtle (Pettis et al. 2004), and linden (Miller and Ware 1999). Besides the field observations on Ulmus procera, U. rubra, and U. americana in Fleming (1972), susceptibility of elm species is based on laboratory experiments with detached leaves or defoliation of plants caged with beetles (Miller et al. 2001). Discrepancies in seasonal results from multi-year field evaluations have been noted and are attributed to the relative abundance of adults from year to year (Fleming 1972; Potter et al. 1998).

The purpose of this paper is to provide landscape architects, professional landscape managers, and arborists a comprehensive list of woody plants and their relative susceptibility to Japanese beetle. Although the results of these resistance screenings were reported in scientific or extension publications, there has been no single source of host plant data for Japanese beetle since Fleming (1972). This paper has compiled the data from Fleming (1972) and amended it with data from recent experiments to produce a comprehensive record of plant susceptibility to Japanese beetle.

DESCRIPTION OF DATA PRESENTATION

Data are presented in table form, alphabetically by family, then scientific name. Tables 1 and 4 use a rating to indicate susceptibility. This rating is an adaptation of the system used by Fleming (1972). When a plant is designated "resistant," it means observed plants were either never fed on or rarely fed on by Japanese beetles. "*" and "**" indicate plants on which feeding has been observed but is either occasional or light, respectively. "***" and "****" indicate plants that are commonly fed on by Japanese beetle, resulting in either moderate or extensive feeding damage, respectively. Plants with the latter two ratings will likely sustain considerable feeding damage or be completely defoliated if Japanese beetles are present.

Qualitative ratings for Prunus serrulata, P. serotina, and P. virginiana came from Fleming (1972), whereas all others were adapted from field defoliation data (Ranney and Walgenbach 1992). In the only field study with birch (Betula) species and cultivars, defoliation was 1% or less for all nine taxa, except for Himalayan birch (B. jacquemontii), which was 16% (Ranney and Walgenbach 1992). Based on these data, most birch are not preferred hosts (Table 1), except for Himalayan, European white, and gray, of which the latter two were ranked as more susceptible by Fleming (1972).

Tables 2 and 3 summarize resistance among cultivars of crapemyrtles and crabapples from field and laboratory experiments. Susceptibility ratings for crapemyrtle varieties are adapted from susceptibility rankings assigned by Pettis et al. (2004). The qualitative ratings assigned to crabapple cultivars (Table 3) were derived from three evaluations conducted in North Carolina (Ranney and Walgenbach 1992) and Kentucky (Spicer et al 1995; Potter et al. 1998). Relative susceptibility of the 26 cultivars common to both sites was similar (Potter et al. 1998).

Crapemyrtle and crabapple species or cultivars are listed under headings indicating their relative susceptibility. As before, "resistant" indicates that observed plants were rarely fed on. For crabapples, only those with less than 10% defoliation in field studies were assigned to this rating. "Moderately resistant" means that beetle feeding was observed but light. Crabapples ranked as moderately resistant generally sustained 20% to 45% defoliation. Plants designated "moderately susceptible" will have noticeable damage by Japanese beetle corresponding to 50% to 70% defoliation for crabapple varieties. All plants considered "susceptible" will be extensively damaged or completely defoliated by Japanese beetle, equivalent to about 75% to 100% defoliation in the crabapple field studies (Ranney and Walgenbach 1992; Spicer et al 1995; Potter et al. 1998).

Ratings for linden taxa (Table 4) were taken from observations in Fleming (1972), a 3-year field study of eight Tilia spp. in Kentucky (Potter et al. 1998), and Miller and Ware (1999), which combined laboratory feeding assays with leaves or leaf discs, with field defoliation data of 16 genotypes in Illinois. Ratings of linden were determined based on both studies; however, field defoliation data were used over laboratory results if there was any inconsistency between the relative rankings of the same variety.

Table 1. Relative susceptibility of deciduous and evergreen woody trees and shrubs to Japanese beetles.
Scientific nameCommon nameRatingz
Aceracea
Acer negundoBoxelder*
Acer palmatumJapanese maple****
Acer platanoidesNorway maple****
Acer pseudoplatanusSycamore maple**
Acer rubrumRed mapleResistant
Acer saccharinumSilver mapleResistant
Acer saccharumSugar maple**
Anacardiaceae
Cotinus coggygriaSmoketree*
Rhus copallinaFlameleaf sumac**
Rhus typhinaStaghorn sumac*
Aquifoliaceae
Ilex aquifoliumEnglish hollyResistant
Ilex cornutaChinese hollyResistant
Ilex crenataJapanese hollyResistant
Ilex opacaAmerican hollyResistant
Ilex verticillataWinterberry holly*
Berberidaceae
Berberis thunbergiiJapanese barberry**
Betulaceae
Alnus glutinosaBlack alder***
Betula ermaniiErman's birchResistant
Betula jacquemontiiHimalayan birch***
Betula nigra River birch*
Betula nigra 'Heritage'Heritage river birch*
Betula papyriferaPaperbark birchResistant
Betula pendulaEuropean white birch***
Betula platyphylla var. Asian Whitespire birchResistant
japonica 'Whitespire'
Betula platyphyllaAsian Szechuan birchResistant
var. szechuanica
Betula populifoliaGray birch****
Corylus americanaAmerican filbert*
Corylus colurnaTurkish filbert**
Bignoniaceae
Catalpa bignonioidesSouthern catalpa***
Buxaceae
Buxus sempervirens Common boxwoodResistant
Calycanthaceae
Calycanthus floridusCarolina allspiceResistant
Caprifoliaceae
Lonicera fragrantissimaWinter honeysuckleResistant
Lonicera japonicaJapanese honeysuckle*
Sambuscus canadensisAmerican elder*
Symphoricarpos albusSnowberryResistant
Symphoricarpos orbiculatusBuckbrushResistant
Viburnum dentatum Arrowwood***
Viburnum opulusEuropean cranberry bush*
Weigela floridaWeigela**
Celastraceae
Celastrus scandensAmerican bittersweetResistant
Euonymus alatus Burning bush*
Euonymus fortuneiWintercreeper euonymusResistant
Clethraceae
Clethra alnifoliaSummersweet clethra****y
Cornaceae
Cornus floridaFlowering dogwoodResistant
Scientific nameCommon nameRatingz
Cupressaceae
Chamaecyparis lawsonianaLawson white cedarResistant
Chamaecyparis obtuseHinoki cypressResistant
Chamaecyparis pisiferaSawara cypressResistant
Chamaecyparis thyoidesAtlantic white cedarResistant
Juniperus chinesisChinese juniper*
Juniperus communisCommon juniper*
Thuja occidentalisAmerican arborvitae*
Thuja orientalisOriental arborvitae*
Ebenaceae
Diospyros virginianaCommon persimmon*
Ericaceae
Kalmia latifoliaMountain laurelResistant
Rhododendron catawbienseCatawba rhododendron*
Rhododendron maximumRosebay rhododendron*
Rhododendron pericylmenoidesPinxterbloom azaleaResistant
Rhododendron viscosumSwamp azalea*
Fabaceae
Albizia julibrissinMimosaResistant
Cercis canadensisEastern redbudResistant
Cercis chinensisChinese redbudResistant
Robinia pseudoacaciaBlack locust*
Sophora japonicaJapanese pagoda tree*
Wisteria sinensisChinese wisteria***
Fagaceae
Castanea crenata Japanese chestnut**
Castanea dentateAmerican chestnut****
Fagus grandifoliaAmerican beech**
Fagus sylvaticaEuropean beech**
Quercus albaWhite oak*
Quercus coccineaScarlet oak*
Quercus falcataSouthern red oak*
Quercus prinusChestnut oak**
Quercus palustrisPin oak***
Quercus rubraRed oak*
Quercus stellata Post oak*
Quercus velutinaBlack oak*
Ginkgoaceae
Ginkgo bilobaMaidenhair tree*
Hamamelidaceae
Hamamelis virginianaWitch hazel*
Liquidambar styracifluaAmerican sweetgum*
Hippocastaneae
Aesculus hippocastanumHorsechestnut****
Aesculus parvifloraBottlebrush buckeye***y
Hypericaceae
Hypericum perforatumCommon St. Johnswort***y
Juglandaceae
Carya glabraPignut hickory*
Carya ovataShagbark hickory*
Carya tomentosaMockernut hickory**
Juglans cinereaButternut*
Juglans nigraBlack walnut****
Lauraceae
Lindera benzoinCommon spicebush***
Sassafras albidumCommon sassafras****
Loganiaceae
Buddleia davidiiButterfly-bush***y
Buddleia alternifoliaAlternate-leaf butterfly-bush***y
Table 1. Relative susceptibility of deciduous and evergreen woody trees and shrubs to Japanese beetles.
Scientific nameCommon nameRatingz
Lythraceae
Lagerstroemia (see Table 2)Crapemyrtle****y
Magnoliaceae
Liriodendron tulipiferaTulip poplarResistant
Magnolia grandifloraSouthern magnolia*y
Magnolia ´ soulangianaSaucer magnoliaResistant
Magnolia virginianaSweetbay magnoliaResistant
Moraceae
Ficus caricaCommon figResistant
Ficus elasticaIndian rubbertree*
Morus rubraRed mulberryResistant
Musaceae
Musa ´ paradisiacalFrench plantain*
Myricaceae
Myrica pensylvanicaNorthern bayberry**
Nyssaceae
Nyssa sylvaticaTupelo**
Oleaceae
Forsythia ´ intermediaBorder forsythiaResistant
Forsythia suspena var. sieboldiiWeeping forsythiaResistant
Fraxinus americanaWhite ashResistant
Fraxinus pennsylvanicaGreen ashResistant
Ligustrum ovalifoliumCalifornia privet**
Ligustrum vulgareCommon privet*
Syringa ´ persica Persian lilacResistant
Syringa vulgarisCommon lilacResistant
Pinaceae
Abies concolorBalsam firResistant
Larix deciduasEuropean larch***
Picea abiesNorway spruceResistant
Picea orientalisOriental spruceResistant
Pinus sylvestrisScotch pineResistant
Pinus virginianaVirginia pine*
Pseudotsuga menziesiiDouglasfirResistant
Tsuga canadensisHemlockResistant
Platanaceae
Platanus ´ acerifoliaLondon planetree****
Platanus occidentalisAmerican planetree***
Rosaceae
Chaenomeles japonicaJapanese flowering quince***
Crateagus laevigataEnglish hawthorn**
Crateagus monogynaSingleseed hawthorn**
Exochorda racemosaCommon pearlbush**
Malus (see Table 3)
Prunus ´ cistenaPurpleleaf sandcherry****
Prunus sargentiiSargent cherry****
Prunus serotinaBlack cherry****
Prunus serrulataOriental cherry***
Prunus serrulata 'Kwanzan'Kwanzan oriental cherry***
Prunus serrulata 'Mt. Fuji'Mt. Fuji oriental cherry****
Prunus serrulata 'Tai Haku'Tai Haku oriental cherry***
Prunus subhirtella 'Autumnalis Rosea'****
Prunus virginianaCommon chokecherry**
Prunus ´ incamp 'Okame'Okame cherry****
Prunus ´ yedoensis 'Afterglow'Afterglow Yoshino cherry***
Prunus ´ yedoensis 'Akebono'Akebono Yoshino cherry***
Pyracantha coccineaFirethorn*
Pseudocydonia sinensisChinese quince***
Pyrus communisPear*
Rosa spp. and hybridsRoses****y
Sorbus americanaAmerican mountain ash****
Spiraea trilobataThree-lobed spirea**
Spiraea ´ vanhouteiVanhoutte spirea**
Rubiaceae
Cephalanthus occidentalisButtonbush***y
Gardenia jasminoidesGardenia*
Rutaceae
Citrus sinensisSweet orange***y
Salicaceae
Populus albaWhite poplarResistant
Populus alba pyramidalisBolleana poplarResistant
Populus nigra italicaLombardy poplar****
Salix babylonicaBabylon weeping willow***
Salix discolorPussy willow****
Saxifragaceae
Deutzia gracilisDeutzia**y
Hydrangea arborescensSmooth hydrangeaResistant
Hydrangea paniculataPanicle hydrangeaResistant
Hydrangea petiolarisClimbing hydrangea*
Philadelphus coronaries MockorangeResistant
Simaroubaceae
Ailanthus altissimaTree of Heaven*
Staphyleaceae
Staphylea trifoliaAmerican bladdernutResistant
Styracaceae
Halesia tetrapteraCarolina silverbell***
Taxaceae
Taxus baccataEnglish yewResistant
Taxus brevifoliaWestern yewResistant
Taxus canadensisCanada yewResistant
Taxus cuspidateJapanese yewResistant
Taxodiaceae
Cryptomeria japonicaCryptomeria*
Taxodium distichumBaldcypress***
Tiliaceae (see Table 4)
Ulmaceae
Ulmus americanaAmerican elm****
Ulmus changii****
Ulmus lanceaefolia***
Ulmus procera English elm****
Ulmus prunifolia***
Ulmus pseudopropinqua***
Ulmus rubraSlippery elm**
Ulmus taihangshanensis****
Ulmus wallichiana****
Verbenaceae
Callicarpa dichotomaPurple beautyberryResistant
Lantana camaraLantanaResistant

zPlants designated "resistant" are never fed on or rarely fed on by Japanese beetles. "*" and "**" indicate plants on which feeding has been observed but is either occasional or light, respectively. "***" and "****" indicate plants that are commonly fed on by Japanese beetle, resulting in either moderate or extensive feeding damage, respectively.
yFlowers of these species are also fed on by Japanese beetles.

Table 2. Relative susceptibility of crapemyrtles to Japanese beetles.
Resistant
'Acoma''Pocomoke'
Moderately resistant
'Biloxi''Cordon Bleu''Potomac'
'Catawba''Lipan''Sioux'
'Chicksaw''Muskogee''Tuskegee'
'Choctaw''Osage''Wichita'
'Comanche''Pink Velour'
Moderately susceptible
'Apalachee''Hope''Seminole'
'Byers Standard Red''Hopi''Tonto'
'Byers Wonderful White''Miami''Tuscarora'
'Carolina Beauty''Natchez''Velma's Royal Delight'
'Centennial''Ozark Springs''Victor'
'Centennial Spirit''Pecos''William Toovey'
'Dynamite''Powhatan''World's Fair'
'Hardy Lavender''Raspberry Sundae''Yuma'
Susceptible
'Red Rocket''Regal Red'
Table 3. Relative susceptibility of crabapples to Japanese beetles.
Resistant
Malus baccata Jackii'Harvest Gold''Strawberry Parfait'
Malus hupehensis'Jewelberry'
'Golden Raindrops''Louisa'
Moderately resistant
'Adirondack'Malus halliana var. parkmanii'Red Jewel'
'Baskatong'Malus tschonoskiMalus sargentii
'Bob White''Madonna''Sentinel'
'Brandywine''Molten Lava''Silver Moon'
'Callaway''Naragansett''Snowdrift'
'Centurion''Ormiston Roy''Sugar Tyme'
'Christmas Holly''Professor Sprenger''Wintergold'
'David''Profusion'Malus ´ zumi 'Calocarpa'
'Doubloons''Ralph Shay'Malus ´ zumi 'Winter' 'Gem'
'Edna Mullins''Red Jade'
Moderately susceptible
'Adams''Indian Magic''Ruby Luster'
'Beverly''Indian Summer''Selkirk'
'Candymint Sargent''Mary Potter''Sinai Fire'
'Coralburst''Pink Princess''Snow Magic'
'Donald Wyman''Purple Prince''Tina'
Malus floribunda'Red Baron''White Angel'
'Henningii''Robinson'
Susceptible
Malus baccata'Liset''Royalty'
'Dolgo''Radiant''Velvet Pillar'
'Hopa''Red Splendor''Weeping Candied Apple'
Table 4. Relative susceptibility of lindens to Japanese beetles evaluated in laboratory or field experiments.
Scientific nameCommon name/cultivarRatingz
Tilia amurensis**
Tilia americana*
Tilia americana'Legend'**
'Redmond'***
Tilia caroliniana*
Tilia chinesis**
Tilia cordata'Chancellor'***
'Fairview'**
'Glenleven'**
'Greenspire'****
'Olympic'****
'Prestige'***
Tilia ´ euchlora***
Tilia heterophylla'Continental Appeal'**
Tilia japonica*
Tilia maximowicziana**
Tilia mongolica**
Tilia oliveri*
Tilia orbicularis***
Tilia petiolarisPendent silver linden*
Tilia platyphyllosLargeleaf linden***
Tilia platyphyllos'Parade'*
Tilia tomentosa**
Tilia tomentosa'Erecta'**
Tilia tomentosa'Sterling'**
Tilia sp.'Sundance'*

z "*" and "**" indicate plants on which feeding has been observed but is either occasional or light, respectively. "***" and "****" indicate plants that are commonly fed on by Japanese beetle, resulting in either moderate or extensive feeding damage, respectively.

DISCUSSION

Susceptibility of plants to Japanese beetle should be one factor, among many, considered when selecting plants, particularly long-lived woody plants, for residential and commercial landscapes. Resistance of one plant species to Japanese beetle does not necessarily imply resistance to other plant-feeding insects or plant pathogens (Smitley and Peterson 1993; Pettis et al. 2004). For example, the crapemyrtle varieties 'Tonto' and 'Tuscarora' are moderately susceptible to Japanese beetle, but the same varieties are resistant to metallic flea beetles (Altica spp.), an important pest of crapemyrtle in production (Pettis et al. 2004).

Resistance of woody host plants to Japanese beetle is probably mediated by the presence or absence of deterrent compounds found in the foliage (Keathley et al. 1999; Potter and Held 2002). Control products containing certain plant extracts, such as neem (azadirachtin), can effectively deter feeding in laboratory choice tests (Ladd et al. 1978; Held et al. 2001) but often fail to provide similar protection when tested on whole plants in the field (Harper and Potter 1994; Witt et al. 1999). Abundant field populations, however, will reduce the efficacy of both conventional and botanical insecticides because of additional adults re-infesting treated plants.

Elms and lindens are considered preferred hosts for the Japanese beetle. Among elms, only U. lancefolia and U. prunifolia were slightly less susceptible than the other species (Miller et al. 2001). Although no lindens are resistant, varieties such as 'Parade', 'Legend', and 'Sterling' appear to be less susceptible (Potter et al. 1998). Moderate to dense leaf pubescence may be an important factor in susceptibility of linden and elm to Japanese beetle. For example, foliage of T. platyphyllos 'Parade', T. tomentosa 'Sterling', and U. lamellose have heavy pubescence and is less preferred by Japanese beetle (Potter et al. 1998; Miller and Ware 1999; Miller et al. 2001). Conversely, certain plants, such as species of Ilex and Rhododendron, with waxy or glossy foliage are also resistant to Japanese beetle (Fleming 1972; Keathley et al. 1999).

Plants with purplish or deep red foliage (e.g., 'Crimson King' Norway maple) are often observed to sustain more damage by Japanese beetle than green-leaved cultivars (Rowe et al. 2002). Foliage color alone, however, does not account for these differences. When two artificial ficus trees with foliage painted either green or purple are placed side by side in the field, significantly more beetles land on the green-leaved plants (Rowe et al. 2002). Flower color, however, does influence susceptibility of flowering plants to Japanese beetle. Rose varieties with yellow or white flowers are more likely to be attacked than those with darker-colored blooms (Held and Potter 2004).

Resistance of certain plants to Japanese beetle also depends on the production of attractive volatile compounds following damage by Japanese beetle or other plant-feeding insects (Loughrin et al. 1995). Japanese beetles use a wide range of floral and fruitlike compounds to locate a host plant (Fleming 1972; Loughrin et al. 1995, 1996). Laboratory tests show that Japanese beetle often cannot discriminate among foliage of plants that differ in susceptibility in the field (Loughrin et al. 1995, 1996). This finding indicates that Japanese beetles are attracted to plants regardless of their status as a host (Potter and Held 2002). However, if susceptible plants suffer feeding damage, they produce an array of attractive volatiles that serve as aggregation stimulants for Japanese beetle (Loughrin et al. 1995, 1996). Therefore, a susceptible plant in the field may not be inherently more attractive, but, if damaged, these plants produce the volatiles that recruit Japanese beetles much like sharks attracted to a blood trail in the water.

Host plant resistance is the most sustainable means of managing feeding damage or plant losses resulting from Japanese beetle adults. Landscape designers in states on the front of this insect's range expansion should consider incorporating resistant plants into residential, commercial, and municipal landscapes as well as any other long-term plantings. This approach can reduce the economic and environmental costs associated with the repeated use of insecticides to prevent or reduce damage to urban landscapes in the future.

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Acknowledgments. I thank P. Knight, C. Pounders, and B. Layton (Mississippi State University) for helpful comments on an earlier draft of this manuscript. I also acknowledge the authors of the numerous field and laboratory evaluations of host plants of Japanese beetles whose careful observations provide the backbone of this review. This paper is no. J10525 of the Mississippi State Agricultural Experiment Station.


Assistant Professor of Entomology
Mississippi State University
Coastal Research and Extension Center
1815 Popps Ferry Road
Biloxi, MS 39532, U.S.

Zusammenfassung. Der japanische Käfer Popillia japonica Newman wurde 1916 in eine Baumschule in New Jersey eingeführt und breitet sich nach Norden und Osten quer durch die Vereinigeten Staaten aus. Die Erwachsenen attackieren Blätter, Blüten und Früchte von mehr als 300 Arten, dennoch sind einige resistent geblieben. Dieses Papier erfasst die Daten der für diesen Käfer anfälligen Gehölze, die aus Beobachtungen und kontrollierten Experimenten stammen. Eine Resistenz gegenüber Jap. Käfer wurde bei einigen Ahornarten , Birken, einigen Kultivaren von Malus, Lagerstroemia und Tilia dokumentiert. Die Pro-duktion bestimmter Pflanzengerüche, Präsenz sekundärer Inhaltstoffe in den Blättern und behaarte Blätter sind Faktoren, die die Resistenz gegenüber diesem Insekt beeinflussen. Die Resistenz der Wirtspflanze ist die meist-zuerhaltene Mittel um Fraßschäden oder Pflanzenverluste durch den Käfer zu managen. Wenn möglich kann die Inkorporation resistenter Pflanzen in neue Landschaften die Ausgaben für die Ersatzpflanzungen beschädigter Gehölze reduzieren und die Insektizidanwendungen minimieren.

Resumen. El escarabajo japonés, Popillia japonica Newman, fue introducido a New Jersey en 1916, y continúa esparciéndose al norte y este a través de los Estados Unidos. Los adultos atacan el follaje, flores y frutos de más de 300 especies de plantas. Sin embargo, algunas plantas son notablemente resistentes. Este reporte resume los datos sobre la susceptibilidad de plantas leñosas a los escarabajos japoneses colectados de observaciones y experimentos controlados. La resistencia al escarabajo japonés ha sido documentada entres especies de maples (Acer), abedules (Betula) y entre cultivares de manzanos (Malus), astronómicas (Lagerstroemia) y tilos (Tilia). La producción de ciertos olores por las plantas, presencia de componentes secundarios en las hojas y pubescencia de las mismas son factores que afectan la resistencia a estos insectos. La resistencia de las plantas hospederos es el medio más sustentable de manejo del daño o pérdida de plantas resultante de los escarabajos japoneses adultos. Cuando se desea, la incorporación de plantas resistentes en nuevos escenarios puede reducir o eliminar los gastos de reemplazo de plantas dañadas o las aplicaciones frecuentes de insecticidas.

Résumé. Le scolyte japonais (Popillia japonica Newman) a été introduit dans une pépinière du New Jersey en 1916 et continue depuis de s'étendre vers le nord et l'est des États-Unis. Les adultes attaquent le feuillage, les fleurs et les fruits de plus de 300 espèces de plantes, mais certaines plantes demeurent résistantes de manière notable. Cet article fait un résumé des données recueillies sur la susceptibilité des plantes ligneuses aux scolytes japonais, et ce à partir de d'observations et d'expériences contrôlées. La résistance au scolyte japonais a été documentée parmi des espèces des genres Acer, Betula et sur certains cultivars de Malus, de Lagerstroemia et de Tilia. La production de certaines odeurs par les plantes, la présence de composés secondaires dans les feuilles et la pubescence foliaire sont des facteurs qui affectent la résistance à cet insecte. La résistance de la plante hôte est le moyen le plus efficace pour gérer les dommages par causés par l'alimentation ou encore les pertes de végétaux résultants des scolytes japonais adultes. Lorsque cela est possible, l'incorporation de plants résistants au scolyte japonais dans les nouveaux aménagements peut réduire ou éliminer les dépenses pour le remplacement de végétaux endommagés ou les applications fréquentes d'insecticide.


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