japanese beetles 101: myth busters: japanese beetle ......§many myths, misunderstandings, and...

2/7/20

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University of Wisconsin: Insect Diagnostic Lab

Japanese Beetles 101: An In-Depth Look at a Top Yard &

Garden PestPJ Liesch

UW-Insect Diagnostic [email protected]

Twitter: @WiBugGuy

insectlab.russell.wisc.edu

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Myth Busters: Japanese Beetle Edition

!

§ Many myths, misunderstandings, and misconceptions exist regarding Japanese beetles and their management

§ This icon will cue you in on important items

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Japanese Beetle: Popillia japonica§ Non-native scarab beetle from Japan

§ Feeds on 300+ types of plants; highly destructive pest

§ Estimated to cause > $450 Million in damage each year

Photo Credit: Joseph Berger, Bugwood.org

Japanese Beetle

Photo Credit: Jon Yuschock, Bugwood.org

Multicolored Asian Lady Beetle

!

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Native Range of Japanese beetle

Map Credit: Google Maps

Honshu

Hokkaido

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North American Arrival§ Discovered in Riverton, NJ in

August of 1916

§ Accidentally introduced to local nursery ~5-6 years earlier with Japanese irises

§ Plant Quarantine Act 1912§ Regulated import of plant goods§ Nursery stock inspections by USDA Map Credit:

Google Maps!

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Estimated Early Spread in US:Washington

Oregon

Montana

California

Arizona

Wyoming

Nevada

Idaho

UtahColorado

NewMexico

Texas

Oklahoma

NorthDakota

SouthDakota

Nebraska

Kansas

Louisiana

Arkansas

Missouri

Iowa

Minnesota

Wisconsin

IllinoisIndiana

Michigan

Ohio

Kentucky

Tennessee

Florida

MississippiAlabama

Georgia

SouthCarolina

NorthCarolina

Virginia

WestVirginia

Pennsylvania

Maryland

NewYork

Maine

Delaware

NewJersey

Vermont

NewHampshire

Massachusetts

Connecticut RhodeIsland

191619201926193219331937194119421944194619511952

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Why Have Japanese Beetles Thrived Here?

§ Come from similar latitudes in native range

§ Feed on an extremely broad range of plants

§ Mobile and relatively long-lived

§ Easily transported (both larvae and adults)

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Current Distribution in US

Map Credit: USDA

Temperature & soil moisture influence the distribution of the JB

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Distribution in Wisconsin

Map Credit: Google Maps

§ Well established in southern WI§ Can occur in pockets

§ Gaining footholds in northern WI

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Life Cycle

Photo Credit: University of Nebraska Lincoln

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Eggs§ Female will lay 40-60 eggs throughout her lifespan

§ Burrow into soil 12+ times over lifetime to lay individual eggs

§ Egg laying influenced by:§ Nearby food plants (adults)§ Preferred groundcover§ Soil conditions

§ Eggs hatch in 10-14 daysPhoto Credit: Glen Obear, UW-Entomology

Egg laying tunnel

Photo credit: David Cappaert, forestryimages.org

Eggs

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Drawing credit: USDA Technical Bulletin No. 1449

Raster Pattern

Larvae (White Grubs)

§ Pale C-shaped grubs§ Orange/brown head capsule§ 3 Pairs of jointed legs

§ Soil-dwelling; feed on plant roots§ Upper ~2” of soil

§ Pass through 3 stages (instars)

§ Overwinter as 2nd/3rd instars

Photo credit: David Cappaert, Bugwood.org

White Grub

Photo credit: UW-Entomology

1st, 2nd & 3rd Instar Grubs

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Winter:

15˚C59˚F

10˚C50˚F

10˚C50˚F

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Influence of Winter Weather

§ Cold temperatures can kill Japanese beetles§ Supercooling point of -7˚C (19˚F)

§ Snow cover has a great influence!

§ Influence of polar vortex?§ 2014§ 2019

Photo Credit: PJ Liesch, UW Entomology

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Life Cycle


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Pupae§ Grubs create a small cell in soil to pupate

§ “Inactive” life stage§ Not moving or feeding

Photo Credit: USDA-APHIS

§ Undergoing dramatic transformation to adult beetles§ 1-2+ weeks

§ New adults remain in earthen cell for up to 2 weeks

Japanese Beetle Pupa

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Adult Japanese Beetles§ Size: 3/8” long

§ Females slightly larger

§ Hard exoskeleton; 3 pairs legs

§ Color: Metallic green w/white spots along sides

§ Coppery-brown wingcovers

§ Live for 4-6 weeksPhoto credit: David Cappaert, Bugwood.org

Japanese Beetle Adult

Drawing credit: USDA Technical Bulletin No. 1449

Adult Forelegs

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Courtship on Six Legs§ Unmated females produce

potent pheromone

§ Males emerge before females

§ Initial mating: “balling”

§ Males mate w/multiple females

§ Females mate multiple times during her life

§ Females will feed while mating

Photo Credit: C Watts, Via Flickr

Photo Credit: PJ Liesch, UW-Entomology

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Adult Behavior: Flight§ Flight influenced by environmental conditions:

§ Need temperatures to be ~70˚+ F to fly

§ Stop flying above 95˚F

§ Increased flight on clear, sunny days with light wind

§ Decreased flight on cool/windy days, cloudy days, rainy days

Photo Credit: Jon Yuschock, Bugwood.org

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Adult Behavior: Feeding§ Feeding also influenced by environmental conditions:

§ Peak feeding: mid-morning to late-afternoon§ Prefer sunny areas / parts of plants§ Feed at top of plant first

Photo Credit: William Fountain, Bugwood.org Photo Credit: William Fountain, Bugwood.org

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Adult Behavior: Aggregation§ Japanese beetles do not have an aggregation pheromone

§ Aggregation due to “blood in the water” phenomenon

§ Plants release volatile chemicals which attract beetles§ Injured plants release greater amounts of volatiles

Photo Credit: M.G. Klein, USDA Agricultural Research Service, Bugwood.org

!

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Host Plant Feeding Range§ Known to feed on 300+ species from 79 plant families!

§ Landscape trees:§ Lindens, maples, birches, crabapple, elms, mountain ash

§ Landscape shrubs & flowers:§ Roses, euonymus, alders, zinnias, milkweeds, geraniums

§ Fruits:§ Apples, stone fruit, raspberries, grapes, strawberries, etc.

§ Vegetables & other garden crops:§ Beans, corn, asparagus, herbs, etc.

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Feeding Damage

§ Mouthpart anatomy dictates plant damage

Photo Credit: Pest and Diseases Image Library, Bugwood.org

Photo Credit: Iowa State Entomology

Adult

Larva

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Adult Plant Damage

Photo Credit: Steven Katovich, Bugwood.org

Photo Credit: Steven Katovich, Bugwood.org

§ Skeletonization

§ Bronzing

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Adult Plant Damage

Photo Credit: Whitney Cranshaw, Bugwood.org

Photo Credit: European and Mediterranean Plant Protection Organization, Bugwood.org

Photo Credit: Daren Mueller, Bugwood.org

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Grub Damage§ Soil dwelling grubs chew on plant roots

§ Damaged turf results in irregular brownish patches

§ Severely damage turf can be rolled back like a rug

Photo Credit: M.G. Klein, Bugwood.org

§ A healthy lawn can tolerate some grubs (~10 grubs / square ft)

§ Foraging animals can cause additional damage

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Dealing with Japanese Beetles & Their Damage

Management Scenarios:1. Turfgrass2. “Small” plants (gardens, flowers, shrubs, small trees)3. “Large” plants (trees)

§ Many factors can influence management approaches:§ How much free time you have?§ How many plants are affected and how big are they?§ How large of an area?§ Personal preferences—aesthetics, organic, etc.

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Management Approaches

Cultural Manipulation of the local environment to reduce pest populations or damage

Physical Physical activities performed to help prevent or reduce pests

Biological Use of natural enemies to reduce pest levels (i.e., predators, parasites, pathogens)

ChemicalUse of pesticides to reduce pest levels; this can include conventional, organic, and biopesticide options

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IPM Pyramid

Cultural Practices

Physical/Mechanical Control

BiologicalControl

ChemicalControl

Prevention

Intervention

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§ Manipulation of the local environment to prevent pest problems or reduce the amount of damage

§ Plant location in the landscape§ Choosing less-preferred plants§ Lawn care§ Tolerance

Cultural Practices

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Lawn Care:§ Good general lawn care practices help (fertility, etc.)

§ Fertilizing in fall may help increase tolerance

§ Mow at a higher setting; have sharp mower blades

§ Modify irrigation practices

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Tolerance:§ Varies from person to person with individual preferences for

aesthetic factors

§ Healthy turf can tolerate 10+ grubs/sq ft; re-seed if needed

§ Healthy trees/shrubs usually tolerate occasional defoliation

§ Many plants put out an overabundance of leaves; moderate feeding damage can have minimal impacts

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Physical Control§ Physical activities performed to help prevent or

reduce pests

§ Hand-picking § Squishing § Barriers/row cover§ Traps

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Hand-Picking & Squishing§ Must be done regularly to maximize effectiveness

§ Limited by amount of free time & size / number of plants§ No residual protection

§ Defensive behavior: fly or drop to ground


§ OK to dump in yard when done?§ Yes! !

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Can manual removal make a difference? § Yes!—especially early in season before significant damage

occurs

§ Picking beetles even once a day in late afternoon or early evening can make a difference

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Barriers & Row Cover§ Fine mesh screening can physically block access to plants

Photo Credit: Aaron Baugher, via flickr

§ Considerations: § Plant size§ Pollinator access§ Aesthetics

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Traps§ Contain:

§ Synthetic version of JB sex pheromone § Plant volatiles

§ Traps can collect a lot of Japanese beetles!

§ Limited applicability for control

§ Tend to result in increased damage

!

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Biological Control§ Use of natural enemies to reduce pest levels

§ Many natural enemies feed on or attack Japanese beetles:§ Predators§ Parasites§ Pathogens

i.e., Relying on Mother Nature to help out!

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Biological Control: Predators

Photo Credit: Michael Coghlan via flickr

Ants

Photo Credit: David Cappaert, Bugwood.org

Predatory Ground Beetle

Photo Credit: Tom Friedel via Wikipedia

Insectivorous Mammals

Photo Credit: Alexey Komarov via Wikipedia

Wild and Domestic Birds

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Vertebrates: A Double-Edged Sword?

From: USDA Technical Bulletin 1383

Crow digging for grubs

Photo Credit: Marie-Lan Nguyen via Wikipedia

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Biological Control: ParasitesTiphia sp. Wasp Attacking White Grub

Photo Credit: M. Rogers and D. Potter, University of Kentucky

Entomopathogenic Nematodes

Photo Credit: Peggy Greb, Bugwood.org

Winsome Fly


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Biological Control: Pathogens

Photo Credit: David Cappaert, Bugwood.org

Milky Spore Disease (Paenibacillus popilliae)

[Bacterial]Green Muscaridine Disease

(Metarhizium anisopliae)[Fungus]

!Photo Credit: Svetlana Y. Gouli, Bugwood.org

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Chemical Controls:

§ Each approach uses different products and/or tactics

§ Targeting one life stage has minimal impacts on the others

§ Focus on what plant(s) you’re trying to protect!

Disclaimer: The mention of products and active ingredients is not an endorsement

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Grub Control in Turfgrass§ To protect lawn…not prevent future damage by adult beetles

§ Preventative:§ “Proactive”§ Prevents grub damage from occurring—but is it needed?

§ Curative:§ “Reactionary”§ In response to presence of grubs

Regardless of approach and products used, grub control products mustbe watered in to reach the root zone where grubs are feeding

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§ Applied before or around the time of egg hatch§ Most effective against very small grubs (90+% control)

§ NOT effective against large grubs§ Products have long-residual activity (> 100 days)

§ Product Ingredients:§ Chlorantraniliprole§ Cyantraniliprole

§ Imidacloprid § Dinotefuran§ Clothianidin* § Thiamethoxam*

Preventative Grub Control

Neonicotinoid Class:These products are highly toxic to bees, if exposed

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Conserving Pollinators in Turfgrass Areas§ Several tactics can greatly

minimize risks to pollinators when grub controls are used:

§ Weed control§ Mow before applying grub

control§ Use granular products§ Choose non-neonicotinoid

products

Extension Publication A4128

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§ Applied once grubs are observed at threatening levels§ Most effective against smaller grubs

§ Not as effective as preventative controls§ Products have short residual activity (<10 days)

§ Product Ingredients:§ Carbaryl (Sevin†)§ Trichlordon (Dylox)

§ Bacillus thuringiensis galleriae§ Entomopathogenic nematodes§ Milky spore§ Metarhizium

Curative Grub Control

Broadcast Spreader

Photo Credit: Wikipedia

Conventional

Organic

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Timing of Grub Control


Preventative Curative

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Small Plants (Shrubs, Flowers, Gardens)§ Foliar applications of contact insecticides typically used§ Applications to blooming flowers pose risks to pollinators§ Short residual activity

§ Carbaryl§ Bifenthrin§ Cyfluthrin§ Cyhalothrin§ Cypermethrin§ Deltamethrin§ Permethrin§ Chlorantraniliprole

ConventionalOrganic

§ Insecticidal soap§ Horticultural oils (neem, etc.)

§ Azadirachtin§ Pyrethrins§ Bacillus thuringiensis galleriae

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Large Plants (Trees)§ Systemic products can be applied preventatively

§ Typically applied as a soil drench§ Ex. Imidacloprid, Thiamethoxam

§ Can take several weeks for uptake in large trees

§ Can pose risks to bees§ Wait until after plants have bloomed to apply§ Use restricted on lindens due to pollinator concerns

Do not apply this product, by any application method to linden, basswood, or other Tilia species

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Questions?

Notes available at:

insectlab.russell.wisc.edu

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japanese beetles 101: myth busters: japanese beetle ......§many myths, misunderstandings, and...

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