Key Blueberry Insect Pests & IPM

Dr. Rufus IsaacsDepartment of Entomology

Michigan State University

East Lansing, Michigan

Insect may be present in blueberry

fields to feed on, or infest:

buds

flowers

leaves and stems

fruit

and roots….

pre-bloom bloom mid-season pre-harvest harvest post-harvestInsect Pest

BB bud mite

Scale

Cutworms

Spanworms

Cranberry weevil

Thrips

Leafrollers

Gypsy moth

Aphids

Thrips

Cranberry FW

Cherry FW

Plum curculio

BB maggot

Japanese beetle

Tussock moth

Mealybug

Economically-important activity periods of arthropod pests*

*grey bars show period when scouting and management of the pest is most important

Insect pests - buds

• Blueberry bud mite

• Cutworms

• Spanworms

Blueberry

Bud Mite

Acalitus vaccinii Keifer - from Eriophyid family of mites

White body, 1/128 inch long. Spherical eggs.

Sporadic pest. More important in southeast US

Spend fall and winter under bud scales

Leads to mis-formed flowers and fruit, poor yield

Typically few mites per bud, but can be >50

Cultivars vary in sensitivity

CUTWORMS - Larvae of Noctuid moths (1-1.5 inch)

Some overwinter as larvae, get active at first warm days

Spend days in leaf litter or just under soil at base of plants

Feed at night on young tissues

More of a problem in weedy, grassy fields than cultivated

Chew off large section or all of bud

SPANWORMS - Larvae of Geometrid moths (1-1.5 inch)

Several species in eastern US

Thin bodies with legs at front and rear. Looping movement.

Feeding on young buds by chewing a hole through

side or top of bud.

Insect pests - flowers

• Cranberry weevil

• Thrips

CRANBERRY WEEVIL – Anthonomus musculus (1/16 inch)

Also named blueberry blossom weevil

Dark reddish-brown beetle with white marks on elytra

Mouthparts on a short snout

Overwinters in wooded areas and unkempt fields

Active on bushes as early as bud swell. Falls off when

disturbed, and retreats if it cools down.

Some feeding on young buds, but most damage occurs when

flower buds open. Drill holes into flowers, and lay an egg into

each drilled flower. May clip flower pedicel. Small white grub

develops inside flower bud.

Adults may feed on leaves, leaving puncture marks

FLOWER THRIPS (1-2 mm)

Many species found in blueberry

Frankiniella tritici (NJ)

Scirtothrips ruthvini (NJ)

Frankiniella vaccinii, F. bisipinosa, F. occidentalis

Thrips feed on leaf and flower surfaces

Active before, during, and after bloom

May move from other flowers to blueberry

Feed on the internal parts of flowers, preferring style

tissues, reducing pollination and fruit set

Damage to Southern highbush up to 60% lower set (GA)

Cause tight curling and malformation of leaves

Insect pests - leaves and shoots

• Blueberry aphid

• Leafrollers

• Sharpnosed leafhopper

• Tussock moth

• Gypsy moth

BLUEBERRY APHIDS

Many species of aphid found in blueberry – state specific

Aphids transmit viruses – shoestring, scorch

Overwinter as eggs on bushes

In spring, eggs hatch before bloom and young

aphids seek new foliage

Populations build during June and July, by

parthenogentic reproduction

Aphids are suppressed by many natural enemies

Some winged forms may be produced once colonies are

crowded, and move within or between fields

Fall conditions stimulate true males and egg-laying

females

Aphid colonies on blueberry

Aphid colony Mummified aphids

LEAFROLLERS – family Tortricidea

Many leafrollers in blueberry – state specific complexes

Overwinter as pupae or mature larvae

Multiple generations per year

Larvae construct a shelter from leaves and silk

In spring, use buds and may web some together

Later, larvae feed on leaves and surface of fruit

Moths can be monitored using pheromone-baited traps

Larvae and eggs can be monitored on the bush

Species Moth Egg Lavae

Leafroller Identification - Adults

OBLR

RBLR

Pandemis

5/8 inch

7/8 - 1 inchEgg mass greenish

Egg mass flat and

yellow-green

Egg mass green

becoming orange7/8 - 1 inch

SHARPNOSED LEAFHOPPER – Scaphytopius magdalensis

Overwinters as egg inside leaves that fall to the ground

Egg hatch mid-May and 5 wingless instars, adult in June-July

Eggs are laid and this generation matures until August

Adults deposit overwintering eggs

Transmits MLO disease, blueberry stunt

TUSSOCK MOTH - Orgyia leucostigma

Overwinters as egg mass

Larvae hatch in spring and grow gradually

Distinctive yellow, black and red coloration

Become mature during harvest

Causes skin irritation

GYPSY MOTH - Lymantria dispar

Brown-black larvae with white and yellow hairs

Up to 2 inches long

First instar larvae ‘ balloon’ into fields from woods

May be active during bloom

Other leaf and shoot feeders

Insect pests - fruit

• Plum curculio

• Cranberry fruitworm

• Blueberry maggot

• Japanese beetle

PLUM CURCULIO – Conotrachelus nenuphar (1/4 inch)

Snout weevil that overwinters as an adult in leaf litter

Single generation per year

Feeds on young fruit just after bloom, causing feeding scar

Lays eggs in fruit causing crescent-shaped oviposition scar

Fruit may color prematurely and fall off bush

White maggot-like larva develops inside fruit

Mature larva exits fruit to pupate in the ground, and

becomes adult in July and August

CRANBERRY FRUITWORM – Acrobasis vaccinii

Overwinters under bushes as a mature larva in a

hibernaculum

Adults emerge during bloom (1/2 inch)

After mating, females wait for petal fall to lay eggs

Eggs are laid singly inside the calyx cup

Larvae emerge and bore into the fruit at the stem end

Webbing of fruit together and frass provide indications of

infestation

CHERRY FRUITWORM – Grapholita packardii

Similar biology to cranberry fruitworm. Much less webbing

caused by larvae, due to less feeding

Eggs

Larvae

Cranberry Fruitworm on fruit

JAPANESE BEETLE – Popillia japonica (3/4 inch)

Scarab beetle introduced from Japan in 1916

One generation per year, with adults present during summer

Adult beetle feeds on over 300 spp. of plants

Egglaying underground in grassy areas with soil moisture

Eggs hatch and larvae feed on roots of grass and weeds

Larvae go through three molts, reaching up to 1 inch

Spend winter in the soil, pupation in early summer

JB watch: www.pmcenters.org/northcentral/jbeetle/

Japanese beetle life cycle

Blueberry Maggot Adult

Identification

• Blueberry Maggot

adults are about 5

mm in length. Most

characteristic is the

wing banding with

an ‘M’ pattern (three

lines that join

together).

Blueberry Maggot Fruit

Infestation

As the maggot feeds, fruit

becomes soft, with sunken areas.

Some berries drop prematurely,

others can be harvested.

Biological Control of

Blueberry Maggot• There are parasitic

wasps that attack

blueberry maggot in

their larval stages. Their

abundance peaks late

in BBM activity, and

they cannot be relied

upon for full control.

Monitoring for Blueberry

Maggot Adults

• Monitoring adult flight is

the key to effective

treatment strategies and

provides

– A relative estimate of

population level

– An indicator to when

control measures

should begin

Monitoring for Blueberry

Maggot Adults

• Adult emergence is best

monitored using yellow

boards

– Place in perimeter rows

– Bait with ammonium acetate

– Check weekly

– Can also use green sphere,

but not very economical

Blueberry Maggot

Adult Emergence Curve

6/18 6/25 7/2 7/9 7/16 7/23 7/30 8/6 8/13 8/20 8/27

0.0

2.0

4.0

6.0

8.0

10.0

Ave

rag

e #

Flie

s/T

rap

Date

2001 Trevor Nichols Research Complex Pheromone Trapline Data

Fennville, MI

Blueberry Maggot

Chemical Control of Blueberry Maggot

• Once they are laid, eggs are protected from sprays.

• Conventional contact poisons are toxic to flies.

• Timed for adult egg laying period (within 7-10 days

of first emergence).

• Residual activity is important due to

immigrating flies.

Alternative Insecticides

•Compounds requiring ingestion are timed for early in the

oviposition period, right after first emergence (e.g. neonics).

• Oviposition deterrents need to be applied before

emergence and coverage maintained through flight (e.g.

Surround).

0

20

40

60

80

100

1-Jun 15-Jun 1-Jul 15-Jul 1-Aug 15-Aug 1-Sep

BB

M e

merg

en

ce

Adults Eggs Larvae

Optimal Timing for Blueberry Maggot Sprays

Preoviposition

Period

Pre-harvest

Sprays:

SpinTor

GF-120

Surround

Pyrethroids

Neonics

Imidan

Egg Laying

Adult targeted

Cover sprays:

OPs

Neonics

Harvest period

Cover sprays:

Pyrethroids

Neonics

Imidan

Summary

BUDS may be damaged by moth larvae and by bud mites

FLOWERS may be damaged by cranberry weevil and thrips

LEAVES & SHOOTS may be damaged by aphids, leafrollers, leafhoppers,

and by larvae of other moth species

STEMS may be damaged by scale and by borers

FRUIT may be damaged or infested by plum curculio, leafrollers, fruitworms,

blueberry maggot, and Japanese beetles

ROOTS may be damaged by mealybugs and oriental beetle

Further information is available

from these sources:

• www.blueberries.msu.edu

A one-stop shop for blueberry-related

information from MSU

• The MSU Fruit CAT Alerthttp://ipmnews.msu.edu/fruit/

Regular in-season updates of fruit management

issues from around Michigan. Subscribe for free

email updates or pay for hard copy delivery.

• The IPM Update newsletterweekly newsletter in-season from MSU’s

Blueberry Team. Email jenki132@msu.edu to

subscribe.