Insect Update - Bioagricultural Sciences and Pest Management ...

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Rocky Mountain Insects –
Some Updates
2013 Tri-River Area
Pesticide Management Conference
Whitney Cranshaw
Colorado State University

Some RM Insects of Interest
• Insects on the Move
– European elm flea weevil
– Banded elm bark beetle
– Root weevils
– Walnut twig beetle
• Insects Acting Badly
– Black pineleaf scale
– European elm scale
– Western conifer seed bug
– Spruce ips

Black Pineleaf Scale (Dynaspidiotus californica)

Photograph courtesy of Steven Katovich

Black Pineleaf Scale
• A species of armored scale
• Outbreaks associated most often with nonnative
pines
– Austrian, Scotch
• Some evidence that plant stress associated
with outbreaks

Present stage of black pineleaf scale outside this building

Overwintered female

Temperature Extremes Heavy Rainfall
Abiotic
(Weather-related)
Controls of
Insects

Egg hatch and
crawler period
normally occurs in
June, shortly after
new growth is
produced.
Crawlers settle on
the new needles.
One generation
normally produced.

Black Pineleaf Scale Controls
• Dormant season horticultural oils
– Directed at overwintering females
• Crawler sprays
– Directed at period of egg hatch
– Insecticides with some persistence can provide
coverage through egg hatch period
• Pyrethroids, neonicotinoids, Sevin, Distance
– Addition of horticultural oils likely useful
• Soil applied systemic insecticides

Dorman season
oil treatments

Horticultural Oils
• Primarily act by smothering insects
• Derived from various sources
– Petroleum/Mineral oils
– Vegetable oils (cottonseed, soybean)
– Neem seed extracts
– Fish oils

Dormant season (dormant oil) applications
of oils tend to work more consistently on
soft scales than armored scales
‘Soft’ Scales Armored Scales
Black pineleaf scale is an
armored scale

Crawler Sprays
Insecticides that will
persist through the
crawler period and kill
on contact – most
pyrethroids, carbaryl,
imidacloprid
Several insect growth
regulators may be
underutilized for scale
control

Post crawler oil sprays
Many current
horticultural oils can
be used on trees
with foliage.
Crawlers and young
settled scales are
targets.

Insecticides with Systemic Activity
Used for Woody Plants
• Neonicotinoids
– Imidacloprid (Merit, Marathon, Touchstone,
many generics)
– Clothianidin (Arena, Celero)
– Thiamethoxam (Flagship, Meridian)
– Dinotefuran (Safari, Zylam)
– Acetamiprid (Tristar)
• Organophosphates
– Acephate (Orthene, Leptotect)

Systemic insecticides
(neonicotinoids) tend
to be effective against
most phloem-feeding
insects

Soft Scales
Armored (Hard) Scales

Soft Scales Include:
Pine Tortoise Scale,
Striped Pine Scale,
European Elm Scale,
Cottony Maple Scale

Like aphids, soft
scales suck sap from
the phloem and
excrete honeydew.

Armored Scales Include:
Oystershell Scale, Pine
Needle Scale, Black
Pineleaf Scale and
others

Soft Scales vs. Armored Scales
Feeding Site:
Mesophyll/Parenchyma
Armored scales do not
produce honeydew
Feeding Site: Phloem
Soft scales produce
honeydew

Imidacloprid
Control Range
Yes
No

Safari (Dinotefuran)
• Neonicotinoid insecticide
• Primarily labeled to control insects
that suck sap (Order Hemiptera)
– Aphids
– Soft scales
–Armored scales
• Has systemic activity in plants
– Apparently more mobile in plant than
other neonicotinoids

Relative Water Solubility of Neonicotinoids:
40000
30000
20000
10000
0
Water Solubility (Active Ingredient)
Clothianidin
Imidacloprid
327 500
2950 4100
39830
Information sources
Clothianidin (Celero), Acetamiprid (Tristar), Dinotefuran (Safari) – EPA Pesticide Fact Sheet
Imidacloprid (Marathon), hiamethoxam (Flagship) – MSDS for Products
Slide information courtesy J. Chamberlin
Acetamiprid
Thiamethoxam
Dinotefuran

K oc Values of Neonicotinoids:
0
166
Clothianidin
440
Imidacloprid
Source Data: EPA Pesticide Fact Sheets
267
Acetamiprid
245
Thiamethoxam
26
Dinotefuran

Safari (Dinotefuran)
• Neonicotinoid insecticide
• Primarily labeled to control insects
that suck sap (Order Hemiptera)
– Aphids
– Soft scales
–Armored scales
• Has systemic activity in plants
– Apparently more mobile in plant than
other neonicotinoids

European Elm Scale – Is resistance
to neonicotinoids the status quo of
the future in Colorado?

Winter is spent on twigs and small branches

Females swell with eggs in May and June

Crawlers are
present in late June
and July

European elm scale nymphs on leaves in summer

Honeydew is excreted.
Where it lands and
persists, sooty molds
grow.

Crawlers return to twigs in late summer for overwintering.

European Elm Scale
– Is resistance to
neonicotinoids going
to be the new status
quo in Colorado?

Soil injection of elms with systemic neonicotinoid
insecticides has been extremely widely used since
their introduction 18 years ago.

Some Neonicotinoid Insecticides
Used for Woody Plants
• Imidacloprid (Merit, Criterion, Marathon,
many generics)
• Clothianidin (Arena, Poncho)
• Thiamethoxam (Flagship, Meridian)
• Dinotefuran (Safari)
• Acetamiprid (Tristar)

Insecticide resistance
develops by selecting
individuals that have
genetic traits that allow
the insect to resist
effects of the pesticide

Insecticide Resistance is:
• Genetically based, heritable
• Develops from concentration of
genes that confer ability to resist
effects of the insecticide
• Is usually permanent once
established in a population

Recipe for Resistance
Sustained applications of
neonicotinoids have been
applied to almost every
scale-infested elm over
large areas in Colorado.

European Elm Scale Options in a
Post-Neonicotinoid Period
• Trunk/Soil Injection?
– Acephate (Leptotect, etc.)
• Foliar Applications
– Horticultural Oils
– Pyriproxifen (Distance)
– Buprofezin (Talus)
– Broad spectrum crawler
treatments
• Pyrethroids
• Carbaryl

Insect Growth Regulators
(IGRs)
• Affect growth processes of
arthropods/disrupt hormones
• Diverse chemistry, mode of action
– Mimic/disrupt molting hormone
(ecdysone)
– Mimic/disrupt juvenile hormone
– Prevent normal chitin synthesis

Disadvantage of an exoskeleton:

Molting is not
Molting is
for not wimps! for
wimps!

Colorado
Potato
Beetle

Potato beetles (top row) killed by IGR insecticide that
prevented successful molting to pupal stage

Cabbage looper

Looper pupae within
a cocoon of silk

Cabbage looper larvae (right, center) that were
prevented from successful molt to pupal stage
(left) due to exposure to IGR-type insecticide

Mosquito Life Cycle
Adult (left)
Larvae/wrigglers (lower left)
Pupae/tumblers (below)

A juvenile hormone-based
insecticide

Pyriproxifen (Distance)
• Mode of Action
– Insect Growth Regulator/Juvenile Hormone Mimic
• Target Pests
– Scales (soft and armored), whiteflies
– Fungus gnats, shore flies
• Target Sites
– Ornamentals (all sites)
– Greenhouse-grown fruiting vegetables

• Mode of Action
Buprofezin (Talus)
– Insect Growth Regulator/Disrupts Chitin
Synthesis
• Target Pests
– Scales (armored and soft), leafhoppers, whiteflies,
mealybugs
• Registered Sites
– Ornamentals (all sites)
– Greenhouse tomatoes

Leaf Notching Symptom

Root Weevils
Otiorhynchus spp., primarily

Top: Black Vine Weevil
Bottom: Rough Strawberry Weevil
Top: Strawberry Root Weevil
Bottom: Lilac Root Weevil

Strawberry Root Weevil – Common
Midsummer Nuisance Invader During
Periods of Hot, Dry Weather

Rough Strawberry Root Weevil

Black Vine Weevil – Occasional
Nuisance Invader of Homes During Fall

Lilac Root Weevil
Otiorhynchus meridionalis

Dyslobus decoratus
Trachyphloeus asperatus
Additional species
of root weevils
recently found in
Colorado
Barypeithes pellucidus

Root Weevil Injuries
• Leaf notching of foliage by
adults
• Nuisance household invasions
by certain species
• Root pruning by larvae

Weevil making leaf notching wounds

Root weevil
leaf
notching
injuries

Root weevil damage to base of branch near soil line
Sharon Collman photograph

Root Weevil Larva

Black Vine Weevil Larval Damage to Taxus

Root Weevil
Control
• Adult Control (foliage)
– Pyrethroids (Tempo, Talstar, Scimitar, etc.)
– Orthene?
• Larval Control (soil drench)
– Neonicotinoids (Merit, Celero, Safari, etc.)
– Heterorhabditis spp. nematodes

Lilac Root Weevil Adult Trial
48 Hour Mortality
• Talstar 100%
• Scimitar 96%
• Tempo Ultra 86%
• Discus 24%
• Orthene 6%
• Untreated Check 4 %

Root Weevil
Control
• Adult Control (foliage)
– Pyrethroids (Tempo, Talstar, Scimitar, etc.)
– Orthene?
• Larval Control (soil drench)
– Neonicotinoids (Merit, Celero, Safari, etc.)
– Heterorhabditis spp. nematodes

Insect Parasitic Nematodes
• Also known as entomopathogenic
nematodes
– Associated with pathogenic fungi
• Commercially available genera
– Steinernema
– Heterorhabditis

= Heterorhabditis spp.
= Steinernema spp.
Nematodes enter
insects through
natural openings
Heterorhabditis spp.
nematodes can penetrate
directly through the body
wall

Insect Parasitic
Nematodes Can Control
Many Turf Insects
White grubs
Billbugs
Cutworms and sod webworms
Mole crickets

Reddish Color Change from Larva Killed by
Heterorhabditis sp. Nematodes

Pinkish root weevil larvae are infected with
Heterorhabditis spp. nematodes

European Elm Flea
Weevil
Orchestes alni

It is a snout
beetle/weevil.
It jumps.
Larvae make
leafmines.

European elm flea weevil
injury – a combination of
leafmining and shothole
wounds to elm leaves

Overwintered adults
move to new growth
in spring.
Mating, feeding
(shotholes), and egg
laying occur at this
time.

Larval mines initially are serpentine and meander.
They then terminate as a blotch at the leaf edge.

Larvae develop
within the leaf
mine

Adults emerge
in early summer
and feed heavily
(shotholes) for
several weeks

Adults chew shothole
wounds in leaves

European Elm Flea Weevil
This insect, unknown
from the western US
until 2006, is now the
dominant elm insect
defoliator in much of
the region.

European Elm Flea
Weevil – are natural
enemies finally
catching up?

Elm leaf beetle –
No Show

Elm bark beetle
hand-off

Smaller European
elm bark beetle
Scolytus multistriatus
SEEBB

Banded elm bark beetle,
Scolytus schevyrewii
BEBB

Most behaviors and aspects of life history of the BEBB are similar to SEEBB

Banded elm bark beetle vs. Smaller
European elm bark beetle
• Both species occupy same ecological
niche
• BEBB spring emergence is ahead of
SEEBB
• BEBB summer generation is ahead of
SEEBB
• Banded elm bark beetle wins!

Banded Elm Bark Beetle as a Shade
Tree Pest
• More aggressively
attacks limbs,
stressed trees than
SEEBB
• Involvement with
Dutch elm disease
uncertain but
appears to have
vector potential

Ips Beetles

Ips beetles. Note the
jagged terminal edge
of the wing covers.

Ips beetle produce a central nuptial chamber

Egg galleries radiate
from the nuptial chamber

Ips tunnelling

Spruce Ips (Ips hunteri)

No water, no
pitch out
Primary bark beetle
defenses are
rapidly depleted
with drought

Spruce Ips Trial 2004-2005
Percent Tree Mortality Spring 2005
• Astro 5 qts/100 gal 12.9%
– March 2004
• Astro 2.5 qts/100 gal 16.7%
– March, August 2004
• Onyx 2 pts/100 gal 2.7%
– March 2004
• Onyx 1 pt/100 gal 0.0%
– March, August 2004
• Untreated Check 49.2%

Thousand Cankers Disease
An Unusual – and Lethal - Collaboration
between Insects and Pathogens
Whitney Cranshaw
Colorado State University

A fungus –
Geosmithia
morbida
A beetle – walnut
twig beetle

Adults enter trees
and excavate
galleries

The Pathogen - Geosmithia morbida

Tree death from
Thousand Cankers
results from
overwhelming
numbers of individual
infections – not a
single inoculation

Thousand Cankers Disease is associated with
the cambium, and does not move systemically
in the xylem or phloem.

Thousand cankers disease killing black walnut in
southeastern Colorado (Olney Springs)

Black Walnut Removals in
Boulder, Colorado

Black Walnut Removals in
Boulder and Denver

Comparison of Epidemics of
Dutch Elm Disease (historical)
and TCD in Boulder

Current distribution of Thousand Cankers Disease/
Walnut Twig Beetle

Trees of interest
Survivors
of TCD
infection

Wanted!
Reports of surviving, non-damaged black
walnut in TCD-ravaged communities

Some Winter Time
Residents of
Colorado Homes

Cluster Flies
A Colorado mystery

Boxelder Bug

Western conifer seed bug, Leptoglossus occidentalis

General Principles for Managing
Nuisance Household Invaders
• Seal openings of home prior to time
when insects enter the building
– Barrier insecticide applications can
supplement
– Dusts are sometimes blown behind walls
• Treat/remove host plants
• Dispatch individual insects as they are
observed

Keep in Mind: These
insects are not
reproducing in the home
Ultimately they will move
back outdoors or die

…and remember -
These kinds of problems
happen to the nicest of
people
Its Not Your Fault!

CSU Insect Information Web Site
Department of Bioagricultural Sciences and
Pest Management
Colorado State University
Search “BSPM CSU”
Click on “Extension and Outreach”
Click on “Insect Information”
Also check Western Colorado Entomology
Site