Neonicotinoid Insecticides - …webdoc.agsci.colostate.edu/bspm/Garden Center Talk July 2014.pdfNeonicotinoid Insecticides Use Characteristics – and Intersections with Pollinators

Neonicotinoid InsecticidesUse Characteristics – and

Intersections with Pollinators

Whitney CranshawColorado State University

Outline

• Introduction – What is a Neonicotinoid?• Brief history of insecticides and the

place of Neonicotinoids• Characteristics and uses of the

Neonicotinoids• Honey bees and Neonicotinoids

– Possible effects– Routes of exposure

Outline

• Honey bees – what are the causes for impacting honey bee colony health?

• Minimizing hazards to pollinators from insecticide use

• Consumer messaging for protecting pollinators

Neonicotinoids• Insecticide class originally developed

commercially in the late 1980s• Mode of action - Nicotinic acetylcholine receptor

agonist• IRAC Mode of Action Group 7A• Nicotine mode of action similar

Neonicotinoids act on the cholinesterase receptors of the nicotinic acid pathway. This is similar to the mode of action of nicotine.

Neonicotinoids• Insecticide class originally developed commercially in the late 1980s• Mode of action - Nicotinic acetylcholine receptor agonist

• IRAC Mode of Action Group 7A• Nicotine mode of action similar

• First new class of insecticide with systemic activity in plants in 30+ years

• Low toxicity to vertebrates accelerated registration as “reduced risk” products

Primary Neonicotinoid Insecticides Used in the United States

• Imidacloprid (Admire, Provado, Merit, Marathon, Gaucho, etc.)

• Clothianidin (Clutch, Celero, Arena, Poncho)

• Thiamethoxam (Actara, Cruiser, Flagship, Meridian)

• Dinotefuran (Venom, Safari, Zylam)• Acetamiprid (Assail, Tristar)• Thiacloprid (Calypso)

Primary Neonicotinoid Insecticides Used in the United States

• Imidacloprid (Admire, Provado, Merit, Marathon, Gaucho, etc.)

• Clothianidin (Clutch, Celero, Arena, Poncho)• Thiamethoxam (Actara, Cruiser, Flagship, Meridian)

• Dinotefuran (Venom, Safari, Zylam)• Acetamiprid (Assail, Tristar)• Thiacloprid (Calypso)

In the beginning…..

there was imidacloprid.

Imidacloprid-containing Products

• Landscape Market– Merit, Criterion, Lesco Bandit, etc.

• Nursery Market– Marathon

• Agriculture Market– Admire, Provado, Gaucho

• Over-the-counter Market– Bayer, Bonide, fertilome – more to come

• Pet care Market– Advantage

Seed treatments are the most common use of neonicotinoid

insecticides in the United States

Map of imidacloprid use in the United States in 2011

Over-the-Counter ImidaclopridFormulations

Commercial formulation for

ornamentals

Commercial formulation for fruits and vegetables

Retail formulation

Acetamiprid formulations

Dinotefuran (Safari, Zylam, Transtect)

Not all Neonicotinoids are alike:

• UV stability• Water solubility• Rate of uptake by plants• Mobilization within plants• Host range of susceptible

insects

Comparison of UV Stability

0

5

10

15

20

25

30

35

Hal

f life

(day

s)

Aquatic Photolysis

AcetamipridImidaclopridThiamethoxamDinotefuranClothianidin

Data obtained from published EPA registration documents

Slide Credit: R. Fletcher

UV Stability

Neonictoinoids are generally not UV stable. Foliar persistence can be shortened by this feature.

Acetamiprid isan exception.

Relative Water Solubility of Neonicotinoids:

Information sourcesClothianidin (Celero), Acetamiprid (Tristar), Dinotefuran (Safari) – EPA Pesticide Fact Sheet Imidacloprid (Marathon), hiamethoxam (Flagship) – MSDS for Products

Water Solubility (Active Ingredient)

327 5002950 4100

39830

0

10000

20000

30000

40000 Clothianidin

Imidacloprid

Acetam

iprid

Dinotefuran

Thiamethoxam

Slide information courtesy J. Chamberlin

Water SolubiilityThere is wide range of water solubility among the neonictoinoids.

Dinotefuran (Safari) is highly water soluble.

Koc Values of Neonicotinoids:

166

440

267245

260

Clothianidin

Imidacloprid

Acetam

iprid Dinotefuran

Thiamethoxam

Source Data: EPA Pesticide Fact Sheets

Koc ValueThere is wide range of Koc values (measure of adsorption to organic matter) among the neonicotinoids. This affects mobility within plants.

Dinotefuran (Safari) has a much lower Koc value than do other neonicotinoids

Some Generalizations…

Neonicotinoid Koc Water Solubility

Acetamiprid Medium High

Clothianidin Medium Low

Dinotefuran Low Very High

Imidacloprid High Low

Thiamethoxam Medium High

Some Generalizations…

Neonicotinoid A.I.

Relative Speed of Uptake

Relative Rate of Persistence

Acetamiprid Med. (?) – Fast Short – Mod. (?)

Clothianidin Slow (?) Mod. – Long (?)

Dinotefuran Fast Short – Mod (?)

Imidacloprid Slow (?) Long

Thiamethoxam Med(?) –Fast

Short – Mod. (?)

Why Use Neonicotinoids?

• Effectiveness against certain pests

• Systemic activity allows desirable application methods

• Relatively low hazard to applicator

Applicator Exposure Hazards

Organophosphates• Primary class used during 1960s through

early 1990s– Identified incidental to discovery of chemical

warfare agents• Some have systemic activity• Persistence in environment: days to weeks

Neonicotinoids – and pyrethroids – have largely replaced the organophosphates for insect control

Organophosphates• Mode of Action: Inhibition of acetylcholinesterase

(IRAC class 1B)– Effects persist and can accumulate with repeated

exposure• Acute Toxicity to Humans: Moderate to very high

– Special concerns about exposure to young

Some Organophosphates Used Historically for Yard/Garden Use

• Acephate (Orthene)• Malathion• Diazinon• Chlorpyrifos (Dursban/Lorsban)• Dimethoate (Cygon)• Disulfoton (DiSyston)

Organophosphates• Non-target Effects:

– Birds – generally high to very high acute toxicity– Fish – moderate to high acute toxicity– Honey bees – high toxicity through contact

• Current Status– Steady restriction of registrations since late

1990s• Increased recognition of neurotoxic effects• Increased availability of alternatives

Some Mammalian LD50 (mg/kg –Oral route) Values

• Methyl parathion (OP)– 18-50

• Dimethoate (OP)– 60-387

• Carbofuran (C)– 4-35

• Carbaryl (C)– 250-850

• Bifenthrin (Py)– 54-70

• Permethrin (Py)– 340-3000

• Table Salt– 3000

• Acetamiprid (NN)– 330

• Imidacloprid (NN)– 450

• Chlothianidin (NN)– >500

• Thiamethoxam (NN)– > 5000

• Dinotefuran (NN)– >8000

• Ethyl alcohol– 7060

Distribution of C14 labeled Thiamethoxam™ 25WG after a foliar application to cucumber leaves

1 hour after application 24 hour after application8 hour after application

Slide Credit: N. Rechcigl

Systemic Insecticides• Capable of some translocation in plant• Range exists in ability to move in plant

– Limited to translaminar movement– Broadly distributes in plant (usually to newer

growth)• Systemic activity is limited to a small number

of insecticides– Some organophosphates and carbamates– Most neonicotinoids– Abamectin (translaminar only)

Some older organophosphate insecticides with systemic activity

Over-the-Counter Imidacloprid Formulations

Acetamiprid is replacing Orthene and other organophsphates as a systemic insecticide to be sprayed

Methods of Applying Systemic Insecticides

• Foliar sprays• Soil applications• Trunk injections

Systemic insecticides that can be soil applied in ways that limit drift associated with spraying

Not all Neonicotinoids are alike:

• UV stability• Water solubility• Rate of uptake by plants• Mobilization within plants• Host range of susceptible

insects

Acute Toxicity of Neonicotinoids to Adult Honey Bees

(Dermal LD50 in micrograms/bee)

• Acetamiprid 8.09• Imidacloprid 0.08• Dinotefuran 0.022• Thiamethoxam 0.024• Chlothianidin 0.044

Acute Toxicity of Neonicotinoids to Adult Honey Bees

(Oral LD50 – micrograms/bee)

• Acetamiprid 14.53• Imidacloprid 0.005• Dinotefuran 0.056• Thiamethoxam 0.005• Chlothianidin 0.0003

Neonicotinoids tend to be effective against most phloem-feeding insects

Potato/tomato psyllid

Soft Scales Armored (Hard) Scales

Effectiveness of neonicotinoid insecticides against scale insects varies by type of scale and mobility of the insecticide

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.

European elm scale produces large amounts of honeydew. Where it lands and persists, sooty molds grow.

‘Soft’ Scales Armored Scales

Armored Scales Include:

Oystershell Scale, Pine Needle Scale, Walnut Scale and others

Pine Needle Scale

Imidacloprid Control Range

Yes

No

Dinotefuran• Neonicotinoid insecticide• Primarily labeled to control insects

that suck sap (Order Hemiptera)– Aphids– Soft scales–Armored scales

• Has systemic activity in plants– Considerably more mobile in plant than

other neonicotinoids

Neonicotinoids tend to be effective against most beetles

Some neonicotinoids (imidacloprid, chlothianidin) are used to control insect pests of turfgrass

Neonicotinoids vary in effectiveness against caterpillars.

Imidacloprid – poor

Dinotefuran – fair

Acetamiprid - good

Spider Mites –and imidacloprid

Imidacloprid can increase problems with spider mites (“flare mites”) on many ornamental plants

Predators of spider mites include minute pirate bugs (left), predatory mites (below left) and predatory thrips (below)

Imidacloprid for Borers?

Yes…..but

Emerald Ash Borer EfficacySmitley, Davis, MSU, 2006

0

1

2

3

4

5

6

7

8

9

Larve/sqM

Control

Bayer Adv Drench Fall 05

Bayer granular Fall 05

Merit Drench Spring 06

Arena Drench Fall 05

Arena Drench Spring 06

Safari Implant

Conserve Drench Spring 06

Conserve Trunk 2x Spring 06

TriStar Inject Spring 06

TriStar Inject Spring 06East Lansing site, 2006

Slide Credit: R. Fletcher

Imidacloprid will not work well on borers that are the larval stage of moths

Lilac/ash borer larvae

Peach tree borer larval tunneling in base of plant

Zimmerman pine moth injury

Imidacloprid will not work well if the borer spends much of its life in the heartwood of the plant

Imidacloprid soil drenches may work well against flatheaded borer larvae (aka metallic wood borers)

Four Agrilus sp. borers found in Colorado

Top Row - Rose stem girdler (left), Bronze birch borer (right)

Bottom Row – Honeylocust borer (left), Gambeloak borer (right)

Imidacloprid will notwork well if there has already been extensive damage to the cambium

Control Options for Management of

Emerald Ash Borer

One good thing about emerald ash borer –

We have learned a lot about insect control

Emerald Ash Borer Control Options

• Soil applications with systemic insecticides– imidacloprid, dinotefuran

• Non-invasive trunk sprays of systemic insecticides– dinotefuran

• Trunk injections of systemic insecticides– Emamectin benzoate (TREE-Age),

azadirachtin (TreeAzin), imidacloprid

Target Life Stages for EAB Treatments

Adults as they feed on foliage

Young larvae that tunnel in the phloem and cambium

Emerald Ash Borer Insecticides

• Imidacloprid (Merit, Xytect, Criterion, etc.)– Soil drench, possible trunk injection

• Dinotefuran (Safari, Zylam, Transtect)– Basal trunk spray, possible soil drench

• Emamectin benzoate (TREE-Age)– Trunk injection only

• Azadirachtin (TreeAzin)– Trunk injection only

Trunk Injections

Method required to apply emamectin benzoate and azadirachtin for EAB control

Neonicotinoid Insecticides for EAB Control

• Imidacloprid– Merit, Xytect, Criterion, Zenith, Bandit……

• 75WSP and 2F formulations– Several retail formulations now available

• Typically 1.47% liquid formulations

• Dinotefuran– Safari, Zylam, Transtect

Soil application option –imidacloprid applied as drench or injection

Over-the-Counter Imidacloprid Formulations

Primary method of imidacloprid application – soil applications for root uptake

Optimal Application – Soil drench within 18-24 inches of the Trunk

Yes

No?

Injections can be very useful to bypass mulch or fabric barriers

Injections also prevent the presence of surface residue of the applied insecticide

Soil applications of systemic insecticides should not be made if there are flowering plants at the application site

Modifying DBH-based rates by tree size

What rate of use for imidacloprid soil treatments?

• 1X rate = 1.4 grams active ingredient/inch trunk diameter

• Rates of use allowed in label directions– 75 WP formulation - 1X/application– 2F and 75WSP formulations - 1X up to 15

inches diameter; 2X in larger trees– Retail nursery formulations – 1/2X

• Limited to single application/year

1 ft.2 ft.

Area increases as the square of the width (diameter)

Example: A circle that is 2 ft. wide has an area 4X greater than a circle of 1 ft. diameter

Bottom line: Larger trees have proportionately much greater volume than do smaller trees. Insecticides used at rates based on DBH will be more diluted in larger trees.

Use of High or Low Rates of Imidacloprid?

Low Rates (1X, 1/2X)• Smaller trees• EAB populations

low, moderate• Spring

applications

High Rates (2X)• Large trees• High EAB

populations present (peak outbreak phase)

• Fall applications

Over-the-Counter Imidaclopridformulations have label use instructions that would allow EAB control only on small diameter trees

All Systemics Need Water

Soil drench Trunk sprays Trunk

injection

Water carries the pesticide

Conditions Optimizing Uptake and Distribution of Systemic Insecticides

• Soil is moist (but not saturated!)• Soil temperatures are above 450F• Ambient air temperatures are between

400-900F

In other words, conditions are most favorable to transpiration.

Fall Application vs. Spring ApplicationWhat are the Trade-offs with

Fall Applications vs. Spring Applications?

Take home message to me: Spring applications are more efficient in the use of soil applied imidacloprid than is a fall application to ash (a deciduous tree)

Another consideration with fall vs. spring applications of systemic insecticides?

Effects on potential residues present in nectar and pollen –residues much more likely if insecticides applied in fall

Pollinators and Systemic Treatments

Ash is Wind Pollinated and Dioecious

Male flowers (with pollen)

Female flowers (no pollen)

Is Ash Pollen from EAB Treated Trees a Threat to Bees?

Present evidence from the midwest suggests that ash pollen is collected infrequently and does not constitute a biologically significant source of possible neoniciotinoid exposure.

Willows

Maples, boxelder

Wind pollinated plants can be used as significant pollen sources by honey bees

Flowering ash (Fraxinus ornus), native to southern Europe, is an important pollen source for honey bees in Europe

Study in progressSurvey of pollen collected by honey bees

Question to answer: What are the important pollen sources used by honey bees in Colorado?

Soil Treatment Options for EAB

• Imidacloprid– Merit, Xytect, Criterion, Zenith, Bandit……

• 75WSP and 2F formulations– Several retail formulations now available

• Typically 1.47% liquid formulations

• Dinotefuran– Safari, Zylam, Transtect

Soil drench with dinotefuran (Safari, Zylam, Transtect)

Basal trunk spray with dinotefuran (Safari, Zylam)




327 5002950 4100

39830

0

10000

20000

30000

40000 Clothianidin

Imidacloprid

Acetam

iprid

Dinotefuran

Thiamethoxam


Koc Values of Neonicotinoids:

166

440

267245

260

Clothianidin

Imidacloprid

Acetam

iprid Dinotefuran

Thiamethoxam

Source Data: EPA Pesticide Fact Sheets

Basal Trunk Sprays of Dinotefuran

• Enters tree through thin areas of bark• Can be expected to reach peak levels in

foliage in about 2-3 weeks• Adjuvant? – May help some to increase

deposition into trunk fissures, slow drying

Whole tree sprays produce surface residues on all foliage. Natural enemies are killed. Natural controls are wasted.

Treatment area limited to bark of lower trunk. Impacts on natural enemies is minimalized




327 5002950 4100

39830

0

10000

20000

30000

40000 Clothianidin

Imidacloprid

Acetam

iprid

Dinotefuran

Thiamethoxam


Dinotefuran Trunk SpraysAdvantages

• Ease of application• Does not require

tree wounding• Rapid uptake

following application

• Applied after bloom (of ash)

Disadvantages• Requires annual

application• Use likely limited to

trees without thick bark

• Higher cost• High leaching

potential if put into soil

Potential of dinotefuran trunk sprays used on ash to affect pollinators

Applications made after flowering. Persistence is short (months). Potential of residues in pollen lower than all other EAB treatments.

Pollinators and Systemic Treatments

Recent Developments Affecting Neonicotinoids and Pollinators

• Description of several new sublethal effects of neonicotinoids on honey bees– Deleterious behaviors– Effects on susceptibility to other stressors

• Studies showing presence of neonicotinoids in plants is more widespread than previously known– Agricultural uses as seed treatment primarily– Chlothianidin mostly involved

• Better understanding that some insecticide is translocated into pollen and nectar

Possible Sublethal Effect of Pesticides on Honey Bee Behaviors

• Effects on activity (agitation, lassitude)• Effects on memory of foraged sources• Decision making when tasking• Increased susceptibility to pathogens

Note: These were experimental studies showing potential effects when exposure levels were sustained at high levels (>10 ppb).

2013 Oregon Bumble Bee Kills

Involved use of dinotefuran, applied shortly before bloom. Treatment timing produced high residues during bloom.

Soil Applied Systemic Insecticides and Honey Bees – Targets for Concern

• Plant is visited heavily by honey bees

• Plant is treated with persisting systemic insecticides for some pest insect

• Treatments are applied before bloom

Top honey bee-visited plants include: most Sedums, most thistles, catmint, Gaillardia, most Agastache, Blue mist spirea, Russian sage, fruit trees, linden, golden raintree ……..

My greatest concern about neonicotinoids and woody plants –Lindens*

*First stated in 2011

Flowering weeds in turfgrass treated with neonicotinoids?

Neonicotinoids and Pollinators: Bottom Line

Avoid applications to plants that bees visit that are in bloom – or soon will be in bloom

Systemic insecticides and honey bees???

Soil Applied Systemic Insecticides and Honey Bees – My Concern

• Plant is visited heavily by honey bees

• Plant is common in a location so many honey bees are visiting it

• Plant is treated often with soil applied systemic insecticides for some pest insect


My greatest concern about neonicotinoids and woody plants -Lindens

Flowering weeds in turfgrass treated with neonicotinoids?

Recent EPA Statements on Neonicotinoids and Honey Bees

• Development of newer methods to assess hazard to honey bees is needed

• Presently known information of hazard to honey bees does not reach threshold for withdrawal of registration withdrawals

• Accelerated reevaluation of neonicotinoid risks in progress



• Presently known information of hazard to honey bees does not reach threshold for withdrawal of registrations




• Presently known information of hazard to honey bees does not reach threshold for withdrawal of registration




• Presently known information of hazard to honey bees does not reach threshold for withdrawal of registration withdrawals


What Pesticides are Found associated with Honey Bees?

Agriculture applications vs. Beekeeper applications

Maximum Pesticide Residues Found in Pollen (parts per billion)

• Fluvalinate 2670• Coumaphos 5828• Chlorthalonil 98,900• Pyrethrins 62• Malathion 61• Methyl parathion

26,000

• Carbaryl 94,000• Permethrin 92• Esfenvalerate 60• Bifenthrin 13• Imidacloprid 912• Thiamethoxam 53

Fluvalinate and coumaphos are insecticides used in the hive by beekeepers to control pests of honey bees

Maximum Pesticide Residues Found in Honey (parts per billion)

• Fluvalinate 750• Coumaphos 2020• Chlorothalonil 10• Pyrethrins ND• Malathion 243• Methyl parathion 50

• Carbaryl 42• Permethrin 11• Esfenvalerate >1• Bifenthrin 3• Imidacloprid 29• Thiamethoxam ND

Maximum Pesticide Residues Found in Wax (parts per billion)

• Fluvalinate 204,000• Coumaphos 94,131• Chlorthalonil 53,700• Pyrethrins 237,000• Malathion 6,000• Methyl parathion

3085

• Carbaryl 820• Permethrin 372• Esfenvalerate 56• Bifenthrin 56• Imidacloprid 14• Thiamethoxam N.D.

Contributors in Declines of Honey Bees in North America

What Honey Bee Health Researchers are Saying• Varroa mite

– Sublethal effects from in-hive varroa mite treatments

• Extremely narrow genetic base of NA honey bees• New viruses (many vectored by Varroa mite)• Nosema ceranae, other new pests• Changes in symbionts/microbes from use of antibiotics by

beekeepers • Effects of fungicides on symbionts that contribute to food

utilization/immune response; synergizm of fungicides with insecticides possible

• Periodic movement and concentration of honey bees for crop pollination which allows transfer of pathogens

• Possibly some insecticides being used in agriculture, including neonicotinoids

Worst Day Ever for Apis mellifera

Varroa mite jumps from Apis cerana to the honey bee -1960s

Asian honey bee

Varroa mite

Varroa mite transferred from an Asian giant bee (Apis cerana) to honey bee in the past few decades.

The worst day in the history of the honey bee


What Honey Bee Health Researchers are Saying• Varroa mite

– Sublethal effects from in-hive varroa mite treatments

• Extremely narrow genetic base of NA honey bees• New viruses (many vectored by Varroa mite)• Nosema ceranae, other new pests• Changes in symbionts/microbes from use of antibiotics by

beekeepers • Effects of fungicides on symbionts that contribute to food

utilization/immune response; synergism of fungicides with insecticides possible

• Periodic movement and concentration of honey bees for crop pollination which allows transfer of pathogens

• Possibly some insecticides being used in agriculture, including neonicotinoids


• Transfer of the Varroa mite from Apiscerana to Apis mellifera – and subsequent spread to North America

• A very narrow genetic base of honey bees through inbreeding that has resulted in extremely deficient capabilities to handle environmental toxins


• Varroa mite• Poor genetics• Several new viruses, many vectored by

varroa mite– Deformed wing virus, Acute bee paralysis

virus, Israeli acute bee paralysis virus……. • Other pathogens/pests that have recently

been established in North America– Nosema ceranae, small hive beetle……


• Varroa mite• Poor genetics• New viruses• Nosema ceranae, other new pests• Sublethal effects of pesticides applied to

control Varroa mites• Changes in symbionts/microbes beneficial

to honey bee health that are disrupted by antibiotics (and maybe fungicides)


• Varroa mite• Poor genetics• New viruses• Nosema ceranae, other new pests• Sublethal effects of pesticides applied to

control Varroa mites• Changes in symbionts/microbes beneficial

to honey bee health that are disrupted by antibiotics (and maybe fungicides)


• Varroa mite• Poor genetics• New viruses• Nosema ceranae, other new pests• Varroa mite pesticides• Changes in symbionts/microbes from use of antibiotics

and fungicides

• Periodic concentration of NA honey bees for certain pollination needs (e.g., almonds)

All available NA bees are used to pollinate California almonds every year


• Varroa mite• Poor genetics• New viruses• Nosema ceranae, other new pests• Varroa mite pesticides• Changes in symbionts/microbes • Periodic movement and concentration of

honey bees • Possibly some insecticides being used in agriculture,

including neonicotinoids

Neonicotinoids and Pollinators –Should we be concerned about their use on landscape plants?

Take Action to Protect Pollinators

• Prevent pesticide uses that pose significant risks to pollinators– Avoid uses on high risk plants– Avoid uses that allow exposure of pollinators

to pesticides• Promote practices that improve habitat for

pollinators– Improve food resources– Improve nesting habitat (solitary bees)

Neonicotinoids and Pollinators: Primary Precaution

Avoid applications to plants that are in bloom – or soon (weeks, months?) will be in bloom


Nesting habitat may be limiting activity of many native bees (leafcutter bees, mason bees)

The Bees Needs Project –University of Colorado, Boulder

Excellent publication on how to improve habitat for native pollinators

This presentation will be posted at the Insect Information web site

• Housed at Department of Bioagricultural Sciences and Pest Management– Search “BSPM CSU”

• Within “Extension and Outreach”• “Insect Information”

– Extension presentations for 2014 posted at bottom of page

Documents

Neonicotinoid Insecticides - …webdoc.agsci.colostate.edu/bspm/Garden Center Talk July 2014.pdfNeonicotinoid Insecticides Use Characteristics – and Intersections with Pollinators