Neonicotinoid Insecticides for Ornamentals The Good, Bad and Ugly Catharine Mannion University of Florida, IFAS Tropical Research and Education Center Neonicotinoids Insecticides

• Use of these • Acetamiprid insecticides has grown • Clothianidin considerably since the forerunner of the group • Dinotefuran (imidacloprid) was first • Imidacloprid introduced in the early 1990’s • Thiamethoxam • Nitempyram • Seven neonicotinoid insecticides • Thiacloprid Neonicotinoid Insecticides What do We Know

• Systemic • Effective against sucking insects but also some chewing insects • Rates tend to be lower than traditional insecticides • Labeled as “Warning” or “Caution” • IRAC Mode of Action –4A Neonicotinoid Insecticides What do We Know • Act on the insect central nervous system • Mode of action is similar to that of nicotine • Both nicotine and neonicotinoids act on an acetylcholine receptor; but neonicotinoids act on a unique receptor in insects making it less toxic to mammals which is unlike nicotine which is more selectively toxic to mammals SPECIFICITY OF NEONICOTINOIDS FOR α4β2 NICOTINIC RECEPTORS IC* nM Selectivity Neonicotinoid 50 Insect Vertebrate Ratio Acetamiprid 8.3 700 84 Clothianidin 2.2 3,500 1,591 Dinotefuran 900 >100,000 >111 Imidacloprid 4.6 2,600 565 Nicotine 4000 7 0.002 *Concentration of neonicotinoid or nicotine that produces 50% inhibition of the nicotinic receptor (Tomizawa and Casida, 2005) What are the Variables Associated with Successful Applications?

Type of Plant Growing Environment (container, field, greenhouse, landscape, etc)

Target Pest(s)

Application Method (foliar, drench broadcast, injection, etc)

Ecological Considerations (runoff, leaching, non-targets) What are the Variables Associated with Successful Applications? Speed of Uptake and Persistence

• Target pest • Acid dissociation

differences constant (pKa) • Half‐life of the • Octanol‐Water insecticide (in soil Coefficient

and water) (Log P or Log Kow) • UV stability • Water solubility • Light intensity • Soil adsorption • Transpiration rate UV Stability of Neonicotinoids

Slide Credit: Presentation by C. Sclar, Longwood Gardens Data obtained from published EPA registration documents (R. Fletcher) pKa and Log P (Log Kow) Values for Neonicotinoids Neonicotinoid Acid Dissociation (AI) Constant Log P Acetamiprid 0.7 0.8

Clothianidin 11.1 0.7

Dinotefuran 12.6 ‐0.64

Imidacloprid “weak base” 0.57

Thiamethoxam n/a ‐0.13

Slide Credit: C. Sclar; F. Byrne Relative Water Solubility of Neonicotinoids

Slide information courtesy C. Sclar. Longwood Gardens Summary of Characteristics

Neonicotinoid pKa Log P Koc Water A.I. (Log Kow) Sol. Acetamiprid Low High Med. High

Clothianidin High High Med. Low

Dinotefuran High Low Low Very High Imidacloprid None? High High Low

Thiamethoxam None Low Med. High

Slide information courtesy C. Sclar. Longwood Gardens Some Generalizations…

Neonicotinoid Relative Speed Relative Rate A.I. of Uptake of Persistence Acetamiprid Fast Short – Mod.

Clothianidin Slow (?) Mod. – Long

Dinotefuran Fast Short – Mod (?)

Imidacloprid Slow (?) Long

Thiamethoxam Med(?) – Short – Mod. (?) Fast Slide information courtesy C. Sclar. Longwood Gardens Acetamiprid

• Trade name: Tristar 30SG (Caution) • For use on ornamental and flowering plants grown outdoors and in greenhouses, shadehouses and lathhouses • Not for homeowner use • Application: Foliar only Clothianidin • Arena 50WDG; – Turfgrass, sod farms, landscape ornamentals, interiorscapes, and non‐bearing fruit and nut trees in the landscape – Drench, broadcast, foliar • Aloft G or SC –contains clothianidin and bifenthrin – Turf and landscape ornamentals around residential, institutional, public, commercial, and industrial buildings, parks, recreational areas, athletic fields and sod farms (specific labels for golf courses) – Drench, broadcast, foliar Dinotefuran

• Safari 20 SG; 2G • For greenhouse, nursery, interiorscapes and outdoor landscapes • Application – foliar, broadcast, soil drench, soil injection, micro‐irrigation, drip irrigation, overhead irrigation, ebb and flood, trunk spray Imidacloprid • Merit 75WP; 75WSP, 2F, 0.5G – Commercial and residential landscapes and interiorscapes – Foliar and soil applications • Marathon II, 60 WP, G – Greenhouses, nurseries and interiorscapes – Foliar and soil applications • CoreTect – Landscapes, interiorscapes, forested areas – Soil application Imidacloprid • Discus – Field and container nurseries – Combined with a pyrethroid (cyfluthrin) – Foliar, soil injection, soil drench • Allectus SC – Turfgrass and landscape of residential lawns, commercial, industrial, institutional, and recreational areas (Not golf courses or sod farms) – Combined with a pyrethroid (bifenthrin) – Foliar, broadcast, drench, soil injection, Thiamethoxam • Flagship 25 WG – Greenhouses, lath and shadehouses, containers, field nurseries – Foliar, broadcast, drench, chemigation, • Meridian 25WG; 0.33G – Turfgrasses on golf courses, residential lawns, commercial grounds, parks, playgrounds, athletic fields and sold farms and ornamentals plants in residential and commercial landscapes, parks, golf courses and interiorscapes – Foliar, broadcast, drench, soil injection Methods of Application There are numerous options on how to apply the neonicotinoids; • Take advantage of the different methods • Take advantage of the different formulations • Fit the method of application for the site • The site and method needs to be on the label • Consider the methods that gets the needed result with the least negative impact on the environment/non‐targets Ornamental Pest Management with Neonicotinoids

Key ornamental pests – Scales – Mealybugs – Whiteflies – Thrips Ornamental Pest Management with Neonicotinoids Examples from South Florida 1. Differences in efficacy 4. Avoiding unnecessary – Cycad aulacaspis applications scale – Ficus thrips – Asian citrus psyllid 5. Soil versus drench 2. Differences due to host – Ficus whitefly stage 6. Insecticide rate – Diaprepes root weevil – Ficus whitefly 3. Difference due to host plant – Lobate lac scale 1. Examples of Differences due to Efficacy • Cycad aulacaspis scale – Dinotefuran and acetamiprid were more efficacious than imidacloprid • Asian citrus psyllid – As foliar sprays, two neonicotinoid products that also contained a pyrethroid and (Discus and Allectus) and thiamethoxam (Flagship) provided longer control than others testes – Not much differences among products used as a drench – Longer control with drenches versus foliar application Management of Cycad Aulacaspis Scale in Florida • Pest of numerous cycads • Fronds eventually become brown and desiccated; ultimately causing plant death Pesticide • Oils – Ultra fine horticultural Oil Options – Oganocide • Insect growth regulators – Distance • Foliar insecticides – Orthene – Malathion – Safari – TriStar • Soil insecticides – Safari Management of Cycad Aulacaspis Scale Control

Merit‐drench Distance ‐foliar

Dimethoate‐foliar

Merit‐foliar Organocide

Dimethoate‐drench Management of Cycad Aulacaspis Scale 100

80

60 Mortality

40

Percent 20

0 0 6 12 18 25 32 Days After Application Control Allect Merit (drench) Merit (foliar) Discus Merit (foliar+drench) Management of Asian Citrus Psyllid (Diaphorina citri)on Orange Jasmine • Vectors citrus greening disease • Pest of citrus and closely related plants 2nd spray application

Percent Mortality of Asian Citrus Psyllid on Orange Jasmine 100

90

80 control

70 Flag 4oz 60 Flag 6oz 50

40 Flag 8oz

30 Flag drench 20 4oz Flag drench 10 8oz 0 2 dat 5 dat 8 dat 38day 12 dat 15 dat 74 day 68 day 59 day 53 day 45 day 29 day 22 day 19 day 2. Examples of Differences Due to Stage of Insect • Diaprepes root weevil – Differences in efficacy of medium (5‐6th instar) larvae among 3 products (imidacloprid, imidacloprid + cyfluthrin, and dinotefuran; however, with larger larvae (9th instar), no difference – One neonicotinoid (dinotefuran) provided control of adults when applied as a drench Management of Diaprepes Root Weevil in Florida • Major pest of citrus, sugarcane, ornamentals, root crops • Regulatory risk – all stages are commonly spread on infested plant material Recovered Live Diaprepes Root Weevil Larvae (5‐6th instar) Recovered Live Diaprepes Root Weevil Larvae (9th instar) Percent Adult Mortality after Feeding on Foliage from Plants Treated with Insecticides 3. Examples of Differences Due to Stage of Insect • Lobate lac scale – efficacy between two neonicotinoids was different on two host plants Management of Lobate Lac Scale in Florida • A pest on more than 300 tropical and subtropical fruits and ornamentals

• Causes branch dieback and sometimes plant death Management of Lobate Lac Scale in Florida

Evaluated 8 weeks after 1st application

Drench application Foliar application UF/IFAS 4. Example of a Comparison with a Non‐ neonicotinoid and Avoiding Unnecessary Applications

• Ficus thrips – No differences among products when populations were low; – Similar efficacy with a non‐neonicotinoid insecticide Ficus Thrips (Gynaikothrips uzeli) • First noted in 2003 due to heavy damage on Ficus benjamina in south Florida • Feeding causes sunken, reddish spots on leaves. Leaves tend to curl and fold inward. MREC

UF/IFAS

Photos:

5. Examples of Differences Due Method of Application • Ficus whitefly – Soil applications provided longer control Management of Ficus Whitefly (Singhiella simplex) in Florida • New continental record • Causes severe leaf drop; branch dieback Ficus Whitefly • “Panic situation” • Continuing to spread in the landscape and nurseries • Management –Nursery • Established whitefly program • Management – Landscape – Homeowner (over‐the‐counter products) – Commercial applicators – High potential for overuse – Potential for disruption of natural enemies Control of Ficus Whitefly Control of Ficus Whitefly Control of Ficus Whitefly Control of Ficus Whitefly Control of Ficus Whitefly Control of Ficus Whitefly Control of Ficus Whitefly Control of Ficus Whitefly Control of Ficus Whitefly Soil and Foliar Applications 6. Example of Differences Due Rate of Application • In this situation, there were no differences in the two products tested or in the rate that was used of each product Exotic Soft Scale (Hemiptera: Coccidae)

• 2008 – Reported from Monroe County on croton • Continues to spread and now found in several southern Florida Counties • New to science; it is has been described as a new genus and species • Hosts – Numerous ornamental and fruit host ; many native plants in Florida Photo: H. Glenn, UF/IFAS Control of Croton Scale Ornamental Pest Management with Neonicotinoids • Very useful, important group of compounds • No, they do not always work • Consider the differences among the different ai’s, formulations, and methods of application and use to your advantage • Recognizing – When, where and how to use them – Recognizing “added” benefits – Manage the “popularity” of these products – Recognizing situations for overuse or misuse Web Resources

• http://trec.ifas.ufl.edu/mannion • http://mrec.ifas.ufl.edu/lso/IAWG/ • http://edis.ifas.ufl.edu/ • http://creatures.ifas.ufl.edu/ • Pest Alerts – University of Florida (http://extlab7.entnem.ufl.edu/pestalert/) – DOACS (http://doacs.state.fl.us/~pi/enpp/pi- pest-alert.html) Catharine Mannion Research and Extension Specialist Ornamental Entomology

University of Florida, IFAS Tropical Research and Education Center 18905 SW 280th Street Homestead, FL 33031

305-246-7000 [email protected] http://trec.ifas.ufl.edu/mannion