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Neonicotinoid Insecticides for Ornamentals The Good, Bad and Ugly Catharine Mannion University of Florida, IFAS Tropical Research and Education Center. Neonicotinoids Insecticides. Acetamiprid Clothianidin Dinotefuran Imidacloprid Thiamethoxam Nitempyram Thiacloprid.
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Neonicotinoid Insecticides for Ornamentals The Good, Bad and Ugly Catharine Mannion University of Florida, IFAS Tropical Research and Education Center
Neonicotinoids Insecticides • Acetamiprid • Clothianidin • Dinotefuran • Imidacloprid • Thiamethoxam • Nitempyram • Thiacloprid • Use of these insecticides has grown considerably since the forerunner of the group (imidacloprid) was first introduced in the early 1990’s • Seven neonicotinoid insecticides
Neonicotinoid InsecticidesWhat 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 InsecticidesWhat 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
What are the Variables Associated with Successful Applications? Growing Environment (container, field, greenhouse, landscape, etc) Type of Plant Target Pest(s) Application Method (foliar, drench broadcast, injection, etc) Ecological Considerations (runoff, leaching, non-targets)
What are the Variables Associated with Successful Applications? How fast will it work? How long will it last?
Speed of Uptake and Persistence • Target pest differences • Half-life of the insecticide (in soil and water) • UV stability • Light intensity • Transpiration rate • Acid dissociation constant (pKa) • Octanol-Water Coefficient (Log P or Log Kow) • Water solubility • Soil adsorption
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 Slide Credit: C. Sclar; F. Byrne
Clothianidin Acetamiprid Dinotefuran Imidacloprid Thiamethoxam Relative Water Solubility of Neonicotinoids Slide information courtesy C. Sclar. Longwood Gardens
Summary of Characteristics Slide information courtesy C. Sclar. Longwood Gardens
Some Generalizations… 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 NeonicotinoidsExamples from South Florida • Differences in efficacy • Cycad aulacaspis scale • Asian citrus psyllid • Differences due to host stage • Diaprepes root weevil • Difference due to host plant • Lobate lac scale • Avoiding unnecessary applications • Ficus thrips • Soil versus drench • Ficus whitefly • Insecticide rate • Ficus whitefly
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 Options • Oils • Ultra fine horticultural Oil • Oganocide • Insect growth regulators • Distance • Foliar insecticides • Orthene • Malathion • Safari • TriStar • Soil insecticides • Safari
Control Merit-drench Distance -foliar Dimethoate-foliar Merit-foliar Organocide Dimethoate-drench
Management of Asian Citrus Psyllid (Diaphorina citri)on Orange Jasmine • Vectors citrus greening disease • Pest of citrus and closely related plants
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
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. Photos: UF/IFAS MREC
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