Mode of Action of Insecticides (Vegetable Crops)

Dr. Ayanava MajumdarExtension Entomologist (Peanuts, Vegetables)

State SARE Coordinator (Auburn U)Alabama Cooperative Extension System

Cell phone: 251-331-8416bugdoctor@auburn.edu

Quick survey by a raise of hands…

How many participants…– Were here last year?– Conventional vegetable/fruit producers? – Organic vegetable/fruit producers?– Backyard fruit/vegetable gardeners?

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www.aces.edu/go/87

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Major Insect Pests – Sentinel Plots (2010 - A drought year)

Tomato hornworm, Manduca quinquemaculata

Colorado potato beetleLeptinotarsa decemlineata

Brown stink bug, Euschistus servus Aphid outbreak

on bell pepper

GrasshopperYellowstriped armyworm, Spodoptera ornithogalli

Major Insect Pests – Sentinel Plots (2010 - A drought year)

Spider mites (Tetranychus sp.)

Beet armyworm, Spodoptera exigua

Fall armyworm, Spodoptera frugiperda

Tomato fruitworm, Helicoverpa zea

Major Insect Pests – Sentinel Plots (2010 - A drought year)

Squash vine borer, Mellitia cucurbitae Sugarcane borer,

Euetheola rugiceps

Tomato hornworm, Manduca quinquemaculata

Emerging Pest on Vegetables: Leaffooted Bugs

Leptoglossus phyllopus

Leptoglossus zonatus

Leptoglossus gonagra

Heavy fruit drop in eggplants and tomatoes (LFBs)

Emerging Crop Pests: Invasive Insects

Brown marmorated stink bug, Hyalomorpha halys

Bean plataspid, Megacopta cribrariaDetected in AL in 2010Seeks shelter in homesInfests kudzu, soybean…what’s next? UGA Photos

Why practice IPM?• Economic & environmental sustainability principle

• Integrated pest management (IPM): a threshold-based decision management system that uses multiple pest control tactics.

• Impact of vegetable IPM adoption: $19 return per $ spent*

• Profits with IPM: $247 per acre (ACES survey)

*L. Gianessi, 2009. Crop Protection Research Institute.

Insecticide usage in AL (all crops): ~770,000 lb/year

Major Issues with IPM

• Poor crop selection = stressed plants = more pests

• Lack of early detection of insects = last minute decision = over dependence on insecticides

• Insecticide resistance

• Pest resurgence

• Environmental impact

….IPM is unsustainable if it is ‘pesticide intensive’

Knowledge of insecticide MoA essential to successful IPM adoption!

Insecticide Mode of Action (MoA)

Receiving neuron

Sensory neuron

Neonicotinoids, Spinosyn (mimic neurotransmitter)

Cyclodienes, Pyrethroids (act on receiving neuron)

Carbamates, OP (act in the synaptic gap)

Inhibit enzyme that breaks down neurotransmitter

Flow of info

Insecticide Resistance Action Committee (IRAC): 28 MoA classification

Trends in synthetic insecticidal chemistries

• Early insecticides were short chain>>quick activation• New insecticides: need “activation” by insect enzyme

systems (target-specific)

CarbarylMalathion

Zeta-cypermethrin Imidacloprid

Spinetoram

Chlorantraniliprole

Review of Insecticides/MoA (Open page 182 of Veg. Prod. Handbook)

Mode of ActionSt = Stomach poisonCo = Contact poisonSys = Systemic actionIn = InsecticideMi = Miticide

Insecticide arrangement on slides: Least toxic to most toxic AI

Make sure to read PESTICIDE LABEL before using!

Common name Product Pesticide type OralLD50 (mg/kg)

Carbaryl Sevin In, Ac (St, Co) 300

Methamidophos Monitor In, Ac(Sys) 16

Methomyl Lannate In, Ac (Sys, Co) 17

IRAC Chemical class: 1A (Carbamates) MoA: inhibitor of enzyme (AChE), hyperexcites insects, nonselective

Common name

Product Pesticide type

OralLD50 (mg/kg)

Malathion Malathion In (Co) 1000+Acephate Orthene In (Sys) 800+

Diazinon Diazinon (RUP)

I (Co) 400

Chlorpyrifos Lorsban In (Co) 95

IRAC Chemical class: 1B (Organophosphates) MoA: inhibitor of enzyme (AChE), hyperexcites insects

Common name Product Pesticide type

OralLD50 (mg/kg)

Best against

Endosulfan ThionexThiodan (GUP)

In, Ac (Co)

18-160 FB, SB, SqB

IRAC Chemical class: 2A (Cyclodienes)

MoA: Block the action of neurotransmitter, hyperactivity

CANCELLED IN JULY 2010

Common name Product Pesticide type Oral LD50 (mg/kg)

Cyfluthrin Baythroid In (Co, St) 1200+

Gamma cyhalo Proaxis In (Co) -

Fenpropathrin Danitol In, Ac (Co, St) 450

Zeta-cyper Mustang Max In (Co) 150-400

Bifenthrin Brigade In, Ac (Co) 54

IRAC Chemical class: 3A (Pyrethroids) MoA: Act on sodium channels (receiving neuron)

Contact/stomach: use for quick knock-down, nonselective

Common name

Product Pesticide type

OralLD50 (mg/kg)

Thiamethoxam Platinum In (Sys) >5000Dinotefuran Venom In (Sys) >5000Clothianidin Belay In (Sys) 4700Imidacloprid Admire

Provado

In (Sys, Co, St)

450

Acetamiprid Assail In (Sys) -

IRAC Chemical class: 4A (Neonicotinoids) MoA: Mimic neurotransmitter at neuromuscular joints, hyperactivity Systemic action: many weeks of protection against pests, apply early

Common name Product Pesticide type

OralLD50 (mg/kg)

Spinosyn A, D Entrust (SpinTor phase out)

In (St) >5000

Spinetoram Radiant In (St) >5000

IRAC Chemical class: 5A (spinosyn) MoA: Mimic neurotransmitter, hyperexcites insects

Spinetoram (Radiant 1SC):• Microbial fermentation derivate• Application rate = 6-8 oz• Preharvest interval (PHI) = 1-3 days• Registered for many leafy veg., fruit crops, root crops…

Entrust: excellent for ORGANIC producers

Common name Product Pesticide type

OralLD50 (mg/kg)

Pymetrozine (9B) Fulfill In (St) >5000

Flonicamid (9C) Beleaf In(St) >2000

IRAC Chemical class: 9 (new chemistry)

MoA: Unknown; selective homopteran feeding blockers

Fulfill 50WDG (Syngenta):

• Selective insecticide for aphid control

• Good residual, rainfast

• Application rates low: 2-2.8 oz/acre

• PHI = 0 days

Common name Product Pesticide type

OralLD50 (mg/kg)

Chlorantraniliprole Coragen In (St, Co, Sys)

>5000

Flubendiamide Synapse In (Sys) >2000

IRAC Chemical class: 28 (new chemistry - diamides) MoA: Ryanodine receptor modulators (acts inside muscles)

Diamides:• Rapid inhibition of feeding, paralysis• Selective + contact/stomach action• No aphid or mite flaring• Appl. rate = 3-5 oz (Coragen), 2-3 oz (Synapse)• 1 day PHI

Growth Regulators

Common name Product Pesticide type

OralLD50 (mg/kg)

Methoxyfenozide Intrepid 2F I (Co) >5000Buprofezin Courier I, Mi (Co) >5000Pyriproxifen Knack I (Co) >5000

IRAC Chemical class: 7C, 16, 17, 18

Growth regulators:• Methoxyfenozide forces molting, long-lasting, 4-10 oz, 1 day PHI

• Buprofezin inhibits chitin biosynthesis (homopteran), 9-13 oz, 7 day PHI

• Pyriproxifen mimics juvenile hormone (homop.), 8-10 oz, 14 day PHI

Suggestions• Use pheromone traps (first detection is important)• No substitute for scouting!• Insecticides for rescue treatments only• Careful with insecticide generics (phytotoxicity)• Integrate using newer insecticides (IPM):

• Diamides with drip irrigation• Rotate pyrethroids with spinosyns, IGRs• Apply systemic insecticides timely

• Use the SE Vegetable Prod. Handbook & call for help!• Come to the Regional Ext., ASAN meetings

Mode of Action of Insecticides (Vegetable Crops)

QUESTIONS FOR DR. A?Return feedback surveys before you go home!