The Benefits of Agrochemical Research: Case Study of Imidacloprid Sujatha Sankula & Leonard Gianessi National Center for Food and Ag. Policy Washington, DC

Agrochemical categories

Herbicides (47%) Insecticides (29%) Fungicides (18%) Fumigants & growth regulators (6%)

Agrochemicals are necessary to…

  

Prevent yield losses Ensure quality Make crop production easier & cheaper

Crop yield response to agrochemicals Without agrochemical use ; With agrochemical use 80 60 40 20 0 Corn Soybean Potato Wheat Cotton Rice

Area farmed globally for food production in 2000 4 1 0 3 2 With agrochemicals Without agrochemicals

Global value of agrochemicals in 1998

$31.25 billion (crop uses) $10.5 billion (non-crop uses)

Worldwide crop protection markets in 2001 8000 6000 4000 2000 0 U SA Ja pa n B ra zi l Fr an ce C hi na G er m an y C an ad a A rg en tin a It al y UK In di a A us tr al ia Me xi co

Goal of a grochemical research To discover, develop, and understand new products for the safe and effective pest control and to maximize food production

Agrochemical discovery & development programs are driven by:



Population growth



Food and health needs



Pest resistance issues



Safety considerations



Economic incentives



Replacements and phase-outs

Recent setbacks to agrochemical discovery programs:



Fewer players



Large investments



Great risks



High stakes



Economics



Higher standards of potency and safety

Insecticide categories

Organic (eg. DDT, chlorpyriphos) Botanicals (eg. pyrethrum, nicotine) Inorganic (eg. boric acid, sulfur)

Market dominance of commercial insecticide categories Category Inorganics Botanical Synthetic organics # 8 5 192

Major insecticide classes by importance as of 1995 Class ~ Entry year Chlorinated hydrocarbons Organophosphates Methylcarbamates Pyrethroids Benzoylureas Others 1947 1965 1969 1979 1983 1982 Market value (%) 5 34 20 23 5 8

Human toxicity and insect resistance to the first generation neuro-active insecticides such as carbamates and OPs led to the search for new agrochemicals Significant discovery - Imidacloprid

Imidacloprid

Classification: Chloronicotinyl First registered insecticide in its class Year of registration in US: 1995

World sales of top selling pesticides in 2001

Glyphosate Imidacloprid $2.4 billion $540 million Source: PANUPS 2002

Structural comparison of nicotine and imidacloprid

Characteristics of imidacloprid

Novel mode of action Broad spectrum of activity Favorable environment fate

Mode of action of imidacloprid

Binds to nerve receptors called nicotinic acetylcholine receptors (nAChRs), interferes with the transmission of stimuli in the insect nervous system leading to the accumulation of acetylcholine resulting in paralysis.

Site of action is different than other insecticides to which insects developed resistance.

Low toxicity to vertebrates due to low binding to nACh receptors.

Imidacloprid provides a broad spectrum of activity against:

Sucking insects (leaf and plant hoppers, aphids, thrips, whiteflies, scales, and plant bugs) Some coleopteran insects (CPB, leaf beetles) Select lepidopteran and dipteran insects No activity on mites and nematodes

Imidacloprid has both contact and systemic action.

Imidacloprid can be applied as a soil, seed, or foliar treatment.

Readily absorbed by plant roots and transmitted through xylem.

Effective at low rates than conventional insecticides (0.33 lb versus 1-2 lb of OPs)

Trade names of imidacloprid

Gaucho (seed treatment) Admire (soil applied) Provado (foliar)

Use range of imidacloprid

Potato Tomato Broccoli Apple Grape Citrus Lettuce Sugarbeet Cotton Tobacco Corn Hops Rice

Impacts of imidacloprid on US crop production

Silverleaf whitefly

First discovered in 1986 in FL Widespread damage in 1991 in CA and AZ Reduction in planted crop acreage Yield and quality losses; transmits viruses (ToMoV and YLCLV)

Silverleaf whitefly is a billion dollar pest

Primary hosts of silverleaf whitefly

Broccoli Cauliflower Cabbage Lettuce Melons Cucumbers Tomatoes Cotton

Silverleaf whitefly management

Three classes of effective insecticides (pyrethroids, OPs, & chlorinated hydrocarbons) Most common combination: bifenthrin + endosulfan (2-3) fb. esfenvalerate + endosulfan (1-3) No residual control and periodic treatments (4-6 sprays) Insect resistance to three chemical classes

Section 18 permits for imidacloprid (Admire) in California

Broccoli/Cauliflower Lettuce Cucurbits Tomatoes

First issue Reissue

1993 1993 1995 1994 1994 1994 1997 -

Vegetable production statistics for CA 2001 Acreage (% of US total)

Broccoli Lettuce Cauliflower Tomato Cantaloupe 92 71 (head) 88 (leaf) 89 32 (fresh) 92 (processed) 58

Use of imidacloprid (Admire) in California in 1995 80 40 0 Br oc col i C au lifl ow er H ead le ttu ce Le af l ettu ce Fr es h toma to C an tal ou pe

Impacts of imidacloprid (Admire) on CA crop production

Number of insecticide applications with Admire and next best alternative 6 4 2 0 Br oc col i C au lifl ow er H ead le ttu ce Le af l ettu ce Fr es h toma to C an tal ou pe

Cost of insecticide programs with Admire and next best alternative 250 200 150 100 50 0 Br oc col i C au lifl ow er H ead le ttu ce Le af l ettu ce Fr es h toma to C an tal ou pe

Yield increase due to Admire compared to traditional alternatives in CA 5 4 3 2 1 0 Broccoli Cauliflower Head lettuce Leaf lettuce Cantaloupe

Value of delayed planting

Warm weather: heavy whitefly pressure Growers shift the planting date to cooler periods to avoid peak infestations Imidacloprid facilitated marketing at the height of infestation

Increase in grower benefits due to delayed planting facilitated by Admire 10 8 6 4 2 0 Broccoli Cauliflower Head lettuce Fresh tomato Cantaloupe

Impact of imidacloprid on insecticide use in FL fresh tomato for whitefly and other sucking pest control

Buprofezin Chlorpyrifos Endosulfan Esfenvalerate Imidacloprid Methamidophos Methomyl Permethrin

1992 2000 ------------- lb --------------

2000 22,000 89,000 5,700 34,900 2,200 74,500 47,100 10,900 8,400 9,100 8,000 Total 249,200 64,600

Colorado Potato Beetle

Green peach aphids

Insecticide use: CPB/aphids

• •

1920’s - 1940’s 1950’s - 1960’s

•

1970’s - Present Lead arsenate DDT, Parathion, Endrin Aldicarb, Phorate, Methamidophos, Carbofuran, Endosulfan Permethrin

CPB management problems

CPB resistance to all synthetic insecticides registered for use Cross-resistance of CPB between insecticide classes Imidacloprid – unrelated chemistry and thus a new tool in resistance management programs

Imidacloprid treated potato acreage (%) in 1999

Idaho Maine Michigan Minnesota North Dakota Oregon Pennsylvania Washington Wisconsin 8 90 93 70 68 35 81 4 74

Leading insecticides used for CPB control in 2001 (in order of importance) Imidacloprid Carbofuran Permethrin Phorate Esfenvalerate Endosulfan Methamidophos Azinophos-methyl Aldicarb Methyl parathion Dimethoate

Reduction in insecticide use following imidacloprid use in potato (1994 –1999) 80 40 0 Maine Michigan Source: NASS

Pierce’s disease on grapes

Sharpshooters Bluegreen Glassy-winged

Pesticides registered for sharpshooter control

Dimethoate Kaolin Imidacloprid (Admire) Average use rate (lb/A) 1.32

23.75

0.05

Other grape insects controlled by Admire

Grape mealybug Vine mealybug Leafhopper Phylloxera

Insect management problems in citrus in

CA

and

FL Glassy-winged sharpshooter (overwintering host) California red scale (resistant to OP &carbamates) Citricola scale (increasing in problem) Brown citrus aphid (vectors citrus tristeza virus)

Use of imidacloprid on citrus (Section 18 in

CA

and

FL

)

Glassy-winged sharpshooter CA red scale Citrus brown aphid Citrus leaf miner

Cotton pest problems Escalation of secondary pest problems Insecticide resistance

Losses due to aphids in CA cotton in 1997 Aphids All insects and mites Crop loss Control costs --------------- Million $ ---------------- 34 66 38 167

Imidacloprid treated cotton acreage in California 80 40 0 1995 1996 1997 1998 Source: NASS

Summary

Sucking pests have not been a significant problem to growers in the recent years, largely because of the advances in agrochemical research that resulted in the development of imidacloprid.

American growers were able to increase crop yields, reduce crop production costs, and insecticide use following the introduction of imidacloprid.

No agrochemical is immune to problems.

Conclusions

With the increasing safety and environmental concerns, there will be loss of some agrochemicals. Search for replacement products that can live up to both regulatory and grower standards necessitates continued agrochemical research. Agrochemical research should continue to meet the increasing demands of growing population.

Continued agrochemical research will provide solutions to evolving pest and their management problems.

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