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

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 Theoretical attainable yield Without agrochemical use; With agrochemical use

Area farmed globally for food production in 2000 Billion ha

Global value of agrochemicals in 1998 $31.25 billion (crop uses) $10.5 billion (non-crop uses)

Worldwide crop protection markets in 2001 Sales in mil. $

Goal of a grochemical research 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: Agrochemical discovery & development programs are driven by: è Population growth è Food and health needs è Pest resistance issues è Safety considerations è Economic incentives è Replacements and phase-outs

Recent setbacks to agrochemical discovery programs: Recent setbacks to agrochemical discovery programs: è Fewer players è Large investments è Great risks è High stakes è Economics è 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 # Category # Inorganics 8 Botanical 5 Synthetic organics 192

Major insecticide classes by importance as of 1995 Class ~ Entry year Market value (%) Class ~ Entry year Market value (%) Chlorinated hydrocarbons Chlorinated hydrocarbons Organophosphates Organophosphates Methylcarbamates Methylcarbamates Pyrethroids Pyrethroids Benzoylureas Benzoylureas Others Others

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$2.4 billion Imidacloprid$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 interferes 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 Site of action is different than other insecticides to which insects developed resistance. 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 has both contact and systemic action. Imidacloprid can be applied as a soil, seed, or foliar treatment. 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 PotatoApple TomatoGrape BroccoliCitrus LettuceCorn SugarbeetHops CottonRice Tobacco

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 issueReissue

Vegetable production statistics for CA Broccoli92 Lettuce 71 (head) 88 (leaf) Cauliflower89 Tomato32 (fresh) 92 (processed) Cantaloupe Acreage (% of US total)

Use of imidacloprid (Admire) in California in 1995 % treated acreage

Impacts of imidacloprid (Admire) on CA crop production

Number of insecticide applications with Admire and next best alternative # treatments

Cost of insecticide programs with Admire and next best alternative Cost of programs ($)

Yield increase due to Admire compared to traditional alternatives in CA % yield increase

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 % increase

Impact of imidacloprid on insecticide use in FL fresh tomato for whitefly and other sucking pest control Buprofezin Chlorpyrifos22,000 - Endosulfan89,000 34,900 Esfenvalerate 5,700 2,200 Imidacloprid - 8,400 Methamidophos74,500 9,100 Methomyl47,100 - Permethrin10,900 8,000 Total249,200 64, lb

Colorado Potato Beetle

Green peach aphids

Insecticide use: CPB/aphids 1920’s ’sLead arsenate 1950’s ’sDDT, Parathion, Endrin 1970’s - PresentAldicarb, 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 8 Maine90 Michigan93 Minnesota70 North Dakota68 Oregon35 Pennsylvania81 Washington 4 Wisconsin74

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) % reduction Source: NASS

Pierce’s disease on grapes

Glassy-winged Bluegreen Sharpshooters

Pesticides registered for sharpshooter control Dimethoate 1.32 Kaolin23.75 Imidacloprid 0.05 (Admire) Average use rate (lb/A)

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 Crop loss Control costs Aphids3438 All insects and mites Million $

Imidacloprid treated cotton acreage in California % treated acres 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.