Catch-22. What are the Benefits of Pesticides? Economics of Pesticide Use. What are the Benefits of Pesticides? What are the Benefits of Pesticides?

Transcription

1 Economics of Pesticide Use What are the Benefits of Pesticides? Despite well-deserved demonization, pesticides have many benefits e.g. Americans pay less of their income on food (7-8%), than any other country even though they eat more Attributed to efficient agricultural industry However, may want to consider subsidies and fast food culture What are the Benefits of Pesticides? In 1850, each US farmer produced enough food for themselves and 3 other people 1950 = farmer + 24 others 1970 = farmer + 45 others 1990 = farmer + 78 others 2000 = farmer others (94 in USA and 34 abroad) What are the Benefits of Pesticides? Still, 1/4 of world s population undernourished Up to 1/3 in underdeveloped nations In USA, agricultural losses to pests 20-25% Would be double without pesticides Consequences of Giving up Pesticides Farming costs increase 2) Average consumer cost increases 3) Need to increase manual labour on farms 4) Farm exports reduced 5) Need to increase acreage vastly (+ 400M acres) Catch-22 Modern agricultural and forestry practices encourage pest and disease Large acreage, monoculture, row planting etc.) Therefore, advanced food and fibre production actually increases need for pest control 1

2 Economics of Pesticides (EPA ) What is the Cost of Pesticides? Upfront cost of $8.5 Billion paid to industry (1993) Pimentel et al. (1993) suggest that society pays an extra $8.1 Billion $10B in 1998 e.g. $800M treating human poisoning illness and cancers e.g. $30M losses of livestock due to pesticide contamination e.g. $1.8B decontamination of polluted sites Does not include degradation of ecosystem services, non-target effects etc The Value of Ecosystem Services Costanza et al calculated value of ecosystem services in terms of replacement cost For example: Pollination costs approx $117/ha*yr Biological control costs approx $417/ha*yr Economic considerations e.g. US corn production was greatly increased due to pesticides against corn rootworm e.g. WHO estimates cost of malaria eradication via pesticides dwarfs loss of work-day manpower In USA, total terrestrial area = 15,323ha Therefore, these 2 services would cost approx $8M/ yr to replace (is this possible???) Cost of all services (terrestrial and marine) $16-54 Trillion (global GNP WAS $18T. Today GWP=$45T) Economic considerations BUT pesticides have caused economic problems too: e.g. in NS, orchards never had spider mite problem until sprayed with DDT for codling moth e.g. in NE N.Am. apple orchards, red-banded leaf roller wasn t problem until chemicals were used Also, see Pimentel et al. (1993) 2) Health considerations if not all pesticides are toxic Most, Few are taxon specific Environment ever contains more chemicals than Many pesticides persist in environment and bioaccumulate/bioamplify Cumulative, long-term effects often unknown 2

3 2) Health considerations Insects vector 15 major diseases Quality of life: cockroaches cause allergies in 8% of people Threats to life: 25,000 people seek medical attention for fire ant stings annually 3) Political considerations contexts create different perspectives on pesticide use Different Generally, industry is pro-pesticide, environmentalists are against World is not actually as black and white e.g. farmers have enviro concerns but must pay the bills 3) Political considerations Time has the effect of changing political views on pesticides e.g. Winston Churchill called DDT that miraculous powder due to its control of a typhus outbreak 20 yrs later, Rachel Carson called DDT an elixir of death 3) Political considerations differences influence perspective Socioeconomic e.g. Western world recognizes perils of DDT and can afford alternatives Third world still uses DDT for malaria control because don t have $$$ for alternatives ( M cases annually, 1-3% death rate) 4) Environmental considerations Pesticides have pervaded every corner of globe Some are specific, most are general 5) Non-target effects may be unpredictable May disrupt ecosystem function Pollination (CCD), predation, parasitism, herbivory, decomposition etc See Constanza et al. (1997) Moral considerations Pesticides may dramatically improve the quality of life for some people e.g. many people are starving and pesticides help to guarantee food production Many populations limited for food production e.g. world s most important food plant: RICE Attacked by 70 different insect species 20 of these are major pests in areas where rice is grown 3

4 5) Moral considerations Have seen major reductions in infant mortality and adult illness due to pesticides Malaria, typhus, bubonic plague, yellow fever etc. Especially in Asia, Africa and South America Moral issue is a conundrum: Pesticides have allowed increase in human population Currently there are more people than can be fed Overpopulation creates environmental burdens 6) Psychological considerations be positive or negative May Some view pesticides with alarm, seen as unnatural and unhealthy Others panic if they see a blemish or an insect, afraid of spiders and mice 6) Psychological considerations the potential to impact economic considerations Have e.g. pestophobia = domestic pesticide industry e.g. health/enviro concerns = organic products e.g. aesthetics of lawns = domestic herbicides Economic Decision Making Obviously There Definitions Injury: The effect of pest activity on host physiology that is deleterious Damage: Measurable loss of host utility Most often yield quantity and quality, aesthetics Also disease and public health Economics of Intervention Economic Damage: The amount of injury that justifies intervention of artificial control measures are economic costs to action Labour, materials (cost/gain) Residue, non-target effects (IPM) of primordial importance Is damage assessable? If not, when does it become? In pest management, economic damage begins when the cost of suppressing pest injury equals the potential monetary loss from pest population Gain Threshold (GT) = management costs / market value Therefore, injury focusses on pest activities and damage focusses on host response 4

5 Gain Threshold Example cost of pesticide application $10/acre and corn fetches $2/bushel Gain Threshold = $10 / $2 = 5 bushels/acre Therefore, an application of pesticides would have to save 5 bushels/acre in order to be profitable More Definitions If Damage More Definitions Economic Injury Level (EIL): The lowest number of pests that would cause economic damage Economic Threshold (ET): AKA Action Threshold Number of pests (density or intensity) that would trigger management action ET is set lower than EIL under assumption that pest population would otherwise grow to EIL levels Economic Threshold (ET) Complex Value on EIL (must be known 1st) Requires understanding of pest population dynamics Based Calculating EIL Required steps: 1) Estimate loss per pest 2) Determine gain threshold 3) Determine loss avoided by intervention EIL Boundary: The lowest level of injury where damage can be detected Calculating EIL Example First step is the hardest (determine damage per pest) e.g. Determine damage from Potato Leafhopper (Empoasca fabae) on Soy = Gain Threshold / loss per pest * amount of loss avoided 5

6 Importance of Phenology Damage intensity is different at different stages of development Soy has 3 stages of susceptibility Early vegetative, flowering, pod formation Calculating Loss per Insect From experiments with 1 insect/plant 1) 1.55 bushels/acre 2) 0.17 bushels/acre 3) 0.08 bushels/acre (greater leaf area) Calculating Gain Threshold Cost of airspray of 1lb of Malathion = $9.50/acre Grain Gain can fetch $4.15/bushel Threshold = 9.50/4.15 = 2.29 bushels/ acre Setting the ET Calculating EILs EIL = 2.29/1.55*1.00 = 1.48 leafhoppers/ plant 2) EIL = 2.29/0.17*1.00 = ) EIL = 2.29/0.08*1.00 = Insects cause more damage early on because plants are young and have less leaf area Complexity of Calculating EIL Can set at approx. 75% of EIL monitoring of harvest crop for threshold levels of pest population to determine if/when ET is reached Under ET, no intervention Involves 6

7 Next Class What are the pests? 7