Reduction in use of cotton insecticides

Bt cotton has resulted in a significant decrease in the number of insecticide sprays required for the control of the major Lepidopteran insect pests. In turn, this reduction has had a major impact on the total number of insecticide sprays applied to Bt cotton. As expected, the reduction in the number of sprays is related to the degree of infestation which varies significantly in different seasons and countries. The listing in Table 55 indicates that the highest recorded reduction on a national basis was for China in 2001 when the number of sprays required by Bt cotton decreased by half, from 28 sprays to 14 sprays, a saving of 14 sprays.

Indonesia has reported a decrease from 10 to 2 sprays for a saving of 8 sprays (ISAAA 2002e), and South Africa a decrease from 11 to 4 sprays for a saving of 7 sprays on the small farms in the Makhathini Flats (Ismael et al 2002a,b,c). Conventional cotton in Australia usually requires 10 or more sprays, and for Bt cotton, the number of sprays has been reduced on average from 11.2 to 6.5 for a saving of 4.7 sprays (Fitt 2002/In Press). Other sources report that cotton growers in Australia benefit from significant reductions ranging from 27% to 61% with an average reduction of 43% or 7.7 fewer sprays per hectare (Betz et al 2000). Prior to commercialization of Bt cotton in India in 2002, data from a large number of multilocational trials indicated that on average, Bt cotton would reduce the need for insecticides from 7, to 2 - 3 sprays, for a saving of 4 - 5 sprays. In Mexico, the average number of insecticide applications was reduced by 42% in 1999 and 33% in 2000 (Sanchez-Arellano 2000) and Traxler et al (2001) also reported a decrease from 5 to 2 - 3 sprays for Mexico. Argentina (Qaim and de Janvry 2002) reported a reduction from 5 sprays to 2 - 3 sprays, for a saving of 2 - 3 sprays. In the US the savings associated with Bt cotton have been estimated at 2.2 sprays (Benedict and Altman 2001). Taking into account the scope and scale of the reduction in the number of insecticide sprays in eight countries that grow Bt cotton, it can be concluded that on average the number of sprays has been reduced by at least half, with the absolute reduction ranging from 2 to 14 sprays. This is a significant reduction with enormous implications in terms of the environment, health, water savings, economics and the social impact on the lives of small farmers in developing countries.

In terms of absolute volume of insecticide savings, the largest savings are for China and the US because they have large Bt cotton areas. For China, the saving of 14 sprays in 2001 was equivalent to a corresponding saving in amount of formulated insecticide of 54.6 /kg/hectare [from 87.5kg/hectare (non-Bt) to 32.9kg/hectare (Bt)], for a national saving of 78,000 tons of formulated insecticide (Pray et al 2002, Huang et al 2002). In 2000, the number of sprays required by Bt cotton in China also decreased by almost two thirds from 21 to 9 sprays, a saving of 12 sprays. The corresponding saving in amount of insecticide was 28.0/kg/hectare [from 48.5kg/hectare (non-Bt) to 20.5kg/hectare (Bt)] for a national saving of approximately 25,000 tons of formulated insecticide. For China in 1999 the number of sprays required by Bt cotton again decreased by two thirds from 20 to 7 sprays, a saving of 13 sprays; the corresponding saving in amount of insecticide was 48.9/kg/hectare from 60.7kg/hectare (non-Bt) compared with 11.8kg/hectare for Bt. The data of Pray et al (2002) indicate that Bt cotton in China alone reduced insecticide usage by 20,000 tons of formulated insecticide in 1999 on 0.4 million hectares, 25,000 tons in 2000 on approximately 0.9 million hectares, and 78,000 tons in 2001 on approximately 1.5 million hectares, for a three-year total savings of 123,000 tons of formulated insecticide (Table 56). In summary, for the three period 1999 to 2001 in China, the annual average saving in cotton insecticide due to the use of Bt was 13 sprays equivalent to 44.7 kg/hectare of formulated insecticide for a total substantial savings of 123,000 MT of formulated insecticide for the three year period.

These savings in insecticide are substantial by any standard and will increase as area of Bt cotton increases, especially in large highly infested cotton-growing countries like India. Further, insecticide savings will also occur in countries such as Australia and the US as new technologies, such as Bollgard® II, are introduced that will provide more effective control of the major lepidopteran and other pests and a broader spectrum of the secondary pests. The highest savings per hectare associated with reduced need for insecticides have been reported for China, up to $300/hectare, followed by Mexico $150/hectare, USA ($50/hectare), South Africa ($45/hectare), Australia ($20/hectare) and Argentina ($17/hectare); savings are also likely to be significant in India from 2002 onwards.

The global cotton insecticide market, measured in metric tons (MT) of active ingredient (a.i.), was estimated at 81,200 MT for 2001 (Wood Mackenzie 2002). Of the countries that grew Bt cotton in 2001, the major cotton insecticide markets were China 16,000 MT, the USA 12,000 MT, and Australia 1,200 MT; combined, they represented over one third (36%) of the global cotton insecticide market of 81,200 MT in 2001. The US market is atypical at this time in that a large portion of the market, up to 75% in 2000, is related to the eradication campaign for boll weevil. However, this is not a confounding factor in the calculation of Gianessi et al (2002) who estimated a saving of 848 MT (a.i.) of insecticides due to the cultivation of 2.08 million hectares of Bt cotton in the US in 2001, 1,224 MT in 1999 and 907 MT in 1998 (Carpenter and Gianessi, 2001) for a three year total of 2,979 MT (a.i.) of cotton insecticides. Note that the US insecticide savings are in active ingredient (a.i.) and that the China estimates are in formulated product, so they are not comparable.

Benedict and Altman (2001) estimated that in the US, a reduction of 2.2 insecticide sprays on 1.1 million hectares of Bt cotton resulted in elimination of 1.09 million kg (1,090 MT) of insecticide active ingredient (a.i.) in 1998; this calculation is based on 0.45 kg/hectare of a.i. per single spray/hectare. This quantity, 0.45 kg/hectare is comparable to the amount of active ingredient often applied per spray/hectare in developing countries, where the number of sprays is usually much higher than the US because of significantly higher pest infestations, pest-conducive tropical or sub-tropical climates, and where inefficient control programs often have to cope with severe problems related to insect resistance to insecticides.

The 0.45 kg/a.i./hectare/spray calculation used by Benedict and Altman (2001), to estimate the savings in insecticide (active ingredient), can also be utilized to generate estimates of insecticide savings for the major Bt cotton countries in 2001 by multiplying 0.45kg x the reduction in number of sprays x the Bt cotton hectarage. Thus, for Australia in 2001, the estimated saving in insecticides (a.i.) is 0.45 kg x 5 sprays x 146,000 hectares of Bt cotton = a saving of 329,000 kg (329 MT) of active ingredient insecticide. The total estimated amount of insecticide applied to cotton in Australia in 2001 was 1,200 MT a.i., and thus the estimated saving of 329 MT is equivalent to 27 % of the 1,200 MT or 22% of 1,660 MT (1,200+329) that would have been used if Bt cotton was not available (Table 57).

A similar estimate for China generates a saving of 9,450 MT in 2001 compared with an estimated market for all cotton insecticides in China of 16,000 MT (Wood Mackenzie 2002). The saving of 9,450 MT is equivalent to 61% of the 16,000 MT of cotton insecticides used in China in 2001, or 37% of the 25,450 MT that would have been necessary had Bt cotton not been available. Three countries grew 98% of the 4.3 million hectares of Bt cotton in 2001. The US grew 60%, China 35% and Australia 3% with the balance of 2% in the other four countries, Indonesia, Mexico Argentina and South Africa. Taking the estimated savings of 329 MT for Australia, the 9,450 MT for China and 848 MT for USA (Gianessi et al 2002), the estimated total savings of insecticide (a.i.) on Bt cotton in 2001 was of the order of 10,627 MT. This is equivalent to 13% of the 81,200 MT (a.i.) of all insecticides used on cotton globally in 2001 (Wood Mackenzie 2002).