Bt Brinjal The scope and adequacy of the GEAC environmental risk assessment

12 Bt Brinjal: The GEAC environmental risk assessmentTable 1. Brinjal losses to BFSB in India. Yield loss is calculated for a damaged fruit either being totally lost or the damagedpart trimmed away (not consumed) so that the undamaged parts of damaged fruits are still considered in yield. Fruit damageis a measure of the proportion of fruits that have BFSB damage at any particular time. Probably all of the listed studies wereconducted on the land of the Agricultural College. NA = not available. The NA season is most likely kharif. The NA varietiesare most likely high yielding varieties (HYVs).State Season Variety Yield loss (%) Comment ReferenceNotconsumedWest Bengal NA NA 5.3* IPM neem v. control Chakraborti 2001West Bengal NA NA 25.2* Chemical v. control Chakraborti 2001Orissa Kharif NA 10.8–54.8 Range, 2 years Paitnaik et al. 1997Uttar Pradesh NA Local 25.3 7.3 Haseeb et al 2009Uttar Pradesh NA NA 13.1 3.6 Mall et al. 1992Delhi NA NA 20.7 9.7 Peswani and Lall1964Gujarat NA NA 5.3 Thanki and Patel1988Rajasthan kharif NA 40.8–71.8* Range, 4 years Pareek andBhargava 2003Madhya Pradesh kharif HYV 23.3–47.8* Range during growth Dhamdhere et al.1995Madhya Pradesh ziyad HYV 17.2–30.9* Range during growth Dhamdhere et al.1995Maharashtra kharif NA 53.1 12.52** High yeild v.control Naitam and Markad2003Andhra Pradesh rabi Local 53.4 Best v.control Naik et al 2008Andhra Pradesh rabi Local 34 Neem v. control Naik et al 2008Karnataka kharif NA 26.0–45.0* Range planting density Shukla andPrabhakar 1985?Tamil Nadu NA NA 1.67** clusterbean polyculture/ Elanchezhyam et albrinjal monoculture 2008* Difference in fruit damage, not yieldWhile there have been a number of studies on yield loss to BFSB throughout India wherever brinjal is grown, many ofthe studies are in publications available in certain Indian States and are difficult to obtain. A partial review of this rather largeliterature is given in Table 1. These are the reported yield losses to BFSB comparing no control with some control measure,and are therefore estimates of the maximum yield loss from BFSB. As discussed below, few farmers do nothing to controlBFSB, so actual yield losses suffered by farmers are much less than reported in Table 1. This means that the actual yieldbenefits of Bt brinjal need to be estimated as the marginal benefits (or costs) over presently available control practices. This willbe elaborated in more detail in the socioeconomic analysis below.Although losses from BFSB can reach the high levels (70%, Table 1), under most conditions the losses are significantlylower, and average losses are much less. Based on these experiments conducted on Agricultural College lands, 50% yield losswas not unusual, but typically, yield loss was observed to average around 30% (Table 1). EC-II reported 60-70% yield losseven when insecticides are used; this is obviously an over-estimate of yield loss to BFSB. Moreover, the data reported in Table1 probably overestimate yield loss. As will be discussed in greater depth in the socioeconomic section, yields on experimentstations and agricultural colleges tend to exceed the yields farmers can obtain on their own fields. This “yield gap” implies that