Monarch Butterflies and Bt corn--Table 3

Table 3 shows the concentrations of pollen deposited on leaves at various distances from corn fields. You can see from the table that the highest amount of pollen measured within a corn field--1,600 pollen grains per square centimeter of leaf surface (shown in bold red type)--is harmless to Monarch larvae if the corn type is Bt 11 or MON810, both of which have no harmful effect on butterfly larvae at concentrations of more than 1,600 pollen grains per square centimeter.

distance pollen grains per square centimeter pollen grains per square inch source
in the field 0 to 506 0 to 3,264 Hansen-Jesse and Obrycki, 2000
0 to 1,600 0 to 10,320 Pleasants et al., 2001
65 to 425 419 to 2,741 Sears et al., 2001
at the edge of the field 0 to 1,100 0 to 7,095 Pleasants et al., 2001
158 to 266 1,019 to 1,716 Sears and Stanley-Horn, 2000)
0.2 meters away 0 to 427 0 to 2,754 Hansen-Jesse and Obrycki, 2000
0.5 meters away 260 1,677 Zangerl et al., 2001
1 meter away 0 to 222 0 to 1,432 Hansen-Jesse and Obrycki, 2000
0 to 1,300 0 to 8,385 Pleasants et al., 2001
170 1,097 Zangerl et al., 2001
2 meters away 0 to 400 0 to 361 Pleasants et al., 2001
192 1,238 Zangerl et al., 2001
3 meters away 0 to 56 0 to 361 Hansen-Jesse and Obrycki, 2000
5 meters away 0 to 11 0 to 71 Hansen-Jesse and Obrycki, 2000
0 to 200 0 to 1,290 Pleasants et al., 2001
34 to 175 219 to 1,129 Sears and Stanley-Horn, 2000)
10 meters away 0 to 4 0 to 25 Hansen-Jesse and Obrycki, 2000

 


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