GMO zabija motyle-‚Nature’ 1999

Już w 1999 były znane pewne istotne badania. Transformowany (genetycznie modyfikowany) pyłek szkodzi larwom:

„Although plants transformed with genetic

material from the bacterium Bacillus

thuringiensis (Bt) are generally thought to

have negligible impact on non-target

organisms1, Bt corn plants might represent

a risk because most hybrids express the Bt

toxin in pollen2, and corn pollen is dispersed

over at least 60 metres by wind3.

Corn pollen is deposited on other plants

near corn fields and can be ingested by the

non-target organisms that consume these

plants. In a laboratory assay we found that

larvae of the monarch butterfly, Danaus

plexippus, reared on milkweed leaves dusted

with pollen from Bt corn, ate less, grew

more slowly and suffered higher mortality

than larvae reared on leaves dusted with

untransformed corn pollen or on leaves

without pollen.

Pollen for our assay was collectedfrom

N4640-Bt corn and an unrelated, untransformed

hybrid, and was applied by gently

tapping a spatula of pollen over milkweed

(Asclepias curassavica) leaves that had been

lightly misted with water. Pollen density

was set to visually match densities on milkweed

leaves collected from corn fields. Petioles

of individual leaves were placed in

water-filled tubes that were taped into plastic

boxes. Five three-day-old monarch larvae

from our captive colony were placed on

each leaf, and each treatment was replicated

five times. Milkweed leaf consumption,

monarch larval survival and final larval

weight were recorded over four days.

Larval survival (56%) after four days of

feeding on leaves dusted with Bt pollen was

significantly lower than survival either on

leaves dusted with untransformed pollen or

on control leaves with no pollen (both

100%, P40.008) (Fig. 1a). Because there

was no mortality on leaves dusted with

untransformed pollen, all of the mortality

on leaves dusted with Bt pollen seems to be

due to the effects of the Bt toxin.

There was a significant effect of corn

pollen on monarch feeding behaviour

(P40.0001) (Fig. 1b). The mean cumulative

proportion of leaves consumed per

larva was significantly lower on leaves dusted

with Bt pollen (0.5750.14, P40.001) and

on leaves dusted with untransformed pollen

(1.1250.09, P40.007) compared with

consumption on control leaves without

pollen (1.6150.09). The reduced rates of

larval feeding on pollen-dusted leaves

might represent a gustatory response of this

highly specific herbivore to the presence of

a ‘non-host’ stimulus. However, such a

putative feeding deterrence alone could

not explain the nearly twofold decrease

inconsumption rate on leaves with Bt pollen

compared with leaves with untransformed

pollen (P40.004).

The low consumption rates of larvae fed

on leaves with Bt pollen led to slower

growth rates: the average weight of larvae

that survived to the end of the experiment

on Bt-pollen leaves (0.1650.03 g) was less

than half the average final weight of larvae

that fed on leaves with no pollen

(0.3850.02 g, P40.0001). [….]”