Scientist Rishi Kumar and colleagues conducted a tritrophic study to
investigate the transfer of Cry proteins from Bt cotton to herbivore onion
thrips (Thrips tabaci) and its predator insidious flower bug (Orius
insidiosus). They also aimed to know the effects of the proteins on the
predator's development, survival, and reproduction.

The average protein titers in Bt cotton leaves were 1,256 and 43,637 ng
Cry1Ac and Cry2Ab per gram fresh leaf tissue, respectively. At the second
trophic level, larvae of onion thrips reared on Bt cotton for 2 to 4 days
had 22.1 and 2.1 percent of the Cry1Ac and Cry2Ab levels expressed in
leaves, respectively. At the third trophic level, insidious flower bugs that
fed on onion thrips larvae had 4.4 and 0.3% of the Cry1Ac and Cry2Ab protein
levels, respectively, expressed in Bt plants.

Results showed that insidious flower bug's survivorship, time of nymphal
development, adult weight, preoviposition and postoviposition periods,
fecundity, and adult longevity were not significantly affected by Bt
proteins. These results indicate that the insidious flower bug is not harmed
by Bt cotton when exposed to Bt proteins through its prey. Thus, the
insidious flower bug can continue to provide important biological control
services in the cotton ecosystem when Bt cotton is used to control primary
lepidopteran pests.

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