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Abstract
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Transgenic cotton expressing the Cry 1Ab protein of Bacillus thuringiensis developing against Helocoverpa
armigera may be affect on secondary pest such as Bemisia tabaci. In this study effects of Bt cotton on
demographic parameters of B. tabaci were assessed and the data analyzed using the age specific, two-sex life
table parameters. Results showed that getting to the adulthood stage, was faster on non-Bt cotton in
comparison with Bt cotton. Also the fecundity was higher on non-Bt cotton than that on Bt cotton. Some of the
population parameters (r, R0 and T) of B. tabaci were affected by the Bt cotton significantly. The intrinsic rate
of increase (r) on Bt and non-Bt cotton was 0.07 day-1 and 0.1 day-1, respectively. The net reproductive rate (R0)
was 20.68 and 15.04 offspring/individual on Bt and non-Bt cotton, respectively. Mean generation time (T) in
non-Bt cotton was 27.22 and 34.62 days in Bt cotton. The results indicated that the life history of B. tabaci in
the laboratory condition was influenced by host plant quality and Bt cotton was not a suitable host for B. tabaci.
The western immunoblot method showed that the Cry protein detection in honeydew was positive which
indicated that the Cry protein was ingested. Results revealed that the transgenic cotton could adversely affect
the secondary pest and the natural enemies which feed on such pests as a host or their honeydew as a food
source should be considered.
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