Spiders produce peptide ?-Hexatoxin-Hv1a (Hvt), a venom toxin with proven
insecticidal properties against arthropods belonging to orders Lepidoptera,
Diptera, and Orthroptera. The gene coding for Hvt has been transferred into
cotton and tobacco to develop plants with resistance to lepidopteran pests.
Researchers from National Institute for Biotechnology and Genetic
Engineering (NIBGE), Pakistan and partners assessed the expression of the
?-HXTX-Hv1a gene in transgenic plants, and the toxicity of plant-expressed
and purified Hvt on target lepidopteran insects and on several non-target
species. Insect resistant cotton (Bollgard II) plants were included in the
study as comparators.

Results showed that larval mortality was 100% on Hvt-transgenic tobacco
plants but not on Hvt-transgenic cotton which can be due to significantly
lower Hvt expression level in the transgenic cotton. Studies on non-target
organisms were conducted with larvae of the predators common green lacewing
(Chrysoperla carnea) and seven-spot ladybird (Coccinella septempunctata),
adults of the aphid parasitoid (Aphidius colemani), and adult workers of the
honey bee (Apis mellifera). Even at greater concentrations (40 ?g/ml) Hvt
did not adversely affect the four non-target species. Purified Cry2Ab2 from
Bollgard II plants at 10 ?g/ml also did not adversely affect any of the
non-target species.

Based on the results, Hvt might be useful for developing insecticidal plant
varieties to control lepidopteran pests.


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