Abstract
The development of advanced biotechnological control strategies opens a new era of environment friendly pest management. The current study is part of such an effort, in which we developed a control strategy based on gene pyramiding that confers broad-spectrum resistance against lepidopteran (Helicoverpa armigera and Spodoptera litura) and hemipteran (Myzus persicae, Phenacoccus solenopsis, and Bemisia tabaci) insect pests. Previously, we reported a double gene construct expressing Hvt and lectin in tobacco (Nicotiana tabacum) plants under phloem specific promoters which confers resistance against hemipteran insects. Here we extended our studies by evaluating the advanced generation of these tobacco plants expressing hvt-lectin against lepidopteran insects. Tobacco plants expressing both toxins were tested against H. armigera and S. litura. Insect bioassay results showed 100% mortality of H. armigera within 48–72 hours and 100% mortality of S. litura within 72–96 hours. Our results suggest that the use of both toxins as a gene pyramiding strategy to control both lepidopteran and hemipterans insects on commercial basis to reduce the use of chemical pesticides.
Highlights
The losses of crops caused by insect-pests are quite high and it is estimated that more than 10,000 insect species pose serious damage to important food crops[1]
We have extended our previous study and used the same construct to evaluate the toxic effect of both Hvt-lectin, when expressed in combination under phloem specific promoter in tobacco plants against H. armigera and S. litura
Bioassays were conducted with transgenic and control plants to evaluate the toxicity of the Hvt and lectin against H. armigera and S. litura
Summary
The losses of crops caused by insect-pests are quite high and it is estimated that more than 10,000 insect species pose serious damage to important food crops[1]. H. armigera is able to cause economic damage to crops estimated to be in couple of billion dollars annually[6,7] This pest has a diverse host range and attacks more than 180 plants from 45 families including fiber and food crops. In 2003, In vitro studies confirmed the development of resistance in H. armigera against Cry1Ac, after which numerous cases of resistance against Cry1Ac were reported[3,8,9] Spodoptera litura, another species in the Noctuidae family, is a cosmopolitan insect herbivore with a wide host range. Spider venom consists of a diverse mixture of chemical compounds, including peptides and proteins[17] These compounds have insecticidal properties with a wide range of mechanisms, with significant potential to improve plant resistance against insect pests. We have extended our previous study and used the same construct to evaluate the toxic effect of both Hvt-lectin, when expressed in combination under phloem specific promoter in tobacco plants against H. armigera and S. litura
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