RECENT DEVELOPMENTS AND FUTURE PROSPECTS IN INSECT PEST CONTROL IN TRANSGENIC CROPS Arana, Alejandro Echaide, Alberto San Martin, Eneko
INTRODUCTION <ul><li>The adoption of insect-resistance transgenic crops has been increasing annually at double-digit rates since the commercial release of first-generation maize and cotton expressing a single modified Bt toxin , nine years ago. </li></ul><ul><li>However, the sustainability and durability of pest resistance continues to be discussed. We review strategies that are being developed for novel approaches to transgenic insect pest control. </li></ul><ul><li>Transgenic control consists in introduced a gen which produced a toxin that damaged the larves when they eat the roots. </li></ul>
Benefits of transgenic crops <ul><li>Many varieties of crops of rice and corn are beneficial to small and poor farm households because crop yields are higher and pesticide use is reduced. </li></ul><ul><li>In USA, these crops produced an additional 2,4 million tones of food, and 1,9 billion dollar in 2003 . </li></ul><ul><li>Its use reduced the use of pesticides by 21.000 tones. </li></ul><ul><li>These crops have passed examinations and studies. And they didn´t have a negative impact on non target pests in the field or on natural predators. </li></ul><ul><li>They are more effective than soil and seed applied insecticides in protecting the roots of corn plants from larval feeding damage. </li></ul>
Problems of transgenic crops <ul><li>There is a posibility that Bt insect resistance crops would be of limited durability because mutations would be selected and give tolerance to toxins. But it isn´t demostrated. </li></ul><ul><li>Pollution of biological crops. </li></ul>
The aplication of wild plant genes and culture measures <ul><li>There is a new investigation about the incorporation of genes from wild plants to transgenic plants, with the objective of improving these. </li></ul><ul><li>In addition, if in some area of the crop it stay in fallow, these not transgenic plants have the effect of refuge for pest and the possible resistance allele can dilute out. </li></ul>
Effects of insect – resistant transgenic crops on non target beneficial insects in the context of Integrated Pest Management . <ul><li>A tactic in integrated pest management is to preserve the natural enemies of crops. </li></ul><ul><li>For example carabid beetles and parasitic wasps. </li></ul><ul><li>Insect resistance in crops might not have a direct effect on natural enemies of pests. </li></ul><ul><li>Transgenic crops expressing Bt are respectful in the environment due to lack of specificity and direct effects on biological control agents. </li></ul>
New strategies and non-conventional sources for insect resistance <ul><li>We show that so far transgenic plants expressing protease inhibitors have a marginal effectiveness against insect pests. </li></ul><ul><li>Nevertheless, PIs have the potential to be effective insecticidal proteins if insect adaptation to them can be overcome. </li></ul><ul><li>The use of novel inhibitors, such as the barley trypsin inhibitor, equistatin, cystatins or lectins might also prove useful. </li></ul><ul><li>Bt toxins killed insects by producing septicemia in their bodys. </li></ul>
Conclusions <ul><li>Wild plants have some level of endogenous resistance to resist insect pest. </li></ul><ul><li>However cultivable plants for humans don’t have those mechanisms because of years of evolution. </li></ul><ul><li>If we could understand better molecular events in genes, we could manipulate it for resistance to pests. </li></ul><ul><li>We have to care of this new transgenic products, because we don’t know the spectrum of action in other insects. </li></ul>
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