Can biological control benefit from genetically-modified crops? Tritrophic interactions on insect-resistant transgenic plants

摘要

The use of recombinant DNA technology to develop genetically-modified crops is considered as a major breakthrough for agriculture by many scientists. However, some scientists, and an even larger proportion of the general public, are sceptical about the advantages and are even more concerned about the potential risk of this new technology. To evaluate this novel technology, cost-benefit analyses are needed in which the real risks are measured and judged against the benefits. A tiered risk assessment scheme is described herein. This allows comparisons to be made with other insect-control technologies (e.g. insecticides) and risks to be determined, rather than only hazards being identified. Recombinant DNA technology could allow plants to be designed that are well suited for use alongside biological control programmes. Unfortunately, plant breeders have continued to attempt to breed for total resistance, and biocontrol specialists have ignored the role of the plant in ensuring successful foraging behaviour by insect natural enemies. Although some scientists have highlighted the need to consider both the bottom-up (plant defence) and top-down (biocontrol) control of insect pests, there have been few serious attempts to combine these approaches. As more is understood about the proximate and ultimate causes of direct and indirect defences, the potential exists for engineering plants that combine both strategies. This new possibility for controlling insect pests, which will combine both 'nature's' own defences with man's ingenuity, may stack the odds in our favour in the continual struggle against insect pests.