years (since 1963). The total number of sterile insects shipped has been estimated at more than one trillion in thousands of shipments across borders to 23 recipient countries from 50 sterile insect factories in 25 countries. During this long period and many precedents, no problems associated with possible hazards have been identified, and thus the shipment of sterile insects have never been subjected to any regulatory action. The table shows the history of transboundary shipments which started in 1963 with the shipments of sterile Mexican fruit fly (Anastrepha ludens, Loew), from Monterrey, Mexico, to Texas, US. Drawbacks Naturally low population periods or repeated pesticide treatment are sometimes required to suppress populations before the use of sterile insects. Sex separation can be difficult, though this can be easily performed on a large scale where genetic sexing systems have been developed as for the Mediterranean fruit fly. Radiation, transport and release treatments can reduce male mating fitness. The technique is species-specific. For instance, the technique must be implemented separately for each of the 6 economically important tsetse fly species. Mass rearing and irradiation require precision processes. Failures have occurred when unexpectedly fertile breeding males were released. Area-wide approach is more effective, as migration of wild insects from outside the control area could recreate the problem. The cost of producing sufficient sterile insects can be prohibitive in some locations but decreases with economies of scale. Conclusion and perspectives Biotechnological approaches based on genetically modified organism (transgenic organisms) are still under development. However, since no legal framework exists to authorize the release of such organisms in nature, sterilization by irradiation remains the most used technique. A meeting was held at FAO headquarters in Rome, 8 to 12 April 2002 on "Status and Risk Assessment of the Use of Transgenic Arthropods in Plant Protection". The resulting proceedings of the meeting have been used by the North American Plant Protection Organization (NAPPO) to develop NAPPO Regional Standard No. 27 on "Guidelines for Importation and Confined Field release of Transgenic Arthropods", which might provide the basis for the rational development of the use of transgenic arthropods. Economic benefits Economic benefits have been demonstrated. The direct benefits of screwworm eradication to the North and Central American livestock industries are estimated to be over $1.5 billion/year, compared with an investment over half a century around $1 billion. Mexico protects a fruit and vegetable export market of over $3 billion/year