Sterile Insect Technique: international framework to facilitate transboundary shipments of sterile insects

to expand the use of this effective and environment friendly technology. The scope of this chapter is limited to insects that have been sterilised using ionising radiation.


Introduction
The sterile insect technique (SIT) has been successfully applied in large-scale operational programmes to prevent, contain, suppress, and eradicate pests in many countries worldwide (1). The SIT is speciesspecific and, as such, it enables pest control without introducing potentially invasive insect species into ecosystems with threats to biodiversity. Unlike insecticides and other control methods, it acts in an inversely density-dependent manner and as a result increases its efficiency with decreasing population density (2). The SIT, as described in this article, specifically uses ionising radiation (Gamma, X-rays, or e-beam) to sterilise mass-reared insects so that they cannot produce offspring when released in the field and mating with wild females. As a result of the physical action of radiation, chromosomes break in the germinative cells of the insect's sperms and ovules, causing lethal dominant mutations that prevent the development of the embryos (3). This results in the introduction of sterility in the wild population and the reduction of a pest population over time.
The SIT relies on the sustained and area-wide release of large numbers of sterile insects over areas infested with target pests. Prior to their release, sterile insects are mass-reared, sterilised, packed, shipped, emerged as adults from the puparia, fed and matured, and then loaded into delivery vehicles for aerial or ground releases (Fig. 1). The conditions under which these activities are conducted are as relevant to the overall success of -and negligible risk from -SIT activities as is the production of high-quality sterile insects (4).

Benefits and risks of Sterile Insect Technique
The return on investment of past and current SIT programmes is unquestionable, with benefit to cost ratios ranging from US$ 2.80 for each dollar invested in the case of a Mediterranean fruit fly population suppression programme in South Africa, to as high as 1,000 to 1 in the case of a Mediterranean fruit fly prevention programme in Chile (14). Through the pilot trials the impact of releases of sterile male mosquitoes over the wild populations and the reduction in the transmission and incidence of disease in the human population has been shown (15).
Sterile insects used in SIT programmes have been shipped across borders to many countries successfully since 1963. In the 58 years of transboundary shipments, although not well documented, it is known in the industry that very few incidents have occurred. Some incidents related to production protocols, demonstrating the need for quality assurance in the sterilisation process prior to shipping and highlighting the advantages of well-resourced, centralised production facilities. For

Production and sterilisation processes
Proper production conditions are key to virtually eliminating the risk from the large shipments of sterile insects. Production of sterile insects for use in SIT programmes involves mass rearing at high standards.
Mass rearing facilities employ standard operating procedures or manuals that describe the production process in detail. The process involves breeding colonies, egg seeding, larvae rearing, pupae rearing, In this way, the risk to the utility of the live insects is managed.

Post-production process
As in the case of the production process, the post-production handling of sterile insects is a delicate and rigorous process. Standard operating procedures are available to assure proper handling and good sterile insect quality. Strict biosecurity protocols are also in place in the emergence and release facility as well as for long distance transportation to assure the integrity of the consignment and prevent the accidental spread of unwanted insects (hitchhikers) (16,22). [Place Table I This approach would require significant capital investment for each facility.
In order to take advantage of larger centralised facilities, an international framework is needed for transboundary shipments and importation (as a consignment in transit or for entry to the country of destination) of sterile insects for use in control programmes. Such a framework should recognise the extensive record of quality control and safe shipments of mass reared insects sterilised through ionizing radiation. This would serve as the basis for more harmonised regional or national phytosanitary and zoosanitary measures (23) and should apply for both government and private entities which follow the same procedures.

Conclusions
The SIT is a cost-effective and environment friendly pest control tool that has been extensively applied to control some major insect pests.   Signatures and names redacted for data protection purposes