## 4 Discussion
### Different Perspectives and Measures of Success of SIT Operation  
Remarkably, from a farmer's perspective, nearly all simulated SIT-only scenarios were successful. Even in location A with the relatively highest medfly population and with the lowest sterile male release rate, significant reductions in medfly population were achieved, which translated into reduced fruit infestation to levels acceptable to farmers. Such results are consistent with published cases of small- to medium-scale SIT application in 2.5 ha experimental plots in citrus plantations in Morocco [18], 18 ha apple plantations in Uruguay [17] and 1000 ha citrus (mandarin) areas in Croatia [14]. It is important to emphasize that the 50 m buffer used in our simulations was intended to provide minimal separation of the treated site and was not expected to serve as an effective barrier to prevent the movement of flies into or out of the SIT-treated area. However, our simulations indicate that in areas with very low fly density, even this minimal buffer may be sufficient for IPM applications where the goal is simply to seasonally suppress (but not eliminate entirely) medfly population to reduce fruit infestation.  
For more demanding applications, such as eradication or maintaining fly-free zones, much wider buffers, on the order of 2 km or more, are needed [42]. Indeed, our simulations have shown that achieving goals such as eliminating or containing local invasions of medfly has proven more problematic. Although the starting cohort and seasonal medfly population in each site were very small, even assuming the release of a relatively large number of males (200,000 sterile pupae per week in an area of 25 ha) did not lead to the complete eradication of the medfly in any of the hypothetical sites. Moreover, the simulated SIT interventions, although they caused significant population suppression, were not able to prevent the spread of descendant medfly generations outside the area of the treated location.  
Such a result is not unusual for short (seasonal, approximately 6 months) releases of sterile males, without support of other IPM methods. In an eradication program conducted in Australia on a relatively small area of 25 km\({}^{2}\), the release of 7.5 million sterile flies per week (which corresponds to 75,000 males per 25 ha site) for 15 months, without the support of chemical methods, was insufficient to affect and suppress the medfly population. Eradication was achieved only after releasing 12 million sterile flies per week for 34 months, combined with intensive use of other control measures, such as spraying of hydrolys protein and trichloron baits, pesticide cover sprays and fruit stripping [62].  
Our results do not exclude the possibility of obtaining positive results in specific cases but strongly suggest the need for very careful and pragmatic selection of locations where the specific and medfly suboptimal spatiotemporal configuration of host fruits, terrain topography and weather conditions might offer a chance for success in the application of SIT alone, without the usually needed heavy support of pesticide sprays and other methods. The use of the developed modelling DSS tool enables rational decisions about site selection and optimisation of the response to local conditions.