**8. Waste conversion in mass-rearing facilities**

The most common insect for which the sterile insect technique has been used is *Ceratitis*. Following that, a large number of mass-rearing facilities were established around the world. Mexico and Guatemala have facilities that rear over 1.5 billion medflies per week. The most important factor in mass-rearing is diet. Each massrearing facility generates a large amount of waste on a daily basis, the majority of which comes from the remaining rearing diet that does not respond to increasing requirements for economic efficiency and environmental standards [123], combined with global warming. At the El Piño biofactory in Guatemala, 31 tons of larval diet per day are produced [124]. Waste recycling initiatives are not published even if they exist. It is obvious that this waste is autoclaved before being used in order to eliminate any stage of the pest. Mastrangelo et al., (2009) [124] stated after conducting analyses on medfly diet that it has the potential as an alternative ruminant feedstuff. Likewise, Sayed et al., [125] showed that this diet is a potential feed ingredient for the production of BSF pre-pupae and could be applied to valorize this rearing waste into highvalue feed.

The conversion of waste, such as agricultural by-products and food preparation wastes, into novel animal feeds, has received a lot of attention. The addition of exogenous probiotics is a promising strategy that enhances the biotransformation of food wastes [126], water treatment [127], and compost production [128]. The probiotics were shown to exert a positive effect through the extracellular enzyme secretions to break down carbohydrates, proteins, and fats into micronutrients in the waste that is transformed into feed [126]. Consequently, the probiotics added to the medfly larvae diet in the rearing facilities could improve the degradation of the diet and its use as feed for livestock after the larvae have left the medium. Probiotics may *Probiotics as a Beneficial Modulator of Gut Microbiota and Environmental Stress… DOI: http://dx.doi.org/10.5772/intechopen.110126*

also reduce antinutritional compounds and lignocellulose from the finisher diet bran, which is used as a substrate [129], and inhibit endogenous pathogens [130]. Therefore, WHO specifies that converted products for the animal feed chain should not be degraded or contaminated while maintaining an acceptable nutritional value [131].
