Entomoremediation: Influence of a Plastic Diet on the Development of Tenebrio Molitor to Generate Biofertilizer

Abstract

Plastic is widely used and responsible for negative environmental impacts. Such is the case of expanded polystyrene (EPS), a material that presents revaluation challenges due to its low density. The ability of certain insects larvae, such as Tenebrio molitor, to mineralize plastic has been demonstrated, although its insect farming still focuses on obtaining sustainable protein and biofertilizer. This study investigates the influence of an EPS diet on the larval development of T. molitor for 6 months and examines how the diet affects the volume of biofertilizer collected in this period. Trials were developed with three diets, performing periodic measurements and collection of material. The results indicate that larvae fed a combined substrate, as well as those fed an organic diet, demonstrate survival rates of up to 66%. The final length is lower in the inorganic diet (112 mm), and in the other diets it exceeds 162 mm. Larvae on an inorganic diet did not progress to pupal stage, demonstrated a disappointing lowest Feed Conversion Ratio (3.87) and produced less frass (1.28g), compared to the combined diet which recorded 5.11g. The data suggest that plastic entomoremediation works optimally if larvae are raised on a combined diet substrate of EPS and organic elements. This condition not only produces positive results, but also is aligned well with the principles of the circular economy. Therefore, a combined diet proves to be an ideal candidate for tackling EPS waste.