Low-density polyethylene (LDPE), a common polymer, resists environmental degradation because of its high molecular weight and hydrophobic nature. Although microbial agents have shown some potential for plastic biodegradation, their effectiveness is often limited. Recent studies have shown that insect larvae may also be promising candidates for the biological breakdown of plastic waste. This study aimed to quantify the biodegradation of commercial LDPE sheets by Tenebrio molitor (mealworm) larvae over 21 days. The extent of degradation was assessed by gravimetric analysis and by examining physical, morphological, and chemical changes in the polymer. Larval frass was analysed using Fourier-transform infrared spectroscopy (FTIR) and gas chromatography-mass spectrometry (GC-MS) to identify metabolic by-products. The results showed that T. molitor larvae actively consumed and degraded LDPE sheets, leading to an average weight reduction of 34.28%. Scanning electron microscopy revealed significant surface deterioration, characterised by pits and cavities. FTIR analysis of frass indicated cleavage of polymer chains and oxidation, evidenced by the disappearance of C-H stretching bands and the appearance of new hydroxyl and carbonyl groups. GC-MS analysis detected several intermediate compounds, such as esters, alkanes, and fatty acids, confirming the metabolic breakdown of LDPE. This study supports the potential of T. molitor as an effective biological agent for degrading LDPE plastic.
Singh et al. (Tue,) studied this question.