Testing Analytical Methods for Antibiotic Detection in Tenebrio molitor Larvae: A Controlled Feeding Trial

Background: As edible insects gain importance as sustainable protein sources, their integration into the food system requires that they meet the same safety standards as conventional animal products. This includes systematic testing for residues of pharmacologically active substances, such as antibiotics. To enable such monitoring, validated analytical methods for insect matrices are essential—but currently lacking. This study evaluates whether LC-MS/MS methods already validated for conventional animal products are suitable for detecting antibiotics in edible insects. Methods: A feeding trial was conducted with Tenebrio molitor larvae using three antibiotics—tiamulin, chloramphenicol, and erythromycin—selected based on prior trace detections, known associations with insect use, or the presence of related resistance genes in insect-based products. The antibiotics were incorporated into feed, and their homogeneity and stability were confirmed. After seven days of feeding and a 24-hour fasting period, larvae were analyzed. Results: All three antibiotics were detected in the insects, although residue levels significantly declined after fasting. Conclusion: These results demonstrate the applicability of existing methods to insect matrices and highlight the need for further validation. The study provides a reproducible model for further feeding trials and discusses potential drivers of antibiotic misuse in insect farming as a foundation for developing and expanding testing methods to ensure the food safety of edible insects.