As humanity discovers more and more remote parts of the universe, the food supply for long-term space missions becomes an increasingly critical issue, and thus the need for sustainable food systems becomes more obvious. In space environments, where resources are limited and recycling is essential, insects can play a vital role as valuable actors in a circular food system. This study aims to assess the effect of combining semolina with dried green duckweed, alfalfa, and green pepper as feeding substrates for yellow mealworm larvae (Tenebrio molitor). The weight ratio of wheat semolina: green mustard was constant (75% : 25%) throughout the different feed treatments. During the feeding experiment, the samples were kept in a programmable incubator at 23°C, 60% relative humidity, and 0% light intensity for 20 days. The research extended to examining production parameters (growth rate, average weight change, survival rate, feed conversion ratio), and the dry matter, carbon, sulfur, nitrogen, and crude protein content of the larvae. The results show that all feed supplements used had a positive effect on the protein content of yellow mealworm larvae.The results demonstrate that the 25:75 ratio of duckweed, alfalfa, pepper, and semolina as forage positively affects the protein content of yellow mealworm larvae. The highest protein content was realized in the larvae fed the alfalfa supplemented diet.The highest protein content, as measured by the Kjeldahl and Dumas methods, was reached by the S75A25 group. In addition to increasing the larvae's protein content, the plant substrates also increased their organic carbon content compared to the S group. Larvae fed with the pepper supplement with the lowest mean individual weight were associated with the highest FCR, whereas larvae fed with the duckweed supplement with the highest mean individual weight were associated with the lowest FCR.In terms of survival rate, all treatments achieved a value above 90%. Our experiment also suggests that a high protein content in feed does not necessarily ensure high protein content in the larvae. By using the stems and leaves of peppers, which can be grown in microgravity, as well as duckweed, which can be used for wastewater treatment on space bases, and alfalfa, which, according to recent research, may survive on Martian soil, to produce food, the protein supply for long-term missions would become more sustainable and economical. If insect larvae were used to process these organic matters and turn them into edible animal proteins, astronauts' dependence on resource-intensive food supplies from Earth could be reduced . This research highlights the potential of integrating innovative agricultural techniques and entomophagy to increase the efficiency and sustainability of food production in terrestrial and possibly extraterrestrial environments.