University of Guilan Plant Pest Research 2538-6123 16 1 2026 05 22 Effect of different diets on biological characteristics of Tenebrio molitor (Col.: Tenebrionidae) Effect of different diets on biological characteristics of Tenebrio molitor (Col.: Tenebrionidae) 1 11 9642 10.22124/iprj.2026.33395.1683 FA Hosein Ojaghi Department of plant protection, Faculty of Agriculture, University of Zanjan, Zanjan, Iran Hamid Reza Sarraf Moayeri Department of plant protection, Faculty of Agriculture, University of Zanjan, Zanjan, Iran Abbas Arbab Department of plant protection, Tak. C., Islamic Azad University, Takestan, Iran Journal Article 2026 04 28 The mealworm, <em>Tenebrio molitor </em>L. is a rich source of protein for livestock, poultry, and aquatic animals. In this study, the effect of 10 diets (including food industry waste: industrial bread, pasta, and biscuit waste and waste from industrial poultry and fish slaughterhouses) on the biological characteristics<strong> </strong>of the mealworm was investigated under laboratory conditions (25 ± 2 °C, relative humidity 65 ± 5%, and 24 hours of darkness). A mixture of 85% wheat bran, 5% baker's yeast, and 10% carrots was used as the control diet. The results indicated that the utilization of food industry and slaughterhouse waste significantly affected the biological parameters of the yellow mealworm. Diets with high levels of biscuit waste and fish waste powder cause 100 % larval mortality. However, substituting fish waste with lower concentration (5%) notably enhanced certain parameters such as the weight of last larval instar (0.132±0.011 g) and larval development time (61.84±4.44 days) compared to other treatments. Conversely, this substitution led to a significant decrease in the total egg laying rate of adult insects (57.8±15.43 eggs) compared to the standard diet (94.20±14.70 eggs). While, a limited inclusion of animal protein-derived sources in the diet of yellow flour beetles may improve some of the growth characteristics of this insect, excessive addition of some of the waste slaughterhouse and food industry wastes can have a negative impact on its survival and reproductive performance The mealworm, <em>Tenebrio molitor </em>L. is a rich source of protein for livestock, poultry, and aquatic animals. In this study, the effect of 10 diets (including food industry waste: industrial bread, pasta, and biscuit waste and waste from industrial poultry and fish slaughterhouses) on the biological characteristics<strong> </strong>of the mealworm was investigated under laboratory conditions (25 ± 2 °C, relative humidity 65 ± 5%, and 24 hours of darkness). A mixture of 85% wheat bran, 5% baker's yeast, and 10% carrots was used as the control diet. The results indicated that the utilization of food industry and slaughterhouse waste significantly affected the biological parameters of the yellow mealworm. Diets with high levels of biscuit waste and fish waste powder cause 100 % larval mortality. However, substituting fish waste with lower concentration (5%) notably enhanced certain parameters such as the weight of last larval instar (0.132±0.011 g) and larval development time (61.84±4.44 days) compared to other treatments. Conversely, this substitution led to a significant decrease in the total egg laying rate of adult insects (57.8±15.43 eggs) compared to the standard diet (94.20±14.70 eggs). While, a limited inclusion of animal protein-derived sources in the diet of yellow flour beetles may improve some of the growth characteristics of this insect, excessive addition of some of the waste slaughterhouse and food industry wastes can have a negative impact on its survival and reproductive performance https://iprj.guilan.ac.ir/article_9642_8bdb44830eb51ae623f25a36cd7072f6.pdf