Impact of density, reproduction period and age on fecundity of the yellow mealworm Tenebrio molitor (Coleoptera: Tenebrionidae)

Abstract

The impact of adult density, reproduction period (days in the same container) and age on reproduction of Tenebrio molitor Linnaeus (Coleoptera: Tenebrionidae) were studied. Data were analysed as total number of larvae in each container (38 cm2) and as daily reproduction per capita. The study was divided in two experiments. Experiment 1 examined the influence of four densities (0.11, 0.21, 0.42 and 0.84 beetles/cm2) and five reproduction periods (1, 2, 3, 4 and 6 days) on reproduction. Experiment 2 examined the effect of age (30-92 days) and three densities (0.11, 0.21 and 0.32 beetles/cm2) on reproduction. The total number of larvae per container was significantly affected by reproduction period and adult density, attaining the highest output at the longest reproduction period of 6 days (214±101 larvae) and highest density of 0.84 beetles/cm2 (215±112 larvae). Daily per capita reproduction, however, was highest at the second lowest density of 0.21 beetles/cm2 (8.58±3.82 larvae/female/day) and shortest reproduction period of 1 day (8.34±4.68 larvae/female/day). In experiment 2, age had a significant effect on reproduction both as total number of larvae per container and number of larvae per female per day. The highest reproduction was found when beetles were 30 days old, but reproduction was in general highest for 13-29 days old females (experiment 1). For production context the highest density of beetles provides highest output of larvae, and beetles are not expected to be stressed under these conditions.