Strain effect on larval growth and performance of Tenebrio molitor reared for food or feed

The optimization of insect mass-rearing is one of the current priorities in insect production for food and feed. Although considerable research has been directed to diet improvement, the strain effect on insect development is often overlooked. In the present study, we comparatively evaluated the larval development and egg production of seven strains of the yellow mealworm, Tenebrio molitor.
In laboratory bioassays, the larval development of strains from Greece, Italy (2), Turkey, Germany, USA and Spain was studied, using wheat bran and dry yeast (9:1) as feeding substrate and carrot as moisture source. Larval weight and survival, feed conversion ratio and total development time were determined. In another bioassay, the egg production of the tested strains was investigated. Groups of 10 adults were placed in plastic vials, together with white flour as oviposition substrate, and left undisturbed to mate and oviposit. Eggs laid were collected every 4 d. Adult survival and larval hatchability were also recorded.
Significant differences among strains were recorded with regard to the final individual larval weight, which ranged between 87-154 mg, as well as the total development time (67-156 days). Egg production and adult survival also varied considerably among strains. These results suggest that the strain used in T. molitor mass-rearing can exert a substantial impact on insect biomass production and should be taken into consideration in insect-producing facilities.
 Acknowledgements
This work was supported by a postdoctoral scholarship program (Acronym: FISHECT, Project number: 5394.02.13) implemented by University of Thessaly and funded by Stavros Niarchos Foundation.