Inheritance of two traits with high plasticity, developmental speed and body size, in Tenebrio molitor (Coleoptera: Tenebrionidae)

Authors: Morales Ramos, Juan; Rojas, Maria - Guadalupe; TWEEDY, DAMIAN - Beta Hatch Inc; KELSTRUP, HANS - Beta Hatch Inc; EMERY, VIRGINIA - Beta Hatch Inc

Submitted to: Journal of Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/24/2022
Publication Date: 12/30/2022
Citation: Morales Ramos, J.A., Rojas, M.G., Tweedy, D., Kelstrup, H.C., Emery, V. 2022. Inheritance of two traits with high plasticity, developmental speed and body size, in Tenebrio molitor (Coleoptera: Tenebrionidae). Journal of Insect Science. 22(6):13. https://doi.org/10.1093/jisesa/ieac075.
DOI: https://doi.org/10.1093/jisesa/ieac075

Interpretive Summary: The yellow mealworm, one of the most important industrialized insects in the world, has the potential to be a substitute for fish meal in animal feed formulations. Fish meal prices rise continuously as this increasingly unsustainable resource becomes more scarce. Insect meal can potentially provide more of the essential nutrients than other alternatives to fish meal such as soybean flour. However, the production of insect protein must increase substantially to mach the required volumes to become a viable alternative to fish meal in the market. One way to increase production of insect protein could be by increasing the insect growth rates by genetically improving mealworm lines. Two traits linked to mealworm growth rates, body size and development time, were studied to determine in what percentage they were inherited by the next generation (heritability). Mealworms with different levels of development speed and body size were established. The resulting progeny from these groups were then analyzed for the frequency of the different levels of the two traits studied and correlated with the parental groups to determine heritability levels. Results showed that development speed and body size have genetic determination of 62.7 and 40.7%, respectively. These results show that the development speed and body size of mealworms potentially can be impacted by selection, opening the possibilities for the genetic improvement of this insect to increase its productivity for animal feed purposes.

Technical Abstract: Heritability of larval development time and body size in Tenebrio molitor L. was determined using the method of parent-offspring regression. The parental group was obtained from a cohort consisting of one day oviposition from a stock colony. Adults resulting from this cohort were divided into 28 class groups according to their larval development time and pupal weight. The progeny resulting from these parental classes was grouped in experimental units of 27 larvae and allowed to develop to the pupal stage. Larval development time and pupal weight were measured individually at 27°C, 75% RH, and no lights. Experimental unit means of larval development time and pupal weight of the progeny were compared with their parental classes using linear regression. Larval development time and pupal weight parental classes had a significant impact on progenies means of larval development time and pupal weight, respectively. The regression coefficient (ß) for larval development time had a value of 0.627 ± 0.01 and a value of 0.407 ± 0.01 for pupal weight. These values represent the proportion of genetic determination of these two characters based on the principles of the method of parent-offspring regression. The apparent independence of larval development time and pupal weight based on their poor linear correlation is discussed.