Location: Biological Control of Pests Research
Title: Estimating optimal temperature conditions for growth, development, and reproduction of tenebrio molitor (coleoptera: tenebrionidae)Author
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Morales Ramos, Juan |
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Macchiano Jr, Anthony |
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Rojas, Maria |
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 12/7/2024 Publication Date: 12/26/2024 Citation: Morales Ramos, J.A., Macchiano Jr, A., Rojas, M.G. 2024. Estimating optimal temperature conditions for growth, development, and reproduction of tenebrio molitor (coleoptera: tenebrionidae). Journal of Economic Entomology. Journal of Economic Entomology, 2024, Vol. XX, No. XX. Interpretive Summary: A source of animal protein is required in animal feed formulations to provide essential nutrients lacking or found in insufficient quantities in vegetable-based ingredients. Fish meal has been the most important source of these nutrients in animal feed formulations; however, fish meal has become increasingly unsustainable and prices of this commodity are constantly rising. Insect protein is being explored as a potential replacement of fish meal in animal feed formulations. The yellow mealworm is one of the most important industrialized insects in the USA and the world, but some of the most basic aspects of its production are still being learn. Temperature is one of these aspects, because insects are unable to control their body temperature (poikilotherm) and they need to be grown under controlled temperature. The objective of this study was to determine the optimal temperature for growth, development, and reproduction of the yellow mealworm to optimize biomass productivity with the minimal heat energy requirements. Results of this study showed the optimal temperature for development and reproduction was 27°C and the overall fitness of the population was also the best at this temperature. Higher temperatures resulted in an increase in development time and a reduction in fecundity and immature survival. Currently, the industry standard temperature conditions to grow mealworms are between 29 and 33°C, which are considered to be optimal for growth. Our results show that, while growth may be faster at these temperatures, the resulting losses due to immature mortality and reduced fecundity cause an overall and substantial decrease of productivity. Reducing the temperature of the rearing facilities to 27°C will result in a gain in productivity and a reduction on the energy requirements, thereby increasing profitability. Technical Abstract: The yellow mealworm, Tenebrio molitor L., is one of the most important industrialized insects around the world. Its economic importance has been growing in the United States where insect farming has increased in the last decade. Temperature has significant economic implications on insect farming. Determining the optimal temperature conditions for T. molitor could potentially increase biomass productivity and reduce the energy costs and the carbon footprint of this new industry. Pupae of T. molitor were exposed to 8 different temperatures (18, 21, 24, 27, 30, 33,36, and 39°C) during their development. Developmental rates (=1 / days to develop) were calculated at 8 temperatures and fitted in a poikilotherm model to determine the temperature with the highest developmental rate (developmental maximum, To). The developmental maximum was 33°C and the thermal maximum (tm) (lethal temperature) was 39°C. The biological parameters of T. molitor were compared at three favorable temperatures below the To (31, 29, and 27°C) to estimate the optimal temperature conditions for rearing. Life table analysis was used to determine the fitness of T. molitor populations at these temperatures. Fecundity and egg viability were the highest at 27°C (5.25 eggs/female/d and 73.99%, respectively) and the lowest at 31°C (1.55 eggs/female/d and 27.14%, respectively). The shortest larval development time was observed at 27°C and the longest at 31°C (142.81 and 161.97 d, respectively). The highest fitness was observed at 27°C with a population doubling time of 32.78 d compared to 40.58 and 239.4 d at 29 and 31°C, respectively. |