Efficiency comparison of different egg-laying systems in the industrial insect breeding of Tenebrio Molitor

Industrial insect breeding faces numerous challenges, particularly with regard to egg laying and the reproduction of Tenebrio molitor. In this article, we compare three different methods and best practices of egg laying in industrial breeding facilities from different countries to evaluate the efficiency and effectiveness of each system.

Substrate-based oviposition
In this system, beetles live on a substrate that is sieved regularly, every few days. After sieving, the eggs in the substrate are transferred to trays where they continue to grow. This process is relatively simple and inexpensive, but carries the risk of eggs being damaged during the sieving process. At the same time, the beetles can get to the eggs and eat them. In addition, a variance of the beetles in age, sex, activity and genetic lineage per tray cannot be excluded, which makes the exact number of young larvae deviate and makes the determination of young larvae per tray impossible.

Laying insert with net installation
With this method, the beetles live on a special laying insert that is equipped with a net. The beetles cannot eat their eggs and lay them through the net directly into the substrate. The laying insert is then removed every few days together with the beetles. The eggs in the substrate are then transferred to trays for further breeding. This method reduces the risk of feeding damage, as the beetles cannot reach the eggs due to the netting. However, even with this method a variance of the beetles in age, sex, activity and genetic lineage per tray cannot be excluded, which makes the exact number of juvenile larvae deviate and makes the determination of juvenile larvae per tray impossible.

SmartBreed egg storage system

SmartBreed has developed an innovative egg-laying system in which beetles live throughout their entire egg-laying cycle. The beetles lay their eggs in the ovipositor, and the eggs remain protected in the ovipositor until they hatch. Vibrations and stress caused by sieving or other influences are thus avoided. As soon as the young larvae hatch from the eggs, they automatically fall from the egg tray into a collecting box below. This prevents young larvae from eating the eggs and allows the offspring to be treated more gently. The offspring can then be accurately counted without substrate residues and divided into trays for rearing.

A Cost-Benefit Analysis for each system has shown that the substrate-based egg-laying system is the most cost-effective for small farms with a few tonnes of live larvae per year. The use of laying inserts is worthwhile from as little as 100 tonnes of larvae per year, as the reduced egg losses mean that a significantly smaller beetle population has to be reared. If a high degree of automation is required, SmartBreed’s egg deposition systems must be considered from an annual production of 500 tonnes of larvae. Due to the efficiency, a lower beetle population (and thus reproduction) is necessary and the automation of the egg-laying systems is cheaper and easier to realise than laying inserts with net installation, no beetle pool is required. It is also scalable as required.

A comparison of the survival rates reflects the efficiencies of the three egg-laying systems. Deruytter et al. (2019) and Frooninckx (2022) investigated the influence of cannibalisuns on egg laying rates in their studies and came to the conclusion that reducing cannibalism (by netting) can significantly increase the efficiency and thus the production of a mealworm farm. The number of eggs produced per female decreases rapidly as the egg-laying period and density increases, which is (partly) due to cannibalism. A reduction in cannibalism (through netting) can significantly increase efficiency, as the density effect (more beetles lead to reduced laying performance) is almost cancelled out if the beetles cannot reach their eggs. This influence also applies to the SmartBreed egg-laying system. As the egg-laying period has no influence because the hatched larvae fall directly into a collecting basin, the beetles can live on the laying inserts for the entire egg-laying period. This enables efficient feeding with important nutrients and minimises stress for the beetles.

When choosing an egg-laying system, legal regulations and standards should also be taken into account. In the poultry industry, the separation of reproduction (production of young animals) and fattening/rearing is an industry standard, especially for laying hens and in poultry fattening. This practice is carried out for several reasons, in particular for production efficiency, health management and disease prevention and control over reproduction. With SmartBreed egg-laying, the production of young animals and fattening/rearing are completely separate and no parent animals come into contact with the substrate where the young larvae are reared.

When selecting the appropriate system, industrial growers should consider the specific needs of their insect species and fattening solution as well as the available resources and the desired level of automation.