Feeding the larvae: the first results of a large scale mealworm ring test

Tenebrio molitor is one of the main species currently used for food and feed. Unsurprisingly, this results in a plethora of studies assessing the optimal feed for the larvae of this species. Due to the differences in experimental designs of the different studies it is not easy to compare the results and draw conclusions. In order to improve the comparability of future experiments, a consortium of researchers and companies has attempted to create a standardized protocol for a feed experiment. In a first stage, a theoretical protocol was constructed based on the experiences of the different partners. Ensuring that the protocol was scientifically sound, easy to execute and the results were useful by the industry. Some of the standardized elements were: larvae age, larvae density, control feed, amount of dry and wet feed, etc. The protocol can be summarised as follows, the experiment starts with 10,000 four week old larvae in a 60 * 40 cm crate with wheat bran as control dry feed and agar as wet feed. Mealworm growth progression is checked every week. The experiment ends when only 10 % or less of the dry feed remains or when more than 10 % pupae are present. In a second stage, the theoretical protocol was put to the test by the different partners to determine the practical feasibility, repeatability and reproducibility. Furthermore, this was done for two feeds: a standardized wheat bran (identical for all partners) and a locally sourced wheat bran. Initial results indicate that the protocol is practical but there are differences between partners. The initial weight of the larvae plays herein an important role in the outcome. Furthermore, for some partners a growth differences between mealworm growth on standardized wheat bran was observed. This indicates a further need for feed standardization.