The effect of prolonged cold storage period on total lipid content and adult cannibalism of Tenebrio molitor

Abstract

With the discovery that the larvae of Tenebrio molitor (Coleoptera: Tenebrionidae) have a high protein and lipid content in recent years, they are grown in mass as additive feed or live feed. However, one of the most common problems faced by producers in production facilities is cannibalism, which occurs as a result of population density. For this reason, especially when the population is very dense, producers separate the insects that are in the pupa or larvae stage from the culture and keep them in coolers such as refrigerators. Then, when needed, they take the insects out of the refrigerator and use them. However, because insects are ectotherm organisms, their life cycles are extremely dependent on temperature. Although the cold storage method extends the shelf life of insects, exposing them to low temperatures for long periods can both damage their life cycle and significantly affect their lipid and protein content. In this study, the effects of cold storage on total lipid content, total lipid percentage and cannibalism rate of T. molitor larvae, pupae and adults were evaluated. In first stage of the study, the larvae were fed until they weighed 100-190 mg (larval stages 12-17). Afterwards, they were randomly selected and exposed to cold for 10, 20 and 30 days. In the second stage of the study, the larvae were exposed to cold for 10, 20 and 30 days after pupation. Then, they were put under normal laboratory conditions and their development was expected to be completed, and lipid analyzes were made and cannibalism rates were checked. As a result, as the duration of exposure to cold increased, the total lipid content and percentages decreased in the larvae of the unfed control group, while it increased or remained constant in the unfed and cold-exposed group. In addition, cannibalism was observed in T. molitor adults when they werent fed, that is, in cases of hunger and thirst.