Beyond carrots: Evaluation of gelling agents as wet feeds for Tenebrio molitor L. (Coleoptera: Tenebrionidae) larvae

Abstract

Previous studies have shown that larvae of the yellow mealworm, Tenebrio molitor L. (Coleoptera: Tenebrionidae), need a source of moisture to grow and perform well. Currently, much research has been oriented towards the effect of dry feed on larval growth and performance. The effect of different wet feeds as moisture source on the performance traits of T. molitor larvae has not been thoroughly investigated yet. This study aims to investigate in laboratory trials the effect of various gelling agents (agar, carrageenans, guar gum, xanthan gum, sodium alginate, modified starch, and pectin) on the growth and performance of T. molitor larvae. A number of 50 newly emerged larvae obtained from the rearings of the LEAZ were inserted in plastic vials together with 4 g of wheat bran as dry feed. Additionally, 1 g of gelling agents was provided 3 times per week as moisture sources. Carrot slices served as control. Larval survival and weight were recorded weekly until the appearance of the first pupa. Dry feed was replenished when depleted. Our data showed that gelling agents efficiently supported the growth of T. molitor larvae, in terms of larval survival and weight, as well as feed utilization expressed as FCR. Interestingly, carrageenans seem to be the most appropriate gelling agent for T. molitor larvae rearing as it can enhance their weight and is also able to reduce their development time and their specific growth rate.