Feeding of cuticles from Tenebrio molitor larvae modulates the gut microbiota and attenuates hepatic steatosis in obese Zucker rats

an alternative and sustainable source of food and feed. A byproduct from mass-rearing of insect larvae are the shed cuticles - the most external components of insects which are a...

Gut Microbiome and Degradation Product Formation during Biodegradation of Expanded Polystyrene by Mealworm Larvae under Different Feeding Strategies

Polystyrene (PS) is a plastic polymer extensively used for food packaging. PS is difficult to decompose and has low recycling rates, resulting in its accumulation in the environment, in the form of microplastic particles causing pollution and harming oceans and wildlife. Degradation of PS by mealworms (Tenebrio molitor) has been suggested as a possible biological strategy for plastic contamination; however, the biodegradation mechanism of PS by mealworms is poorly understood. It is hypothesized that the gut microbiome plays an important role in the degradation of PS by mealworms. This study carried out a comparative analysis of the gut microbiome of Tenebrio molitor larvae under different feeding strategies, and of the formation of degradation compounds (monomers, oligomers). A diet of bran:PS at 4:1 and 20:1 ratios was tested. The diet with the low ratio of bran:PS led to the presence of higher amounts of these compounds, compared to that with the high ratio. In addition, it was demonstrated that the addition of H2O significantly improved the biodegradation of PS monomer and oligomer residues, which could be identified only in the frass. The protein and nitrogen contents in insects’ biomass and frass varied amongst treatments. The diets resulted in differences in the gut microbiota, and three potential bacterial strains were identified as candidates involved in the biodegradation of PS.

Growth Performance of Hermetia illucens and Tenebrio molitor in Different Organic Waste Biconversion Process

The amount of organic waste in Indonesia has increased. One solution to reduce the amount of organic waste is to use the concept of bioconversion. Bioconversion can be done using the larvae of insects Hermetia illucens and Tenebrio molitor. The type of organic waste and the amount of organic waste given affects the change in body weight of the larvae Hermetia illucens and Tenebrio molitor (P>0.01). The largest change in the body weight of Hermetia illucens larvae occurs in the market waste media and the largest change in the body weight of Tenebrio molitor larvae occurs in chicken manure. The survival rates of Hermetia illucens and Tenebrio molitor are highest in the market waste media.

The effects of density on the growth, survival and feed conversion of Tenebrio molitor larvae

An appropriate stocking density is beneficial to run an efficient business and improve animal welfare. In most traditional livestock this is defined as the number of animals per area. However, the larvae of the mealworm (Tenebrio molitor), one of the most important commercial insects, live both on top and inside their feed. In this study we assessed if different areal stocking densities (2D, range 0.6-10.4 larvae/cm2) resulted in a different growth rate and feed efficiency when the volumetric stocking density remained constant (1 larvae/cm3). In a first experiment the larvae received wheat bran once at the start, but in the second experiment wheat bran was added throughout the experiment to ensure that the larvae remained at 1 larvae/cm3. The results indicate that, given a stable volumetric density, the areal density can vary between 0.6 and 10.4 larvae/cm2 without extreme variation in growth, survival or feed efficiency. The lowest assessed densities did result in a slightly lower average weight and yield. A maximum yield per volume of feed was observed at 2.5 larvae/cm2 (feed conversion ratio (FCR) of 1.76 dry feed/live larvae). Yet, the overall highest yield was observed at 10.4 larvae/cm2 as the increased areal density far outweighed the slight decrease in FCR. In conclusion: when mealworm larvae are provided with an equal volume of wheat bran the influence of areal density is low and could be as high as 10.4 larvae/cm2 for optimal yield.