# Determining the Effectiveness of Saccharomyces cerevisiae as a Postbiotic in Mass-Reared Acheta domesticus (House Cricket)

## TL;DR

Adding a postbiotic made from yeast to crickets' food improved their survival and biomass, likely by changing their gut bacteria.

## Contribution

Demonstrates that a 0.5% postbiotic inclusion in cricket diets enhances survival and biomass through gut microbiome shifts.

## Key findings

- A 0.5% postbiotic inclusion increased cricket survival and total biomass.
- Postbiotic-fed crickets showed higher abundances of beneficial gut bacteria like Akkermansia and Catenibacillus.
- No significant changes in viral prevalence were observed in postbiotic-fed crickets.

## Abstract

Nutritional supplements such as pre-, pro-, and post-biotics have been used in several feeder insect species to increase yields and improve health outcomes. This study provided commercially reared crickets with a Saccharomyces cerevisiae postbiotic product and found that a 0.5% inclusion rate within their normal diet was able to increase survival and produce a higher total biomass. No changes were seen in viral prevalence rates, but there were differences found within the gut microbiome that likely contributed to increased survival rates. Overall, the inclusion of a postbiotic appeared to be beneficial and further study is warranted.

Pre-, pro-, and post-biotics have been used with success in several commercially grown insect species to increase yields and improve health outcomes. However, few studies have been published evaluating the use of nutritional supplements in Acheta domesticus. For this study, we fed day-old, farm-raised, A. domesticus a Saccharomyces cerevisiae postbiotic product at one of three different inclusion rates (0, 0.25, and 0.5%) for 32 days. Crickets were analyzed for differences in average weights, total biomass, percent survival, nutritional analyses, viral qPCR, and 16S/18S microbiomes. Crickets receiving the 0.5% inclusion feed trended towards having a higher total biomass (F = 3.823, p = 0.052) and a higher percent survival per bin (F = 3.667, p = 0.057) than the crickets receiving lower inclusion feeds. No significant differences were found in viral prevalences or loads. Significant changes to the microbiomes were mostly defined by increased abundances of presumed beneficial bacteria (Akkermansia, Catenibacillus, and Odoribacter) in the groups receiving postbiotics rather than by losses of harmful bacteria. For the 18S results, there was an increased abundance of a Gregarian apicomplexan, Leidyana erratica in the treatment groups. Overall, the 0.5% inclusion feed appeared to be beneficial and further study investigating other forms of feed additives is warranted.