Can farm weeds improve the growth and microbiological quality of crickets (Gryllus bimaculatus)?

Abstract

Farming of edible insects has been proposed as a means to reduce current practices of harvesting from the wild. While farming could relieve the pressure on wild populations, as well as on their natural habitats, and generate a continuous supply of edible insects to the consumers, the high cost of commercial chicken feeds is still a challenge to many farmers. The aim of this study was to investigate whether the partial replacement of commercial chicken feed with the farm weed, wandering Jew (Commelina sinensis), would have an impact on weight gain and microbial quality of farmed field crickets (Gryllus bimaculatus). Therefore, we have experimentally compared two types of feed: (1) starter commercial chicken feed only (SO); and (2) starter commercial chicken feed supplemented with fresh wandering Jew weeds (S+W). After a feeding period of thirty days, the final body weight differed significantly (P=0.026) between crickets fed with SO and with S+W, which averaged at 1.11 and 1.39 g, respectively. Generally, high counts of total aerobic,Enterobacteriaceae, lactic acid bacteria, bacterial endospores, yeasts and moulds were observed in both experimental groups. However, bacterial endospore counts of S+W fed crickets (2.7 log cfu/g) were significantly lower (P=0.021) than these of the SO fed ones (3.9 log cfu/g). Metagenetic analyses indicated that Proteobacteria, Firmicutes and Tenericutes were the most abundant phyla, while members of the family Coxiellacea, and the generaLactobacillus, andSpiroplasma were the most abundant operational taxonomic units (OTUs). Concerning the food safety, a few OTUs could be associated with potential food pathogens, such asClostridiaceae,Staphylococcus andEnterobacteriaceae. In summary, the inclusion of fresh wandering Jew weeds in commercial starter chicken feed produced crickets with increased body weight and improved microbial quality.