Effect of dietary supplementation with powder derived from Moringa oleifera and Azadirachta indica leaves on growth and microbial load of edible crickets

Abstract

Cricket farming has shown its potential to address food and nutrition insecurity in parts of the world. However, one of the remaining challenges limiting mass production of edible insects is the affordability of feeds. One possible way to address this issue would be to explore the use of traditional plants such as Moringa oleifera leaf (MOL) and Azadirachta indica leaf (AIL) that are locally available, are protein-rich and possesses some antibacterial properties in insect feed formulation. In this regard, a study was conducted to evaluate the effect of supplementation of MOL (5 or 10%) and AIL (5 or 10%) powder in the commercially used starter chicken feed on growth and microbial load of house cricket (Acheta domesticus) and field cricket (Gryllus bimaculatus). After feeding for four weeks, the supplemented feeds with 10% MOL or 10% AIL in A. domesticus and G. bimaculatus significantly decreased (P<0.05) the body weights. Also, supplementation with MOL (5 or 10%) and AIL (5 or 10%) increased the mortality in both cricket species. Although high counts of total aerobic, Enterobacteriaceae, lactic acid bacteria, bacterial endospores, yeasts and moulds were observed, significantly lower counts (P<0.05) of lactic acid bacteria and bacterial endospores were observed in treatments containing MOL (5 or 10%) and 10% AIL in both cricket species. After processing (toasting and boiling), significant reductions (P<0.001) of all vegetative microbial cells were observed but bacterial endospores were not completely eliminated. Thus, during production and processing of insects and insect-derived products, bacterial endospores would require special attention. Salmonella and Escherichia coli were not detected in processed crickets’ samples. In conclusion, supplementation with 5% MOL or 5% AIL can produce crickets with similar body weight as control feed. Mortality increased significantly when feeds were supplemented with either MOL or AIL powder. Supplementation with MOL and AIL powders significantly reduced the cell numbers for some bacterial groups in both cricket species.