Effects of antibiotics on the development and intestinal bacterial diversity of black soldier fly larvae

The effects of four antibiotics (metronidazole (M) levofloxacin (L), sodium ampicillin (A), and streptomycin sulphate (S)) and their pair-wise combinations at three doses on the development and intestinal bacterial diversity of the black soldier fly (BSF; Hermetia illucens) larvae were studied. At a low dose M and L were able to inhibit larval growth. At a high dose, all antibiotics were shown to inhibit larval growth. However, the pair-wise combinational use of the antibiotics did not effectively enhance the inhibitory effect. The gut bacterial diversity of the normal control (NC) was significantly higher than the antibiotic-treated groups with 737 operational taxonomic units (OTUs) from the larval guts of NC, compared to 305 and 227 from ML and AS. The number of anaerobic bacteria in ML was significantly lower than in NC and AS, with the relative abundance of OTUs from larval guts of ML being only about 0.01, compared to 0.4 for NC and 0.15 for AS. These results indicated that antibiotics at the experimental concentration did not affect the palatability of food for insects, but they would affect the diversity of food and intestinal microorganisms of BSF larvae, and the inhibitory effect of antibiotics on growth and development of BSF larvae displayed in this study was a complex effect.

Evaluation of microwave-dried black soldier fly (Hermetia illucens) larvae meal as a dietary protein source in broiler chicken diets

Here, the effect of microwave-dried black soldier fly (Hermetia illucens) larvae meal (HILM) as a dietary protein source on the growth performance and health of broilers was evaluated. A total of 126 male broilers were randomly allocated to three treatments (six replicates of seven birds per group): control diet (CON) of corn and soybean meal and two experimental diets in which soybean meal was replaced with 25% (25HILM) or 50% (50HILM) HILM. The broilers were slaughtered at 35 d to determine the apparent ileal digestibility (AID), volatile fatty acid (VFA) profiles, and length and weight of the small intestine. Blood samples were collected from 36 randomly selected birds (12 broilers per treatment) to determine serum parameters and haematological traits. Average daily gain, feed intake, and AID of protein were decreased (P<0.05) in the 50HILM group compared with those in the CON group. Dietary HILM increased (P<0.05) the relative length of the entire digestive tract and total VFAs in the caecal digesta. Serum low-density lipoprotein cholesterol was the lowest (P<0.01), but the triglyceride levels were the highest (P<0.05) in the 50HILM group. The serum phosphorus level was lower in both HILM diet-fed groups (P<0.01), whereas the creatine phosphokinase level was lower in the 50HILM group than in the CON group. In contrast, the 50HILM group showed higher (P<0.05) monocyte and red blood cell distribution width-standard deviation. In conclusion, dietary microwave-dried HILM positively influenced the VFA and cholesterol levels; however, growth performance was negatively affected by malnutrition caused by low protein digestibility in the 50HILM group. Microwave-dried HILM is a valuable ingredient for broiler diets, with up to 25% substitution showing no detrimental effects on growth performance and health. Further studies are needed to improve HILM digestibility.

Bioconversion of Cattle Manure by Hermetia Illucens Larvae: Mineral Content Changes in Manure and Larval Biomass.

Bioconversion by Hermetia illucens larvae is a novel technology for organic waste treatment and valorization. However, since the possible uses of products from this process are in agriculture and livestock, the bioconversion must guarantee the mineral quality of both the Hermetia illucens larvae frass and larval biomass. Therefore, this study aimed to assess the mineral content changes for both the larval biomass and larvae frass of Hermetia illucens after the manure bioconversion to determine their suitability as animal feed and organic fertilizer, respectively. Hermetia illucens larvae were put into a plastic box containing fresh cattle manure, and the control treatment with the same conditions without larvae was established. After the first pre-pupae were detected, frass and larvae were collected, and their mineral content was analyzed. At the end of the experiment, the larvae showed increases in some micro and macronutrients, especially calcium and manganese, increasing up to 2.6 and 22.6 times the initial concentration, respectively. The toxic elements concentration was increased in larval biomass, but these levels met the international legislation for animal feed. As a result, the mineral content in larval biomass revealed that Hermetia illucens could be potentially used as animal feed, which could be comparable with fish meal, and is probably better than soybean meal. However, the larvae frass could only be used as organic fertilizer in a Canadian context, with further treatment for decreasing the chromium content being necessary.

Effect of Feed Containing Hermetia illucens Larvae Immunized by Lactobacillus plantarum Injection on the Growth and Immunity of Rainbow Trout (Oncorhynchus mykiss)

We investigated the effects of a feed containing Hermetia illucens larvae injected with bacteria on the growth and immunity of Oncorhynchus mykiss. The feed was prepared by replacing fishmeal in feed with 25 and 50% nonimmunized (HIL25, HIL50) or immunized HIL (ImHIL25, ImHIL50), and its protein:fat:carbohydrate ratio was 45:15:18. ImHIL extracts showed inhibitory activity against fish pathogenic bacteria. Both red blood cell count and insulin-like growth factor-1 as the growth indicator were the highest among the groups at week 6 after feeding in the ImHIL50 group. As immune indicators, blood aspartate aminotransferase levels were lower in the ImHIL25 and ImHIL50 groups than in that of other groups at week 6 after feeding, and lysozyme content was significantly higher in ImHIL25 and ImHIL50. The above results demonstrate that ImHIL has a beneficial effect on the improvement of growth and immunity. Accordingly, we suggest that ImHIL has the potential to be a good feed source in aquaculture.

Food Safety of Consuming Black Soldier Fly (Hermetia illucens) Larvae: Microbial, Heavy Metal and Cross-Reactive Allergen Risks

Black soldier fly (Hermetia illucens) larvae (BSFL) are a promising, sustainable source of nutrients, however, there is limited knowledge regarding the food safety of consuming BSFL. This study determined the safety of consuming BSFL for direct human consumption in terms of microbial, heavy metal and allergen content. Microbial counts were determined using ISO (International Organization for Standardization) methods, heavy metals were determined using inductively coupled plasma mass spectrometry and allergens were determined via Orbitrap mass spectrometry and ELISA (enzyme-linked immunosorbent assay) kits. Feed and killing method influenced the presence of Bacillus cereus (p = 0.011), and only the killing method influenced Escherichia coli (p < 0.00) and total viable count (TVC) (p < 0.00). Blanching resulted in a 3-log reduction in E. coli and a 3.4 log reduction in the TVC counts. Salmonella spp. and Listeria spp. were not detected in the BSFL samples. Heavy metals were detected although they were below maximum legal limits. Cross-reactive allergens, tropomyosin and arginine kinase, were detected in the BSFL samples, although the clinical significance requires research. The feed fed to the BSFL and blanching were found to influence the safety of consuming BSFL, highlighting the importance of incorporating sufficient decontamination steps, such as blanching, to ensure food safety.

Consistent changes in the intestinal microbiota of Atlantic salmon fed insect meal diets

Background: Being part of fish's natural diets, insects have become a realistic, sustainable feed ingredient for aquaculture. While nutritional values of insects have been extensively studied in various fish species, their impact on the fish microbiota remains to be fully explored. In an 8-week freshwater feeding trial, Atlantic salmon ( Salmo salar ) were fed either a commercially relevant reference diet or an insect meal diet wherein black soldier fly ( Hermetia illucens ) larvae meal comprised 60% of total ingredients. Microbiota of digesta and mucosa origin from the proximal and distal intestine were collected and profiled along with feed and water samples. Results: The insect meal diet markedly modulated the salmon intestinal microbiota. Overall, the microbial diversity was lower in the digesta of salmon fed the insect meal diet but higher in the mucosa. A group of bacterial genera, dominated by members of the Bacillaceae family, was enriched in salmon fed the insect meal diet, which confirms our previous findings in a seawater feeding trial. We also found that microbiota in the intestine closely resembled that of the feeds but was distinct from the water microbiota. Notably, bacterial genera associated with the diet effects were also present in the feeds. Conclusions: We conclude that salmon fed the insect meal diets show consistent changes in the intestinal microbiota. The next challenge is to evaluate the extent to which these alterations are attributable to feed microbiota and dietary nutrients and what these changes mean for fish physiology and health.

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.