Abdul Aziz Soomro1, Minmin Cai1, Kashif ur Rehman1,2, Longyu Zheng1, Xiaopeng Xiao1, Alexander Mathys3, Moritz Gold3,4, Jeffery K. Tomberlin5, Ziniu Yu1, Jibin Zhang1* 1State Key Laboratory of Agricultural Microbiology, National Engineering Research Center of Microbial Pesticides, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China 2Livestock and Dairy Development Department, Poultry Research Institute, Government of Punjab, Pakistan 3Laboratory of Sustainable Food Processing, Institute of Food, Nutrition and Health, ETH Zurich, Zürich, Switzerland 4Department of Sanitation, Water and Solid Waste for Development (Sandec), Swiss Federal Institute of Aquatic Science and Technology (Eawag), Dübendorf, Switzerland 5Department of Entomology, Texas A&M University,USA *Corresponding author e-mail address: zhangjb@mail.hzau.edu.cn (J. Zhang) Abstract The processing of organic waste with black soldier fly larvae is an emerging waste treatment technology. To enhance the conversion efficiency of soybean curd residues (SCR) by black soldier fly larvae (BSFL) assisted by different gut bacteria and subsequently obtain high-quality insect protein and lipid for human and livestock consumption, we pretreated SCR with different gut bacteria (108 cfu/ml) and used BSFL for conversion. All gut bacterial strains showed significant impact on BSFL conversion efficacy, nutrition, and safety. FCR and protein and lipid content in BSFL are the most important parameters for evaluating BSFL conversion efficacy. Among the bacterial strains, BSFL with Bacillus subtilis BSFL-CL (Group R1) showed the highest co-conversion efficiency and best performance and showed significant enhancement in nutrient content and decrease in FCR. BSFL assisted by microbes enhanced the co-conversion process of BSFL and reduced the development time of BSFL from 19 days to 15 days.

Larvae of the black soldier fly (BSF), Hermetia illucens, are voracious feeders that can grow on a wide variety of organic materials. When grown on organic side streams, they are able to convert such low value materials into high value biomass composed of fats, proteins and chitin. These components can be used as a sustainable resource for food, feed and technical applications. The potential of a side stream as an ingredient of a rearing diet for BSF depends among other things on its chemical and physical properties. The influence of chemical parameters such as pH, macronutrient concentration and ratio have already been reported in literature, but the influence of the physical characteristics have been neglected so far. In this study we investigate the influence of dynamic and kinematic viscosity, syneresis and water holding capacity of semi-artificial BSF rearing diets on growth, biomass conversion and material reduction of BSF larvae. The output of these experiments will give us more insight on the potential of side streams with specific chemical and physical properties as an ingredient of a BSF rearing diet.

Grass clippings from maintenance of our roadside verges pose a problem throughout Europe. The high volumes of biomass involved, result in high (waste) processing costs. Both industry and local authorities, however, are interested in the possibility of using roadside grass clippings as a novel biobased resource. One possible application is using the grass fibres for the production of building panels and bio-composites. This requires separating the solid (fibres) and the liquid fractions. The liquid fraction (grass juice) contains the grass proteins. The feasibility of bio-converting these proteins to insect protein was assessed by using the juice as a feedstock for black soldier fly larvae.

The mass production of black soldier fly larvae (BSF) is an opportunity to bioconvert many types of residual organic matter (ROM) in sustainable alternative livestock feed ingredients rich in proteins and lipids. By products of this upcycling – called frass – include feces, exuviae rich in chitin and residual organic matter and may offer interesting fertilizing potential. This study examined how BSF larvae convert pre-consumer organic matter collected from grocery stores in the Quebec City area. ROM was composed of 52% vegetables, 38% fruits and 10% bread and cereals products. Six different iso-lipidic (3,6% dw) and iso-energetic (18,3 MJ/Kg) containing 85% moisture (plus a 70% RH reference) were formulated with varying ratios of ROM (0, 30, 50, 70 and 100%) incorporated to the Gainesville control (50% wheat bran, 30% alfalfa and 20% corn, mass in dry weight). A total of 144 g dw were given to 600 larvae per bin, and the experiment was conducted in triplicate. Frass was collected following 10-13 days growth experiments conducted at 27°C and 80% relative humidity. Higher moisture content prevented microbial decomposition activity based on temperature remaining at ambient levels and low pH (<5). Despite a stable C/N ratio, enhanced mineralization of the Gainesville diets increased from day 10 to 13 while nitrogen availability (N-NH4/Ntot) dropped in higher moisture treatments. Because the C/N ratio and moisture content of the frass for all treatments outside the optimal range for composting (25-30/1 and >65%, respectively) addition of a dry carbon rich bulking agent is recommended for further biological stabilization through composting. The fertilizing value (N-P-K) of 13d old frass harvested from the Gainsville 70% RH treatment is 6-9-8, but only 3-3-3 in the control at 85% RH and 3-1-4 in the 100% ROM treatment. All Gainesville controls contained higher concentrations of trace elements (Ca, Mg, Mn, Zn, Fe) and OM compared to treatments with increasing concentrations of ROM, except for Na which increased with the addition of ROM (≤0,05%), while remaining at least 100 times below maximal agronomic guidelines (5%). In conclusion, black soldier fly frass appears to have some interesting soil conditioning (10-22% OM) and fertilizing properties, but based on laboratory scale results obtained, it may require additional stabilization through composting before it can safely be used as a soil amendment.

Insects show great potential as a natural tool for the bioremediation of mycotoxin-contaminated feed wastes. Our research along with those of others have shown that the yellow mealworm (Tenebrio molitor) can dramatically reduce the level of mycotoxins (e.g., aflatoxin, deoxynivalenol and zearalenone) in feed, and the concentration of the toxin does not appear to impact larval growth or mortality. The detoxifying prowess of the mealworm gut may open new waste streams that insect growers can uniquely exploit. For example, ethanol production from corn fermentation and distillation creates a by-product called Dried Distillers Grains with Solubles (DDGS). Corn is one of the most susceptible crops to mycotoxin contamination, and mycotoxins are concentrated 3x in the DDGS, making it problematic to sell as conventional animal feed. Yet for insects, contaminated DDGS pose no such problem, and our research is showing that DDGS is a preferred ingredient for the yellow mealworm. However, due to their high protein and lipid but low carbohydrate content, DDGS are not adequate as insect diets when used in high concentrations or by themselves. In this presentation, we report results from our research on mycotoxin detoxification by the yellow mealworm, and in turn show the progress we have made in formulating diets high in corn DDGS that will maximize mycotoxin bioremediation, while at the same time providing adequate nutrition for mealworm production.