Biochemical characterization of digestive enzymes in the black soldier fly,Hermetia illucens (Diptera: Stratiomyidae)

The black soldier fly, Hermetia illucens, is beneficial because its larvae feed on organic materials derived from plants, animals and humans and promote the recycling of food waste and organic materials. We investigated the biochemical properties of digestive enzymes released from the salivary gland and gut of the black soldier fly. Because the gut extracts of the black soldier fly larvae had high amylase, lipase and protease activities, we suggested that the black soldier fly might belong to the polyphagous insect group. In addition, a strong trypsin-like protease activity was observed in the gut extracts of the black soldier fly larvae. Higher activities of leucine arylamidase, α-galactosidase, β-galactosidase, α-mannosidase and α-fucosidase were observed from the gut extracts of the black soldier fly larvae compared with those of house fly larvae. These findings may explain previous reports that the black soldier fly larvae can digest food wastes and organic materials more efficiently than any other known species of fly.     

Enhancement of fruit byproducts through bioconversion by Hermetia illucens (Diptera: Stratiomyidae)

Bioconversion is a biological process by which organic materials are converted into products with higher biological and commercial value. During its larval stage the black soldier fly Hermetia illucens is extremely voracious and can feed on a wide variety of organic materials. To study the impact of different fruit byproducts on the insect's growth, final larval biomass, substrate reduction, bioconversion parameters, and larval nutritional composition, 10 000 black soldier fly larvae (BSFL) were reared on 7.0 kg of one of three substrates (strawberry, tangerine, or orange) or on a standard diet as a control. The results highlight that BSFL can successfully feed and grow on each of these diets, though their development time, growth rate, and final biomass were differently impacted by the substrates, with strawberry being the most suitable. The lipid and protein contents of BSFL were similar among larvae fed on different substrates; however, major differences were detected in ash, micronutrient, fiber, fatty acid, and amino acid contents. Overall, the results indicate that fruit waste management through the BSFL bioconversion process represents a commercially promising resource for regional and national agrifood companies. Our study offers new perspectives for sustainable and environmentally friendly industrial development by which fruit byproducts or waste might be disposed of or unconventionally enhanced to create secondary products of high biological and economic value, including BSFL biomass as animal feed or, in perspective, as alternative protein source for human nutrition.     

黑水虻幼虫处理餐厨垃圾过程中体内养分组成与消化酶活性变化规律的研究

黑水虻Hermetia illucens作为一种新型资源环境昆虫,其幼虫可以处理餐厨垃圾、畜禽粪便、蔬菜残体等各种有机废弃物。幼虫富含蛋白质和油脂,可以作为水产饲料的蛋白来源。本研究探索黑水虻幼虫处理餐厨垃圾过程中其养分组成与消化酶活性变化之间的关系。通过黑水虻幼虫自由取食餐厨垃圾,每日采集样品用于物质养分和消化酶活性的测定。结果显示：黑水虻幼虫粗蛋白含量呈现先下降后上升的变化规律,而幼虫总糖含量呈现先上升后下降的变化规律,粗脂肪含量维持上升的趋势。幼虫处理餐厨垃圾过程中,体内蛋白酶在初期迅速上升,第6天后逐渐下降,而淀粉酶呈现出先缓慢上升再迅速上升最后下降的变化规律。脂肪酶在黑水虻幼虫处理餐厨垃圾前期保持较高的活性然后缓慢下降。同时,通过相关性分析,黑水虻幼虫粗蛋白含量变化与蛋白酶活性没有相关性,而总糖与粗脂肪含量变化分别与淀粉酶、脂肪酶有相关性。因此,部分消化酶活性变化与黑水虻幼虫养分组成具有一定的联系,本研究结果为工厂化养殖黑水虻提供一定的理论基础。     

进境小麦下脚料养殖黑水虻幼虫的饲料配比研究

黑水虻Hermetia illucens是一种备受关注的资源昆虫,主要用于处理粪便和餐厨余垃圾,虫体也可作为蛋白源进入下游的牲畜饲料。本研究以黑水虻幼虫为试验对象,设置5个不同配比的黑水虻饲料配方,探究进境小麦下脚料用于黑水虻饲养的可行性。研究发现,黑水虻幼虫抗逆性极好,不同饲料配方饲养的黑水虻幼虫存活率均超过95%。幼虫干虫的营养成分分析表明,进境小麦下脚料所养殖的幼虫蛋白成分可达45%,油脂含量可达30%,比常规蛋白饲料豆粕的44.2%蛋白含量稍高。综合黑水虻幼虫鲜重、干重、干重率以及饲料降解量的养殖结果,小麦下脚料含量为60%的饲料配方具有最佳的转化产出。     

Effects of food substrates and moxidectin on development of black soldier fly,Hermetia illucens

Black soldier fly is a common and widely distributed saprophagous species that has an excellent potential for being used for biological conversion of organic wastes on an industrial scale. The main goal of the reported study was expanding the list of wastes suitable for utilization by this species. We compared larval growth on cull potatoes, horse manure and cafeteria food waste in 100‐L bins in a greenhouse. We also conducted laboratory experiments to investigate whether black soldier fly larvae are affected by the presence of moxidectin, a common endectocide used to treat an array of domestic animals and readily excreted in faeces, in their food substrates. Feeding on potatoes resulted in slower growth, and the final size of potato‐fed larvae was smaller compared to the larvae fed on cafeteria waste. Nevertheless, potatoes supported substantial biomass accumulation, and could be a valuable option for rearing fly larvae for commercial feed production. Larvae feeding on horse manure gained very little weight and eventually failed to pupate. Moxidectin had a strong negative effect on larval survivorship; however, ca. 30% of larvae reared in the substrate containing a realistic field concentration of moxidectin still survived to adulthood. Our findings confirm that using black soldier fly larvae is a promising technology for recycling organic wastes, including those of plant origin.     

黑水虻幼虫和预蛹的饲料价值研究进展

黑水虻Hermetia illucens L.是一种全世界广泛分布的资源昆虫,幼虫在自然界以动物粪便、腐烂的有机物,如腐肉、腐烂的水果、蔬菜和植物性垃圾为食,能够被用于畜禽粪便的无害化处理。黑水虻幼虫在将粪便转化成昆虫生物量的同时,减少了粪便的污染。利用畜禽粪便饲养的黑水虻幼虫干重达到42%～43%,其中粗蛋白含量占干重的42%～44%,脂肪含量占干重的31%～35%,灰份占干重的11%～15%,钙质占干重的4.8%～5.1%,磷占干重的0.60%～0.63%。使用粪便饲养的幼虫和预蛹,含有丰富的必需氨基酸和矿物质,是家禽、家畜和鱼类养殖的良好饲料来源。文章综述利用不同动物粪便饲养的黑水虻幼虫和预蛹的饲料价值及其幼虫和预蛹用于鸡、猪和鱼类饲料添加剂的研究进展。     

Susceptibility of black soldier fly (Diptera: Stratiomyidae) larvae and adults to four insecticides

Dosage-mortality regressions were determined for black soldier fly, Hermetia illucens (L.), larvae fed cyromazine or pyriproxifen treated media. Cyromazine LC50 for larvae dying before becoming prepupae ranged from 0.25 to 0.28 ppm with dosage-mortality regression slopes between 5.79 and 12.04. Cyromazine LC50s for larvae dying before emergence ranged from 0.13 to 0.19 ppm with dosage-mortality regression slopes between 3.94 and 7.69. Pyriproxifen dosage-mortality regressions were not generated for larvae failing to become prepupae since <32% mortality was recorded at the highest concentration of 1,857 ppm. LC50s for larvae failing to become adults ranged from 0.10 to 0.12 ppm with dosage mortality-regression slopes between 1.67 and 2.32. Lambda-cyhalothrin and permethrin dosage-mortality regressions were determined for wild adult black soldier flies and house flies, Musca domestica L., and for susceptible house flies. Our results indicate that the wild house fly, unlike the black soldier fly, population was highly resistant to each of these pyrethroids. Regression slopes for black soldier flies exposed to lambda-cyhalothrin were twice as steep as those determined for the wild house fly strain. Accordingly, LC50s for the black soldier fly and susceptible house fly were 10- to 30-fold lower than those determined for wild house flies. The differential sensitivity between wild black soldier flies and house flies might be due to behavioral differences. Adult house flies usually remain in animal facilities with the possibility of every adult receiving pesticide exposure, while black soldier fly adults are typically present only during emergence and oviposition thereby limiting their exposure.     

Inoculating poultry manure with companion bacteria influences growth and development of black soldier fly (Diptera: Stratiomyidae) larvae

The growth and development of black soldier fly, Hermetia illucens (L.), larvae fed chicken manure inoculated with bacteria isolated from black soldier fly larvae and associated larval feed was evaluated. Four strains of Bacillus subtilis were evaluated. B. subtilis strains S15, S16, S19, were isolated from the gut of black soldier fly larvae. B. natto strain D1 was isolated from the diet fed to black soldier fly larvae. These bacteria were added individually into nonsterile 200 g fresh hen manure at 10(6) cfu/g and homogenized. Treated manure was then inoculated with 4-d old black soldier fly larvae. Prepupal weight ranged from 0.0606 g in the control to 0.0946 g in manure treated with the S15 strain. Larval survivorship to the prepupal stage in all treatments ranged from 98.00 ± 2.65% to 99.33 ± 1.15%. Prepupal survivorship to the pupal stage ranged from 91.92 ± 1.87% to 97.95 ± 1.03%. Adult emergence from the pupal stage did not significantly (P < 0.05) differ across treatments and ranged from 98.95 ± 1.82% to 100.00 ± 0.00%. Adult body length resulting from the larvae in each of the treatments was significantly greater than those from the control. Longevity of adults did not differ significantly between treatments. Time from hatching to the development of the first pupa did not differ significantly across treatments; however, development time from hatching to 90% reaching the prepupual stage was significantly different between treatments and ranged from 29.00 ± 1.00 d to 34.33 ± 3.51 d. Development time from hatching to 90% reaching the adult stages was significantly different between treatments. Our results demonstrate that inoculating poultry manure with bacteria from black soldier fly larvae influences the growth and development of conspecific larvae feeding on the manure.     

黑水虻幼虫及预蛹抗逆性的初步研究

本文初步研究了老熟和预蛹阶段的黑水虻Hermetiaillucens对于酒精毒性、氧胁迫和高渗透压条件下的耐受特性,结果显示黑水虻幼虫和预蛹在三种胁迫因子处于20%～60%(浓度)的较低水平时,其平均死亡率低于20%,表现出良好的抗逆性。高浓度的酒精、矿物油和氯化钠溶液对于黑水虻的生存都会产生负面影响,但是幼虫与预蛹由于其生理形态上的变化,致使其在抗逆性方面表现出显著差异,预蛹阶段的黑水虻对矿物油较为敏感,而幼虫则对高盐环境的耐受性表现较弱。     

Behavior of dimethyl phthalate (DMP) in simulated landfill bioreactors with different operation modes

The behavior of dimethyl phthalate (DMP) from municipal solid waste (MSW) in the leachate and refuse of two simulated landfill bioreactors was compared. In one reactor, the leachate was circulated between a landfill and a methanogenic reactor, while the other reactor was operated using direct recirculation of the leachate. The results revealed that the original concentration of DMP in the refuse was approximately 3.3 μg g⁻¹, and the concentration decreased greatly during decomposition of the waste in both reactors. The major loss of DMP from the landfill occurred in an active methanogenic environment in the later period, while the environment was acidic due to a high concentration of chemical oxygen demand (COD), volatile fatty acids (VFA), and contained a large volume of biologically degradable material (BDM) during the early stage. In addition, a high correlation was found between the residual DMP concentrations and the BDM of the refuse in both systems. Circulating the leachate between the landfill and a methanogenic reactor resulted in an increase in the biodegradability of MSW and the degree of waste stabilization. Furthermore, the removal of DMP was enhanced 14% in the landfill that was operated in conjunction with the methanogenic reactor when compared to the landfill in which there was direct leachate recirculation.     

Development of black soldier fly (Diptera: Stratiomyidae) larvae fed dairy manure

Black soldier flies, Hermetia illucens L., are a common colonizer of animal wastes. However, all published development data for this species are from studies using artificial diets. This study represents the first examining black soldier fly development on animal wastes. Additionally, this study examined the ability of black soldier fly larvae to reduce dry matter and associated nutrients in manure. Black soldier fly larvae were fed four rates of dairy manure to determine their effects on larval and adult life history traits. Feed rate affected larval and adult development. Those fed less ration daily weighed less than those fed a greater ration. Additionally, larvae provided the least amount of dairy manure took longer to develop to the prepupal stage; however, they needed less time to reach the adult stage. Adults resulting from larvae provided 27 g dairy manure/d lived 3-4 d less than those fed 70 g dairy manure. Percentage survivorship to the prepupal or adult stages did not differ across treatments. Larvae fed 27 g dairy manure daily reduced manure dry matter mass by 58%, whereas those fed 70 g daily reduced dry matter 33%. Black soldier fly larvae were able to reduce available P by 61-70% and N by 30-50% across treatments. Based on results from this study, the black soldier fly could be used to reduce wastes and associated nutrients in confined bovine facilities.     

Dimethyl sulfide emission behavior from landfill site with air and water control

Municipal solid waste landfills are responsible for odors affecting the environment and human health. Dimethyl sulfide (DMS) is one of the major odorous compounds known for its low odor threshold and wide distribution. This study examined the generation, migration and emission of DMS in four artificial landfill-simulating reactors: Reactor 1 and Reactor 2, running under anaerobic and semi-aerobic conditions, respectively, without leachate recirculation; and Reactor 3 and Reactor 4, running under anaerobic and semi-aerobic conditions, respectively, with leachate recirculation. From the odor control perspective, aeration can efficiently inhibit maximum DMS headspace concentration by 31.7–93.7%, especially with the functioning of leachate recirculation. However, leachate recirculation in anaerobic conditions may double the DMS emission concentration but may also shorten the period over which DMS is effective because of the upward migration of liquid DMS in the recirculated leachate. The DMS generation was active in the acidification and methane fermentation phase of the simulated landfill and was possibly affected by the volatile fatty acid concentration, chemical oxygen demand, total organic carbon concentration and pH of the leachate, as well as total organic carbon in the refuse. Most significantly, DMS emission can be effectually dealt with by aeration along with leachate recirculation.     

Cellulolytic activity in leachate during leach-bed anaerobic digestion of municipal solid waste

The degradation of municipal solid waste (MSW) under mesophilic conditions can be enhanced by exchanging leachate between fresh waste and stabilised waste. The optimum point in time when leachate from an anaerobically digesting waste bed can be used to initiate degradation of another waste bed might occur when the leachate of the digesting waste bed is highly active with cellulolytic and methanogenic bacteria. In this study, the cellulolytic activity of the leachate was measured using the cellulose-azure assay. As products of hydrolysis are soluble compounds, the rate of generation of these compounds was estimated based on a soluble chemical oxygen demand (SCOD) balance around the fresh waste bed. It was found that once the readily soluble material present in MSW was washed out there was very little generation of SCOD without the production of methane, indicating that flushing leachate from a stabilised waste bed resulted in a balanced inoculation of the fresh waste bed. With the onset of sustained methanogenesis, the rate of SCOD generation equalled the SCOD released from the digester as methane. The experimental findings also showed that cellulolytic activities of the leachate samples closely followed the trend of SCOD generation.     

黑水虻油的研究与综合利用

黑水虻Hermetia illucens L.是一种高脂肪昆虫,其体脂中不饱和脂肪酸与饱和脂肪酸的比例适宜,月桂酸等中链脂肪酸含量丰富,具有开发为饲用油、食用油及工业用油的广阔前景。本文从影响黑水虻油产量和质量的因素（黑水虻发育阶段、环境因子、养殖基质及制取工艺）、黑水虻油在饲料（畜禽和水产饲料）、食品（食用油）中的应用及其作为生物柴油和化妆品用油开发等方面,总结和归纳了国内外相关研究进展,为黑水虻油的深入开发与应用提供理论参考。     

Maximization of acetic acid production in partial acidogenesis of swine wastewater.

Swine wastewater was biologically treated to produce short-chain volatile organic acids (VOAs) in laboratory-scale continuously stirred tank reactors. The maximum production rates of acetic and butyric acids associated with simultaneous changes in pH and hydraulic retention time (HRT) were investigated, in which the degree of acidification of swine wastewater to the short-chain VOAs was <25% of influent chemical oxygen demand (COD) concentration. A constant inoculum system was used to minimize the experimental error due to the use of inconsistent inoculum. The inoculum system was operated with synthetic wastewater at 6000 mg soluble chemical oxygen demand per liter (pH 6.0) and 35 degrees C at 0.5 day hydraulic retention time. Response surface methodology was applied successfully to determine the optimum physiological condition for which the maximum rate of acetic acid production occurred, which was pH 5.90 and 0.88 day hydraulic retention time at 35 degrees C. The partial acidification process to manage swine waste should be operated in the optimum condition for acetic acid production because the optimum operating condition for butyric acid production approached the washout point.     

Cover Caption

Researchers and producers are exploring ways to repurpose organic waste. Larvae of the black soldier fly (BSF), Hermetia illucens, offer a solution for converting organic waste into high-quality protein and organic fertilizers. These saprophagous insects can fully utilize abandoned organic resources, promoting waste reduction. In order to make the BSF more efficiently use organic waste, scientific and technological workers have carried out a series of studies to solve various basic and transformational problems that BSF may face in its application (see pages 888-1021). Due to limited space, this issue only covers part of the BSF research. We encourage further publication of research papers on this topic. Photo provided by Quan Zhou.     

不同含水率饲料对黑水虻生长发育的影响及其对饲料的转化特征研究

饲料的含水率是影响黑水虻生长发育及其对饲料养分转化的重要因素,本研究旨在探究黑水虻生物转化过程中饲料最佳含水率。将3龄黑水虻幼虫接入含水率为40%、50%、60%、70%、80%的饲料中,每隔3 d记录黑水虻的体重,至预蛹数达总数的50%时结束试验,计算预蛹历期、预蛹总产量及有效转化率,测定黑水虻及饲料残渣养分及总能。结果发现：1）黑水虻预蛹总产量及其对饲料的有效转化率随水分含量升高而线性增加,在80%水分下达到最大值。2）黑水虻在70%水分下最先预蛹,预蛹历期为14 d。3）黑水虻体内CP含量随水分含量增加而线性下降,EE、GE含量随水分增加线性上升。4）黑水虻对饲料GE的代谢消耗率在60%水分下最高,而在80%水分下对饲料养分的累积量最高。因此,生产中为了高效运转黑水虻生物转化体系,应根据生产目的调节饲料水分以获取最大效益。     

The potential of soil amendment with insect exuviae and frass to control the cabbage root fly

Reliable options to control the cabbage root fly, Delia radicum L., are lacking in many countries as restrictions on insecticide use have tightened due to environmental concerns. Although microbial control agents are often considered as a sustainable alternative, their application in agriculture is constrained by inconsistent efficacy owing to low field persistence. To stimulate naturally occurring beneficial microbes, soil amendment with the residual streams of insect production has been suggested as an alternative to synthetic fertilization and a new approach to microbial crop protection. In a set of greenhouse experiments, exuviae and frass of black soldier fly larvae, Hermetia illucens L., house crickets, Acheta domesticus L. and exuviae of mealworms, Tenebrio molitor L., were added to soil from an organically managed field. Exuviae and frass treatments were compared to treatments with synthetic fertilizer. Brussels sprouts, Brassica oleracea L., plants were grown in amended soil for 5 weeks before being infested with cabbage root fly larvae. Insect and plant performance were assessed by recording cabbage root fly survival, biomass and eclosion time and seed germination and plant biomass, respectively. Whereas soil amendment with black soldier fly frass or exuviae reduced cabbage root fly survival and biomass, respectively, amendment with house cricket or mealworm residual streams did not negatively affect root fly performance. Furthermore, seed germination was reduced in soil amended with house cricket exuviae, while amendment with either residual stream derived from black soldier fly larvae or house crickets resulted in lower plant shoot biomass compared with the synthetic fertilizer treatment. Amending soil with black soldier fly residual streams could become a novel and low-cost tool to be integrated in cabbage root fly management programmes, especially where methods currently available are insufficient. Therefore, the mechanisms underlying the effects of insect-derived soil amendments described here should be the focus of future research.     

Morphofunctional characterization of hemocytes in black soldier fly larvae

In insects, the cell-mediated immune response involves an active role of hemocytes in phagocytosis, nodulation, and encapsulation. Although these processes have been well documented in multiple species belonging to different insect orders, information concerning the immune response, particularly the hemocyte types and their specific function in the black soldier fly Hermetia illucens, is still limited. This is a serious gap in knowledge given the high economic relevance of H. illucens larvae in waste management strategies and considering that the saprophagous feeding habits of this dipteran species have likely shaped its immune system to efficiently respond to infections. The present study represents the first detailed characterization of black soldier fly hemocytes and provides new insights into the cell-mediated immune response of this insect. In particular, in addition to prohemocytes, we identified five hemocyte types that mount the immune response in the larva, and analyzed their behavior, role, and morphofunctional changes in response to bacterial infection and injection of chromatographic beads. Our results demonstrate that the circulating phagocytes in black soldier fly larvae are plasmatocytes. These cells also take part in nodulation and encapsulation with granulocytes and lamellocyte-like cells, developing a starting core for nodule/capsule formation to remove/encapsulate large bacterial aggregates/pathogens from the hemolymph, respectively. These processes are supported by the release of melanin precursors from crystal cells and likely by mobilizing nutrient reserves in newly circulating adipohemocytes, which could thus trophically support other hemocytes during the immune response. Finally, the regulation of the cell-mediated immune response by eicosanoids was investigated.     

Black soldier fly (Diptera: Stratiomyidae) larval heat generation and management

Mass production of black soldier fly, Hermetia illucens (L.) (Diptera: Stratiomyidae), larvae results in massive heat generation, which impacts facility management, waste conversion, and larval production. We tested daily substrate temperatures with different population densities (i.e., 0, 500, 1000, 5000, and 10 000 larvae/pan), different population sizes (i.e., 166, 1000, and 10 000 larvae at a fixed feed ratio) and air temperatures (i.e., 20 and 30 °C) on various production parameters. Impacts of shifting larvae from 30 to 20 °C on either day 9 or 11 were also determined. Larval activity increased substrate temperatures significantly (i.e., at least 10 °C above air temperatures). Low air temperature favored growth with the higher population sizes while high temperature favored growth with low population sizes. The greatest average individual larval weights (e.g., 0.126 and 0.124 g) and feed conversion ratios (e.g., 1.92 and 2.08 g/g) were recorded for either 10 000 larvae reared at 20 °C or 100 larvae reared at 30 °C. Shifting temperatures from high (30 °C) to low (20 °C) in between (∼10-d-old larvae) impacted larval production weights (16% increases) and feed conversion ratios (increased 14%). Facilities should consider the impact of larval density, population size, and air temperature during black soldier fly mass production as these factors impact overall larval production.