Effects of brewery by-products on growth performance, bioconversion efficiency, nutritional profile, and microbiota and mycobiota of black soldier fly larvae.

Brewery by-products are recognised as suitable rearing substrates for Hermetia illucens, better known as black soldier fly (BSF) but information about the impact of different ratios of brewer's spent grains (BSG) and brewer's spent yeast (BSY) are still scarce. This study evaluated the effects of BSG-BSY-based diets on BSF larval growth, survival, bioconversion efficiency, nutritional profile, and microbiota and mycobiota. A total of 3 000 6-day-old BSF larvae were allotted to five dietary treatments (six replicate boxes/diet, 100 larvae/box): (i) BSY2.5 (25 g/kg of BSY+975 g/kg of BSG), (ii) BSY5 (50 g/kg of BSY+950 g/kg of BSG), (iii) BSY7.5 (75 g/kg of BSY+925 g/kg of BSG), (iv) BSY10 (100 g/kg of BSY+900 g/kg of BSG), and (v) control (Gainesville diet). Larval weight and substrate pH were recorded every 4 days. At the end of the trial (5% of prepupae), bioconversion efficiency corrected for residue (BER), reduction rate (RR), and waste reduction index (WRI) were calculated, and the larval proximate composition, microbiota and mycobiota characterised. At 10 and 14 days of age, BSY7.5 and BSY10 larvae displayed higher weight than BSY2.5 and BSY5 (P < 0.05), with BSY10 larvae showing the highest weight among the BSG-BSY-based diets at the end of the trial (P < 0.05). The BSY7.5 and BSY10 larvae also displayed a better BER than BSY2.5 and BSY5 (P < 0.01), whereas similar RR, WRI, survival and development time, as well as pH, were, however, observed among the BSG-BSY-based diets (P > 0.05). The BSY10 larvae displayed lower ether extract content than the other BSG-BSY-based diets (P > 0.001). The use of BSG-BSY-based diets did not influence the alpha diversity of larval microbiota and mycobiota (P > 0.05), but a specific microbial signature was identified per each dietary treatment (Porphyromonadaceae [BSY5], Sphingomonas [BSY7.5], Bacillus [BSY10] and Ruminococcus and Myroides [BSG-BSY-based diets]; P < 0.05). Co-occurrence and co-exclusion analysis also showed that Saccharomyces cerevisiae and Pichia excluded and favoured, respectively, the presence of Streptomyces and Fluviicola, while Clavispora lusitaniae was associated with Myroides (P < 0.05). In conclusion, BSG-BSY-based diets are suitable for rearing HI in terms of larval performance, nutritional profile, and microbiota and mycobiota, with 7.5 and 10% of BSY inclusion levels being able to improve larval growth and bioconversion efficiency.

Deeper insight into the storage time of food waste on black soldier fly larvae growth and nutritive value: Interactions of substrate and gut microorganisms.

Biological treatment of food waste (FW) by black soldier fly larvae (BSFL) is considered as an effective management strategy. The composition and concentrations of nutrients in FW change during its storage and transport period, which potentially affect the FW conversion and BSFL growth. The present study systematically investigated the effect of different storage times (i.e., 0-15 d) on FW characteristics and its substantial influence on the BSFL growth. Results showed that the highest larvae weight of 282 mg and the shortest growth time of 14 days were achieved at the group of FW stored for 15 days, but shorter storage time (i.e., 2-7 d) had adverse effect on BSFL growth. Short storage time (i.e., 2-4 d) improved protein content of BSFL biomass and prolonged storage time (i.e., 7-10 d) led to the accumulation of fat content. The changes of substrate characteristics and indigenous microorganisms via FW storage time were the main reasons for BSFL growth difference. Lactic acid (LA) accumulation (i.e., 19.84 g/L) in FW storage for 7 days significantly limited the BSFL growth, leading to lowest larvae weight. Both the substrate and BSFL gut contained same bacterial communities (e.g., Klebsiella and Proteus), which exhibited similar change trend with the prolonged storage time. The transfer of Clostridioides from substrate to BSFL gut promoted nutrients digestion and intestinal flora balance with the FW stored for 15 days. Pathogens (e.g., Acinetobacter) in BSFL gut feeding with FW storage time of 7 days led to the decreased digestive function, consistent with the lowest larvae weight. Overall, shorter storage time (i.e., 2-7 d) inhibited the BSFL digestive function and growth performance, while the balance of the substrate nutrients and intestinal flora promoted the BSFL growth when using the FW stored for 15 days.

Unlocking the potential of black soldier fly frass as a sustainable organic fertilizer: A review of recent studies.

Using Hermetia illucens, or Black Soldier Fly (BSF) frass as an organic fertilizer is becoming increasingly popular in many countries. As a byproduct derived from BSF larvae that feed on organic waste, BSF frass has tremendous potential for preserving the environment and promoting the circular economy. Since it has diverse biochemical properties influenced by various production and environmental factors, further research is needed to evaluate its potential for extensive use in crop production and agriculture. Our review summarizes recent findings in BSF frass research by describing its composition and biochemical properties derived from various studies, including nutrient contents, biostimulant compounds, and microbial profiles. We also discuss BSF frass fertilizers' effectiveness on plant growth and contribution to environmental sustainability. Great compositions of BSF frass increase the quality of plants/crops by establishing healthy soil and improving the plants' immune systems. Special emphasis is given to potentially replacing conventional fertilizer to create a more sustainable cropping system via organic farming. Besides, we discuss the capability of BSF bioconversion to reduce greenhouse gas emissions and improve the socioeconomic aspect. The prospects of BSF frass in promoting a healthy environment by reducing greenhouse gas emissions and improving the socioeconomic aspects of communities have also been highlighted. Overall, BSF frass offers an alternative approach that can be integrated with conventional fertilizers to optimize the cropping system. Further studies are needed to fully explore its potential in establishing sustainable system that can enhance socioeconomic benefits in the future.

Wheat starch processing by-products as rearing substrate for black soldier fly: does the rearing scale matter?

Rearing scale may influence black soldier fly (BSF) larvae traits when they are fed on a single diet, but different feeding substrates have not been tested yet. This study evaluated the effects of wheat starch processing by-products-based diets on growth performance, bioconversion efficiency, and nutritional profile of BSF larvae reared in different scales. Four diets (D1 and D2 [isonitrogenous, isolipidic and isoenergetic]; D3 and D4 [displaying 1:1 and 1:2 as protein to carbohydrate ratios, respectively]) were tested at 3 rearing scales (4 replicate boxes/diet, with a constant volume [0.84 cm3]/larva and feed [0.7 g]/larva): 1) small (S; 12 × 12 cm, substrate height: 4 cm, 686 6-day-old larvae (6-DOL)/box), 2) medium (M, 32 × 21 cm, substrate height: 7 cm, 5 600 6-DOL/box), and 3) large (L, 60 × 40 cm, substrate height: 7 cm, 20 000 6-DOL/box). Larval weight was recorded at the beginning of trial and every 4 days, and growth rate (GR), specific growth rate (SGR), feed conversion ratio (FCR), survival, bioconversion efficiency corrected for residue (BER), reduction rate (RR), and waste reduction index (WRI) calculated at the end of larval growth (frass DM ≥ 55%). Substrate pH, T and height were measured at the beginning, every 4 days, and end of trial. Larval proximate composition was analysed at the end of trial. Data were analysed by generalised linear mixed model (SPSS software, P < 0.05). The D1 larvae showed higher weight, GR, SGR and WRI (along with higher substrate T) than D2 at M scale, while increased SGR and FCR - as well as decreased survival, RR and WRI - were observed in D2 larvae at S scale (P < 0.05). Larval CP and ether extract (EE) contents were influenced by M and L scales only, being higher in D2 group than in D1 (P < 0.001). Differently, decreased ash was recorded in D2 larvae when reared at S and M scales, while L scale revealed higher ash in D2 group than D1 (P < 0.001). The D3 larvae displayed greater weight, SGR, survival, RR and WRI (along with greater substrate T) than D4 at M scale, with increased survival and substrate T being also highlighted in L scale (P < 0.05). The D3 larvae also showed lower DM and EE - as well as higher CP - than D4 at all the rearing scales (P < 0.001). In conclusion, D1 and D3 led to better BSF larval growth performance, bioconversion efficiency and nutritional profile mainly at M and L scales, as a consequence of their ability to facilitate larval aggregation and, in turn, allow achieving a higher substrate T.

Growth performance, proximate composition and fatty acid profile of black soldier fly larvae reared on two grape pomace varieties.

The black soldier fly (Hermetia illucens) is attracting increasing interest for its ability to convert low-value substrates into highly nutritious feed. This study aimed at evaluating grape pomace from two varieties (Becuet - B; Moscato - M) as rearing substrates for black soldier fly larvae (BSFL), focusing on the related effects on larval growth performance, proximate composition, and fatty acid profile. A total of six replicates per treatment, and 1 000 BSFL per replica, were used. Larval development was assessed by larvae weight, which was recorded eight times during the trial: the day after the beginning of the trial, and then on days 5, 8, 13, 15, 20, 22, and 27 (day in which the 30% of BSFL reached the prepupal stage). Production and waste reduction efficiency parameters, namely the growth rate, substrate reduction and substrate reduction index, were calculated. The two grape pomace varieties were analysed for their proximate composition and fatty acid profile; the same analyses were conducted on BSFL (30 larvae per replica) that were collected at the end of the trial (day 27). The growth rate of BSFL showed a higher value when the larvae were reared on B substrate (4.4 and 3.2 mg/day for B and M, respectively; P < 0.01). The rearing substrate did not significantly affect the proximate composition of BSFL. The percentage of total lipids (TL) in M-fed BSFL was significantly higher than in B ones. Total saturated (P < 0.001) and monounsaturated fatty acids (P < 0.05) were significantly higher in M-fed BSFL, while an opposite trend was observed for total branched-chain (P < 0.001) and total polyunsaturated fatty acids (P < 0.001). Interestingly, some conjugated linoleic acid (CLA) isomers [i.e., C18:2 c9t11(+t7c9+t8c10) and t9t11] were detected in low amounts in both rearing substrates (total CLA equal to 0.085 and 0.16 g/100 g TL in B and M substrate, respectively). Some CLA isomers (i.e., C18:2 c9t11, t7c9, and t10c12) were also found in BSFL, reaching a total CLA concentration equal to 2.95 and 0.052 g/100 g of TL in B-fed and M-fed BSFL, respectively. This study demonstrates that winery by-products from different grape varieties can significantly affect the development and lipid composition of BSFL. The CLA biosynthesis potential of BSFL opens newsworthy perspectives for a new valorisation of winery by-products to produce full-fat black soldier fly meal and black soldier fly oil enriched in specific fatty acids of potential health-promoting interest.

Tracking lipid synthesis using 2H2O and 2H-NMR spectroscopy in black soldier fly (Hermetia illucens) larvae fed with macroalgae.

Black soldier fly (Hermetia illucens) larvae are used to upcycle biowaste into insect biomass for animal feed. Previous research on black soldier fly has explored the assimilation of dietary fatty acids (FAs), but endogenous FA synthesis and modification remain comparatively unexplored. This study presents a 1H/2H-NMR methodology for measuring lipid synthesis in black soldier fly larvae using diluted deuterated water (2H2O) as a stable isotopic tracer delivered through the feeding media. This approach was validated by measuring 2H incorporation into the larvae's body water and consequent labelling of FA esterified into triacylglycerols. A 5% 2H enrichment in the body water, adequate to label the FA, is achieved after 24 h in a substrate with 10% 2H2O. A standard feeding trial using an invasive macroalgae was designed to test this method, revealing de novo lipogenesis was lower in larvae fed with macroalgae, probably related to the poor nutritional value of the diet.

Reproductive output and other adult life-history traits of black soldier flies grown on different organic waste and by-products.

The interest in mass-rearing black soldier fly (Hermetia illucens) larvae for food and feed is rapidly increasing. This is partly sparked by the ability of the larvae to efficiently valorise a wide range of organic waste and by-products. Primarily, research has focused on the larval stage, hence underprioritizing aspects of the adult biology, and knowledge on reproduction-related traits such as egg production is needed. We investigated the impact of different organic waste and by-products as larval diets on various life-history traits of adult black soldier flies in a large-scale experimental setup. We reared larvae on four different diets: spent Brewer's grain, ground carrots, Gainesville diet, and ground oranges. Traits assessed were development time to pupa and adult life-stages, adult body mass, female lifespan, egg production, and egg hatch. Larval diet significantly impacted development time to pupa and adult, lifespan, body size, and egg production. In general, flies reared on Brewer's grain developed up to 4.7 d faster, lived up to 2.3 d longer, and produced up to 57% more eggs compared to flies reared on oranges on which they performed worst for these traits. There was no effect of diet type on egg hatch, suggesting that low-nutritious diets, i.e. carrots and oranges, do not reduce the quality but merely the quantity of eggs. Our results demonstrate the importance of larval diet on reproductive output and other adult traits, all important for an efficient valorisation of organic waste and by-products, which is important for a sustainable insect-based food and feed production.

The cluster digging behavior of larvae confers trophic benefits to fitness in insects.

Collective behaviors efficiently impart benefits to a diversity of species ranging from bacteria to humans. Fly larvae tend to cluster and form coordinated digging groups under crowded conditions, yet understanding the rules governing this behavior is in its infancy. We primarily took advantage of the Drosophila model to investigate cooperative foraging behavior. Here, we report that Drosophila-related species and the black soldier fly have evolved a conserved strategy of cluster digging in food foraging. Subsequently, we investigated relative factors, including larval stage, population density, and food stiffness and quality, that affect the cluster digging behavior. Remarkably, oxygen supply through the posterior breathing spiracles is necessary for the organization of digging clusters. More importantly, we theoretically devise a mathematical model to accurately calculate how the cluster digging behavior expands food resources by diving depth, cross-section area, and food volume. We found that cluster digging behavior approximately increases 2.2 fold depth, 1.7-fold cross-section area, and 1.9 fold volume than control groups, respectively. Amplification of food sources significantly facilitates survival, larval development, and reproductive success of Drosophila challenged with competition for limited food resources, thereby conferring trophic benefits to fitness in insects. Overall, our findings highlight that the cluster digging behavior is a pivotal behavior for their adaptation to food scarcity, advancing a better understanding of how this cooperative behavior confers fitness benefits in the animal kingdom.

Description of the male of Simulium triglobus Takaoka & Kuvangkadilok (Diptera: Simuliidae) from Thailand.

Simulium triglobus Takaoka & Kuvangkadilok from Thailand, in the Simulium (Simulium) multistriatum species-group, is unique among species in the family Simuliidae in having the female terminalia with three spermathecae (rather than one spermatheca). This species was described from Nan province, northern Thailand based on larvae, pupae and females but its male has remained unknown. In this study, the male of S. triglobus is described for the first time based on adult males reared from pupae collected from the type locality. The most distinctive characteristic of the male of S. triglobus is the shape of the ventral plate, which is hexagonal when viewed ventrally. No other members of S. multistriatum species group known thus far have such a unique ventral plate. In addition, the number of upper-eye (large) facets and color patterns of the legs can be used to differentiate this species in the male from other members of the S. multistriatum species-group. Mitochondrial cytochrome c oxidase I sequences enabled association of adult male specimens of S. triglobus with previously known life stages. Phylogenetic analysis based on these sequences revealed that specimens of S. triglobus formed a strongly supported monophyletic clade, being genetically distinct from other members of S. multistriatum species-group in Thailand.

Destabilization of the Bacterial Interactome Identifies Nutrient Restriction-Induced Dysbiosis in Insect Guts.

Stress-associated dysbiosis of microbiome can have several configurations that, under an energy landscape conceptual framework, can change from one configuration to another due to different alternating selective forces. It has been proposed-according to the Anna Karenina Principle-that in stressed individuals the microbiome are more dispersed (i.e., with a higher within-beta diversity), evidencing the grade of dispersion as indicator of microbiome dysbiosis. We hypothesize that although dysbiosis leads to different microbial communities in terms of beta diversity, these are not necessarily differently dispersed (within-beta diversity), but they form disrupted networks that make them less resilient to stress. To test our hypothesis, we select nutrient restriction (NR) stress that impairs host fitness but does not introduce overt microbiome selectors, such as toxic compounds and pathogens. We fed the polyphagous black soldier fly, Hermetia illucens, with two NR diets and a control full-nutrient (FN) diet. NR diets were dysbiotic because they strongly affected insect growth and development, inducing significant microscale changes in physiochemical conditions of the gut compartments. NR diets established new configurations of the gut microbiome compared to FN-fed guts but with similar dispersion. However, these new configurations driven by the deterministic changes induced by NR diets were reflected in rarefied, less structured, and less connected bacterial interactomes. These results suggested that while the dispersion cannot be considered a consistent indicator of the unhealthy state of dysbiotic microbiomes, the capacity of the community members to maintain network connections and stability can be an indicator of the microbial dysbiotic conditions and their incapacity to sustain the holobiont resilience and host homeostasis. IMPORTANCE Changes in diet play a role in reshaping the gut microbiome in animals, inducing dysbiotic configurations of the associated microbiome. Although studies have reported on the effects of specific nutrient contents on the diet, studies regarding the conditions altering the microbiome configurations and networking in response to diet changes are limited. Our results showed that nutrient poor diets determine dysbiotic states of the host with reduction of insect weight and size, and increase of the times for developmental stage. Moreover, the poor nutrient diets lead to changes in the compositional diversity and network interaction properties of the gut microbial communities. Our study adds a new component to the understanding of the ecological processes associated with dysbiosis, by disentangling consequences of diets on microbiome dysbiosis that is manifested with the disruption of microbiome networking properties rather than changes in microbiome dispersion and beta diversity.

Comparisons of Respiratory Pupal Gill Development in Black Flies (Diptera: Simuliidae) Shed Light on the Origin of Dipteran Prothoracic Dorsal Appendages.

During the transformation of immature aquatic dipteran insects to terrestrial adults, the prothoracic pupal respiratory organ enables pupae to cope with flood-drought alternating environments. Despite its obvious importance, the biology of the organ, including its development, is poorly understood. In this study, the developing gills of several Simulium Latreille (Diptera: Simuliidae) spp. were observed using serial histological sections and compared with data on those of other dipteran families published previously. The formation of some enigmatic features that made the Simulium gill unique is detailed. Through comparisons between taxa, we describe a common developmental pattern in which the prothoracic dorsal disc cells not only morph into the protruding respiratory organ, which is partially or entirely covered with a cuticle layer of plastron, but also invaginate to form a multipart internal chamber that in part gives rise to the anterior spiracle of adult flies. The gill disc resembles wing and leg discs and undergoes cell proliferation, axial outgrowth, and cuticle sheath formation. The overall appendage-like characteristics of the dipteran pupal respiratory organ suggest an ancestral form that gave rise to its current forms, which added more dimensions to the ways that arthropods evolved through appendage adaptation. Our observations provide important background from which further studies into the evolution of the respiratory organ across Diptera can be carried out.

Pedrowygomyia (Diptera: Simuliidae): Discovery of a New Species After 30 yr.

Pedrowygomyia is a Neotropical genus of Simuliidae composed of four species; all were described in 1989 from high-elevation (above 3,000 m) areas in the Andean region. In this article, a new species for this genus, Pedrowygomyia hanaq n. sp., is described based on all stages of development. The new species was collected in the south-central Andes of Peru at an altitude above 4,000 m, and its known distribution is currently restricted to the type-locality. Based on the pupal stage, the new species appears to be more closely related to Pedrowygomyia punapi (Wygodzinsky & Coscarón) (Diptera: Simuliidae), a species known from Argentina, Bolivia, and Chile.

Biochar and gypsum amendment of agro-industrial waste for enhanced black soldier fly larval biomass and quality frass fertilizer.

Black soldier fly (BSF) (Hermetia illucens L.) is one of the most efficient bio-waste recyclers. Although, waste substrate amendments with biochar or gypsum during composting process are known to enhance nutrient retention, their impact on agro-industrial waste have not been documented. Hence, this study focuses on a comparative effect of agro-industrial waste amended with biochar and gypsum on BSF larval performance, waste degradation, and nitrogen (N) and potassium retention in frass fertilizer. Brewery spent grain was amended with biochar or gypsum at 0, 5, 10, 15 and 20% to determine the most effective rates of inclusion. Amending feedstock with 20% biochar significantly increased wet (89%) and dried (86%) larval yields than the control (unamended feedstock). However, amendment with 15% gypsum caused decrease in wet (34%) and dried (30%) larval yields but conserved the highest amount of N in frass. Furthermore, the inclusion of 20% biochar recorded the highest frass fertilizer yield and gave a 21% increase in N retention in frass fertilizer, while biomass conversion rate was increased by 195% compared to the control. Feedstock amendment with 5% biochar had the highest waste degradation efficiency. Potassium content in frass fertilizer was also significantly enhanced with biochar amendment. At maturity, frass compost with more than 10% inclusion rate of biochar had the highest cabbage seed germination indices (>100%). The findings of this study revealed that initial composting of biochar amended feedstocks using BSF larvae can significantly shorten compost maturity time to 5 weeks with enhanced nutrient recycling compared to the conventional composting methods.

Hermetia illucens (Diptera: Stratiomydae) larvae and prepupae: Biomass production, fatty acid profile and expression of key genes involved in lipid metabolism.

The Black Soldier Fly (BSF) Hermetia illucens provides a promising strategy in the waste valorisation process and a sustainable alternative source of valuable nutrients, including lipids for food and feed. In the present study, the differences in growth performances and nutritional values of BSF V instar larvae and prepupae reared on vegetable waste were analyzed and compared focusing on fat content. V instar larvae showed higher capacity to bioconvert the substrate into biomass than prepupae. The nutritional composition and the fatty acid profiles were dependent on the developmental stage. The expression levels of acetyl-CoA carboxylase (acc), fatty acid synthase (fas), lipase (lip) and acyl-CoA dehydrogenase (acd) genes involved in the lipid metabolism pathway and herein characterized for the first time, were evaluated in order to understand the molecular basis underlying the observed differences in fatty acid profiles. Our results suggest that the different fatty acid profiles of BSF V instar larvae and prepupae may be related to the modulation of the lipid metabolism-related genes expression during larval development. Our study highlights substantial differences between H. illucens V instar larvae and prepupae giving important features regarding the opportunity to modulate the preferable fatty acid profile to meet the industrial requirements.

Revision of Simulium rufibasis (Diptera: Simuliidae) in Japan and Korea: Chromosomes, DNA, and Morphology.

The widespread nominal black fly Simulium (Simulium) rufibasis Brunetti was reexamined morphologically, chromosomally, and molecularly to determine the status of populations in Japan and Korea with respect to S. rufibasis from the type locality in India and to all other known species in the S. (S.) tuberosum species-group. Morphological comparisons established that the species previously known as S. rufibasis in Japan and Korea is distinct from all other species. Consequently, it was described and illustrated as a new species, Simulium (S.) yamatoense. Simulium yokotense Shiraki, formerly a synonym of S. rufibasis, was morphologically reevaluated and considered a species unplaced to species-group in the subgenus Simulium. Chromosomal analyses of S. yamatoense sp. nov. demonstrated that it is unique among all cytologically known species of the S. tuberosum group and is the sister species of the Taiwanese species tentatively known as S. (S.) arisanum Shiraki. Populations of S. yamatoense sp. nov. included two cytoforms, based on the sex chromosomes. Cytoform A, including topotypical representatives, was found in Kyushu, Japan, whereas cytoform B was found in Korea and Honshu, Japan. Molecular analysis based on the COI mitochondrial gene generally corroborated morphological and chromosomal data that S. yamatoense sp. nov. is a distinct species and, like the chromosomal data, indicate that it is most closely related to S. arisanum, with interspecific genetic distance of 2.92-4.63%.

Modelling exposure heterogeneity and density dependence in onchocerciasis using a novel individual-based transmission model, EPIONCHO-IBM: Implications for elimination and data needs.

BACKGROUND: Density dependence in helminth establishment and heterogeneity in exposure to infection are known to drive resilience to interventions based on mass drug administration (MDA). However, the interaction between these processes is poorly understood. We developed a novel individual-based model for onchocerciasis transmission, EPIONCHO-IBM, which accounts for both processes. We fit the model to pre-intervention epidemiological data and explore parasite dynamics during MDA with ivermectin. METHODOLOGY/PRINCIPAL FINDINGS: Density dependence and heterogeneity in exposure to blackfly (vector) bites were estimated by fitting the model to matched pre-intervention microfilarial prevalence, microfilarial intensity and vector biting rate data from savannah areas of Cameroon and Côte d'Ivoire/Burkina Faso using Latin hypercube sampling. Transmission dynamics during 25 years of annual and biannual ivermectin MDA were investigated. Density dependence in parasite establishment within humans was estimated for different levels of (fixed) exposure heterogeneity to understand how parametric uncertainty may influence treatment dynamics. Stronger overdispersion in exposure to blackfly bites results in the estimation of stronger density-dependent parasite establishment within humans, consequently increasing resilience to MDA. For all levels of exposure heterogeneity tested, the model predicts a departure from the functional forms for density dependence assumed in the deterministic version of the model. CONCLUSIONS/SIGNIFICANCE: This is the first, stochastic model of onchocerciasis, that accounts for and estimates density-dependent parasite establishment in humans alongside exposure heterogeneity. Capturing the interaction between these processes is fundamental to our understanding of resilience to MDA interventions. Given that uncertainty in these processes results in very different treatment dynamics, collecting data on exposure heterogeneity would be essential for improving model predictions during MDA. We discuss possible ways in which such data may be collected as well as the importance of better understanding the effects of immunological responses on establishing parasites prior to and during ivermectin treatment.

Do dietary soy alternatives lead to pork quality improvements or drawbacks? A look into micro-alga and insect protein in swine diets.

Pork quality characteristics related to the dietary substitution of soybean meal by the micro-alga Spirulina (Arthrospira platensis) or black soldier fly (Hermetia illucens) partly-defatted larval meal were observed. Through a duplicated study totalling 48 individually-fed barrows (Pietrain × (Large White × Landrace)) allocated into two experimental groups and a control, the effect of dietary protein source on physico-chemical and sensory pork quality was monitored under current industrial packaging conditions (highly­oxygenated modified atmosphere packaging). The results show that physico-chemical characteristics are not degraded by including alternative protein sources in pig diets. Hermetia illucens increased lauric acid levels in backfat indicating that this fatty acid may be suitable as a biomarker for Hermetia illucens-fed pork. This goes to show that protein alternatives do not compromise pork quality.

Killing method affects the browning and the quality of the protein fraction of Black Soldier Fly (Hermetia illucens) prepupae: a metabolomics and proteomic insight.

Insects are being explored as novel protein sources in order to overcome the future food demands connected to world growing population. Insects for food/feed uses are currently slowly killed through freezing by most insect rearing companies, and typically, enzymatic browning takes place in the insect proteins fractions. However, very little is known about the influence of these enzymatic reactions on the protein physical, chemical, nutritional and technological properties. In this work a metabolomics and proteomic study was conducted on Black Soldier Fly (Hermetia illucens) prepupae, killed by two different methods: freezing (commonly used), and blanching (with the aim to inhibit the enzymatic activities). Proton nuclear magnetic resonance (1H NMR) metabolomics demonstrated that slow killing method by freezing, compared with blanching, elicits the activation of several enzymatic pathways, among them melanisation with tyrosine consumption, energetic metabolism and lipolysis. These metabolic changes have an impact also on protein nutritional quality, with a loss of cysteine and lysine, likely involved in the process of melanisation and enzymatic browning. A strong effect was also observed on protein extractability: proteins from prepupae killed by blanching were found to be more extractable in milder conditions by chemical methods, and more prone to enzymatic digestion (97% of proteins released in solution upon proteolysis) than proteins from prepupae killed by freezing. All these data indicate that killing by blanching inhibits the browning reaction and other enzymatic changes occurring during slow killing by freezing, increasing the extractability of proteins in aqueous solutions, avoiding essential amino acid loss, and improving enzymatic digestibility.

Threshold temperatures and thermal requirements of black soldier fly Hermetia illucens: Implications for mass production.

Efforts to recycle organic wastes using black soldier fly (BSF) Hermetia illucens into high-nutrient biomass that constitutes a sustainable fat (biodiesel) and high-quality protein ingredient in animal feeds have recently gained momentum worldwide. However, there is little information on the most suitable rearing conditions for growth, development and survivorship of these flies, which is a prerequisite for mass production technologies. We evaluated the physiological requirements for growth and reproduction of H. illucens on two diets [spent grains supplemented with brewers' yeast (D1) and un-supplemented (D2)]. Development rates at nine constant temperatures (10-42°C) were fitted to temperature-dependent linear and non-linear day-degree models. Thereafter, life history table parameters were determined within a range of favourable temperatures. The thermal maximum (TM) estimates for larval, pre-pupal and pupal development using non-linear model ranged between 37.2 ± 0.3 and 44.0 ± 2.3°C. The non-linear and linear day-degree model estimations of lower developmental temperature threshold for larvae were 11.7 ± 0.9 and 12.3 ± 1.4°C for D1, and 10.4 ± 1.7 and 11.7 ± 3.0°C for D2, respectively. The estimated thermal constant of immature life stages development of BSF was higher for the larval stage (250±25 DD for D1 and 333±51 for D2) than the other stages evaluated. Final larval wet weight was higher on D1 compared to D2. The population growth rate was most favourable at 30-degree celsius (°C) with higher intrinsic rate of natural increase (rm = 0.127 for D1 and 0.122 for D2) and shorter doubling time (5.5 days for D1 and 5.7 days for D2) compared to the other temperatures. These results are valuable for the optimization of commercial mass rearing procedures of BSF under various environmental conditions and prediction of population dynamics patterns using computer simulation models.

The effect of assortative mixing on stability of low helminth transmission levels and on the impact of mass drug administration: Model explorations for onchocerciasis.

BACKGROUND: Stable low pre-control prevalences of helminth infection are not uncommon in field settings, yet it is poorly understood how such low levels can be sustained, thereby challenging efforts to model them. Disentangling possible facilitating mechanisms is important, since these may differently affect intervention impact. Here we explore the role of assortative (i.e. non-homogenous) mixing and exposure heterogeneity in helminth transmission, using onchocerciasis as an example. METHODOLOGY/PRINCIPAL FINDINGS: We extended the established individual-based model ONCHOSIM to allow for assortative mixing, assuming that individuals who are relatively more exposed to fly bites are more connected to each other than other individuals in the population as a result of differential exposure to a sub-population of blackflies. We used the model to investigate how transmission stability, equilibrium microfilarial (mf) prevalence and intensity, and impact of mass drug administration depend on the assumed degree of assortative mixing and exposure heterogeneity, for a typical rural population of about 400 individuals. The model clearly demonstrated that with homogeneous mixing and moderate levels of exposure heterogeneity, onchocerciasis could not be sustained below 35% mf prevalence. In contrast, assortative mixing stabilised onchocerciasis prevalence at levels as low as 8% mf prevalence. Increasing levels of assortative mixing significantly reduced the probability of interrupting transmission, given the same duration and coverage of mass drug administration. CONCLUSIONS/SIGNIFICANCE: Assortative mixing patterns are an important factor to explain stable low prevalence situations and are highly relevant for prospects of elimination. Their effect on the pre-control distribution of mf intensities in human populations is only detectable in settings with mf prevalences <30%, where high skin mf density in mf-positive people may be an indication of assortative mixing. Local spatial variation in larval infection intensity in the blackfly intermediate host may also be an indicator of assortative mixing.