Black Fly Larvae Research Articles

Evolution of the Black solider fly larvae gut antibiotic resistome during kitchen waste disposal

Kitchen waste (KW) is an important reservoir of antibiotic resistance genes (ARGs). Black solider fly larvae (BSFL) are extensively employed in KW disposal, closely linking to their robust gut microbes. However, antibiotic resistome in BSFL gut during the KW disposal processes and the mechanism remain unclear. In the present study, the antibiotic resistome in BSFL gut within the 12 days KW disposal processes were investigated. Results showed that, ARGs abundance initially increased and subsequently decreased, the five most prevalent core ARG classes were tetracycline, aminoglycoside, cephalosporin, lincosamide and multidrug. A total of 7 MGE types were observed and the horizontal gene transfer (HGT) of ARGs was predominantly mediated by plasmids. Host microbes were mainly categorized into Proteobacteria (98.12 %) and their assemblies were mainly classified into the deterministic processes. To elucidate the driving mechanisms, the mantel test and the structural equation model (SEM) were developed. Results indicated that microbial functions (0.912, p < 0.0001) and microbial community (1.014, p = 0.036), consistently showed very significant relationships with the patterns of ARGs, which presented higher direct effects than indirect effects. Overall, this study makes an initial contribution to a more deepgoing comprehension of the gut antibiotic resistome of BSFL during KW disposal.

Ongoing transmission of onchocerciasis in the Pru District of Ghana after two decades of mass drug administration with ivermectin and comparative identification of members of the Simulium damnosum complex using cytological and morphological techniques

Background Human onchocerciasis remains a public health problem in Ghana. Mass drug administration (MDA) with ivermectin (IVM) has reduced disease morbidity and prevalence, but the transmission of onchocerciasis remains ongoing in several endemic foci. We investigated parasite transmission in some endemic communities in Ghana that had received > 18 rounds of annual MDA with IVM and determined the species composition of black fly (Simulium damnosum) vectors in these areas.MethodsAdult female black flies were collected using human landing catches and identified as either forest or savanna species using morpho-taxonomic keys. The adult flies underwent dissection to determine their parity and detect any O. volvulus larvae, followed by the calculation of entomological indices. Simulium damnosum s.l. larvae were collected and preserved in freshly prepared Carnoy’s fixative and were later used for cytotaxonomic studies.ResultsA total of 9,983 adult flies were caught: 6,569 and 3,414 in the rainy and dry seasons respectively. Black fly biting activities over the study period showed bimodal or trimodal patterns. The highest monthly biting rate (MBR) of 10,578.75 bites/person/month was recorded in July in Beposo, while the highest monthly transmission potential of 100.69 infective bites/person/month was recorded in Asubende in August. Morphological analysis of 2,032 flies showed that 99.8% (2,028) of the flies were savanna species, with only 4 (0.2%) adult flies being of the forest species. Cytogenetic studies on 114 black fly larvae revealed three cytospecies (Simulium damnosum s.s., S. sirbanum and S. sanctipauli) in the study area.ConclusionsThe present studies confirmed an ongoing transmission of onchocerciasis in the study communities except Abua-1. It also provides further information on biting behaviors and onchocerciasis transmission indices in the study communities. Further, our data confirmed the savanna species (S. damnosum s.s. and S. sirbanum) of the S.damnosum s.l. to be the major vectors of onchocerciasis in the study areas, with only an occasional influx of forest cytotypes.Graphical

Alleviating heavy metal accumulation and pathogens’ abundance through processing proper ratio of duck feces and food waste by Black solider fly larvae

ABSTRACT The efficient and sustainable utilization of duck feces is critically essential in China, given its expansive livestock and poultry breeding industry. While the use of black solider fly (BSF) larvae for composting duck feces has gained recognition, public apprehensions concerning the nutritional value and safety of the resultant by-products remain prevalent. This study presents the inaugural assessment of potential risks and quality of resource-based products derived from various proportions of food waste and duck feces processed by BSF larvae. Our findings indicate that mixed substrate A2 yielded BSF larvae with the highest level of N and P, alongside the lowest accumulation of As, Pb and Cd, as well as reduced total pathogen abundance in the remaining substrate when compared to other mixed substrates (A3 and A4). This suggests that an appropriate nutrient composition ratio in the substrates not only facilitated effective conversion but also diminished heavy metal accumulation by BSF larvae. Additionally, a significant negative correlation was observed between N, P, and Cd (R 2 = −0.989, −0.996, p < 0.01), implying that elevated N and P concentrations in BSF larvae may enhance immune function and while further mitigating heavy metal enrichment. Overall, achieving a suitable nutrient ratio of duck feces and food waste is imperative for their scientific and safe utilization, providing valuable insights for the bioconversion of organic solid waste through BSF larvae.

Morphological description and genetic analysis of a new black fly species (Diptera: Simuliidae) in the subgenus Asiosimulium from central Thailand

BackgroundBlack flies are among the most medically and veterinary important insects, as adult females of certain species are the sole vector of Onchocerca volvulus. Here, a new black fly species belonging to the subgenus Asiosimulium Takaoka & Choochote, 2005, is described and formally named as Simulium (Asiosimulium) kittipati sp. nov.MethodsPupae and larvae of black flies were collected from available substrates in the stream from central Thailand. Pupae were individually separated in plastic tubes and maintained until adult flies emerged. The emerged adult flies associated with their pupal exuviae and cocoon as well as mature larvae preserved in 85% ethanol were used to describe the new species based on an integrated approach of morphological examination and molecular analysis of the COI gene.ResultsThe new species is characterized in the female by the medium-long sensory vesicle with a medium-sized opening apically, scutum with three faint longitudinal vittae, and the ellipsoidal spermatheca; in the male by the number of upper-eye (large) facets in 20 vertical columns and 21 horizontal rows, hind basitarsus slender, nearly parallel-sided, and median sclerite much wider and upturned apically; in the pupa by the head and thoracic integument densely covered with tiny tubercles, and the pupal gill of arborescent type with 28–30 filaments; and in the larva by the postgenal cleft deep, nearly reaching the posterior margin of the hypostoma, and dark pigmented sheath of the subesophageal ganglion. The DNA barcode successfully differentiated the new species from its congeners with an interspecific genetic divergence of 1.74–18.72%, confirming the morphological identification that the species is a new member of the subgenus Asiosimulium. Phylogenetic analyses also indicated that the new species is genetically closely related to Simulium phurueaense Tangkawanit, Wongpakam & Pramual, 2018, further supporting its morphological classification.ConclusionsThis is the ninth species assigned to the subgenus Asiosimulium within the genus Simulium Latreille, 1802. Taxonomic notes and identification keys are given to distinguish this new species from the eight known species members in its same subgenus. Additionally, a distribution map of all species members in this subgenus occurring in Thailand and other countries is provided.Graphical abstract

Nutritional Value of the Larvae of the Black Soldier Fly (Hermetia illucens) and the House Fly (Musca domestica) as a Food Alternative for Farm Animals-A Systematic Review.

Dietary alternatives using insect-based products as an alternative for farm animal nutrition have been the object of study due to the high nutritional value of these feeds and the costs related to both their production and consequently their commercialization. Thus, the use of flies, especially larvae, has a high content of proteins and lipids (fat), as well as minerals and essential nutrients for development and growth, directly impacting the production of these animals, whether meat or milk. Therefore, the objective of this study was to compile data from the literature on the nutritional value of adults and larvae of Black soldier (Hermetia illucens) and housefly (Musca domestica) as a dietary alternative for animal feed. The Prisma checklist was used. After reviewing the data found in the literature, following the systematic review, it was noted that studies emerge that larvae of black soldier flies and domestic flies of the order Diptera obtain essential sources in the nutrition of ruminants, in addition to obtaining rapid digestibility, thus adhering to reproduction with high nutritional content, due to incident levels of protein, lipids, and minerals in M. domestica and Lucilia sericata, making it a target for inclusion in the diet of farm animals. In addition, it is concluded that both species are studied for their sustainable potential as well as for offering greater economic and nutritional viability when compared to ingredients present in production animal feed.

Onchocerciasis in the Cameroon–Chad border area after more than 20 years of annual mass ivermectin distribution

BackgroundThe main vectors of onchocerciasis in Africa are Simulium damnosum sensu lato, which transmit the causative agent Onchocerca volvulus. The force of transmission is driven by the vector density, hence influencing the disease prevalence and intensity. Onchocerciasis is currently targeted for elimination using mass drug administration (MDA) of ivermectin, a potent microfilaricide. MDA in Cameroon began in 1987 in the Vina Valley, an endemic cross-border area with Chad, known for high vector densities and precontrol endemicity. Evaluations in 2008–2010 in this area showed ongoing transmission, while border areas in Chad were close to interrupting transmission. This study aimed to evaluate transmission in this area after several rounds of MDA since the last evaluation surveys.MethodsBlack flies were collected by human landing catches at seven border sites in Cameroon, twice a week, from August 2021 to March 2022. A fraction of the flies was dissected for parity assessment and identification of Onchocerca larval stages. The transmission indices were estimated. Black fly larvae were also collected from the breeding sites at the fly catching sites and identified to species level by cytotaxonomy.ResultsA total of 14,303 female flies were collected, and 6918 were dissected. Of these, 4421 (64.0%) were parous. The total biting rates were high, reaching up to 16,407 bites/person/study period, and transmission potential (third-stage larvae (L3) from head/all L3) were 367/702, 146/506, 51/55, 20/32, 0/3, 0/0, and 0/0 infective larvae/person, respectively, for Mbere-Tchad, Babidan, Hajam/V5, Gor, Djeing, Touboro, and Koinderi. Infectivity rates (L3 from head) were 16.00, 12.75, 5.15, and 4.07 infective females (L3H)/1000 parous flies for Haijam, Mbere-Tchad, Babidan, and Gor, respectively. These values exceed the World Health Organization (WHO) thresholds of ≤ 20 annual transmission potential (ATP) or < 1 infective female/1000 parous females. The major vectors identified were Simulium damnosum sensu stricto, S. squamosum, and for the first time in the area, S. yahense.ConclusionsMore than 20 years of MDA has not eliminated onchocerciasis in the study area; hence, this area is a potential source of reintroduction of onchocerciasis in Chad and would require alternative treatment strategies. Many factors such as MDA efficiency, effectiveness of ivermectin, and cytospecies composition may be contributing to transmission persistence.Graphical

Comparison of Composting Method using Black Slodier Fly Larvae and Takakura Method on Compost Quality and Quantity

Organic waste needs to be processed so as not to pollute the environment. Processing of organic waste can be done through composting. This study aims to see the effect of composting method using BSF larvae and composting using takakura method on the quality and quantity of compost produced. The variety of waste types in this study consisted of variations A (65% vegetable waste + 35% fruit waste) and B (60% vegetable waste + 40% food waste). Bioconversion using BSF larvae aged 7 days with bidaily litter as much as 0.5 kg for 14 days. The results of the analysis of the quantity, maturity, and quality of variations A1, A2, B1 and B2 meet compost standards according to SNI 19-7030-2004. The most optimal variation of the study (A2 variation). This variation produces compost for (20 days), the quality of physical and macro elements has met the quality standards of domestic waste compost and the quantity of compost produced is more than 1.10 kg.

Community composition of black flies during and after the 2020 vesicular stomatitis virus outbreak in Southern New Mexico, USA

BackgroundVesicular stomatitis virus (VSV), a vector-borne pathogen of livestock, emerges periodically in the western US. In New Mexico (NM), US, most cases occur close to the Rio Grande River, implicating black flies (Simulium spp.) as a possible vector. In 2020, VS cases were reported in NM from April to May, although total black fly abundance remained high until September. We investigated the hypothesis that transience of local VSV transmission results from transient abundance of key, competent black fly species. Additionally, we investigated whether irrigation canals in southern NM support a different community of black flies than the main river. Lastly, to gain insight into the source of local black flies, in 2023 we collected black fly larvae prior to the release of water into the Rio Grande River channel.MethodsWe randomly sub-sampled adult black flies collected along the Rio Grande during and after the 2020 VSV outbreak. We also collected black fly adults along the river in 2021 and 2022 and at southern NM farms and irrigation canals in 2022. Black fly larvae were collected from dams in the area in 2023. All collections were counted, and individual specimens were subjected to molecular barcoding for species identification.ResultsDNA barcoding of adult black flies detected four species in 2020: Simulium meridionale (N = 158), S. mediovittatum (N = 83), S. robynae (N = 26) and S. griseum/notatum (N = 1). Simulium robynae was only detected during the VSV outbreak period, S. meridionale showed higher relative abundance, but lower absolute abundance, during the outbreak than post-outbreak period, and S. mediovittatum was rare during the outbreak period but predominated later in the summer. In 2022, relative abundance of black fly species did not differ significantly between the Rio Grande sites and farm and irrigation canals. Intriguingly, 63 larval black flies comprised 56% Simulium vittatum, 43% S. argus and 1% S. encisoi species that were either extremely rare or not detected in previous adult collections.ConclusionsOur results suggest that S. robynae and S. meridionale could be shaping patterns of VSV transmission in southern NM. Thus, field studies of the source of these species as well as vector competence studies are warranted.Graphical

Monitoring compositional changes in black soldier fly larvae after processing (drying and blanching) using near infrared spectroscopy

Determining which processing technique is better to guarantee the safety and nutritional value of black soldier fly larvae (BSFL) is of critical importance for the food waste industry. This study evaluates the utilization of near infrared reflectance (NIR) spectroscopy as a proxy technique to monitor the effect of two processing treatments commonly used by the food waste industry, namely blanching and the combination of blanching plus drying, on the composition of BSFL. The 5th instar BSFL samples were harvested from a commercial waste processing facility and subjected to drying (2 and 12 hrs at 100 °C) and blanching (4 s and 5 min) treatments. The samples were scanned using a NIR instrument (11,550 to 3950 cm−1) where the data was analysed using principal component analysis (PCA) and linear discriminant analysis (LDA). A correct classification rate above 83 % was obtained for the identification of samples according to the drying treatment, while 56 % of the samples were correctly classified according to the blanching treatment. Overall, NIR spectroscopy has shown great potential as a rapid tool for real-time monitoring of the processing of BSFL (drying and blanching), and thereby assisting in improving the treatment of BSFL samples intended to be used by the animal feed industry.

Basil (Ocimum basilicum) growth and biochemical attributes are influenced by various black soldier fly (Hermetia illucens) larvae frass types

Abstract A major by-product of black solider fly larvae (BSFL) farming is the leftover mineral-rich ‘frass’, which shows promise as a soil amendment. The composition of BSFL frass, and potentially their efficacy, is influenced by the initial substrate. In this study, expired fish diets (EFD) or fruits/vegetables (FV) were used to produce BSFL frass, which were separately used as a soil amendment for basil versus basil that received weekly applications of a synthetic fertilizer (SF) (nitrogen, phosphorus, and potassium; 18-18-21). After five weeks, measurements of the sugar content, total phenol/antioxidant capacity, and mineral composition were determined. Basil heights became significantly taller with more biomass in SF (283 g) compared to the EFD frass treatment (115 g) but not the FV frass treatment (186 g). Compared with SF, basil leaves were significantly lower in manganese, calcium, zinc and iron in both frass treatments, but magnesium was significantly higher in the frass treatments. While soluble and insoluble sugar were significantly lower in both frass treatments (total of 26 and 13 mg/g in EFD and FV, respectively) compared to SF (43 mg/g), an opposite trend occurred with total phenol/antioxidant capacity. Results indicate deficiencies of some nutrients and more frequent applications of the BSFL frass might be necessary to overcome reduced production. Overall, FV frass enhanced basil production compared to EFD frass indicating that frass type influences plant growth.

Improvement Of Maggot Drying Machine Using the Verein Deutsche Ingenieuer (VDI) 2222 Method

Maggots are the larvae of Black Soldier Flies (BSF) that consume organic waste and offer various benefits, one of which is using dried maggots as livestock feed, such as poultry and fish. Currently, maggots are dried using manual methods involving stoves and kettles, microwaves, and rotary maggot drying machines. However, each of these three methods has its own shortcomings. There is a need for the redesign of an effective and efficient maggot drying machine that produces high-quality maggots. The designed maggot drying machine combines principles of both rotary and oven drying. The redesign process of this maggot drying machine follows the Verein Deutsche Ingenieure (VDI) 2222 methodology. The research sequence includes problem formulation, literature review, data collection, improvement concepts, machine design, cost calculations, and analysis, which involves comparison with the previous machine, durability testing, and machine maintenance. The machine design utilizes the rotary principle to ensure even drying, while the oven principle allows for temperature control to obtain good-quality maggots that meet the needs of maggot enthusiasts.

The influence of protein from black soldier fly larvae (Hermetia illucens) on the reproductive functions of roosters

Our research is devoted to studying the possibility of using food from the larvae of black soldier flies (Hermetia illucens) (low-fat flour) in the diets of breeding roosters of the Hisex Brown cross. The inclusion of 7.5% low-fat flour in the diet structure of the roosters of the experimental group led to an increase in the quality indicators of the sperm of breeding roosters, activated metabolic processes and antioxidant protection. By the time of full physiological maturation (25 weeks), the roosters of the experimental group had a superiority (P&lt;0.05) over the control in live weight and testes weight by 2.80 and 4.25%. An increase in ejaculate volume was found by 7.55% (P&lt;0.05), sperm concentration by 24.36% (P&lt;0.05), sperm survival time of up to 139 hours, while reducing the number of morphologically abnormal germ cells. A connection has been established between the amino acid and mineral compositions of the experimental feed and rooster sperm. Bioactive substances of insect larvae are able to activate enzymes of the antioxidant defense of birds. In the blood of experimental roosters, the level of glutathione peroxidase increased by 2.51% (P&lt;0.05), superoxide dismutase - by 8.37 (P&lt;0.01), and the amount of reduced glutathione by 12.62% (P&lt;0.01). A decrease in oxidized glutathione by 29.67% (P&lt;0.01) was found. The end product of fat oxidation (malondialdehyde) decreased, relative to the control, by 16.51% (P&lt;0.01). The conducted studies have proven the effectiveness of the experimental feed in the nutrition of breeding roosters.

Using black solider fly larvae (Hermetia illucens) to clean unwanted beeswax from equipment

In beekeeping, unwanted beeswax periodically needs to be cleaned from equipment, especially queen excluders and frames. This process is usually costly, laborious, or needs specialized equipment. A simple, insect-based method for cleaning beeswax is presented, which is based on black solider fly larvae (BSFL, Hermetia illucens). BSFL were shown to prefer dirty, brown wax over cleaner yellow wax, and are able to completely remove wax from equipment within 24 h, even in hard-to-reach crevices, without prior scraping. Bees are further shown to accept and build comb on BSFL-cleaned plastic frames, with a preference for frames that had been rubbed with a block of wax.

A gut commensal bacterium promotes black soldier fly larval growth and development partly via modulation of intestinal protein metabolism.

Black solider fly larvae and the gut microbiota can recycle nutrients from various organic wastes into valuable insect biomass. We found that Citrobacter amalonaticus, a gut commensal bacterium of the insect, exerts beneficial effects on larval growth and development and that the expression of many metabolic larval genes was significantly impacted by the symbiont. To identify the larval genes involved in the host-symbiont interaction, we engineered the symbiont to produce double-strand RNA and enabled the strain to silence host genes in the larval gut environment where the interaction takes place. With this approach, we confirmed that two intestinal protease families are involved in the interaction and provided further evidence that intestinal protein metabolism plays a role in the interaction. This work expands the genetic toolkits available to study the insect functional genomics and host-symbiont interaction and provide the prospective for the future application of gut microbiota on the large-scale bioconversion.

A novel variable power microwave (VPM) drying technology for lowering energy consumption and improving the in vitro protein digestibility of black solider fly larvae

In this study, a novel variable power microwave (VPM) drying process that can automatically and continuously adjust microwave power according to temperature feedback was developed to dry black soldier fly larvae (BSFL). The influence of VPM and constant power microwave (CPM) drying on the drying time, energy consumption, and product quality of BSFL and the potential relationship between BSFL quality and microstructural properties were investigated. The results showed that VPM drying could reduce 17.14% ∼ 27.50% of the drying time and 3.37% ∼ 12.24% of the energy consumption compared with CPM drying. BSFL protein produced by VPM drying exhibited higher digestibility. VPM drying decreased the formation of β-sheets and disulfide bonds within the protein, reducing the aggregation of protein molecules. Scanning electron microscopy and differential scanning calorimetry analysis also demonstrated that VPM-dried BSFL products had smaller protein particle sizes and less protein denaturation. Industrial relevanceVPM drying can reduce energy consumption while improving BSFL drying efficiency and help to maintain the quality of dried products. The control system that can adjust the microwave power in real time according to the temperature feedback can be easily applied to the continuous tunnel microwave drying equipment widely used in the food industry to realize large-scale VPM drying of insects. The results obtained in this study can help to improve insect-based product quality by using VPM drying and provide technical support for edible insects as an alternative protein source in the future.

Black Soldier Fly Larva Oil in Diets with Roughage to Concentrate Ratios on Fermentation Characteristics, Degradability, and Methane Generation.

Currently, the scarcity of high-quality, expensive animal feed is a primary factor driving up the cost of animal husbandry. As a result, most researchers have focused on improving the potential of using alternative feed resources derived from the black soldier fly larva. In particular, the utilization of oil from black fly larvae is a byproduct of the industry. The aim of this study was to investigate the influence of black soldier fly larva oils and the proportion of roughage-to-concentrate ratios on gas kinetics, rumen characteristics, degradability, and mitigate CH4 production by using in vitro gas production techniques. The in vitro investigation used a completely randomized design (CRD) with a 2 × 4 factorial arrangement. The level of R:C ratios (60:40 and 40:60) were factor A, while BSFO levels (0, 2, 4, and 6% of DM) were factor B. Under this investigation, the combined impact of R:C ratio and BSFO on the kinetics of gas and accumulative gas production was found to be significant (p < 0.01). After 4 h of incubation, the pH and ammonia-nitrogen (NH3-N) concentration were found to be impacted by the inclusion of BSFO levels at different R:C-ratios (p < 0.01). Moreover, after 4 and 8 h of incubation, supplementing the BSFO at 4% with the level of R:C ratio at 40:60 resulted in a significant reduction in the amount of CH4 in the rumen (p < 0.05). However, the inclusion of BSFO levels at different R:C ratios had no effect on the degradability of DM after 12 and 24 h of incubation (p > 0.05), whereas increasing the concentration of BSFO in concentrate at 6% reduced the DM degradability after 24 h of incubation (p < 0.05). Furthermore, adding BSFO to the diet at various R:C ratios enhanced the propionate (C3) concentration, with the highest level observed with the level of R:C ratio at 40:60 and 4% BSFO inclusion (p < 0.05). To summarize, the addition of BSFO at 4% with a 40:60 of R:C ratio increased C3 levels, decreased CH4 emission, and preserved DM degradability. A R:C ratio of 40:60 could improve the total volatile fatty acids and digestibility. Moreover, the inclusion of 6% BSFO at different R:C ratios lowered the in vitro dry matter digestibility, in vitro organic matter digestibility, NH3-N, and protozoal populations.

Nutritional value of black solder fly (Hermetia illucens Linnaeus, 1758) larvae reared on fermented milk industry waste as an ingredient of fish feed

Black soldier fly larvae are omnivorous and have high activity of amylases, lipases and proteases in their gastrointestinal tract, so they are of interest concerning the processing of various organic industrial and agricultural wastes into biomass suitable for feeding farm animals. Black soldier fly larvae are a new protein-lipid component that seems quite promising for inclusion in the diet of fish, since its cultivation allows processing waste from various industries and agriculture. The protein obtained from black soldier fly larvae has been approved for use as a component of the feed ration for farm animals in the European Union, but the possibility of using black soldier fly larvae in aquaculture has not been fully studied and requires studying of a number of issues. In this study, the nutritional value of larvae grown using fermented milk waste was assessed by the content of fat, protein, moisture, macronutrients (K, Ca, Mg) and micronutrients (Fe, Cu, Mn, Zn, Co, Se), as well as amino acid composition. The content of fat, protein and water was estimated by the extraction/gravimetric method. The content of macro— and micronutrients was measured by inductively coupled plasma mass spectrometry (ICPMS). The amino acid composition was determined by a high performance liquid chromatography (HPLC) method adapted to this task. Chemical analysis showed that the larvae are generally of nutritional value, but additional data on fatty acid analysis and vitamin content are required. In addition, it is necessary to test the feed on fish of various species and ages in order, in particular, to evaluate the effect of the studied component on the palatability of the feed, as well as the digestibility of the chitinous cover of the insect.

Nutritive value, material reduction, biomass conversion rate, and survival of black solider fly larvae reared on palm kernel meal supplemented with fish pellets and fructose

Nutritive value, material reduction, biomass conversion rate, and survival of black solider fly larvae reared on palm kernel meal supplemented with fish pellets and fructose

Dietary inclusions of black soldier fly (Hermetia illucens) larvae frass enhanced production of channel catfish (Ictalurus punctatus) juveniles, stevia (Stevia rebaudiana), and lavender (Lavaridula angustifolia) in an aquaponic system

In aquaponic systems, adding supplemental nutrients to enhance plant production is common. Frass, which is the manure of insects, can be used to enhance fish and plant production, but no study has yet examined the potential to enhance both using a dietary approach in an aquaponic system. In this 8-week study, channel catfish (Ictalurus punctatus) juveniles were fed diets with, or without, 10% black solider fly (Hermetia illucens) larvae (BSFL) frass in an aquaponic system. Each aquaponic system had two different plant bed types; floating raft or media. Each plant bed consisted of three stevia (Stevia rebaudiana) and three lavender (Lavaridula angustifolia) plants in a 2 × 2 factorial design, with the main effects of dietary frass inclusion and media type. After 8 weeks, channel catfish grew significantly faster when fed a diet containing 10% BSFL frass compared to fish fed the control diet. Further, dietary frass upregulated the hepatic expression of IGFβ, IGF-1 and GHR as well as reduced intestinal inflammation based on histological observations and scoring. The muscle proximate composition of channel catfish was unaffected by diet, while only taurine was significantly reduced by dietary frass. Muscle calcium and phosphorus as well as C14:0 and C15:0 were significantly elevated by dietary frass. For plants, both stevia and lavender had significantly more biomass when frass was added to the system, while plants grown in media beds were larger than plants grown in a floating raft subsystem. Frass significantly increased phosphorus in both stevia and lavender at week 8. The higher water calcium, magnesium, and nitrate levels may have allowed for better plant growth as these are essential nutrients. The significant increase of catfish growth was likely due to the upregulation of genes responsible for growth, mitigating intestinal inflammation, and significantly enhancing diet intake. Thus, it may be recommended that feeding catfish with BSFL frass and culturing stevia and lavender in media beds can substantially improve overall productivity.

Occurrence of five distinct clades of mermithid nematodes (Nematoda: Mermithidae) infecting black fly larvae (Diptera: Simuliidae) in tropical streams in Malaysia.

Mermithids are the most common parasites of black flies and are associated with host feminization and sterilization in infected hosts. However, information on the species / lineage of black fly mermithids in Southeast Asia, including Malaysia requires further elucidation. In this study, mermithids were obtained from black fly larvae collected from 138 freshwater stream sites across East and West Malaysia. A molecular approach based on nuclear-encoded 18S ribosomal RNA (18S rRNA) gene was used to identify the species identity / lineage of 77 nematodes successfully extracted and sequenced from the specimens collected. Maximum likelihood and neighbor-joining phylogenetic analyses demonstrated five distinct mermithid lineages. Four species delimitation analyses: automated simultaneous analysis phylogenetics (ASAP), maximum likelihood Poisson tree processes with Bayesian inferences (bPTP_ML), generalized mixed yule coalescent (GMYC) and single rate Poisson tree processes (PTP) were applied to delimit the species boundaries of mermithid lineages in this data set along with genetic distance analysis. Data analysis supports five distinct lineages or operational taxonomic units for mermithids in the present study, with two requiring further investigation as they may represent intraspecific variation or closely related taxa. One mermithid lineage was similar to that previously observed in Simulium nigrogilvum from Thailand. Co-infection with two mermithids of different lineages was observed in one larva of Simulium trangense. This study represents an important first step towards exploring other aspects of host - parasite interactions in black fly mermithids.