The Performance of Black Soldier Fly Larvae (BSFLs), Hermetia illucens L. (Diptera: Stratiomyidae), as a Function of the Substrate Used: A Review

Organic wastes are one of the greatest challenges that cities face worldwide. In numerous underdeveloped nations, like Cameroon, waste is often disposed of through landfills, composting, or open-air combustion. Unfortunately, the concept of waste sorting and organic waste processing is new to many individuals. This has led to an increase in the amount of organic waste and the costs connected with its management. Consequently, the majority of developing nations have sought out waste management solutions that are more cost-effective. Therefore, it has been determined that the bioconversion of organic wastes by black soldier fly larvae (BSFLs) (Hermetia illucens) into multifunctional prepupae is a viable alternative. Appreciation is given to the employment of the organic waste management approach in developing nations since it is not only environmentally friendly and economically viable, but also provides a means for waste valorisation through the production of diverse resources and potential economic benefits. Studies have proved the usefulness of the insect in controlling organic wastes, but countries such as Cameroon are still unfamiliar with the nuances of this method. Consequently, this timely review examined the performance of the BSFL, specifically in organic waste treatment, as well as the best practices for multiplying them to determine its viability for use in a waste treatment plant, the production of high-quality larvae as a source of protein for livestock, and the production of diesel fuel.

Biodiesel Production from Rhynchophorus ferrugineus Larvae Oil: Physichochemical Properties and Acid Composition of Oil as Affected by Oil Extraction Protocol

Biodiesel, a renewable energy source made from natural oils and fats, can be produced using white raffia larvae as a raw material. These larvae have a high lipid content and a short life cycle, making them suitable for this purpose. One crucial step in biodiesel production is oil extraction, and this study aimed to investigate how the extraction protocol affects the fuel properties of the oil. To study the impact of solvent type, solvent volume, and residence time on oil yield, 200 grams of Rhynchophorus ferrugineus were used in a Soxhlet extractor. The researchers examined the physicochemical properties and fatty acid composition of the crude grease using the European biodiesel standard (EN14214) and gas chromatography methods, respectively. The study found that hexane as a solvent produced the highest oil yield (64.44%) during a four-hour extraction period with a solvent ratio of 300 ml. Furthermore, the hexane-extracted oil had the highest iodine number (3.02 g/100 g) and cetane number (55.69). These values indicate favorable properties for biodiesel production. The Rhynchophorus ferrugineus larvae oil proved to be a rich source of monounsaturated fatty acids (76%), which were found to be significantly affected by the solvent type. Based on quality assessment, Rhynchophorus ferrugineus can be suitable for biodiesel production. In summary, under the given operational conditions, hexane is the most suitable solvent for Rhynchophorus ferrugineus oil extraction for biodiesel production. Further research in optimizing the extraction process can contribute to the efficient utilization of renewable energy sources like white raffia larvae for biodiesel production.

A Case Report on Cutaneous Larva Migrans (CLM)

Cutaneous larva migrans (CLM) is a zoonotic hookworm infection of dogs and cats commonly found in low-income countries in the tropical and subtropical regions and travellers to these regions. It is caused by invasion of the skin by the parasitic larvae of hookworms which, after entry, move under the skin causing an inflammatory reaction resulting in a single or multiple tracks. Patients commonly present with a progressive, itchy, erythematous serpiginous skin rash, affecting the feet, although it can affect any other parts of the body. The diagnosis is mainly clinical, based on history and physical examination. Treatment of this condition can effectively be achieved with either albendazole or ivermectin. We present a case of a 7-year-old boy who was diagnosed with CLM after presenting to the hospital with a history of a progressive itchy rash with tracks on the left foot. Although CLM is a self-limiting disease, it causes a lot of suffering and, therefore, it is of public concern. There is a need to increase awareness of this disease among health workers, and to implement and promote preventive measures against the disease since the cause is known.

Analysis on Survival Rate and Economic Benefit of Apostichopus japonicus Larvae Reared by Raising Water Temperature

In order to control the spawning quality and improve the economic benefit of Apostichopus japonicus Selenka, the indoor temperature and light control methods were employed for artificial maturation, spawning and hatching of A. japonicus, and the larval survival rate, disease incidence rate and economic benefit were analyzed. The results showed that compared with those of conventional temperature-reared larvae, the survival rate of raised temperature-reared larvae was increased by 15.8%, the disease incidence rate was reduced by 10.2%, and the economic benefit was improved by 21.6%. These results will provide theoretical basis and technical support for the artificial breeding of A. japonicus.

Study on the Quantity Dynamic Changes of Heterobacteria and Vibrios in Larvae Industrialized Culture System

[ Objective ] The dynamic change of heterobacteria and vibrios in larvae industrialized culture system was studied to provide scientific reference for healthy cultivation of shrimp. [ Method ] The heterobacteria, vibrios and pathogenic vibrio parahaemolyticus were monitored in larvae industrialized culture system. [ Result] The heterobacteria, vibrios and pathogenic vibrio parahaemolyticus were the most in fertilized eggs of shrimp but the least in nauplius, then their number would increase with growth. During whole rearing period, both boterobacteria in larvae, vibrios in water would increase by one order of magnitude, while both vibrios in larvae and heterobacteria in water would increase by two orders of magnitude. There were many heterobacteria and vibrios but few vibrio parahaemolyticus in living bait. The correlation coefficients between larvae and heterobacteria and vibrios in water were 0. 704 and 0. 840 in culture system respectively, while the correlation among heterobacteria, vibrios in living bait and larvae, water were weak or negative. [ Conclusion ] There was a dynamic relation between water and larvae in rearing period, and restrictly control of culture condition would restrain the occurrence of disease caused by vibrio parahaemolyticus, besides that bacteria number in bait was not obviously correlated with bacteria nubmer in culture system.

Research of Holotrichia diomphalia Larvae Cultivation Technology with Agaricus bisporus Residues

[Objective] The aim was to explore key technology to cultivate Holotdchia diomphalia larvae with Agaricus bisporus residues and to provide, technologicar sup- ports for processing of Agaricus bisporus residues. [Method] In the research, fodder thickness, population density and residues under different treatments were set to re- search effects on Holotrichia diomphalia larvae. [Result] The optimal thickness of fodder was 25 cm and the optimal feeding density was 44-56 larvae per hectare. The dry residues were more suitable, compared with decomposed residues and corn bran powders, for cultivation of Holotrichia diomphalia larvae. [Conclusion] Cultivation of Holotrichia diomphalia larvae with Agaricus bisporus residues is a new method to make use of Agaricus bisporus residues and of significance for extension of agricul- tural circulation chain, increase of economic benefits and ecological benefits.

Observation of Biological Characteristics of Bananamoth[Opogona sacchari (Bojer)]Larvae in Sugarcane

[ Objective] The paper was to understand the biological characteristics of bananamoth [ Opogona sacchari （ Bojer ） ] larvae in sugarcane. [ Method ] Through the rearing test of bananamoth larvae with different hosts, the biological characteristics of bananamoth larvae in sugarcane were observed and analyzed. [ Result ] The mortality rate of bananamoth larvae reared with sugarcane was higher than that of the pests reared with potato. The larva had 8 instars, and the devel- opment duration of the larvae reared with sugarcane was 34.6 d longer than the pests reared with potato. The larvae needed about 98.8 d to complete a generation in average. Viewed from the observation values of head width, body length and weight of larvae, bananamoth larvae reared with sugarcane basically accorded with the growth and development law of larvae. [Condusion ] The results provided theoretical basis for the preparation of effective measures against bananamoth and the assurance of safe production of.sugarcane.

Study on Chironomid Larvae Recognition Based on DWT and Improved KNN

A chironomid larvae images recognition method based on wavelet energy feature and improved KNN is developed. Wavelet decomposition and color information entropy are selected to construct vectors for KNN that is used to classify of the images. The distance function is modified according to the weight determined by the correlation degree between feature and class, which effectively improves classification accuracy. The result shows the mean accuracy of classification rate is up to 95.41% for freshwater plankton images, such as chironomid larvae, cyclops and harpacticoida.

Pesticidal character of phytoecdysteroids from Ajuga multiflora Bunge (Labiatae) on larvae of Cryptorrhynchus lapathi L. (Coleoptera: Curculionidae)

Eight kinds of phytoecdysteroids extracted from different parts of Ajuga multiflora Bunge (Labiatae) that were collected from different places at different time were tested for killing effects on the 2-instar larvae of Cryptorrhynchus lapathi L by adding them to the artificial diet of larvae. The experimental results indicated that adding 1-3-mL phytoecdysteroids to the artificial diet could lead 58%-100% of 2-instar larvae of C. lapathi to death within 24 days. The phytoecdysteroids extracted from the whole plant of A. multiflora which was collected before flowering time were much more effective than those extracted from the plants collected at flowering and after flowering periods, and the modified mortality rate of larvae reached 65.22%, 85.07%, and 98.11% at the dosage level of 1-mL, 2-mL, and 3-mL extracts, respectively. The extract made from root of A. multiflora plant was more effective in killing efficiency than those from stem and leaves, and the average death rates of larvae were up to 100%, 98.20% and 98.32% at dosage levels of 1-mL, 2-mL, and 3-mL extracts, respectively. The killing speed of the extracted phytoecdysteroids was slower than that of triflumuron, hexaflumuron or deltamethrin emulsifiable concentrate. The mortality rate of larvae is closely related to the feeding duration on the diets containing phytoecdysteroids. Feeding on the diets with addition of phytoecdysteroids for 16 days, more than 80% of treated 2-instar larvae of C. lapathi were led to death. The killing effect of the extracts was little affected by the growth areas of A. multiflora plant and the adding way to artificial diet.

Hermetia illucens larvae as a potential dietary protein source altered the microbiota and modulated mucosal immune status in the colon of finishing pigs

Background: Insects, such as Hermetia illucens larvae, are rich in chitin and proteins, and represent a suitable feed ingredient replacement for animals. However, little is known about the effect of administering H. illucens larvae on intestinal microbiota, bacterial metabolite profiles, and mucosal immune status in animals. This study aimed to investigate the effects of administering H. illucens larvae on colonic microbiota and bacterial metabolites production in finishing pigs. Seventy-two crossbred(Duroc × Landrace × Large White) female pigs(initial body weight, 76.0 ± 0.52 kg) were randomly allocated to three different dietary treatments: a control diet(Control group) and two diets corresponding to 4%(H1 group) and 8%(H2 group) H. illucens larvae inclusion levels, respectively. Each treatment consisted of eight pens(replicates), with three pigs per pen. After 46 days of feeding, eight pigs per treatment(n =8) were slaughtered, and the colonic digesta and mucosa were collected for microbial composition and microbial fermentation products, and genes expression analyses.Results: The results showed that the H1 diet significantly increased the abundance of Lactobacillus,Pseudobutyrivibrio, Roseburia, and Faecalibacterium compared with those in the control group(P < 0.05), with a decrease in the abundance of Streptococcus. The numbers of Lactobacillus, Roseburia, and Clostridium cluster XIVa were significantly greater in the H1 group than in the control group(P < 0.05). Meanwhile, H2 diet increased the number of Clostridium cluster XIVa compared with the control group(P < 0.05). For colonic metabolites, total short chain fatty acids, butyrate, and isobutyrate concentrations were significantly higher in the H1 group than those in the control group(P < 0.05);the H1 treatment caused a striking decrease in protein fermentation compared with the control group, as the concentrations of total amines, cadaverine, tryptamine, phenol, p-cresol, and skatole were significantly lower(P < 0.05). Additionally, H2 diet also increased butyrate concentration compared with control group(P < 0.05), while decreased the concentrations of phenol, p-cresol, and skatole(P < 0.05). Pigs in the H1 group down-regulated the expression of TLR-4 and pro-inflammatory cytokines(IFN-γ) compared with pigs in the control group(P < 0.05), and up-regulated anti-inflammatory cytokine(IL-10) and intestinal barrier genes(ZO-1, occludin, and mucin-1). H2 diet up-regulated the expression of ZO-1 compared with control group(P < 0.05). Furthermore, the changes in the colonic mucosal gene expression were associated with changes in the bacterial composition and their metabolites.Conclusions: Collectively, dietary inclusion of Hermetia illucens larvae may enhance mucosal immune homeostasis of pigs via altering bacterial composition and their metabolites. These findings provide a new perspective on insect meal as a sustainable protein source rich in nutrient ingredients for swine.

Comparison of growth and survival of larvae among different shell color stocks of bay scallop Argopecten irradians irradians(Lamarck 1819)

In order to improve production and breed new broods of bay scallop Argopecten irradians irradians, different-colored orange, purple and white lines were established by two mating methods of self-fertilization and mass spawning at a commercial scallop hatchery in spring, 2002. And then larval growth and survival of different lines was compared to test whether there is a relationship between shell color and growth and survival at early developmental stage. Both growth and survival have no significant differences among different experimental larvae of self-fertilization or mass spawning. Results are as following in the order of orange, purple and white shell stock. For the self-fertilization, growth rates of larvae were 6.174, 6.412, and 6.599 μm/d, respectively. Survival rates of larvae at Day 3 were 74.41%, 76.86%, and 82.05%; Day 6 were 49.14%, 65.63%, and 52.79%; and Day 9 were 25.06%, 20.80%, and 26.47%, respectively. For the mass spawning, the growth rates were 7.836, 7.941, and 7.878 μm/d, respectively. Survival rates at Day 3 were 93.05%, 91.95%, and 92.50%; Day 6 were 79.17%, 78.05%, and 82.50%; and Day 9 were 34.72%, 36.67%, and 38.33%, respectively. The absence of any relationship between shell color and growth and survival at the larval stage may be resulted from their common genetic basis.

DISTRIBUTION AND ABUNDANCE OF EGGS AND LARVAE OF ANTARCTIC KRILL(ENPHAUSUA SUPERBADANA)IN ANTARCTIC PENINSULA AREA

During the First Chinese Antarctic Expedition zooplankton samples were collected at each of the oceanography stations in the waters around South Sheltland Islands (S. S. Is.) and in the northern part of the Bellinshausen Sea from 20 January to 12 February, 1985 by vertical tows of an 80 cm diameter conical net from 200 m to surface. Two deep tows with a closing net. were performed in slope water north of S.S. Is, and in the basin of Bransfield Strait. Eggs and larvae of Euphatisia superba Dana in zooplankton samples were identified and counted.There were four records of eggs from 27 stations. Most catches were of small number and restricted to within the nearshore area south of S.S Is.The largest number (1500/1000 cubic meters )was found in the outer side of Smith Island.No Nauplius was found . The earliest stage we found 【was Metanauplius , in two deep tows. The distribution of Calyptopis MI and Furcili I-III were quite similar. They were found mainly in three areas: 1 ) nearshore water along the

Lead levels of Culex mosquito larvae inhabiting lead utilizing factory

Objective:To determine lead level primarily in Culex quinquefasciatus(Cx.quinquefasciatus), and Culex gelidus(Cx.gelidus) larvae inhabiting lead consuming factories,and to putatively estimate eco-toxicological impact of effluents from the firms.Methods:Third instars larvae were sampled by standard dipping method and lead concentrations in the larvae and their respective surrounding factory aquatic environments were determined through standard atomic absorption spectrophotometry(AAS).Results:Cx.quinquefasciatus was the most abundant species followed by Cx.gelidus.The levels of lead were higher in the Cx.quinquefasciatus(1.08-47.47μg/g),than in the wastewaters surface(0.01-0.78 μg/mL) from the factories or closer areas around factories. Other species were not reaching the.criteria for lead determination.Conclusions:The Cx. quinquefasciatus larvae can bio-accumulate the metal and can potentially serve as a biomarker of lead contamination,to complemente conventional techniques.

Effects of rearing temperature and density on growth,survival and development of sea cucumber larvae,Apostichopus japonicus(Selenka)

In laboratory conditions,effects of rearing temperature and stocking density were examined on hatching of fertilized egg and growth of auricularia larvae of Apostichopus japonicus respectively.Data series like larval length and density,metamorphic time,and survival rate of the larvae were recorded.Statistics showed that for A.japonicus,survival rate(from fertilized egg to late auricularia) decreased significantly with the increasing rearing temperature(P<0.05).At different temperatures SGR was statistically significant as well(P<0.05) from day 1,and maximal SGR was found on day 9 at 24℃(159.26±3.28).This study clearly indicated that at low temperature(<24℃),metamorphic rate was remarkably higher than at higher temperature(>26℃).Hatching rate was significantly different between 0.2-5 ind./ml groups and 20-50 ind./ml groups.Rearing larvae at the higher density had the smaller maximal-length,whereas needed longer time to complete metamorphosis.This study suggested that 21℃ and 0.4 ind./ml can be used as the most suitable rearing temperature and stocking density for large-scale artificial breeding of A.japonicus's larvae.

Toxic effects of several phthalate esters on the embryos and larvae of abalone Haliotis diversicolor supertexta

As the most widely used plasticizers in the world, phthalate esters （PAEs） are potential endocrine disruption compounds （EDCs）. In the present study, the toxicity of dimethyl phthalate （DMP）, diethyl phthalate （DEP）, dibutyl phthalate （DBP）, di （2-ethylhexyl） phthalate （DEHP） on embryogenesis and larvae development of the marine univalve Haliotis diversicolor supertexta was examined in laboratory. The results show that the malformation of embryos appeared during the experiment, such as embryos died or lysed, small transparent flocculent rings studded on the periphery of the embryo, and the larvae could failed to hatch. In embryo toxic test, embryos incubated at the highest concentration of DMR DEP and DBP solutions showed significantly high abnormal rate compared with the control, while DEHP solutions displayed no significant difference. In larval toxic test, in all concentrations of DMP, DEP and DBP solutions, larval settlement rates were low significantly than that of the control. Similarly, DEHP solutions show nearly no effect on the larval settlement. The order of toxicity on embryos and larvae is DBP〉DEP〉DMP〉DEHE Being a simple and easy stimulation to indoor spawn, sensitive to environmental factors, and short culture time, the embryos of H. diversicolor supertexta can be used to indicate toxicity of the PAEs.

Spatiotemporal distribution of fish eggs and larvae in the Huanghe(Yellow) River estuary, China in 2005–2016

Decreasing fish resources in estuaries is a subject of anthropogenic activities. Studies of the spatiotemporal distribution of fish eggs and larvae can help identify the status and processes underlying recruitment in a fishery. As the fifth largest river estuary in the world, the Huanghe (Yellow) River estuary (HRE) is a typical estuary that has been seriously aff ected by human activities. Annual surveys on ichthyoplankton and environmental factors were conducted in the months of May of 2005 and 2009-2016 in the HRE to investigate the spatiotemporal distribution of fish eggs and larvae and the associated infl uencing factors. A total of 23 and 20 species of eggs and larvae, respectively, were collected. The dominant orders were Perciformes (51.2%) and Clupeiformes (25.6%). The average number of fish species eggs and larvae were 6.0 and 4.1 in average abundance of 0.91 and 0.13 ind./m^3 , respectively. The dominant species were mainly low-commercial-value small-sized fishes, such as Clupanodon punctatus , Harengula zunasi, and Acanthogobius, whereas certain traditional commercial fishes, such as Trichiurus lepturus , and Clupea pallasii, were not seen. Analysis of the fish egg and larval community revealed four temporal assemblages and two spatial assemblages. Salinity was the main factor on the spatial distribution of ichthyoplankton communities, the species number and Shannon-Weiner diversity index (H′) of the fish egg and larval community near the river mouth with lower salinity were signifi cantly lower than the community far away from the river mouth with higher salinity. In addition, increases of water temperature promoted the number and abundance of fish species eggs, and the areas of abundant prey tended to have a more diversified and abundant of ichthyoplankton species. In overall, overfishing, dam construction, and other human activities were the main drivers that led to the substantial decline in fishery resources in the HRE.

Effects of temperature and salinity on the development of embryos and larvae of the veined rapa whelk Rapana venosa(Valenciennes, 1846)

The major population of the veined rapa whelk Rapana venosa （Valenciennes, 1846）, which is an important fishery resource, is facing a large decline in China. We studied the effects of incubation temperature （16-34℃ at salinity 30） and salinity （5-45 at 25℃） on the incubation period and subsequent larval development. In the temperature experiment, the shortest incubation period was 12 days at 34℃, the lower temperature limit was 16~C, the longest mean shell length （1 193＋17 pan） occurred at 25℃ and the highest survival rate 72.28%＋5.62% was observed at 28℃. In the salinity experiment, the shortest incubation period was 15 days at 25. The salinity tolerance range was 15-40, the longest mean shell length （855-4-9 μm） and the highest survival rate 72.93%~4.85% were both observed at 35. This study demonstrated that, during the egg-mass stage, temperature and salinity regimes influence later growth and survival of larvae. These observations deepen our understanding of the ecology and conservation of natural populations of Rapana venosa.

Development Study on Some Digestive Enzymes of Takifugu rubripes Larvae and Juvenile

The activities of some digestive enzymes are studied for Takifugu rubripes larvae and juvenile from the first feeding to 27 d after hatching at selected stages of development. The homogenate of whole larvae body is used for enzymatic determination. Activity of acid protease decreases notably during the beginning days after the commencement of completely exogenous feeding and the days before the beginning of the juvenile stage. Alkaline protease specific activity also decreases at metamorphosis. The activities are associated with the morphology of the developing digestive tract. Amylase activity increases before the first feeding, followed by a decreasing and then a rather constant level. Lipase activity remains low during the larvae and juvenile periods. Alkaline phosphatase activity increases gradually. This reflects the development of brush border membranes of enterocytes.

Comparative Study of Malathion Toxicity and General Esterases in Larvae and Adults from a Field Population of Oxya chinensis (Thunberg) (Orthoptera: Acridoidea)

The susceptibility of Oxya chinensis to malathion was compared in larvae and adults from a field population, collected from Jinyuan outskirt, Shanxi Province. The results showed that Oxya chinensis was more susceptible to malathion in the adult stage than in the larval stage. The LD50 values for malathion susceptibility of Oxya chinensis were 4.94 and 2.44 mg g-1 body weight in the larvae and adults respectively. The results indicated that the larvae were 2.02-fold less susceptible to malathion than the adults. The general esterases and the kinetics were characterized and compared between the two life stages and between females and males. Larval preparations of Oxya chinensis were more active than adult preparations in females and males. The larvae showed 1.18-, 1.49-, and 1.17- fold higher specific activities than the adults in females with α-NA, α-NB and β-NA respectively. In males, the ratios were 1.34-, 1.70-, and 1.06-fold. Female preparations were more active than those of males in the adults. The reverse results were observed in the larvae where male preparations were more active than female preparations. Kinetic studies showed that Km values of general esterases hydrolyzing α-NA, α-NB, and β-NA in the adult stage were 1.36-, 1.32- and 1.39-fold respectively, higher than those in the larval stage in females. In males, the ratios were 1.24-, 2.14-, and 1.20-fold. The esterase from male insects had a higher affinity (lower Km value) to the substrate than those from females. The results also showed that the Vmax values of general esterase hydrolyzing α-NA, α-NB, and β-NA in the two stages were similar. From the results of bioassays and biochemical analyses, it has been inferred that a higher level of resistance to malathion in larvae than in adults would appear to result from differences in the expression of resistance mechanisms in these two life stages. Enhanced esterase activities appeared to play a major role in resistance to malathion in both larvae and adults. From the analysis of inhibition in vitro, the esterases in the two life stages were B-type, and carboxylesterases were predominant enzymes in the composition of the esterases in the two stages.

Molecular identification of scallop planktonic larvae using species-specific microsatellites

The identification of scallop larvae is essential to understand the population structure and community dynamics and to assess the potential environmental impacts caused by scallop larvae released or escaped. However, the larvae identification by morphological characteristics is notoriously difficult, mainly due to the small size （usually being less than 150 μm） and vague morphological characteristics among different scallop species. A simple and accurate molecular method was developed to identify four economically farmed scallop species, the Zhikong scallop Chlamys farreri, the noble scallop C. nobilis, the bay scallop Argopecten irradians and the Yesso scallop Mizuhopecten yessoensis. The tests used the high degree of species-specific microsatellite markers, which was specified by transferability analyses, assessed by reference individuals and evaluated by BLAST searches. The sensitivity test indicated that the species-specific microsatellites were sensitive enough for the detection of 1% -2% larvae in mixed plankton samples. Larvae collected from scallop hatcheries and their effluents and from the artificially controlled crosses were well identified to the species/hybrid level. The results demonstrated that the one-step PCR-based assay was technically simple, inexpensive and robust in identification analyses, and also less sensitive to initial quality of template DNA extracted from the ethanol-preserved samples for several years.