Effects of dietary urea supplementation on performance of selected insect species.

Feeding costs of farmed insects may be reduced by applying alternative nitrogen sources such as urea that can partly substitute true proteins. The aim of this study was to examine the effects of different nitrogen sources on body weight (BW) and survival rate (SR) of the Jamaican field cricket (JFC, Gryllus assimilis), the house cricket (HC, Acheta domesticus), yellow mealworm larvae (YM, Tenebrio molitor) and superworm larvae (SW, Zophobas morio). Crickets were either housed individually or in groups, and larvae were group-housed. Six isonitrogenous feeds composed of 3.52% nitrogen were designed for all four insect species using four independent replicates with micellar casein: urea proportions of 100-0%, 75-25%, 50-50%, 25-75%, 0-100% and 100% extracted soybean meal. All selected insect species were able to utilise urea. However, urea as the only nitrogen source resulted in low final BW. In the HC, the JFC, and the YM on nitrogen basis urea can replace 25% of micellar casein without having any negative effects on BW and SR in comparison to the 100% micellar casein group. In the SW, a 25% urea level did not have a significant effect on final BW, but SR decreased significantly.

Effects of sodium selenite, yeast selenium, and nano-selenium on toxicity, growth, and selenium bioaccumulation in Lucilia sericata maggots.

In this study, we investigated the effects of different types of selenium (Se) (sodium selenite [SS], yeast selenium [YS], and nano-selenium [NS]) on the toxicity, growth, Se accumulation, and transformation of Lucilia sericata maggots (LSMs). We found that the 50% lethal concentration of LSMs exposed to SS was 2.18 and 1.96 times that of YS and NS, respectively. LSM growth was significantly promoted at exposure concentrations of 10-50 mg kg-1 in group SS and 10-30 mg kg-1 in group YS, whereas NS inhibited LSMs growth at all concentrations (p < 0.05). Total Se content in LSMs, conversion efficiency to organic and other forms of Se, and bioaccumulation factor of Se were the highest in the SS group when exposed to 50 mg kg-1 (81.6 mg kg-1, 94.6%, and 1.63, respectively). Transcriptomic results revealed that LSMs significantly upregulated the amino acid (alanine, aspartate, glutamic, and tyrosine) and tricarboxylic acid cycle signaling pathways (p < 0.05) on exposure to Se, resulting in a significant increase in LSMs biomass and quality. In conclusion, our study indicates that LSMs exhibit good tolerance to SS and can convert it into bioorganic or other forms of Se.

Sustainable use of plastic-derived nanocarbons as a promising larvicidal and growth inhibitor agent towards control of mosquitoes.

Nanoscale carbon was obtained from six widely used plastics (PET, HDPE, PVC, LDPE, PP and PP) via thermal degradation (600 °C) under inert atmosphere. The thermally degraded products were processed through bath sonication followed by lyophilisation and the same was characterized through proximate analysis, UV-Vis spectroscopy, Scanning electron micrograph (SEM) with energy dispersive X-ray (EDX) analysis, Transmission electron micrograph (TEM), Dynamic light scattering (DLS) and Fourier transform infrared spectroscopy (FTIR). A series of aqueous solution of nanoscale carbon (5-30 mg/L) were prepared and same were used as both mosquito growth inhibitor and larvicidal agent against 3rd and 4th instar larvae of Culex pipiens. The significant percent mortality results were recorded for LDPE (p < 0.007) with average particle size of 3.01 nm and 62.95 W% of carbon and PS (p < 0.002) with average particle size of 12.80 nm and 58.73 W% of carbon against 3rd instar larvae, respectively. Similarly, for 4th instar larvae, both significant pupicidal and adulticidal activity were also recorded for PET (F = 24.0, p < 0.0001 and F = 5.73, p < 0.006), and HDPE (F = 26.0, p < 0.0001) and F = 5.30, p < 0.008). However, significant pupicidal activity were observed for PVC (F = 6.90, p < 0.003), and PS (F = 21.30, p < 0.0001). Histological, bio-chemical and microscopic studies were revealed that nanoscale carbon causes mild to severe damage of external and internal cellular integrity of larvae. However, nanoscale carbon does not exhibit any chromosomal abnormality and anatomical irregularities in Allium cepa and Cicer arietinum, respectively. Similarly, non-significant results with respect to blood cell deformation were also recorded from blood smear of Poecilia reticulata. Therefore, it can be concluded that plastic origin nanoscale carbon could be a viable sustainable nano-weapon towards control of insects.

Involvement of Sep38ß in the Insecticidal Activity of Bacillus thuringiensis against Beet Armyworm, Spodoptera exigua (Lepidoptera).

The p38 mitogen-activated protein kinases (MAPKs) are associated with insect immunity, tissue repair, and the insecticidal activity of Bacillus thuringiensis (Bt). Here, a p38 MAPK family gene (Sep38ß) was identified from Spodoptera exigua. Among the developmental stages, the transcription level of Sep38ß was the highest in egg, followed by that in prepupa and pupa. Sep38ß expression peaked in Malpighian tubules and the hemolymph of fifth instar larvae. Knockdown of Sep38ß or injection of SB203580 (a p38 MAPK inhibitor) significantly downregulated the SeDUOX expression and reactive oxygen species (ROS) level in the midgut, accounting for deterioration of the midgut to scavenge pathogens and enhancement of Bt insecticidal activity. In conclusion, all the results demonstrate that Sep38ß regulates the immune-related ROS level in the insect midgut, which suppresses the insecticidal activity of Bt against S. exigua by 17-22%. Our study highlights that Sep38ß is essential for insect immunity and the insecticidal activity of Bt to S. exigua and is a potential target for pest control.

Honeybee symbiont Bombella apis could restore larval-to-pupal transition disrupted by antibiotic treatment.

Numerous studies have demonstrated the vital roles of gut microbes in the health, immunity, nutrient metabolism, and behavior of adult worker honeybees. However, a few studies have been conducted on gut microbiota associated with the larval stage of honeybees. In the present study, we explored the role of a gut bacterium in larval development and larval-pupal transition in the Asian honeybee, Apis cerana. First, our examination of gut microbial profiling showed that Bombella apis, a larvae-associated bacterium, was the most dominant bacterium colonized in the fifth instar larvae. Second, we demonstrated that tetracycline, an antibiotic used to treat a honeybee bacterial brood disease, could cause the complete depletion of gut bacteria. This antibiotic-induced gut microbiome depletion in turn, significantly impacted the survivorship, pupation rate and emergence rate of the treated larvae. Furthermore, our analysis of gene expression pattens revealed noteworthy changes in key genes. The expression of genes responsible for encoding storage proteins vitellogenin (vg) and major royal jelly protein 1 (mrjp1) was significantly down-regulated in the tetracycline-treated larvae. Concurrently, the expression of krüppel homolog 1(kr-h1), a pivotal gene in endocrine signaling, increased, whilethe expression of broad-complex (br-c) gene that plays a key role in the ecdysone regulation decreased. These alterations indicated a disruption in the coordination of juvenile hormone and ecdysteroid synthesis. Finally, we cultivated B. apis isolated from the fifth instar worker larval of A. cerana and fed tetracycline-treated larvae with a diet replenished by B. apis. This intervention resulted in a significant improvement in the pupation rate, emergence rate, and overall survival rate of the treated larvae. Our findings demonstrate the positive impact of B. apis on honeybee larvae development, providing new evidence of the functional capacities of gut microbes in honeybee growth and development.

Molecular responses of sponge larvae exposed to partially weathered condensate oil.

Anthropogenic inputs of petroleum hydrocarbons into the marine environment can have long lasting impacts on benthic communities. Sponges form an abundant and diverse component of benthic habitats, contributing a variety of important functional roles; however, their responses to petroleum hydrocarbons are largely unknown. This study combined a traditional ecotoxicological experimental design and endpoint with global gene expression profiling and microbial indicator species analysis to examine the effects of a water accommodated fraction (WAF) of condensate oil on a common Indo-Pacific sponge, Phyllospongia foliascens. A no significant effect concentration (N(S)EC) of 2.1 % WAF was obtained for larval settlement, while gene-specific (N(S)EC) thresholds ranged from 3.4 % to 8.8 % WAF. Significant shifts in global gene expression were identified at WAF treatments ≥20 %, with larvae exposed to 100 % WAF most responsive. Results from this study provide an example on the incorporation of non-conventional molecular and microbiological responses into ecotoxicological studies on petroleum hydrocarbons.

An extract from the frass of swallowtail butterfly (Papilio machaon) larvae inhibits HCT116 colon cancer cell proliferation but not other cancer cell types.

BACKGROUND: The frass of several herbivorous insect species has been utilised as natural medicines in Asia; however, the metabolite makeup and pharmaceutical activities of insect frass have yet to be investigated. Oligophagous Papilionidae insects utilise specific kinds of plants, and it has been suggested that the biochemicals from the plants may be metabolised by cytochrome P450 (CYP) in Papilionidae insects. In this study, we extracted the components of the frass of Papilio machaon larvae reared on Angelica keiskei, Oenanthe javanica or Foeniculum vulgare and examined the biological activity of each component. Then, we explored the expression of CYP genes in the midgut of P. machaon larvae and predicted the characteristics of their metabolic system. RESULTS: The components that were extracted using hexane, chloroform or methanol were biochemically different between larval frass and the host plants on which the larvae had fed. Furthermore, a fraction obtained from the chloroform extract from frass of A. keiskei-fed larvae specifically inhibited the cell proliferation of the human colon cancer cell line HCT116, whereas fractions obtained from the chloroform extracts of O. javanica- or F. vulgare-fed larval frass did not affect HCT116 cell viability. The metabolites from the chloroform extract from frass of A. keiskei-fed larvae prevented cell proliferation and induced apoptosis in HCT116 cells. Next, we explored the metabolic enzyme candidates in A. keiskei-fed larvae by RNA-seq analysis. We found that the A. keiskei-fed larval midgut might have different characteristics from the O. javanica- or F. vulgare-fed larval metabolic systems, and we found that the CYP6B2 transcript was highly expressed in the A. keiskei-fed larval midgut. CONCLUSIONS: These findings indicate that P. machaon metabolites might be useful as pharmaceutical agents against human colon cancer subtypes. Importantly, our findings show that it might be possible to use insect metabolic enzymes for the chemical structural conversion of plant-derived compounds with complex structures.

Crude Oil and Its Burnt Residues Induce Metamorphosis in Marine Invertebrates.

Metamorphosis is a critical process in the life cycle of most marine benthic invertebrates, determining their transition from plankton to benthos. It affects dispersal and settlement and therefore decisively influences the dynamics of marine invertebrate populations. An extended period of metamorphic competence is an adaptive feature of numerous invertebrate species that increases the likelihood of finding a habitat suitable for settlement and survival. We found that crude oil and residues of burnt oil rapidly induce metamorphosis in two different marine invertebrate larvae, a previously unknown sublethal effect of oil pollution. When exposed to environmentally realistic oil concentrations, up to 84% of tested echinoderm larvae responded by undergoing metamorphosis. Similarly, up to 87% of gastropod larvae metamorphosed in response to burnt oil residues. This study demonstrates that crude oil and its burned residues can act as metamorphic inducers in marine planktonic larvae, short-circuiting adaptive metamorphic delay. Future studies on molecular pathways and oil-bacteria-metamorphosis interactions are needed to fully understand the direct or indirect mechanisms of oil-induced metamorphosis in marine invertebrates. With 90% of chronic oiling occurring in coastal areas, this previously undescribed impact of crude oil on planktonic larvae may have global implications for marine invertebrate populations and biodiversity.

Upcycling of recycled minerals from sewage sludge through black soldier fly larvae (Hermetia illucens): Impact on growth and mineral accumulation.

Phosphorous (P) resources are finite. Sewage sludge recyclates (SSR) are not only of interest as plant fertilizer but also as potential source of minerals in animal nutrition. However, besides P and calcium (Ca), SSR contain heavy metals. Under EU legislation, the use of SSR derivatives in animal feed is not permitted, but given the need to improve nutrient recycling, it could be an environmentally sound future mineral source. Black soldier fly larvae (BSFL) convert low-grade biomass into valuable proteins and lipids, and accumulate minerals in their body. It was hypothesized that BSFL modify and increase their mineral content in response to feeding on SSR containing substrates. The objective was to evaluate the upcycling of minerals from SSR into agri-food nutrient cycles through BSFL. Growth, nutrient and mineral composition were compared in BSFL reared either on a modified Gainesville fly diet (FD) or on FD supplemented with either 4% of biochar (FD + BCH) or 3.6% of single-superphosphate (FD + SSP) recyclate (n = 6 BSFL rearing units/group). Larval mass, mineral and nutrient concentrations and yields were determined, and the bioaccumulation factor (BAF) was calculated. The FD + SSP substrate decreased specific growth rate and crude fat of BSFL (P < 0.05) compared to FD. The FD + SSP larvae had higher Ca and P contents and yields but the BAF for Ca was lowest. The FD + BCH larvae increased Ca, iron, cadmium and lead contents compared to FD. Larvae produced on FD + SSP showed lower lead and higher arsenic concentration than on FD + BCH. Frass of FD + BCH had higher heavy metal concentration than FD + SSP and FD (P < 0.05). Except for cadmium and manganese, the larval heavy metal concentration was below the legally permitted upper concentrations for feed. In conclusion, the SSR used could enrich BSFL with Ca and P but at the expense of growth. Due to the accumulation of Cd and Mn, BSFL or products thereof can only be a component of farmed animal feed whereas in BSFL frass heavy metal concentrations remained below the upper limit authorized by EU.

The nutritional profile, mineral content and heavy metal uptake of yellow mealworm reared with supplementation of agricultural sidestreams.

Insect farming, a potential approach to deal with the increasing global protein demand, is a new activity in the Western world with many unanswered questions regarding product quality and safety. Insects may fulfill an important role in a circular economy by upcycling biowaste into valuable biomass. About half of the total mass of mealworm feeding substrates exists out of wet feed. This can be sourced from biowaste, increasing the sustainability of insect farming. This paper reports on the nutritional profile of yellow mealworm, Tenebrio molitor, reared with supplementation of organic sidestreams. These included unsold vegetables, potato cuttings, fermented chicory roots and horticultural foliage. The evaluation was performed by analyzing proximate compositions, fatty acid profiles, mineral and heavy metal contents. Mealworms fed with potato cuttings doubled their fat content and increased saturated and mono-unsaturated fatty acids. Providing fermented chicory roots increased the mineral content and accumulated heavy metals. Additionally, the uptake of minerals by mealworms was selective as only calcium, iron and manganese concentrations increased. Adding vegetable mix or horticultural foliage to the diet did not significantly change the nutritional profile. In conclusion, sidestreams were successfully recycled into protein-rich biomass and their nutrient content and bio-availability influenced the composition of mealworms.

Effects of Fructose and Palmitic Acid on Gene Expression in Drosophila melanogaster Larvae: Implications for Neurodegenerative Diseases.

One of the largest health problems worldwide is the development of chronic noncommunicable diseases due to the consumption of hypercaloric diets. Among the most common alterations are cardiovascular diseases, and a high correlation between overnutrition and neurodegenerative diseases has also been found. The urgency in the study of specific damage to tissues such as the brain and intestine led us to use Drosophila melanogaster to study the metabolic effects caused by the consumption of fructose and palmitic acid in specific tissues. Thus, third instar larvae (96 ± 4 h) of the wild Canton-S strain of D. melanogaster were used to perform transcriptomic profiling in brain and midgut tissues to test for the potential metabolic effects of a diet supplemented with fructose and palmitic acid. Our data infer that this diet can alter the biosynthesis of proteins at the mRNA level that participate in the synthesis of amino acids, as well as fundamental enzymes for the dopaminergic and GABAergic systems in the midgut and brain. These also demonstrated alterations in the tissues of flies that may help explain the development of various reported human diseases associated with the consumption of fructose and palmitic acid in humans. These studies will not only help to better understand the mechanisms by which the consumption of these alimentary products is related to the development of neuronal diseases but may also contribute to the prevention of these conditions.

Bioaccumulated provitamin A in black soldier fly larvae is bioavailable and capable of improving vitamin A status of gerbils.

The aim was to study whether provitamin A (proVA), which can bioaccumulate in black soldier fly larvae (BSFL), is bioavailable and can restore VA status in mammals. A model for studying the metabolism of this vitamin, the gerbil, was either fed a standard diet (C+ group), a diet without VA (C-), a diet in which VA was provided by ß-carotene (ß-C) from sweet potatoes (SP), or a diet in which VA was provided by ß-C from BSFL that had been fed sweet potatoes (BSFL). The animals were killed at the end of the supplementation period and ß-C, retinol and retinyl esters were measured in plasma and liver. As expected ß-C was not detected in plasma and liver of the C+ and C- groups. ß-C concentrations were lower (p < 0.05) in plasma and liver of the BSFL group as compared to the SP group. Liver retinol and retinyl ester concentrations were lower in the C- group than in all the other groups (p < 0.05). These concentrations were not significantly different in the C+ and SP groups while they were lower in the BSFL group (p < 0.05 for retinyl oleate and retinyl linoleate). In total, the liver stock of retinol equivalent was almost twice lower in the BSFL group than in the SP group. Thus, ß-C present in the BSFL matrix is bioavailable and capable of improving VA status, but this matrix decreases its effectiveness by a factor of around two compared to the sweet potato matrix.

The effect of chemical dispersion and temperature on the metabolic and cardiac responses to physically dispersed crude oil exposure in larval American lobster (Homarus americanus).

Despite their potential vulnerability to oil spills, little is known about the physiological effects of petroleum exposure and spill responses in cold-water marine animal larvae. We investigated the effects of physically dispersed (water-accommodated fraction, WAF) and chemically dispersed (chemically enhanced WAF, CEWAF; using Slickgone EW) conventional heavy crude oil on the routine metabolic rate and heart rate of stage I larval American lobster (Homarus americanus). We found no effects of 24-h exposure to sublethal concentrations of crude oil WAF or CEWAF at 12 °C. We then investigated the effect of sublethal concentrations of WAFs at three environmentally relevant temperatures (9, 12, 15 °C). The highest WAF concentration increased metabolic rate at 9 °C, whereas it decreased heart rate and increased mortality at 15 °C. Overall, metabolic and cardiac function of American lobster larvae is relatively resilient to conventional heavy crude oil and Slickgone EW exposure, but responses to WAF may be temperature-dependent.

Anti-Mitochondrial and Insecticidal Effects of Artemisinin against Drosophila melanogaster.

Artemisinin (ART) is an endoperoxide molecule derived from the medicinal plant Artemisia annua L. and is clinically used as an antimalarial drug. As a secondary metabolite, the benefit of ART production to the host plant and the possible associated mechanism are not understood. It has previously been reported that Artemisia annua L. extract or ART can inhibit both insect feeding behaviors and growth; however, it is not known whether these effects are independent of each other, i.e., if growth inhibition is a direct outcome of the drug's antifeeding activity. Using the lab model organism Drosophila melanogaster, we demonstrated that ART repels the feeding of larvae. Nevertheless, feeding inhibition was insufficient to explain its toxicity on fly larval growth. We revealed that ART provoked a strong and instant depolarization when applied to isolated mitochondria from Drosophila while exerting little effect on mitochondria isolated from mice tissues. Thus, ART benefits its host plant through two distinct activities on the insect: a feeding-repelling action and a potent anti-mitochondrial action which may underlie its insect inhibitory activities.

Processing Properties and Potency of Bacillus thuringiensis Cry Toxins in the Rice Leaffolder Cnaphalocrocis medinalis (Guenée).

Different Cry toxins derived from Bacillus thuringiensis (Bt) possess different insecticidal spectra, whereas insects show variations in their susceptibilities to different Cry toxins. Degradation of Cry toxins by insect midgut extracts was involved in the action of toxins. In this study, we explored the processing patterns of different Cry toxins in Cnaphalocrocis medinalis (Lepidoptera: Crambidae) midgut extracts and evaluated the impact of Cry toxins degradation on their potency against C. medinalis to better understand the function of midgut extracts in the action of different Cry toxins. The results indicated that Cry1Ac, Cry1Aa, and Cry1C toxins could be degraded by C. medinalis midgut extracts, and degradation of Cry toxins by midgut extracts differed among time or concentration effects. Bioassays demonstrated that the toxicity of Cry1Ac, Cry1Aa, and Cry1C toxins decreased after digestion by midgut extracts of C. medinalis. Our findings in this study suggested that midgut extracts play an important role in the action of Cry toxins against C. medinalis, and the degradation of Cry toxins by C. medinalis midgut extracts could reduce their toxicities to C. medinalis. They will provide insights into the action of Cry toxins and the application of Cry toxins in C. medinalis management in paddy fields.

Crude oil exposure of early life stages of Atlantic haddock suggests threshold levels for developmental toxicity as low as 0.1 µg total polyaromatic hydrocarbon (TPAH)/L.

Atlantic haddock (Melanogrammus aeglefinus) embryos bind dispersed crude oil droplets to the eggshell and are consequently highly susceptible to toxicity from spilled oil. We established thresholds for developmental toxicity and identified any potential long-term or latent adverse effects that could impair the growth and survival of individuals. Embryos were exposed to oil for eight days (10, 80 and 300 µg oil/L, equivalent to 0.1, 0.8 and 3.0 µg TPAH/L). Acute and delayed mortality were observed at embryonic, larval, and juvenile stages with IC50 = 2.2, 0.39, and 0.27 µg TPAH/L, respectively. Exposure to 0.1 µg TPAH/L had no negative effect on growth or survival. However, yolk sac larvae showed significant reduction in the outgrowth (ballooning) of the cardiac ventricle in the absence of other extracardiac morphological defects. Due to this propensity for latent sublethal developmental toxicity, we recommend an effect threshold of 0.1 µg TPAH/L for risk assessment models.

Group V Chitin Deacetylases Influence the Structure and Composition of the Midgut of Beet Armyworm, Spodoptera exigua.

Chitin deacetylase (CDA) can accelerate the conversion of chitin to chitosan, influencing the mechanical properties and permeability of the cuticle structures and the peritrophic membrane (PM) in insects. Putative Group V CDAs SeCDA6/7/8/9 (SeCDAs) were identified and characterized from beet armyworm Spodoptera exigua larvae. The cDNAs of SeCDAs contained open reading frames of 1164 bp, 1137 bp, 1158 bp and 1152 bp, respectively. The deduced protein sequences showed that SeCDAs are synthesized as preproteins of 387, 378, 385 and 383 amino acid residues, respectively. It was revealed via spatiotemporal expression analysis that SeCDAs were more abundant in the anterior region of the midgut. The SeCDAs were down-regulated after treatment with 20-hydroxyecdysone (20E). After treatment with a juvenile hormone analog (JHA), the expression of SeCDA6 and SeCDA8 was down-regulated; in contrast, the expression of SeCDA7 and SeCDA9 was up-regulated. After silencing SeCDAV (the conserved sequences of Group V CDAs) via RNA interference (RNAi), the layer of intestinal wall cells in the midgut became more compact and more evenly distributed. The vesicles in the midgut were small and more fragmented or disappeared after SeCDAs were silenced. Additionally, the PM structure was scarce, and the chitin microfilament structure was loose and chaotic. It was indicated in all of the above results that Group V CDAs are essential for the growth and structuring of the intestinal wall cell layer in the midgut of S. exigua. Additionally, the midgut tissue and the PM structure and composition were affected by Group V CDAs.

Traditionally used medicinal plants mediate the biosynthesis of silver nanoparticles: methodological, larvicidal, and ecotoxicological approach.

It has been shown that vegetal species constitute an alternative natural source for the biosynthesis of new nanomaterials. Thus, aiming to expand knowledge about the potential use of plants in the fabrication of metallic nanomaterials, we aimed to synthesize silver nanoparticles (AgNPs) from phyto-formulation (PF) of ten commonly used medicinal plants. Our results demonstrate the formation of spherical, stable, polycrystalline AgNPs with a diameter of 8.42 nm to 18.40 nm, whose biosynthesis confirmation was performed via UV-Vis spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction analysis (XRD), field emission scanning electron microscopy (FE-SEM)-energy dispersive X-ray spectroscopy (EDS) mapping, high-resolution transmission electron microscopy (HR-TEM), dynamic light scattering (DLS), and zeta potential studies. Furthermore, we demonstrated that the biosynthesized AgNPs showed larvicidal activity against Aedes aegypti and Anopheles stephensi larvae, with the histopathology findings from the fourth instar larval stage validating such larvicidal toxicity. The histological examinations showed severe degradation of the larvae's hindgut, epithelial cells, midgut, and cortical area. However, the PF extract and the biosynthesized AgNPs showed high ecotoxicity in Danio rerio larvae exposed to different concentrations. The treatments induced changes in hatchability percentage, animal growth, and heartbeat. Therefore, despite supporting the potential of PF (from ten plant species) as a raw material source for AgNPs biosynthesis, our study also sheds light on its ecotoxicological potential, suggesting that more comprehensive assessments of the ecotoxicity of biosynthesized would be performed before its application in different sectors.

Effect of Dietary Inorganic and Chelated Trace Mineral Supplementation on the Growth Performance and Skeletal Deformities of European Seabass and Senegalese Sole Post-larvae.

Trace elements such as Cu, Fe, Mn and Zn are essential minerals in fish diets, especially important at early larval stages. The chemical speciation of these elements directly influences their uptake efficiency and metabolic utilization. In order to optimize the form of trace elements incorporated into larval feed, two experiments were conducted using two commercial fish species, European seabass (Dicentrarchus labrax) and Senegalese sole (Solea senegalensis), and two chemical forms (inorganic and glycinate chelates). Several fish performance parameters were measured, as well as bone status parameters to assess which form of mineral results in optimal fish biological performance. European seabass and Senegalese sole post-larvae were unresponsive (P > 0.05) to dietary treatments in terms of dry weight (DW), standard length (SL), relative growth rate (RGR) or feed conversion rates (FCR) when fed diets supplemented with chelated over inorganic trace minerals. This study suggests that replacing dietary inorganic mineral supplementation by their organic glycinate-chelated forms brings no beneficial effects on somatic growth and bone development in Senegalese sole and European seabass post-larvae fed high-quality commercial microdiets. Additionally, we show that mineral leaching from diets can be significant, but the use of chelated minerals can potentially mitigate this leaching phenomenon. Therefore, the selection of the dietary mineral form should take into account not only their economic value, but also their biological effect and environmental impact. Data generated in this trial provides new knowledge in trace mineral nutrition of early-stage marine fish.

Co-diet supplementation of low density polyethylene and honeybee wax did not influence the core gut bacteria and associated enzymes of Galleria mellonella larvae (Lepidoptera: Pyralidae).

The current plastic pollution throughout the world is a rising concern that demands the optimization of biodegradation processes. One avenue for this is to identify plastic-degrading bacteria and associated enzymes from the gut bacteria of insect models such as Tenebrio molitor, Plodia interpunctella or Galleria mellonella that have the ability to ingest and rapidly degrade polyethylene. Therefore, this study takes part in understanding the role of the gut bacteria by investigating G. mellonella as a biological model feeding with a diet based on honeybee wax mixed or not with low-density polyethylene. Gut microbiome was analyzed by high throughput 16S rRNA sequencing, and Enterococcaceae and Oxalobacteraceae were found to be the major bacterial families. Compared to the control, the supplementation of low-density polyethylene did not cause significant modification of the bacterial microbiota at community and taxa levels, suggesting bacterial microbiome resilience. The bacterial proteome analysis of gut contents was encouraging for the identification of plastic degrading enzymes such as the phenylacetaldehyde dehydrogenase which participate in styrene degradation. This study allowed a better characterization of the gut bacteria of G. mellonella and provided a basis for the further study of biodegradation of polyethylene based on the bacterial microbiota from insect guts.