Survival Rate Of Larvae Research Articles

Pig manure characteristics and decomposition ability of Protaetia brevitarsis seulensis larval instar stages

AbstractMany types of livestock waste can be treated with insect larvae; however, in‐depth research on the decomposition ability of Protaetia brevitarsis seulensis (PBS) larvae and the characteristics of manure after treatment with PBS is extremely limited. Therefore, this study examined the decomposition ability and survival rates of different instars of PBS larvae and their effects on the characteristics and pathogen counts of pig manure. Two treatments were designed: 1 kg of second instar or third instar PBS larvae per 10 kg of pig manure. Pig manure did not affect the decomposing capacity and survival rates of the two PBS larval instar groups (P > 0.05). However, the decomposition abilities of the different PBS larval instar groups on days 2, 7 and 8 significantly differed (P < 0.05). Over time, the changes observed in pH, moisture, total nitrogen, acid detergent fiber (ADF), neutral detergent fiber (NDF) and hemicelluloses did not significantly differ (P > 0.05) between treatments using second or third instar PBS larvae. On day 15, both total nitrogen and NDF significantly differed (P < 0.05) between the two treatment groups. During the experimental period, no significant (P > 0.05) change in Escherichia coli or Salmonella counts was observed in pig manure treated with different PBS larval instars. Our findings suggest that the decomposition abilities and survival rates of larvae and pig manure characteristics and pathogen counts do not differ for different PBS larval instar stages.

Thyroid and growth hormone endocrine disruption and mechanisms of homosalate and octisalate using wild-type, thrαa-/-, and dre-miR-499-/- zebrafish embryo/larvae

Homosalate (HS) and octisalate (OS), which are used in sunscreen for the purpose of blocking ultraviolet rays, are frequently detected in water environment. Although effects on estrogens and androgens have been reported, studies on thyroid and growth hormone endocrine disruption are limited. In the present study, larval mortality was compared in wild-type and two knockout fish (thyroid hormone receptor alpha a knockout (thrαa-/-) and dre-miR-499 knockout (dre-miR-499-/-)) after 96 h of exposure to HS and OS (0, 0.003, 0.03, 0.3, 3, 30 and 300 µg/L). To investigate the mechanisms of thyroid and growth hormone endocrine disruption, we measured the levels of triiodothyronine (T3), thyroxine (T4), thyroid stimulating hormone (TSH), growth hormone (GH), and insulin-like growth factor-1 (IGF-1), and the regulation of representative genes related to the hypothalamus-pituitary-thyroid (HPT) and GH/IGF axis in wild-type zebrafish exposed to target chemicals. The significantly lower larval survival rate of thrαa-/- and dre-miR-499-/- fish exposed to 300 μg/L of HS and OS suggest that thyroid hormone receptors and dre-miR-499 play a crucial role in the toxic effects of HS and OS. The finding of a significant increase in T3 and T4 in zebrafish larvae exposed to HS and OS supports a significant decrease in the crh gene. The reduction of GH and IGF-1 in fish exposed to HS and OS is well supported by the regulation of genes involved in the GH/IGF axis. Our observations suggest that exposure to HS and OS affects not only thyroid hormone receptors and their associated miRNAs, but also the feedback routes of HPT and GH/IGF axes, ultimately leading to growth reduction.

Agroecological importance of smooth brome in managing wheat stem sawfly (Hymenoptera: Cephidae) via associated braconid parasitoids.

Wheat stem sawfly (WSS), Cephus cinctus Norton (Hymenoptera: Cephidae), is a major pest of cereal crops throughout the Northern Great Plains of North America. Native parasitoids, Bracon cephi (Gahan) and B. lissogaster Muesebeck (Hymenoptera: Braconidae), play a key role in suppressing WSS populations and limiting associated damage. Smooth brome grass (Bromus inermis Leyss.) serves as a potential trap reservoir for WSS when grown in areas surrounding wheat (Triticum aestivum L.) fields in Montana. Its unique biology allows it to support high WSS infestation while promoting significant larval mortality throughout the growing season. Late-season WSS survivors can then serve as hosts for WSS parasitoids. Our study investigated smooth brome as a host refuge for WSS parasitoids. We measured WSS larval infestation and survival rate inside smooth brome grown within WSS-inclusion cages, finding a maximum infestation of 66.5% and an end-of-year WSS survival of 5.7%. In addition, we collected stems from sites in central and north-central Montana to measure the WSS infestation and parasitoid prevalence in wheat and adjacent smooth brome. WSS infestation was high in both Big Sandy (64.5% smooth brome, 65.7% adjacent wheat) and Moccasin, MT (50.6%, 38.6%). Year-end WSS larval mortality was 43.6% greater in smooth brome compared to adjacent wheat at both field sites, but both hosted similar numbers of WSS parasitoids. This research underscores the importance of smooth brome in providing a sustainable host refuge for WSS parasitoids and highlights its significant role in supporting the economics of wheat cultivation.

Impact of Sublethal Insecticides Exposure on Vespa magnifica: Insights from Physiological and Transcriptomic Analyses

Insecticides are widely used to boost crop yields, but their effects on non-target insects like Vespa magnifica are still poorly understood. Despite its ecological and economic significance, Vespa magnifica has been largely neglected in risk assessments. This study employed physiological, biochemical, and transcriptomic analyses to investigate the impact of sublethal concentrations of thiamethoxam, avermectin, chlorfenapyr, and β-cypermethrin on Vespa magnifica. Although larval survival rates remained unchanged, both pupation and fledge rates were significantly reduced. Enzymatic assays indicated an upregulation of superoxide dismutase and catalase activity alongside a suppression of peroxidase under insecticide stress. Transcriptomic analysis revealed increased adenosine triphosphate-related processes and mitochondrial electron transport activity, suggesting elevated energy expenditure to counter insecticide exposure, potentially impairing essential functions like flight, hunting, and immune response. The enrichment of pathways such as glycolysis, hypoxia-inducible factor signaling, and cholinergic synaptic metabolism under insecticide stress highlights the complexity of the molecular response with notable effects on learning, memory, and detoxification processes. These findings underscore the broader ecological risks of insecticide exposure to non-target insects and highlight the need for further research into the long-term effects of newer insecticides along with the development of strategies to safeguard beneficial insect populations.

Activity of polymyxin B combined with cefepime-avibactam against the biofilms of polymyxin B-resistant Pseudomonas aeruginosa and Klebsiella pneumoniae in in vitro and in vivo models

Bacterial biofilms, often forming on medical devices, can lead to treatment failure due to their increased antimicrobial resistance. Cefepime-avibactam (CFP-AVI) exhibits potent activities against Pseudomonas aeruginosa (P. aeruginosa) and Klebsiella pneumoniae (K. pneumoniae) when used with polymyxin B (PMB). However, its efficacy in biofilm-related infections is unknown. The present study aimed to evaluate the activity of PMB combined with CFP-AVI against the biofilms of PMB-resistant Gram-negative bacteria. Five K. pneumoniae strains and three P. aeruginosa strains known to be PMB-resistant and prone to biofilm formation were selected and evaluated. Antimicrobial susceptibility assays demonstrated that the minimal biofilm inhibitory and eradication concentrations of PMB and CFP-AVI for biofilms formed by the eight strains were significantly higher than the minimal inhibitory concentrations of the antibiotics for planktonic cells. The biofilm formation inhibition and eradication assays showed that PMB combined with CFP-AVI cannot only suppress the formation of biofilm but also effectively eradicate the preformed mature biofilms. In a modified in vitro pharmacokinetic/pharmacodynamic biofilm model, CFP-AVI monotherapy exhibited a bacteriostatic or effective activity against the biofilms of seven strains, whereas PMB monotherapy did not have any activity at 72 h. However, PMB combined with CFP-AVI demonstrated bactericidal activity against the biofilms of all strains at 72 h. In an in vivo Galleria mellonella infection model, the 7-day survival rates of larvae infected with biofilm implants of K. pneumoniae or P. aeruginosa were 0-6.7%, 40.0-63.3%, and 46.7–90.0%, respectively, for PMB alone, CFP-AVI alone, and PMB combined with CFP-AVI; the combination therapy increased the rate by 6.7–33.3% (P < 0.05, n = 6), compared to CFP-AVI monotherapy. It is concluded that PMB combined with CFP-AVI exhibits effective anti-biofilm activities against PMB-resistant K. pneumoniae and P. aeruginosa both in vitro and in vivo, and thus may be a promising therapeutic strategy to treat biofilm-related infections.

Multi-omics analysis reveal the fall armyworm Spodoptera frugiperda tolerate high temperature by mediating chitin-related genes

Climate change facilitates the rapid invasion of agricultural pests, threatening global food security. The fall armyworm Spodoptera frugiperda is a highly polyphagous migratory pest tolerant to high temperatures, allowing its proliferation in harsh thermal environments. We aimed to demonstrate mechanisms of its high-temperature tolerance, particularly transcriptional and metabolic regulation, which are poorly understood. To achieve the aim, we examined the impact and mechanism of heat events on S. frugiperda by using multiple approaches: ecological measurements, transcriptomics, metabolomics, RNAi, and CRISPR/Cas9 technology. We observed that several physiological indices (larval survival rate, larval period, pupation rate, pupal weight, eclosion rate, and average fecundity) decreased as the temperature increased, with the 32 °C treatment displaying a significant difference from the control group at 26 °C. Significantly upregulated expression of genes encoding endochitinase and chitin deacetylase was observed in the chitin-binding, extracellular region, and carbohydrate metabolic process GO terms of hemolymph, fat body, and brain, exhibiting a tissue-specific pattern. Significantly enriched pathways (e.g., cutin, suberin, and wax biosynthesis; oxidative phosphorylation and cofactor biosynthesis; diverse amino acid biosynthesis and degradation; carbon metabolism; and energy metabolism), all of which are essential for S. frugiperda larvae to tolerate temperature, were found in metabolites that were expressed differently. Successful RNA interference targeting of the three chitin-related genes reduced gene expression levels and larval survival rate. Knockout of the endochitinase gene by using the CRISPR/Cas9 system significantly reduced the relative gene expression and increased sensitivity to high-temperature exposure. On the basis of our findings, theoretical foundations for understanding the high-temperature tolerance of S. frugiperda populations and latent genetic control strategies were established.

The impact of three thioxothiazolidin compounds on trehalase activity and development of Spodoptera frugiperda larvae.

Trehalases (TREs), serving as crucial enzymes regulating trehalose and chitin metabolism in insects, represent prime targets for pest control strategies. We investigated the impact of three thioxothiazolidin compounds (1G, 2G, and 11G) on TRE activity and summarized their effects on the growth and development of Spodoptera frugiperda (Lepidoptera, Noctuidae). The experimental larvae of S. frugiperda were injected with the three thioxothiazolidin compounds (1G, 2G, and 11G), while the control group received an equivalent volume of 2% DMSO as a control. All three compounds had a strong effect on inhibiting TRE activity, significantly prolonging the pre-pupal development stage. However, compared with the 11G-treated group, the survival rate of larvae treated with 1G and 2G was significantly reduced by 31.11% and 27.78% respectively, while the occurrence of phenotypic abnormalities related to growth and development was higher. These results manifest that only the TRE inhibitors, 1G and 2G, modulate trehalose and chitin metabolism pathways of larvae, ultimately resulting in the failure molting and reduction of survival rates. Consequently, the thioxothiazolidin compounds, 1G and 2G, hold potential as environmentally friendly insecticides.

Emergence of extensively drug-resistant hypervirulent Acinetobacter baumannii isolated from patients with bacteremia: bacterial phenotype and virulence analysis

ObjectivesIndividuals infected with extensively drug-resistant (XDR) Acinetobacter baumannii are difficult to cure and have a high mortality rate. In this study, we compared the genomic and phenotypic differences between XDR and non-multidrug-resistant (MDR) A. baumannii and further characterized hypervirulent XDR A. baumannii. MethodsA total of 1,403 Acinetobacter isolates were collected from patients with bacteremia between 1997 and 2015. Antimicrobial susceptibility test was performed to categorize isolates into non-MDR, MDR, and XDR groups. The presence of selected virulence-associated genes was determined by PCR. Bacterial phenotypes, including iron acquisition, biofilm formation, capsule production, and virulence to larvae and mice, were determined. ResultsMultilocus sequence types revealed the high prevalence of ST2 (81.6%) and ST129 (18.4%) among 49 XDR isolates and sequence types of 18 non-MDR isolates were more diverse. Virulence-associated phenotypic assays showed that XDR isolates had higher iron acquisition ability and capsule production and higher virulence to Galleria mellonella larvae. However, their biofilm formation ability was lower compared to that of non-MDR isolates. XDR isolates contained more virulence genes, tonB, hemO, abaI, and ptk, while non-MDR isolates contained more pld and ompA. Twenty-one XDR isolates caused <20% larvae survival rate after 7 days post-infection were defined as hypervirulent XDR isolates. Among them, isolates 1677 (ST129) and 929-1 (ST2) also caused the death of all infected mice within two days. ConclusionSome subpopulations of highly drug-resistant ST2 also exhibit high virulence. Therefore, it is of utmost importance to continue monitoring the spread of hypervirulent XDR A. baumannii isolates.

Aspirin reduces Ponatinib-induced cardiovascular toxic phenotypes and death in zebrafish

BackgroundPonatinib (Iclusig) is an oral tyrosine kinase BCR-ABL inhibitor for treating patients with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) and chronic myeloid leukemia (CML) who are resistant to the therapies with other tyrosine kinase inhibitors. However, adverse cardiovascular events caused by Ponatinib are a serious issue that affects patients' survival rates. Thus, it is necessary to search for candidate drugs to reduce the cardiovascular toxicity of Ponatinib. PurposeTo investigate the effects of Aspirin on Ponatinib-induced cardiovascular toxicity in zebrafish. MethodsAB strain of wild type zebrafish (Danio rerio), Tg (cmlc2: GFP) transgenic zebrafish, and Tg (gata1: dsRed) transgenic zebrafish were used as in vivo models to assess survival, blood flow, cardiac morphology, and function. Thrombus formation was detected using O-dianisidine staining. The transcriptome of zebrafish larvae treated with Ponatinib was assessed using RNA sequencing. ResultsPonatinib not only reduced survival rate but also caused cardiovascular toxic events such as pericardial edema, abnormal heart structure, low heart rate, and thrombosis. In addition, whole-body transcriptome analysis showed that Ponatinib up-regulated the expression of cyclooxygenase-1 (COX-1). Compared with other antithrombotic drugs, a COX-1 inhibitor Aspirin more effectively reduced ponatinib-induced cardiovascular toxicity events and improved the survival rate of zebrafish larvae. ConclusionOur findings suggest that Aspirin exhibits the potential to reduce Ponatinib-induced cardiovascular toxicity.

Effects of Rearing Temperature on Growth and Survival of Blackthroat Seaperch, Doederleinia berycoides (Hilgendorf, 1879), Post-Flexion Larvae and Juveniles

In post-flexion larval and juvenile stages of hatchery-reared blackthroat seaperch Doederleinia berycoides (Hilgendorf, 1879), the influence of water temperature on growth and survival was examined to identify the optimal rearing temperatures. Temperature treatments were conducted separately for pelagic post-flexion larvae (32 days post hatching [dph]) and settled juveniles (69 dph). Fish were transferred to four replicate 30 L tanks (30 larvae or 15 juveniles per tank) and reared for 15 days under five temperatures (13, 16, 19, 22 and 25 °C) maintained by using heaters and coolers. The mean survival rates (± SD) of post-flexion larvae were high (&gt;73 %) for all temperatures (13 °C: 73.3 ± 6.9 %, 16 °C: 76.7 ± 6.8 %, 19 °C: 80.8 ± 10.7 %, 22 °C: 79.2.7 ± 2.8 %, 25 °C: 71.7 ± 4.4 %). Growth increased at higher temperatures and was significantly faster at 22 and 25 °C (P &lt; 0.05) than lower temperatures. For juveniles, mean survival rates were significantly higher at 16–25 °C (&gt;90%: 16 °C: 91.7 ± 1.7 %, 19 °C: 95.0 ± 3.2 %, 22 °C: 91.7 ± 1.7 %, 25 °C: 91.7 ± 5.0 %) than at 13 °C (71.7 ± 7.9 %) (P &lt; 0.05). Juvenile growth, like that of post-flexion larvae, was faster at 22 and 25 °C. These results suggest that maintaining a high rearing temperature (22–25 °C) is important for enhancing the growth for post-flexion larvae and juveniles of blackthroat seaperch and reducing the rearing period to the size of release seedlings.

Integrated transcriptome and 1H NMR-based metabolome to explore the potential mechanism of Spodoptera litura in response to flupyrimin

Flupyrimin (FLP) is a novel class of insecticide acting on insect nicotinic acetylcholine receptor (nAChR) and shows robust insecticidal activity. However, the toxicological effects of FLP on Spodoptera litura have not been revealed. In this study, the results showed that the larval survival rate decreased significantly with increasing concentration of FLP. The hematoxylin-eosin (HE) staining showed that FLP exposure damages the structure of the larval midgut. Additionally, FLP treatments significantly increased the activities of detoxification (GST and CarE) and digestive (α-Amylase and Trypsin) enzymes and reduced lipase activity. Transcriptome sequencing identified 855, 1493 and 735 differentially expressed genes (DEGs) at 12 h, 24 h and 48 h after exposure to 3 mM FLP, respectively. Gene function enrichment analysis revealed that DEGs were mainly related to fatty acid metabolic, protein processing in the endoplasmic reticulum and drug metabolism-cytochrome P450. The DEGs associated with food digestion and detoxification was validated by reverse-transcription quantitative PCR (RT-qPCR). Furthermore, a total of fifteen energy-related metabolites were identified, among which thirteen metabolisms were significantly influenced after FLP treatment based on 1H NMR-based metabolome analysis, including tyrosine, glucose, trehalose, malate, threonine, proline, glycine, lysine, citrate, alanine, lactate, valine, and leucine. Taken together, these results provide useful information for revealing the toxicological effect of FLP against S. litura.

Effect of Different Opening Diet on the Growth, the Structure of the Digestive Tract and Digestive Enzyme Activity of Larval and Juvenile Mystus macropterus.

One of the crucial factors influencing the growth and viability of larvae and juveniles is their opening diets. The objective of this study was to identify suitable initial feed options for M. macropterus larvae and juveniles. A total of 1200 newly hatched M. macropterus with an average weight of 18.3 mg and an average length of 11.58 mm were selected and randomly divided into four groups. The fish were fed with different opening diets, including rotifer, Artemia nauplii, Tubifex, and micro-diet from six days after hatching (dahs), respectively. Growth indices and activities of digestive enzymes were assessed at 10, 15, 20, 25, 30, 35, and 40 dahs. Histological examination of the structure of the digestive tract was performed at 40 dahs, while survival rates were also documented. The results demonstrated that different diets had no effect on the survival rate of larvae and juveniles of M. macropterus. The growth performance indices were ranked as follows: Tubifex group > Artemia nauplii group > micro-diet group > rotifer group. Remarkably, the Tubifex group exhibited superior growth performance, which was also reflected in the structure of the digestive tract and digestive enzyme activity. Therefore, it is recommended to include Tubifex in the diet of M. macropterus larvae and juvenile during the standardized farming process.

High voltage pulsed electric field: A novel method for killing parasitic eggs on the surface of raisins

Aiming to address the issue of stored grain pests easily breeding during the process of dried fruits in Xinjiang, this study proposes a method and a device for killing raisin parasitic eggs based on a high-voltage pulsed electric field. A one-way test and a Box-Behnken central combination test were conducted to investigate the effects of high-voltage pulsed electric field strength and frequency on the unhatched rate and larval survival rate of Plodia interpunctella eggs on raisin surfaces. The experimental results were qualitatively and quantitatively analyzed using biooptical microscope observation and incubation at constant temperature and humidity post-treatment. The findings revealed that with an output voltage of 22.8 kV, the delivery speed of 0.024 m/s, and the electric field frequency of 3.8 Hz, the unhatched rate of the eggs was 68.14 % while the survival rate of the larvae was 20.36 %. These results can provide new insights for both theoretical development and system implementation regarding the use of high voltage pulsed electric fields for eliminating raisin surface eggs, as well as providing valuable academic references for field crop diseases and pests control strategies.

Evaluation of Klebsiella pneumoniae pathogenicity through holistic gene content analysis

Klebsiella pneumoniae is a Gram-negative bacterium that causes both community- and healthcare-associated infections. Although various virulence factors and highly pathogenic phenotypes have been reported, the pathogenicity of K. pneumoniae is still not fully understood. In this study, we utilized whole-genome sequencing data of 168 clinical K. pneumoniae strains to assess pathogenicity. This work was based on the concept that the genetic composition of individual genomes (referred to as holistic gene content) of the strains may contribute to their pathogenicity. Holistic gene content analysis revealed two distinct groups of K. pneumoniae strains (‘major group’ and ‘minor group’). The minor group included strains with known highly pathogenic clones (ST23, ST375, ST65 and ST86). The minor group had higher rates of capsular genotype K1 and presence of nine specific virulence genes (rmpA, iucA, iutA, irp2, fyuA, ybtS, iroN, allS and clbA) compared to the major group. Pathogenicity was assessed using Galleria mellonella larvae. Infection experiments revealed lower survival rates of larvae infected with strains from the minor group, indicating higher virulence. In addition, the minor group had a higher string test positivity rate than the major group. Holistic gene content analysis predicted possession of virulence genes, string test positivity and pathogenicity as observed in the G. mellonella infection model. Moreover, the findings suggested the presence of as yet unrecognized genomic elements that are either involved in the acquisition of virulence genes or associated with pathogenicity.

Cloning of down-regulated genes under cold stress and identification of important genes related to cold tolerance in zebrafish (Danio rerio)

Low-temperature stress poses a significant risk to the survival of both cultivated and wild fish populations. Existing studies have found that the pre-acclimation of fishes to moderate cold stress can stimulate the activation of acclimation pathways, thereby enhancing their tolerance to cold stress. The fitness of fish relies heavily on appropriately controlled transcriptional reactions to environmental changes. Despite previous characterization of gene expression profiles in various fish species during cold acclimation, the specific genes responsible for essential functions in this process remain largely unknown, particularly the down-regulated genes induced by cold acclimation. To investigate the genes involved in cold acclimation, this study employed real-time quantitative PCR (RT-qPCR), molecular cloning, microinjection techniques, and cold stress experiments to determine the genes that play an essential part in cold acclimation. Consequently, 18 genes were discovered to be down-regulated in larval zebrafish experiencing cold stress. All 18 genes successfully detected overexpression in zebrafish at 96 and 126 hpf (fold change ≥3), which declined with the growth of zebrafish. Following microinjection, it was observed that her8a, cyp51, lss, txnipb, and bhlha9 had an adverse impact on the survival rate of zebrafish larvae under cold stress. These genes have been identified to play significant roles in various biological processes. For instance, bhlha9 has been found to be involved in both limb development and temperature sensing and her8a has been implicated in neural development. Additionally, cyp51 and lss have been identified as participants in the cholesterol synthesis pathway. Txnipb has been reported to induce cell apoptosis, thereby potentially influencing the survival rate of zebrafish larvae under cold stress. These findings offered crucial data for the analysis of molecular processes related to cold tolerance and the development of cold-resistant fish breeding.

Spirulina sebagai Pengganti Artemia untuk Meningkatkan Produksi Larva Ikan Patin Pangasius hypophthalmus

The provision of quality and sufficient shrimp fry for production is largely determined by the management of maintenance during larval stadia. This study aims to obtain the best treatment of natural feed in the form of Spirulina sp. and Artemia sp. as feed supplements to improve the growth performance and survival rate of patin fish larvae. The experiment used a Complete Randomized Design consisting of 4 feed treatments and 3 replicates: A (Artemia sp. 100%), B (Artemia sp. 100% and Spirulina sp. 100%), C (Artemia sp. 50% and Spirulina sp. 50%), and D (Spirulina sp. 100%). The larvae with a density of 50 heads/L were kept in the aquarium and fed according to the treatment. The density of Spirulina sp. administered was 104–105 cells/mL maintained until day 7 according to the treatment. The parameters measured included growth performance, which included specific growth rate (SGR), survival (SR), absolute length growth (PPM), and analysis of larval digestive enzymes (amylase, lipase, and protease). The data were analyzed using one way-analysis of variance and continued with Duncan's Multiple Range Test with a 95% confidence interval using SPSS version 22.0. The results showed that the administration of Spirulina sp. produced better SGR, SR, PPM, amylase enzyme, lipase, and protease activities compared to the control (100% administration of Artemia sp.). The best treatment was given by 100% Spirulina sp. treatment. Keywords: Artemia sp., digestive enzymes, patin fish larvae, Spirulina sp.

Knockdown of the glucosamine-6-phosphate N-acetyltransferase gene by RNA interference enhances the virulence of entomopathogenic fungi against rice leaffolder Cnaphalocrocis medinalis

Insect cuticle acts as a first line of defense and a physical protective barrier against entomopathogens. Chitin biosynthesis pathway plays a crucial role in chitin formation in the cuticle of insects. Glucosamine-6-phosphate N-acetyltransferase (GNA) is a key enzyme in insect chitin biosynthesis that regulate the chitin formation. However, how GNA-mediated cuticle metabolism influences virulence of entomopathogenic fungi is still unknown. In this study, CmGNA gene was cloned and characterized from the rice leaffolder Cnaphalocrocis medinalis. The CmGNA contains an open read frame (ORF) 600 nucleotides, encoding 199 amino acids with an isoelectric point of 8.65 and a molecular weight of 22.30 kDa. The expression profile showed that CmGNA was highly expressed in 4th instar larvae and in the cuticle. Here, we also reported the impact of CmGNA gene and entomopathogenic fungi, Metarhizium anisopliae and Beauveria bassiana, on expression pattern of chitin biosynthesis genes, feeding behavior, survival rate and average body weight of infected larvae, phenotypic deformities, rate of pupation, and adult emergence. Our results showed that knockdown of CmGNA and application of M. anisopliae and B. bassiana three days after RNA interference (RNAi) significantly decreased the expression of CmGNA and other associated genes, reduced feeding efficiency and survival rate, and caused loss of average body weight, less rate of pupation and adult emergence of infected larvae. Knockdown of CmGNA gene also increased the lethality of larvae caused by M. anisopliae and B. bassiana and resulted in significantly phenotypic deformities of infected larvae. Our findings illustrated that RNAi-mediated CmGNA knockdown disturbed the chitin synthesis genes that led to enhancing the virulence of M. anisopliae and B. bassiana, which can provide us new insights to develop novel biocontrol strategies against C. medinalis.

Sustainable aquaculture of West African freshwater prawns Macrobrachium vollenhovenii (Herklots, 1857) and M. macrobrachion (Herklots, 1851) (Decapoda: Caridea: Palaemonidae)

Abstract The river prawn Macrobrachium vollenhovenii (Herklots, 1857) and the brackish river prawn M. macrobrachion (Herklots, 1851) are economically and ecologically significant West African species. Recent molecular studies suggest they might be different ecotypes of the same species, complicating taxonomy and sustainable aquaculture practices. Both species face significant threats from human exploitation, leading to high exploitation rates and smaller average sizes within populations. Seasonal variations affect their abundance, with M. macrobrachion more prevalent during the rainy season and M. vollenhovenii thriving in the dry season. Their omnivorous detritivorous feeding habits involve consuming detritus, diatoms, phytoplankton, and insect larvae during juvenile stages. Aquaculture of M. vollenhovenii and M. macrobrachion encounters difficulties such as limited hatchery technology and low larval survival rates. Efforts to cultivate juveniles or adults in captivity face obstacles like high mortality rates due to moulting stress, handling, feeding, and cannibalism. Reintroducing captive-bred prawns into the wild offers dual benefits: controlling snail populations that host parasite causing schistosomiasis and restoring ecological balance while enhancing local fisheries and providing socio-economic benefits. To achieve sustainable aquaculture, it is crucial to address taxonomic complexities, implement management measures to mitigate overexploitation, improve hatchery technology, optimise feeding strategies, reduce stress during moulting and handling, and engage local communities through capacity building and awareness programs. This review aims to contribute to a better understanding of these prawns, promoting informed decision-making for sustainable management, conservation, and socio-economic benefits in West Africa.

Study of the Biodemographic Parameters of Two Genetically Distinct Strains of Callosobruchus maculatus from Two agroecological Zones of Senegal

During this study, we determined different biological parameters of Callosobruchus maculatus populations from two agro-ecological zones of Senegal (the ZSP and the ZVFS). To do this, strains of C. maculatus were collected in two localities, each representing an agro-ecological zone. The analysis of the results obtained shows that fecundity is greater for the strain coming from the silvopastoral zone (55.60 ± 19.144 eggs per female) than for that coming from the Senegal River valley zone (45 ± 18.577 eggs per female.). Furthermore, the evolution of egg laying shows that whatever the strain or population, more than 95% of eggs are laid during the first four days of the infestation with a peak on the second. In addition, the strains are characterized by an egg fertility rate exceeding 65% with a larval survival rate of over 75% and the Fouta strain has the highest rates. However, the emergence rate of the strain from the silvopastoral zone is lower at 49%. The longevity of adults in the Senegal River valley zone is significantly longer (11.035 ± 1.527 days) than that of adults in the silvopastoral zone. The sex ratio is in favor of males for both populations. The total development time and the oviposition-emergence time are relatively the same in the two strains with an average of 31 days and 21 days respectively.

Vitamin Solutions Effects on Reproduction of Broodstock, Growth Performance, and Survival Rate of Pangasius Catfish Fingerlings.

This study evaluates the effect of different diets supplemented with vitamin solutions on Pangasius catfish broodstock reproduction, growth performances, and the survival rates of fish larvae and fingerling. The growth and reproductive performances of breeders fed with different test diets showed significant differences among the six tested diets (p < 0.05). The highest final body weight (FBW), weight gain (WG), daily weight gain (DWG), specific growth rate (SGR) of broodstock, and survival rate of Pangasius fingerlings were found in Treatment 5, which contained 0.6% H-OVN mixed with 12.6% algal oil, and Treatment 3, which contained 0.6% vitamin premix H-OVN. The average gonadosomatic index (GSI), relative fecundity index (RFI), fertilized eggs, hatching rates of eggs, and survival rate of fingerlings was 9.1 ± 2.8 (6.7-12.8%), 133,224 ± 39,090 (104,267-199,512 eggs/kg), 77.9 ± 22.2 (62.2-93.6%), and 45.3 ± 17.4 (22.0-66.3%), respectively. The findings of this study showed that the diet containing 35% CP contents supplemented with 0.6% vitamin premix H-OVN mixed with algal oils showed the highest results in terms of growth, reproductive performance indices, and survival rates of Pangasius catfish fingerlings.