Larval Development Research Articles

Toxic Features and Metabolomic Intervention of Glabrene, an Impurity Found in the Pharmaceutical Product of Glabridin.

Glabridin is a widely used product in the cosmetics and pharmaceutical industry, which is generally isolated and purified from Licorice (Glycyrrhiza glabra) extract in industrial production. It has wide clinical applications, but significant toxicity has also been reported. The purity of glabridin raw material is generally between 90% and 98%. We have identified a toxic impurity, glabrene, in the industrial product glabridin. Our investigation using an AB wild-type zebrafish toxicity test showed that glabrene has a significant lethal effect with an LC10 of 2.8 μM. Glabrene induced obvious malformation and disrupted cartilage development in zebrafish larvae. Furthermore, the compound significantly reduced larval mobility and caused damage to brain neural tissues. Metabolic pathway analysis and neurotransmitter quantification via ELISA indicated abnormal activation of the phenylalanine metabolic pathway, resulting in elevated dopamine and acetylcholine levels in vivo. These findings provide insights into the potential risks of glabrene contamination and offer a new reference point for enhancing safety measures and quality controls in licorice-derived products.

Developmental analysis of Spalt function in the Drosophila prothoracic gland.

The Spalt transcriptional regulators participate in a variety of cell fate specification processes during development, regulating transcription through interactions with DNA AT-rich regions. Spalt proteins also bind to heterochromatic regions, and some of their effects require interactions with the NuRD chromatin remodeling and deacetylase complex. Most of the biological roles of Spalt proteins have been characterized in diploid cells engaged in cell proliferation. Here, we address the function of Drosophila Spalt genes in the development of a larval tissue formed by polyploid cells, the prothoracic gland, the cells of which undergo several rounds of DNA replication without mitosis during larval development. We show that prothoracic glands depleted of Spalt expression display severe changes in the size of the nucleolus, the morphology of the nuclear envelope and the disposition of the chromatin within the nucleus, leading to a failure in the synthesis of ecdysone. We propose that loss of ecdysone production in the prothoracic gland of Spalt mutants is primarily caused by defects in nuclear pore complex function that occur as a consequence of faulty interactions between heterochromatic regions and the nuclear envelope.

Local differences in robustness to ocean acidification.

Ocean acidification (OA) caused by increased atmospheric carbon dioxide is affecting marine systems globally and is more extreme in coastal waters. A wealth of research to determine how species will be affected by OA, now and in the future, is emerging. Most studies are discrete and generally do not include the full life cycle of animals. Studies that include the potential for adaptation responses of animals from areas with different environmental conditions and the most vulnerable life stages are needed. Therefore, we conducted experiments with the widely distributed blue mussel, Mytilus edulis, from populations regularly exposed to different OA conditions. Mussels experienced experimental conditions prior to spawning, through embryonic and larval development, both highly vulnerable stages. Survivorship to metamorphosis of larvae from all populations was negatively affected by extreme OA conditions (pH 7.3, Ωar, 0.39, pCO2 2479.74), but, surprisingly, responses to mid OA (pH 7.6, Ωar 0.77, pCO21167.13) and low OA (pH 7.9, Ωar 1.53, pCO2 514.50) varied among populations. Two populations were robust and showed no effect of OA on survivorship in this range. One population displayed the expected negative effect on survivorship with increased OA. Unexpectedly, survivorship in the fourth population was highest under mid OA conditions. There were also significant differences in development time among populations that were unaffected by OA. These results suggest that adaptation to OA may already be present in some populations and emphasizes the importance of testing animals from different populations to see the potential for adaptation to OA.

Deficiency of leap2 promotes somatic growth in zebrafish: Involvement of the growth hormone system

PurposeLiver-expressed antimicrobial peptide-2 (LEAP2) is identified as an endogenous antagonist and inverse agonist of the growth hormone secretagogue receptor type 1a (GHSR1a), its effect on the GHSR1a is contrary to the role of GHRELIN. Growth hormone (GH) is a crucial hormone for early development. Previous studies report that LEAP2 dose-dependently attenuates ghrelin-induced GH secretion, and Leap2-knockout mice exhibit increased plasma GH levels after GHRELIN administration. Clinical data revealed a possible correlation between LEAP2 and height development. However, the role of LEAP2 in early development remains unclear. This study aimed to investigate the role of LEAP2 in early development using leap2 mutant zebrafish larvae as a model. MethodWe analyzed the conservation of LEAP2 peptide across multiple species and generated leap2 mutants in zebrafish by CRISPR-Cas9, dynamically observed and measured the growth and development of zebrafish larvae from fertilization to 5 day post fertilization (dpf). In situ hybridization, transcriptome sequencing, quantitative real-time PCR and Western blot were used to detect the expression levels of GH and its signaling in early stage of embryonic development. ResultOur data demonstrate that zebrafish with a knockout of the leap2 gene display a significant increase in hatching rate, body length, and the distance between their eyes, all without visible developmental defects in the early stages of development. In addition, both RNA and protein analyses revealed a significant increase in GH expression in leap2 mutant. ConclusionIn general, this study demonstrates that LEAP2 regulates the expression of GH during early development, particularly influencing body length.

Evolutionary transitions of decapod crustaceans to non-marine, polar, and deep-sea environments: developmental, physiological and biochemical adaptations

Abstract In this brief, non-exhaustive essay, we review major adaptive changes in reproductive and developmental traits of decapod crustaceans, which have passed through evolutionary transitions from ancestral life in coastal marine environments to brackish, limnic, polar, or deep-sea habitats. Two major approaches can be recognised in studies of life-history evolution, focussing on: (1) developmental changes in adaptive physiological or biochemical traits of successive ontogenetic stages, comparing, for instance, osmoregulatory capabilities in larvae, juveniles, and adults (“ontogeny of adaptations” perspective); (2) adaptive changes in the modes of reproduction and development, e.g., enhanced maternal energy investment in egg production, abbreviated, non-feeding larval development (“adaptations in ontogeny”). Using both scientific approaches, Christoph D. Schubart has significantly contributed to our understanding of evolutionary transitions in crustaceans. In our essay, we pay particular attention to the significance of nutritional selection factors in relation to presumably adaptive developmental, physiological, and biochemical traits in different life-history stages. In this context, we highlight the key roles of lipids and carotenoid pigments, in particular of essential polyunsaturated fatty acids (PUFAs) and astaxanthin. While PUFAs and other lipid compounds have received wide scientific attention, we propose that future studies should further analyse also the potential role of astaxanthin and other essential carotenoids.

Different Protein Sources of Larval Diet on the Rearing of Anastrepha fraterculus (Diptera: Tephritidae): Biological and Nutritional Analyses.

Anastrepha fraterculus (Diptera: Tephritidae) is considered an important pest in Neotropical countries. The laboratory rearing of this species should reproduce conditions in nature; thus, special attention is required to the nutritional quality of diets for larval development. Protein components (wheat germ) are costly and account for most production costs in lab insect rearing. In this sense, this work aimed to identify ingredients to replace wheat germ, without compromising diet quality for the lab rearing of A. fraterculus. We tested diets composed of whole rice flour, corn flour, and a mixture of whole wheat flour + soybean flour as substitutes for wheat germ as well as a raw wheat germ diet, considered the control. The protein sources used in the larval diet influenced the biological performance of both the larval and adult stages of A. fraterculus during six generations. The diet containing corn flour and wheat germ showed similar results in the different developmental parameters. The diet with rice flour also provided adequate biological development for A. fraterculus throughout its life cycle and was nutritionally similar to the control. As it is local product, rice flour can replace wheat germ (costly imported product) in artificial diets for A. fraterculus, reducing production costs by roughly 30% without compromising the biological and nutritional parameters of the insects. Faced with this, the rice flour can be considered suitable for the mass rearing of A. fraterculus in the laboratory.

Pastoral grasses and legumes as potential host plants for fall armyworm Spodoptera frugiperda (J.E. Smith) development.

The fall armyworm, Spodopterafrugiperda (J.E. Smith) (Lepidoptera: Noctuidae) is a highly polyphagous, migratory pest native to the tropical and subtropical region of Americas. Grass crops particularly corn have been most heavily impacted since S. frugiperda invaded Australia in 2020. In northern Western Australia, S. frugiperda is primarily a problem in dry season (May to October) crops when there are abundant host plants available in monocultures. During the wet season (November to April) it is not known what host plants may support larval growth and development. Accordingly, this present study undertook a no-choice feeding bioassay to assess larval and pupal development on several grasses and legumes that are present over the wet season in northern Western Australia to evaluate their potential as suitable host plants for S. frugiperda. Maize (control) and sorghum were the most suitable hosts for S. frugiperda development as they supported greater larval and pupal survival, heavier larvae and pupae, and shorter development period. Following maize and sorghum, pastoral grasses, particularly blue grass, and a weedy grass, barnyard grass, had comparable effects on larval and pupal development. Legume pastures (Cavalcade, butterfly pea, and siratro) were unsuitable hosts in this bioassay as very few larvae completed their development to adults. This study demonstrates the potential for rangeland pasture grasses and weedy grasses as wet season host plants for S. frugiperda. They provide the necessary green bridge for S. frugiperda populations to survive. It is recommended that pastoralists monitor their grass forage for S. frugiperda and consider management if significant reductions in biomass are detected.

The transcriptional landscape underlying larval development and metamorphosis in the Malabar grouper (Epinephelus malabaricus).

Most teleost fishes exhibit a biphasic life history with a larval oceanic phase that is transformed into morphologically and physiologically different demersal, benthic, or pelagic juveniles. This process of transformation is characterized by a myriad of hormone-induced changes, during the often abrupt transition between larval and juvenile phases called metamorphosis. Thyroid hormones (TH) are known to be instrumental in triggering and coordinating this transformation but other hormonal systems such as corticoids, might be also involved as it is the case in amphibians. In order to investigate the potential involvement of these two hormonal pathways in marine fish post-embryonic development, we used the Malabar grouper (Epinephelus malabaricus) as a model system. We assembled a chromosome-scale genome sequence and conducted a transcriptomic analysis of nine larval developmental stages. We studied the expression patterns of genes involved in TH and corticoid pathways, as well as four biological processes known to be regulated by TH in other teleost species: ossification, pigmentation, visual perception, and metabolism. Surprisingly, we observed an activation of many of the same pathways involved in metamorphosis also at an early stage of the larval development, suggesting an additional implication of these pathways in the formation of early larval features. Overall, our data brings new evidence to the controversial interplay between corticoids and thyroid hormones during metamorphosis as well as, surprisingly, during the early larval development. Further experiments will be needed to investigate the precise role of both pathways during these two distinct periods and whether an early activation of both corticoid and TH pathways occurs in other teleost species.

The transcriptional landscape underlying larval development and metamorphosis in the Malabar grouper (Epinephelus malabaricus)

Most teleost fishes exhibit a biphasic life history with a larval oceanic phase that is transformed into morphologically and physiologically different demersal, benthic, or pelagic juveniles. This process of transformation is characterized by a myriad of hormone-induced changes, during the often abrupt transition between larval and juvenile phases called metamorphosis. Thyroid hormones (TH) are known to be instrumental in triggering and coordinating this transformation but other hormonal systems such as corticoids, might be also involved as it is the case in amphibians. In order to investigate the potential involvement of these two hormonal pathways in marine fish post-embryonic development, we used the Malabar grouper (Epinephelus malabaricus) as a model system. We assembled a chromosome-scale genome sequence and conducted a transcriptomic analysis of nine larval developmental stages. We studied the expression patterns of genes involved in TH and corticoid pathways, as well as four biological processes known to be regulated by TH in other teleost species: ossification, pigmentation, visual perception, and metabolism. Surprisingly, we observed an activation of many of the same pathways involved in metamorphosis also at an early stage of the larval development, suggesting an additional implication of these pathways in the formation of early larval features. Overall, our data brings new evidence to the controversial interplay between corticoids and thyroid hormones during metamorphosis as well as, surprisingly, during the early larval development. Further experiments will be needed to investigate the precise role of both pathways during these two distinct periods and whether an early activation of both corticoid and TH pathways occurs in other teleost species.

Interactions between migration and immunity among oriental armyworm populations infected with the insect pathogenic fungus, Beauveria bassiana.

Migration and immunity are behavioral and physiological traits that protect organisms from environmental stressors or pathogen infection. Shifting from migration to residency has become more common in some wildlife populations owing to environmental changes. However, other biological shifts, such as interactions between migration and immunity among populations within a species are largely unexplored for many agricultural migratory pests. In the field, entomopathogenic fungi infection and transmission, particularly Beauveria bassiana, can cause reduced fitness and population declines across a broad range of insect species. Here, we investigated migration-immunity interactions between migrant and resident populations of the oriental armyworm, Mythimna separata, infected with B. bassiana (the sole fungus used in this work). We found that migratory M. separata exerted stronger pathogen resistance, faster development and lower pupal weight than residents. High-dose infections (5.0 × 105 and 5.0 × 106 conidia mL-1) led to seriously decreased reproductive capacity in migrants and residents. Low-dose infections (1.0 × 104 and 5.0 × 104 conidia mL-1) led to significantly increased host flight capacities. Consecutive flight tests showed that five flight nights inhibited the reproduction of paternal infected M. separata populations. The flights also led to far-reaching transgenerational impairment of larval development and immune defense among offspring populations. By contrast, two flight nights enhanced the reproductive capacities of both M. separata populations and did not exert negative transgenerational effects on offspring populations, which may facilitate migration. This study provides insights into interactions between migration and immunity among M. separata populations. These insights will guide development of future monitoring and management technologies of this pest. © 2024 Society of Chemical Industry.

INFLUENCE OF TAURINE ON LARVAL EYE DEVELOPMENT AND GROWTH PERFORMANCE OF GOLDEN RABBITFISH (Siganus guttatus)

ARTICLE HIGLIGHTS- Taurine improves eye development in golden rabbitfish larvae- Enhanced growth performance with taurine-enriched rotifers- Taurine positively impacts fish eye and body growthABSTRACTGolden rabbitfish (Siganus guttatus) is an emerging species for aquaculture industry, despite constrains faced on commercial scale of seed production due to the high mortality during the first-feeding stage. An experiment was conducted to determine the effect of taurine through enrichment of rotifers as live-feed on eye development and growth performance of larval golden rabbitfish. Observation of eye development was carried out by measuring eye diameter of the larva and development of the retina based on histology assessment. Growth performance was measured for absolute growth and fin development of the larvae and survival rate. The results showed that taurine-enriched rotifer generally provided better performances for eye development and growth of larval golden rabbitfish compared with control (without taurine). Increase of taurine dose up to 0.050 g/L resulted in an increase of eye diameter, absolute growth, fin development and survival rate. Further increased increment of the taurine tended to decrease the values of the measured parameters. The eye diameter of larval golden rabbitfish fed with 0.050 g/L taurine-enriched rotifer was significantly wider (106.1±9.8 µm) (P < 0.05) compared with control (58.2±14.3 µm), but did not significantly differ from other doses of taurine (P > 0.05). Body width of larvae fed with 0.050 g/L taurine-enriched rotifer was significantly higher (127.3±14.6 µm) (P < 0.05) compared with control (98.8±18.3 µm). In regard to eye development, growth performances (total length, fin development and survival rate), dose of taurine for rotifer enrichment fed to larval golden rabbitfish Siganus guttatus was 0.050 g/L.

Acetylcholine and choline in honey bee (Apis mellifera) worker brood food are seasonal and age-dependent

Nursing honeybees produce brood food with millimolar concentrations of acetylcholine (ACh), which is synthesized through head gland secretions mixed with honey stomach contents. While we previously demonstrated the necessity of ACh for proper larval development, the dynamics of ACh levels throughout ontogenesis and their seasonal variations have remained unclear until now. Our HPLC analysis reveals dependencies of choline and ACh levels on larval development days (LDDs), influenced by seasonal (April–September) variations. Median ACh concentrations peak on LDD 2, declining significantly toward cell capping, while choline levels are lowest during the initial LDDs, rising markedly toward cell capping. Seasonal patterns show peak ACh levels from April to June and a low in August, paralleling choline's peak in July and low in August. This seasonality holds consistently across multiple years (2020–2022) and colonies, despite potential variations in colony performance and environmental conditions. Our analysis found no correlation between temperature, sunshine, precipitation, or favourable foraging days and ACh/choline levels, suggesting the involvement of additional factors. These findings underscore the seasonal fluctuation of ACh levels and its potential implications for the genetic programs governing winter bee development.

Early exposure to glyphosate during larval development induces late behavioural effects on adult honey bees

As the most abundant pollinator insect in crops, Apis mellifera is a sentinel species of the pollinator communities. In these ecosystems, honey bees of different ages and developmental stages are exposed to diverse agrochemicals. However, most toxicological studies analyse the immediate effects during exposure. Late effects during adulthood after early exposure to pollutants during larval development are poorly studied in bees. The herbicide glyphosate (GLY) is the most applied pesticide worldwide. GLY has been detected in honey and beebread from hives near treated crops. Alterations in growth, morphogenesis or organogenesis during pre-imaginal development could induce late adverse effects after the emergence. Previous studies have demonstrated that GLY alters honey bee development, immediately affecting survival, growth and metabolism, followed by late teratogenic effects. The present study aims to determine the late impact on the behaviour and physiology of adult bees after pre-imaginal exposure to GLY. For that, we reared brood in vitro or in the hive with sub-chronic exposure to the herbicide with the average detected concentration in hives. Then, all newly emerged bees were reared in an incubator until maturity and tested when they became nurse-aged bees. Three behavioural responses were assessed as markers of cognitive and physiological impairment. Our results show i) decreased sensitivity to sucrose regardless of the rearing procedure, ii) increased choice latency and locomotor alterations during chemotaxis and iii) impaired associative learning. These late toxicity signs could indicate adverse effects on task performance and colony efficiency.

Teknik Pembenihan Ikan Kerapu Cantang (Ephinephelus sp.) di Balai Budidaya Air Payau, Situbondo, Jawa Timur

Grouper fish (Epinephelus sp.) is one of the popular marine fish species in the market in Indonesia and abroad in Southeast Asia, this fish has high economic value, good taste. Currently, the development of grouper aquaculture has been growing, so the seeds must be available continuously to meet the demand for seeds, therefore the foundation of interspecies crosses between groupers that have a high heterosis effect in growth traits, disease resistance and environmental resistance. This research activity was carried out at the Brackish Water Aquaculture Center located in Situbondo, East Java and was carried out from June 19, 2023 to August 19, 2023. The working method used in the Field Work Practice is descriptive method with data collection including primary and secondary. The technique of grouper hatchery conducted at the Brackish Water Aquaculture Fisheries Center stages include tub preparation, broodstock rearing, hybridization, hatching and egg stocking, larval development, feeding, water quality management, growth sampling and grading, pests and diseases, and harvesting and marketing. The results of the observed parameters are HR 73.25%, SR 15.98%, FR 74.16%. Water quality management carried out in grouper hatcheries is water reduction and water changes according to larval age, siphon once a week and water quality tests.

Effects of the dietary supplementation of manganese on growth, skeletal development, oxidative stress and bone metabolism related genes in gilthead seabream (Sparus aurata) larvae

Manganese (Mn) is an essential element necessary for normal growth, antioxidant defense and maintaining bone health. Knowledge about the effects of dietary Mn levels in gilthead seabream (Sparus aurata) larvae performance is still scarce. To determine the effects of dietary Mn levels on growth, survival, skeletal development and expression of antioxidant and bone metabolism related genes, gilthead seabream larvae were fed six experimental microdiets supplemented with manganese sulfate monohydrate (MnSO4.H2O) (contained 6.3, 39, 75, 79, 200 and 270 mg Mn/kg diet). After 26 days of feeding, dietary Mn levels had no effect on larval survival. However, larvae fed the non-supplemented diet (6.3 mg Mn/kg) showed signs of Mn deficiency, including growth reduction, low whole body Mn content, lower expression of mnsod, runx2, oc, and reduced bone mineralization. The poor vertebral body mineralization and low bone relative gene expression in seabream larvae was related to a marked increase in the number of fish with total skeletal anomalies and anomalies of the caudal vertebrae region. On the contrary, larvae fed with Mn supplemented diet up to 270 mg Mn/kg showed increased growth and whole body Mn content, up-regulated mnsod, runx2, alp, opn and oc expression, as well as increased bone mineralization, and reduced number of fish with skeletal anomalies. Therefore, the findings suggest that adequate dietary Mn supplementation positively influences the growth, skeletal development, and antioxidant defense of gilthead seabream larvae, preventing the manifestation of Mn deficiency-related issues.

Regulatory role of ETS1 transcription factor in hemocytes proliferation in Anadara granosa

The ETS1 transcription factor is crucial in the process of biological development. In vertebrate, ETS1 plays a pivotal role in promoting endothelial cell proliferation and angiogenesis. However, the identity and function of ETS1 remains unclear in mollusks. In this study, an ETS1 homolog (named as AgETS1) was identified in blood clam Anadara granosa (synonym: Tegillarca granosa). The full length of the AgETS1 transcription factor is 1569 bp, consisting of 539 amino acids, including the Sterile Alpha Motif (SAM) domain, which can recognize and bind to sequence of GGAA. Tissue expression analysis of A. granosa showed that AgETS1 exhibits the highest expression level in the gill tissues (51.5-fold of that in hemocyte, p < 0.05). AgETS1 mRNA transcripts were predominantly expressed during larval development, from zygote to trochophore stage. Moreover, the expression levels of AgETS1 in blood clams with high hemoglobin concentration (hemocyte count >1.75 × 108 cells/mL) were significantly higher than that in blood clams with low hemoglobin concentration (hemocyte count <8.5 × 107 cells/mL) (p < 0.05). RNA interfering (RNAi) of AgETS1 induced a corresponding decrease in the number of hemocytes in the hemolymph and a reduction in EdU-marked proliferating cells in the gill tissue. These results indicated that the ETS1 actively regulated the proliferation of hemocytes in A. granosa.

Gut microbial changes in a specialist blister beetle larvae and their nutritional metabolic characteristics.

Insect gut microbiota and their metabolites play a significant role in the shaping of hosts' diets and feeding habits. We conducted 16S rDNA amplicon sequencing on the gut microbiota of specialist blister beetle larvae that feed on locust eggs and artificial food at different instars, to explore the relationship between gut microbiota and the specialized feeding habit of the blister beetle larvae. There is no significant difference in the gut microbial structure among the second to the fourth instar larvae under the same rearing conditions, but the gut microbial structure of the first instar larvae was significantly different from the second to the fourth instar larvae fed by different diets. Bacteria associated with polysaccharide utilization are relatively barren in first instar larvae. Compared to the carbohydrate content between the artificial diet and locust eggs, we speculate that an excessive amount of polysaccharides in the artificial diet may be detrimental to the growth and development of first instar larvae. Gut microbiota of the second to the fourth instar larvae fed with different diets significantly differ in microbial community structure. The different bacteria, especially the metabolism-related intestinal bacteria in locust eggs-fed larvae, may help the hosts adapt to the environment and contribute to the production of active ingredients. The relative abundance of polysaccharide utilization-related bacteria was significantly higher in the artificial diet-fed larvae compared to the locust eggs-fed larvae, which showed the same result when compared to the first instar larvae. Changes in gut microbes of blister beetle larvae and their metabolic inferences could enrich our understanding of the nutritional requirements of the specialist and help optimize the artificial diet of medicinal cantharides.

Effects of different temperatures on the embryonic development of the Lebranche mullet Mugil liza.

We herein investigated the influence of temperature on theembryonic development (from fertilisation to hatching) of Mugil liza larvae. For this purpose, oocytes (>600 μm) and sperm were obtained from breeding stock at the laboratory of marine fish culture (LAPMAR). After fertilisation, 1200 eggs were distributed in 12 cylindrical experimental units of 400 mL under four different temperatures 18, 22, 26 and 30 ºC, all in triplicate. Every 15 min until hatching, about 10 eggs were randomly sampled in each treatment. The eggs were visualized and photographed, and the classification of embryonic stages was performed. Temperature influenced the main events of the embryonic development of M. liza. More accelerated development was observed according to the increase in temperature until the gastrula phase. At temperatures of 22 and 26 °C, embryonic development occurred from fertilisation to hatching of the larvae. In the 18 °C treatment, it was verified that most of the embryos ceased development during the final phase of cleavage and the beginning of blastula formation, while in the 30 °C treatment patterns of embryo malformation were also verified, with erratic divisions of the blastomeres, resulting in irregular cells. Unlike what was observed at a temperature of 18 °C, none of the embryos incubated at 30 °C reached the blastopore closure phase, stopping in the gastrula. The larvae hatched in the treatments at 22 and 26 °C were viable and exhibited intense swimming, with a large amount of reserve material (yolk) and an evident drop of oil.

Impact of Maize Nutrient Composition on the Developmental Defects of Spodoptera frugiperda

Spodoptera frugiperda (J.E. Smith) is a crucial agricultural pest owing to its global impact on &gt;300 crops. Among these, the corn strain of S. frugiperda causes significant damage to maize (Zea mays L.). However, limited research exists on the influence of maize nutrients on the metamorphosis of S. frugiperda and the underlying mechanisms. In this study, the effects of different growth stages of maize leaves, namely, tender leaves (tender) and mature leaves (mature), on various aspects of larval development, including body weight, body length, developmental age, pupation rate, and eclosion rate, were investigated. Additionally, we measured the levels of 20-hydroxyecdysone (20E) and three types of juvenile hormone (JH; i.e., JH I–III) in S. frugiperda larvae fed on tender or mature. The results revealed that larvae fed on Tender exhibited significantly prolonged instar duration, reduced body weight and length, and decreased pupation and eclosion rates, with the emergence of abnormal adults. Analysis of nutritional components in maize leaves revealed significantly higher levels of amino acids, soluble sugars, and sterols in mature than in tender. Hormone analysis in S. frugiperda larvae revealed higher 20E titers in individuals feeding on mature during prepupal and pupal stages. We demonstrated the crucial role of sterols in regulating the level of 20E and pupation rate of S. frugiperda. Based on these findings, we propose that isoleucine, arginine, glutamic acid, sucrose, campesterol, and β-sitosterol serve as key nutrients influencing the development of S. frugiperda. Moreover, β-sitosterol is a significant factor influencing the interaction between maize leaves and S. frugiperda. Our research results provide a reference for the control strategy of S. frugiperda based on breeding insect-resistant varieties by altering host nutrition.

Review: Nutritional Needs of Honeybees and Legislation on Apiculture By-Products in Animal Nutrition.

Honeybees are some of the smallest farmed animals, and apiculture by-products, e.g., honey, beeswax, propolis, royal jelly, and pollen contribute to animal nutrition. For the effective production of these by-products, the optimal development and nutrient supply of the honeybee is required. Beginning with the development of the mouth and anal pores on the second day of embryonic development, the digestive tract differentiates into the mouth and fore-, mid-, and hindgut during the pupal stage. The various glands within the oral cavity are particularly important, secreting enzymes and substances that are crucial for digestion and hive nutrition, e.g., invertase and royal jelly. Honeybees rely on a specialized caste system, with worker bees collecting nectar, pollen, water, and resin for the nutrition of the entire hive. Macronutrients, including proteins, carbohydrates, and lipids, obtained primarily from pollen and nectar, are essential for the growth and development of larvae and the overall health of the colony. Inadequate nutrient intake can lead to detrimental effects on larval development, prompting cannibalism within the hive. Apiculture by-products possess unique nutritional and therapeutic properties, leading to a growing interest in the use of honey, beeswax, propolis, and pollen as a feed additive. In recent years, the use of apicultural by-products in animal nutrition has been primarily limited to in vivo studies, which have demonstrated various positive impacts on the performance of farm animals. Honey, beeswax, propolis, royal jelly, and pollen are listed feed stuffs according to Regulation (EC) No. 68/2013. However, for animal nutrition there is not any specific legal definition for these products and no legal requirements regarding their ingredients as given for honey or beeswax in European food law.